Rozprawy doktorskie na temat „Nanomaterials - Catalytic Applications”

In der Entwicklung von Technologien für die nachhaltige Erzeugung, Speicherung und Umwandlung von Energie werden Hochleistungskatalysatoren benötigt. Im Rahmen dieser Arbeit werden verschiedene Übergangsmetall-basierte Katalysatoren, namentlich TiO2/Kohlenstoff-Komposite, anorganisch-organische Hybridsysteme auf Basis von NiFe Phosphonaten sowie Ni Phosphide, synthetisiert, charakterisiert und hinsichtlich ihrer photo- und elektrokatalytischen Eigenschaften untersucht. Es wird gezeigt, dass die Grenzflächeneigenschaften der TiO2/C-Komposite signifikant durch die Gestaltung des Heizvorgangs während der Synthese beeinflusst werden. Insbesondere der Einsatz von Mikrowellenstrahlung vermag die Synthese von Kohlenstoff-basierten Materialien positiv zu beeinflussen. Schnelles Erwärmen führt zu stärkeren Wechselwirkungen zwischen Nanopartikeln und Kohlenstoff, einheitlicheren Beschichtungen und kleineren Partikeln mit schmaleren Partikelgrößenverteilungen, wodurch die photokatalytische Aktivität verbessert wird. Schichtartige, hybride NiFe-Phenylphosphonat-Materialien werden ausgehend in Benzylalkohol dargestellt und ihre Aktivität in der OER im basischen Milieu untersucht. Die Hybridpartikel werden in-situ in NiFe-Hydroxid Nanoschichten umgewandelt. Röntgenspektroskopische Untersuchungen deuten auf eine induzierte, teilweise verzerrte Koordinationsumgebung der Metallzentren im Katalysator hin. Die Kombination der synergistischen Effekte zwischen Ni und Fe mit den strukturellen Eigenschaften des Hybridmaterials ermöglicht einen effizienten Katalysator. Weiterhin werden Nickel-Phosphide durch die thermische Behandlung der Phenyl- oder Methylphosphonate des Nickels, welche Schichtstrukturen aufweisen, in H2(5%)/Ar-Atmosphäre synthetisiert. Ni12P5, Ni12P5-Ni2P und Ni2P Nanopartikel, die mit einer dünnen Schicht aus Kohlenstoffmaterial beschichtet sind, werden erhalten. Ni12P5-Ni2P und Ni2P Nanopartikel katalysieren die Wasserstoffentwicklungsreaktion (HER) im Sauren effektiv.
High-performance catalysts play a key role in the development of technologies for sustainable production, storage, and conversion of energy. In this thesis, transition-metal-based catalysts, including TiO2/carbon composites, hybrid organic-inorganic NiFe phosphonates, and Ni phosphides are synthesized, characterized, and investigated in photocatalytic or electrocatalytic reactions. TiO2 is frequently combined with carbon materials, such as reduced graphene oxide (rGO), to produce composites with improved properties. TiO2 is more efficiently stabilized at the surface of rGO than amorphous carbon. Rapid heating of the reaction mixture results in a stronger coupling between the nanoparticles and carbon, more uniform coatings, and smaller particles with narrower size distributions. The more efficient attachment of the oxide leads to better photocatalytic performance. Layered hybrid NiFe-phenylphosphonate compounds are synthesized in benzyl alcohol, and their oxygen evolution reaction (OER) performance in alkaline medium is investigated. The hybrid particles transformed in situ into NiFe hydroxide nanosheets. X-ray absorption spectroscopy measurements suggest the metal sites in the active catalyst inherited partly the distorted coordination. The combination of the synergistic effect between Ni and Fe with the structural properties of the hybrid results in an efficient catalyst that generates a current density of 10 mA cm-2 at an overpotential of 240 mV. Moreover, nickel phosphides are synthesized through thermal treatment under H2(5%)/Ar of layered nickel phenyl- or methylphosphonates that act as single-source precursors. Ni12P5, Ni12P5-Ni2P and Ni2P nanoparticles coated with a thin shell of carbonaceous material are produced. Ni12P5-Ni2P and Ni2P NPs efficiently catalyze the hydrogen evolution reaction (HER) in acidic medium. Co2P and CoP NPs are also synthesized following this method.

Nanocatalysis has emerged in the last decades as an interface between homogeneous and heterogeneous catalysis, offering simple solutions to problems that conventional materials have not been able to solve. In fact, nanocatalyst design permits to obtain structures with high superficial area, reactivity and stability, and at the same time presenting good selectivity and facility of separation from reaction mixtures. In this work, we prepared hybrid structures comprising gold, palladium and silver nanoparticles (Au, Pd and Ag NPs), titanate nanosheets (TixO2), graphene oxide (GO), and partially reduced graphene oxide (prGO). We focused on bi- and tri-components hybrids, namely TixO2, M/(pr)GO and M/TixO2/(pr)GO (M = Au, Pd or Ag) and developed facile, versatile and environment-friendly preparation methods with an emphasis on control over physicochemical features such as size, shape and composition. In order to exploit the catalytic applications, we employed the reduction of 4-nitrophenol as a model reaction, followed by visible-light assisted oxidation of p-aminothiophenol (PATP). With these tests, we unraveled metal-support interactions and cooperative effects that render hybrid structures superior to their individual counterparts.
A nanocatálise surgiu nas últimas décadas como uma interface entre catálise homogênea e heterogênea, oferecendo soluções simples a problemas que os materiais convencionais não conseguiram resolver. De fato, o design de nanocatalisadores permite obter estruturas com grande área superficial, reatividade e estabilidade, e ao mesmo tempo apresentando boa seletividade e facilidade de separação de misturas reacionais. Neste trabalho apresentamos a preparação de estruturas híbridas compostas por nanopartículas de ouro, paládio e prata (Au, Pd e Ag NPs), nanofolhas de titanato (TixO2), óxido de grafeno (GO) e óxido de grafeno parcialmente reduzido (prGO). Focamos em híbridos do tipo M/TixO2, M/(pr)GO e M/TixO2/(pr)GO (M = Au, Pd ou Ag) e desenvolvemos métodos de preparação simples, versáteis e ambientalmente amigáveis, com ênfase no controle sobre tamanho, forma e composição. Para explorar as potencialidades catalíticas utilizamos a redução do 4-nitrofenol como reação modelo, e em seguida a oxidação assistida por luz do p-aminotiofenol (PATP). Com esses testes, investigamos interações metal-suporte e efeitos cooperativos que tornam as estruturas hibridas superiores a cada um dos materiais que as compõem.

This thesis consists of a structural investigation of a range of gold and silver nanomaterials and associated core-shell structures, using X-ray absorption spectroscopy (XAS) as the primary tool; other techniques, including UV-Vis spectroscopy and transmission electron microscopy (TEM), were also used, demonstrating the wider applicability of XAS and other methods to nanomaterials. Dilute, gold/silver core@shell colloids with nominal Au@Ag and Au@Ag@Au structures were prepared and then characterised by extended X-ray absorption fine structure (EXAFS) and TEM. Au@Ag and Au@Ag/Au structures, respectively, were assigned to each sample. Combining EXAFS and energy-dispersive X-ray spectroscopy (EDS) results for Au@Ag@Au, the presence of a concentration gradient through the shells, arising from interfacial alloying, is suggested. This extends the conclusions made from TEM alone. The reduction of AgNO3 by Na3C6H5O7 to produce pure Ag and Au@Ag colloids was investigated using Ag K-edge X-ray absorption near-edge structure (XANES). This was found to be a first order process, which is consistent with the unimolecular decomposition proposed in the literature. The seeded reaction had a reduced rate constant which was attributed to the presence of Cl− ions, leftover from HAuCl4, forming AgCl. Similar studies on Au colloids were attempted at the Au L3-edge, but beam induced reduction was found to be the dominant effect. Finally, a suite of metal-oxide supported gold and silver samples were prepared by impregnation and characterised by XAS. Electron donation from the support to the gold was observed. The stability of oxidised gold on the supports increased with metal cation electropositivity, following the trend MgO > TiO2 > Al2O3 > SiO2. Additionally, in the case of MgO, gold hydroxide was formed and found to be stable up to at least 300 °C, before its decomposition to gold metal. The opposite trend was observed for silver, and this was attributed to the formation of metal-surface bonds.

In the present work new methods were developed for preparation of novel nanosized and nanostructured ceramic materials. Ordered mesoporous silica SBA-15 was found to be useful as a hard template for the nanocasting of silicon carbide and allowed the preparation of high temperature stable mesoporous silicon carbide ceramics. Chemical vapor infiltration of SBA-15 with dimethyldichlorosilane at elevated temperatures yields SiC/SBA-15 nanocomposites. The subsequent HF treatment of those composites resulted in silica removal and preparation of mesoporous silicon carbide with surface areas between 410 and 830 m2g-1 and high mesopore volume (up to 0.9 cm3g-1). The pore size (between 3 and 7nm in diameter) and surface area of mesoporous silicon carbide were controlled by adjusting the infiltration conditions (time, atmosphere). The mesoporous silicon carbide prepared via this method showed high structural thermal stability at 1300 oC, exceeding that of the SBA-15 template. However, the ordering on the mesoscopic scale was low. Nevertheless, highly ordered mesoporous silicon carbide materials were obtained via polymer melt infiltration in SBA-15. The low molecular weight polycarbosilane used as a preceramic precursor was converted at 1300 oC to silicon carbide inside the SBA-15, and after subsequent silica removal by HF, a highly ordered mesoporous material was obtained. Ordered mesoporous silicon carbide prepared by the methods reported here, may be an interesting material as a support due to its high temperature stability, chemical inertness, high thermal conductivity and semiconductor properties. In contrast to the nanocasting approach, based on the complete pore filling, also a new in-situ procedure for the preparation of finely dispersed metal and metal oxide particles inside ordered mesoporous silica was developed. A swelling agent (toluene) was used to deliver a hydrophobic platinum precursor into the surfactant micelles before addition of silica source. Such an in-situ method resulted in very high platinum incorporation (80-100%), not achieved for any other in-situ preparation procedures. Additionally, the presence of platinum allowed to decrease the template removal temperatures. Moreover, the method was also extended to other metal or metal oxide/ordered mesoporous silica systems. This may be especially interesting for the preparation of ordered mesoporous materials with low melting points, where typically the structure collapses during the high temperature calcinations process. The in-situ synthesized V2O5/MCM-41 materials were used to prepare VN/MCM-41 composites via nitridation in ammonia at 800oC. This method allowed to prepare highly dispersed, X-ray amorphous vanadium nitride species, with high activity in the propane dehydrogenation. Compared to nitridation of supported vanadium oxide prepared via the ex-situ procedure, in-situ synthesized materials showed similar catalytic activity, in spite of having significantly lower vanadium loading. As an alternative for the preparation of supported nitride materials, a novel preparation procedure of bulk not supported nanocrystalline vanadium nitride with high surface area was presented. Instead of pure oxide powder (which was typically used in the preparation of high surface area vanadium nitride catalysts), a macroporous amine intercalated V2O5 was used as the starting material. The obtained nitride consisted of small crystallites and had a surface area up to 198 m2g-1. Moreover, this foam-derived VN showed significantly improved activity as a catalyst in propane dehydrogenation. This novel preparation method could also be extended to other systems such as ternary VMoxNy nitrides.

In the present work new methods were developed for preparation of novel nanosized and nanostructured ceramic materials. Ordered mesoporous silica SBA-15 was found to be useful as a hard template for the nanocasting of silicon carbide and allowed the preparation of high temperature stable mesoporous silicon carbide ceramics. Chemical vapor infiltration of SBA-15 with dimethyldichlorosilane at elevated temperatures yields SiC/SBA-15 nanocomposites. The subsequent HF treatment of those composites resulted in silica removal and preparation of mesoporous silicon carbide with surface areas between 410 and 830 m2g-1 and high mesopore volume (up to 0.9 cm3g-1). The pore size (between 3 and 7nm in diameter) and surface area of mesoporous silicon carbide were controlled by adjusting the infiltration conditions (time, atmosphere). The mesoporous silicon carbide prepared via this method showed high structural thermal stability at 1300 oC, exceeding that of the SBA-15 template. However, the ordering on the mesoscopic scale was low. Nevertheless, highly ordered mesoporous silicon carbide materials were obtained via polymer melt infiltration in SBA-15. The low molecular weight polycarbosilane used as a preceramic precursor was converted at 1300 oC to silicon carbide inside the SBA-15, and after subsequent silica removal by HF, a highly ordered mesoporous material was obtained. Ordered mesoporous silicon carbide prepared by the methods reported here, may be an interesting material as a support due to its high temperature stability, chemical inertness, high thermal conductivity and semiconductor properties. In contrast to the nanocasting approach, based on the complete pore filling, also a new in-situ procedure for the preparation of finely dispersed metal and metal oxide particles inside ordered mesoporous silica was developed. A swelling agent (toluene) was used to deliver a hydrophobic platinum precursor into the surfactant micelles before addition of silica source. Such an in-situ method resulted in very high platinum incorporation (80-100%), not achieved for any other in-situ preparation procedures. Additionally, the presence of platinum allowed to decrease the template removal temperatures. Moreover, the method was also extended to other metal or metal oxide/ordered mesoporous silica systems. This may be especially interesting for the preparation of ordered mesoporous materials with low melting points, where typically the structure collapses during the high temperature calcinations process. The in-situ synthesized V2O5/MCM-41 materials were used to prepare VN/MCM-41 composites via nitridation in ammonia at 800oC. This method allowed to prepare highly dispersed, X-ray amorphous vanadium nitride species, with high activity in the propane dehydrogenation. Compared to nitridation of supported vanadium oxide prepared via the ex-situ procedure, in-situ synthesized materials showed similar catalytic activity, in spite of having significantly lower vanadium loading. As an alternative for the preparation of supported nitride materials, a novel preparation procedure of bulk not supported nanocrystalline vanadium nitride with high surface area was presented. Instead of pure oxide powder (which was typically used in the preparation of high surface area vanadium nitride catalysts), a macroporous amine intercalated V2O5 was used as the starting material. The obtained nitride consisted of small crystallites and had a surface area up to 198 m2g-1. Moreover, this foam-derived VN showed significantly improved activity as a catalyst in propane dehydrogenation. This novel preparation method could also be extended to other systems such as ternary VMoxNy nitrides.

Au début du XXIème siècle, la Microscopie Electronique à Transmission en mode Environnemental (ETEM) est devenue l’une des techniques les plus fiables de caractérisation de nanomatériaux dans des conditions simulant leur vie réelle. L’ETEM est maintenant en mesure de suivre l’évolution dynamique des nanomatériaux dans des conditions variables comme l’exposition à des températures élevées, l’observation en milieux liquide ou gazeux à diverses pressions. Parmi différents domaines de recherche et développement concernés, la catalyse peut bénéficier de manière significative des avancées permises par la microscopie électronique environnementale. Cette thèse, dédiée au développement de l’ETEM au laboratoire MATEIS, a commencé avec l’étude du système catalytique Pd-alumine. Les nanoparticules de Pd déposées sur alpha -Al2O3 et delta-Al2O3 sont très utilisées en physicochimie avec un impact environnemental important : en particulier dans le domaine de l’hydrogénation sélective, pour la synthèse de polymères ou l’hydrogénation de CO2 pour la production de méthane. Nous avons tout d’abord effectué des analyses 2D aux différentes étapes du processus de synthèse du catalyseur : imprégnation du précurseur, séchage et chauffage pour la calcination dans l’air à la pression atmosphérique. La motivation de cette approche a été de comparer des analyses post mortem avec des traitements en ETEM où l’évolution des nanoparticules peut être mesurée in situ et pas seulement « avant » et « après ». De manière générale, les études faites en ETEM en 2D donnent un aperçu limité sur la morphologie des objets et la distribution spatiale des nanoparticules supportées. Nous avons développé une nouvelle approche d’acquisition rapide pour collecter dans des temps très courts des séries d’images sous différents angles de vue pour la tomographie électronique, la rapidité de cette acquisition étant un prérequis pour appréhender correctement la morphologie d’un nano-système au cours de son évolution dynamique in situ. La technique a ensuite été utilisée pour l’étude de plusieurs systèmes où une acquisition tridimensionnelle rapide est indispensable, notamment sur un sujet concernant un enjeu sociétal important, la dépollution des moteurs diesel : l’oxydation de la suie a été étudiée in situ sur des supports à base de zircone entre 400 et 600°C et une pression de 2 mbar d’oxygène à différents degrés de combustion, ce qui a permis d’extraire des données cinétiques telle que l’énergie d’activation du processus. La tomographie électronique rapide a été également appliquée à des matériaux sensibles au faisceau électronique, comme des nanocomposites polymères et des objets biologiques, montrant le large spectre d’applications possibles pour cette technique, qui constitue un pas important vers la caractérisation operando 3D de nanomatériaux en temps réel
In the beginning of the XXIst century, Environmental Transmission Electron Microscopy has become one of the reliable characterization techniques of nanomaterials in conditions mimicking their real life. ETEM is now able to follow the dynamic evolution of nanomaterials under various conditions like high temperature, liquid or various gas pressures. Among various fields of research, catalysis can benefit significantly from Environmental Microscopy. This contribution starts with the study of the Palladium-Alumina catalytic system. Pd nanoparticles supported by α-Al2O3 and δ-Al2O3 are of an important physicochemical and environmental interest, particularly in the field of selective hydrogenation in petrochemistry, for the synthesis of polymers or CO2 hydrogenation for methane production. We first performed 2D analyses at different steps of the synthesis process, then the same synthesis steps were performed under in situ conditions. The motivation of this approach was to compare post mortem treatments with ETEM observations. In general, 2D data provide limited insights on, for example, the morphology and position of supported nanoparticles. We have then developed a new fast acquisition approach to collect tomographic tilt series in very short times, enabling to reconstruct nano-systems in 3D during their dynamical evolution. Taking advantage of this approach, we have determined the activation energy for soot combustion on YSZ oxidation catalysts for diesel motors from volumetric data extracted from in situ experiments. Fast electron tomography was also applied to electron beam sensitive materials, like polymer nanocomposites and biological materials, showing the wide spectrum of possible applications for rapid 3D characterization of nanomaterials

This thesis is an exploratory study of nanomaterials stabilized Pickering emulsions and their applications. The study illustrates some novel emulsion behaviour through dynamic observation and develops a mechanically switchable emulsion based on the microstructure design of nanomaterials. The droplets of emulsion are demonstrated as an effective microreactor for chemical reactions that happen at the oil-water interface, showing the potential application of Pickering emulsion in catalysis.

Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 19 Dec 2004.
Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2397" Seong Huh. US Department of Energy 12/19/2004. Report is also available in paper and microfiche from NTIS.

The birth of nanotechnology era has revolutionized materials science, catalysis and field of optoelectronics. Novel and unique phenomena emerge when material dimensions are reduced to ultra-small size regime and enter nanometre (2-100 nm) realm. Such novel materials are expected to replace bulk materials, offering lower cost of manufacturing and enabling progress in many areas such as solar cell, drug delivery, quantum communication and computing, catalysis and sensing applications. With the progress in nanomaterial synthesis and fabrication, the need for the state-of-art characterization techniques became obvious; such techniques help to establish a complete understanding of the nature and interactions of nanosized materials. In this thesis, the first part focuses on the synthesis of gold and ruthenium clusters, namely Au8, Au9, Au101, Ru3, Ru4 and AuRu3, using the well-established synthetic protocols in the literature. Apart from the standard lab-based characterization techniques such as nuclear magnetic resonance (NMR), UV-visible spectroscopy (UV-vis) and Fourier Transform Infra-red (FTIR), a less explored but useful technique far infra-red (far IR) spectroscopy, available at the Australian Synchrotron (AS), was employed to investigate the vibrational modes in these clusters. Peaks in the experimental far IR spectra were assigned unambiguously to specific vibrations by comparing with the ones generated via DFT calculations with the help of collaborators, group of Professor Gregory Metha, University of Adelaide. For the Au9 cluster, three significant gold core vibrations are observed at 157, 177 and 197 cm-1 in the experimental spectrum. In the case of the Ru3 cluster, only a single ruthenium core vibration is identified within the spectrum, at 150 cm-1 with the calculated force constant, k = 0.33 mdyne/Å. The Ru4 cluster exhibits two metal core vibrations at 153 and 170 cm-1 with force constants of 0.35 and 0.53 mdyne/Å, respectively. Substitution with a gold atom yielding a mixed metal AuRu3 cluster shifts the core transitions toward higher wavenumbers at 177 and 299 cm-1 with an increase in force constants to 0.37 and 1.65 mdyne/Å, respectively. This is attributed to the change in chemical composition and geometry of the metal cluster core. A combination of the DFT calculations and high quality synchrotron-based experimental measurements allowed the full assignment of the key transitions in these clusters. Next, these clusters were fabricated into heterogeneous catalysts by depositing on different metal oxide nanopowders. Synchrotron X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) studies were performed at the Australian Synchrotron and the Photon Factory synchrotron in Japan to investigate the electronic structure of Au8, Au9 and Au101 on TiO2 catalysts. The XPS analysis reveals that “as-deposited” Au8 and Au9 retain some un-aggregated clusters while Au101 show bulk-like gold. These findings are in line with TEM observations, where the aggregates (large particles, > 2 nm) of Au8, Au9 and Au101 are hardly seen under HRTEM. UV-visible diffuse reflectance spectroscopy (UV-vis DRS) studies show the absence of localised surface plasmon resonance (LSPR) peaks in these “as-deposited” clusters, suggesting they are below 2 nm in size. Importantly, the XAS spectrum of “as-deposited” Au9 clusters estimates that 60% of pure, un-aggregated Au9 clusters and 40% of bulk gold in the sample. Upon calcination under O2 and combined O2 and H2 (O2-H2), Au8, Au9 and Au101 clusters form larger nanoparticles (> 2 nm) with the appearance of LSPE peak in UV-vis DR spectra. In addition, majority of the phosphine ligands (that stabilise the gold core) dislodge and form phosphine oxide-like species by interacting with oxygen on the TiO2 surface. The third part focused on testing the catalytic performance of the supported Au8, Au9, Au101, Ru3, Ru4 and AuRu3 clusters on different TiO2, SiO2, ZnO and ZrO2 in benzyl alcohol oxidation. Au101-based catalysts display the highest catalytic activity with a turn-over frequency (TOF) up to 0.69 s-1. The high catalytic activity is attributed to the formation of large Au nanoparticles (> 2 nm) that coincides with the partial removal of capping ligands. Au8 and Au9 clusters which contain NO3- counter anions are found to be inactive in benzyl alcohol oxidation. Further work shows that the presence of NO3- species diminishes the catalytic activity. Monometallic ruthenium clusters, Ru3 and Ru4, are found to be inactive yet the bimetallic AuRu3 clusters are active in benzyl alcohol oxidation, suggesting the synergistic effect between ruthenium and gold metal. Investigation of catalytic testing parameters reveals that tuning selectivity of the product is possible through manipulating the reaction temperature. Finally, a joint experiment with Prof. Wojtek Wlodarski’s group at RMIT, Melbourne was undertaken to test the sensing ability of Au9 clusters for hydrogen detection. Au9 clusters were deposited onto radio-frequency (RF) sputtered WO3 films at two different concentrations; 0.01(S1) and 0.1(S2) mg/mL. It was found that the optimal temperatures for sensor S1 and S2 were 300 °C and 350 °C, respectively. The sensor with lower Au9 concentration (S1) displays a faster response and recovery time, and a higher sensitivity toward H2. HRTEM studies reveal that the sensor S1 contain a significant population of sub-5 nm Au nanoparticles which might be responsible for a faster rate of H2 adsorption and dissociation. The key finding in this study suggest that the addition of catalytic layer such as ultra-small Au9 clusters results in improved sensitivity and dynamic performance (response and recovery time) of H2 sensors. In summary, this thesis demonstrated that cluster-based nanomaterials have wide range of applications spanning from catalysis to sensing. Further improvements in material synthesis and use of multiple complimentary characterization techniques allowed better understanding of the nature of the key active species (metal nanoparticles) assisting design of catalysts and sensors with enhanced performance.

This thesis describes the synthesis and anion recognition properties of a variety of interlocked host receptors and the application of metal nanoparticles in the areas of catalysis and sensing. Chapter One introduces the field of anion supramolecular chemistry, with particular emphasis on areas relevant to the research discussed in later chapters. Following this, the synthesis and applications of metal nanoparticles are outlined. Chapter Two details the synthesis of a range of halo-triazolium based rotaxanes and explores the effects of altering both the halogen bond donor atom and degree of preorganisation on the anion recognition properties of the interlocked host system. A halogen bond containing catenane is also prepared and its anion binding properties investigated. Chapter Three initially reports the anion-templated synthesis of a series of neutral pyridine N-oxide axle containing rotaxanes before their ability to recognise anions in aqueous solvent mixtures is studied. Attempts to enhance anion binding through the incorporation of a positive charge into the macrocyclic component of the rotaxane structure are also explored. Chapter Four outlines the preparation of β-cyclodextrin functionalised metal nanoparticles and investigations of their catalytic and sensing properties. Chapter Five describes in detail the synthetic and analytical procedures discussed in chapters two to four. Chapter Six summarises the conclusions of this thesis.

Chemical methods are generally used for the synthesis of active nanoparticles (metals, semi-metals, metal oxides, and etc) supported on high surface area materials. Chemical methods involve using strong solvents, harmful gases (H2 & CO), and high temperature techniques such as high boiling solvents, calcination and pyrolysis. The main drawbacks of using this approach, is the prevalence of chemical agents on nanomaterials which tends to negate its applications. Alternatively, photochemical and photothermal methods are widely being considered for the synthesis and design of nanomaterials. For these studies, the active nanomaterials incorporated within high surface area materials were prepared by the laser vaporization-controlled condensation (LVCC) technique or by the laser irradiation in solution (LIS) technique. The LVCC technique involves the irradiation of a solid target at the focal point of a laser beam (532 nm, 30 Hz) by the Nd: YAG laser inside a chamber that is sandwiched between two steel plates in the presence of high purity He. Whereas, the LIS technique involves the laser irradiation of chemical precursors in aqueous solvents using an unfocused beam. The LVCC technique was used for the preparation of carbonaceous and N-doped carbonaceous TiO2 support materials from MIL-125(Ti) and NH2-MIL-125(Ti) metal organic frameworks, Ge and GeO2 nanostructures, GeOx/PRGO nanocomposite, and the Fe3O4/PRGO nanocomposite. On the other hand, Pd supported on MIL-125(Ti) and NH2-MIL-125(Ti) nanocatalysts, GeO2/RGO, and the poly(ethylene glycol methacrylate-co-bisacrylamide) hydrogels were all prepared by the LIS technique.

ZnO based materials, such as Zn1-xTMxO (TM = Mn, Co, Cu) nanopowders, were synthesised by a Sol gel route to investigate their properties in three fields: catalysis, optics and magnetism. These materials were characterised by complementary techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and UV-Vis Spectroscopy. The fine structure and electronic properties of these nanomaterials were studied by X-ray Absorption Spectroscopy (XAS) and Electron Paramagnetic Resonance (EPR). These techniques give site, element and chemical specific measurements which allow a better understanding of the interplay and role of each element in the functionality of the system. The catalytic performance of undoped and Cu-doped ZnO nanosystems were tested with respect to the Methanol Steam Reforming (MSR) reaction. Contrary to what is generally accepted in literature, the results obtained in this study demonstrate that ZnO also plays a prominent role in this catalytic process. The structure–activity relationship of ZnO and copper-doped ZnO catalysts described in this work give an insight into the effective function of each component which is vital to enable the rational design of improved catalysts. The luminescence properties of the doped Zn1-xTMxO nanopowders were investigated with X-ray Excited Optical Luminescence (XEOL) techniques: these experiments provided a better understanding of the relationship between the electronic structure of the systems and their properties. Results showed how it is possible to manipulate the luminescence of ZnO grown by Sol gel by modifying synthesis conditions – i.e. the annealing temperature and the nature and concentration of the transition metal ion. Finally, preliminary results were presented on the materials' magnetic properties, obtained by SQUID (Superconducting Quantum Interference Devices) magnetometry, where the coexistence of different contributions has been detected. Even though further characterisation is still needed, this study is a step towards the determination of the nature of magnetic interactions in such systems, of which there has been considerable debate in the scientific community.
Materiali a base di ZnO, in particolare nano-polveri di Zn1-xTMxO (TM = Mn, Co, Cu), sono stati sintetizzati via Sol gel per studiarne le proprietà in tre diversi campi applicativi quali la catalisi, l’ottica ed il magnetismo. Tali materiali sono stati caratterizzati utilizzando diverse tecniche, complementari tra loro, quali X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) e UV-Vis Spectroscopy. X-ray Absorption Spectroscopy (XAS) ed Electron Paramagnetic Resonance (EPR) vengono invece impiegate per studiare le proprietà elettroniche e di struttura fine delle nano-polveri. Tali caratterizzazioni si sono dimostrate fondamentali per la comprensione delle proprietà del sistema ed, in particolare, per cercare di identificare le interazioni sussistenti tra struttura, composizione, morfologia dei materiali e la loro capacità di espletare una determinata funzionalità. Nano-polveri di ZnO tal quali e drogate con ioni rame vengono testate come catalizzatori nella reazione di Steam Reforming del metanolo. I risultati ottenuti in questo studio dimostrano il ruolo attivo dell’ossido di zinco nel processo catalitico, contrariamente a quanto solitamente accettato in letteratura. La relazione sussistente tra struttura-attività nei catalizzatori a base di ZnO permette di ottenere informazioni circa l’effettiva funzione di ogni componente, aspetto di estrema importanza per la progettazione razionale di catalizzatori con elevate performance. Le proprietà di luminescenza dei sistemi drogati Zn1-xTMxO vengono studiate mediante spettroscopia X-ray Excited Optical Luminescence (XEOL); tali esperimenti forniscono una migliore comprensione del rapporto che sussiste tra la struttura elettronica dei sistemi in esame e le loro proprietà di emissione. I risultati mostrano come sia possibile modulare la luminescenza di ZnO prodotto via Sol gel modificando le condizioni di sintesi – i.e. temperatura di trattamento, natura e concentrazione del metallo di transizione utilizzato come drogante. Infine, risultati preliminari sulle proprietà magnetiche dei materiali ottenuti mediante SQUID magnetometer (Superconducting Quantum Interference Devices) hanno rivelato la coesistenza di diversi contributi magnetici. Nonostante ulteriori caratterizzazioni siano sicuramente necessarie, questo studio si è rivelato un passo avanti verso una comprensione della natura delle interazioni magnetiche in tali sistemi, da tempo causa di vivace dibattito nella comunità scientifica.

Nanomaterials have attracted great interest due to the unique physical properties and great potential in the applications of nanoscale devices. Two dimensional atomic crystals, which are atomic thickness, especially graphene, have triggered the gold rush recently due to the fascinating high mobility at room temperature for future electronics. The crystal structure of nanomaterials will have great influence on their physical properties. Thus, this thesis is focused on developing the methods to control the crystal structure of nanomaterials, namely quantum dots as semiconductor, boron nitride (BN) as insulator, graphene as semimetal, with low cost for their applications in photonics, structural support and electronics. In this thesis, firstly, Mn doped ZnSe quantum dots have been synthesized using colloidal synthesis. The shape control of Mn doped ZnSe quantum dots has been achieved from branched to spherical by switching the injection temperature from kinetics to thermodynamics region. Injection rates have been found to have effect on controlling the crystal phase from zinc blende to wurtzite. The structural-property relationship has been investigated. It is found that the spherical wurtzite Mn doped ZnSe quantum dots have the highest quantum yield comparing with other shape or crystal phase of the dots. Then, the Mn doped ZnSe quantum dots were deposited onto the BN sheets, which were micron-sized and fabricated by chemical exfoliation, for high resolution imaging. It is the first demonstration of utilizing ultrathin carbon free 2D atomic crystal as support for high resolution imaging. Phase contrast images reveal moiré interference patterns between nanocrystals and BN substrate that are used to determine the relative orientation of the nanocrystals with respect to the BN sheets and interference lattice planes using a newly developed equation method. Double diffraction is observed and has been analyzed using a vector method. As only a few microns sized 2D atomic crystal, like BN, can be fabricated by the chemical exfoliation. Chemical vapour deposition (CVD) is as used as an alternative to fabricate large area graphene. The mechanism and growth dynamics of graphene domains have been investigated using Cu catalyzed atmospheric pressure CVD. Rectangular few layer graphene domains were synthesized for the first time. It only grows on the Cu grains with (111) orientation due to the interplay between atomic structure of Cu lattice and graphene domains. Hexagonal graphene domains can form on nearly all non-(111) Cu surfaces. The few layer hexagonal single crystal graphene domains were aligned in their crystallographic orientation over millimetre scale. In order to improve the alignment and reduce the layer of graphene domains, a novel method is invented to perform the CVD reaction above the melting point of copper (1090 ºC) and using molybdenum or tungsten to prevent the balling of the copper from dewetting. By controlling the amount of hydrogen during the growth, individual single crystal domains of monolayer over 200 µm are produced determined by electron diffraction mapping. Raman mapping shows the monolayer nature of graphene grown by this method. This graphene exhibits a linear dispersion relationship and no sign of doping. The large scale alignment of monolayer hexagonal graphene domains with epitaxial relationship on Cu is the key to get wafer-sized single crystal monolayer graphene films. This paves the way for industry scale production of 2D single crystal graphene.

Nanotechnology has enable us to develop various novel and advanced materials with unique optical, catalytic, magnetic, electrical and, structural properties for various exciting applications. With the progress of nanoscience and technology, emphasis of the materials are changed from simple nanomaterials to the multi-functional nanomaterials (MFNMs) because of their improved as well as multiple activities. In general, the MFNMs are made with the combination of different components in the same structure, which in turn not only show the additive properties of individual components but also new properties because of the synergistic effect. Multifunctionality in nanomaterials can be achieved in two ways, either by changing the morphology (anisotropic, hollow), or the composition (doped, QDs, heterostructures, core/shell, and yolk/shell). Over the years, continuously growing research interest on this area is mainly because of unique advantages in various applications such as catalysis, sensors, environmental remediation, photovoltaics, energy storage, biomedical, and so on. In recent years, the sustainable routes of nanomaterials are preferred over the conventional chemical routes, which is also applicable for the MFNMs. In view of the importance of MFNMs, the overall aim of this thesis is to develop novel MFNMs via green synthesis route with improved properties for sensing and catalytic applications. In this study following materials were developed: the hollow and doped nanostructures (TiO2, -Fe2O3) synthesized using natural fibers templates. The metallic (Au, Ag, Pd), alloy (Au-Pd), and metal oxides/hydroxide (-Fe2O3, β-FeOOH) NPs were synthesized using the renewable resources (green tea extract and glucose) in aqueous medium. The carbon dots (C-dots) and graphitic carbon were synthesized from tender coconut water and glucose under hydrothermal condition, respectively. The Ag NPs were deposited on semiconductor (AgBr, TiO2) and polymer (PVP) materials by photo-mediated and dissolution approach for the development of plasmonic catalyst, respectively. The C-dots were used for fluorometric thiamine sensor with ultra-low level detection (280 nM) and bio-imaging of fungus cells. β-FeOOH nanorods were used for sulfide ions and thiamine detection with ultra-low level detection limits of 2.19 μM and 44 nM, respectively. The Ag deposited PVP structures showed enhanced SERS activity for the sensing and detection of very low level (nM) organic molecules. Metal NPs (Au, Ag, Pd) decorated -Fe2O3 magnetic hollow tubes showed excellent recyclable catalytic reduction of 4-nitrophenol to 4-aminophenol. Carbon-doped high surface area TiO2 multi-tubes showed visible light induced photo-reduction activity for Cr(VI) reduction to Cr(III). Graphitic carbon coated Au-Pd alloy showed stable, durable, and enhanced electro-catalytic activity for ethanol oxidation. The Au/AgBr–Ag and TiO2/Ag core/shell heterostructures were also showed very good visible-light driven photocatalytic and photo-electrochemical activity. The present research work addresses a new perspective for green synthesis of distinct novel MFNMs and provide valuable insight into the role of the multi-functional properties to stimulate the outstanding sensing and catalytic applications.

Submitted in fulfillment of the requirements of the Degree of Doctor of Technology: Chemistry,Durban University of Technology, 2014.
Aromatic heterocycles are highly important structural units found in a large number of biologically active natural compounds, pharmaceuticals and catalytic compounds. They have a crucial role in organic syntheses, which results in the generation of high value products. Among heterocycles, those containing nitrogen are the most indispensable structural motifs and are widely used against dreaded diseases such as Malaria, TB, HIV/AIDS and Cancer. The inclusion of highly electronegative atoms such as fluorine in these organic molecules render them very reactive towards proteins. Furthermore these molecules exhibit strong interactions with surfaces of quantum range particles of elemental gold. Various approaches for the synthesis of novel gold nanoparticles linked to potent bioactive molecules are documented and their application as drug delivery systems are of immense value to human health. Also many chemical and physical methods are available for the synthesis of gold, silver and palladium nanoparticles however these methods are usually laborious and produce toxic by-products. The green approach is to use plant extracts to synthesise various size and shape nanoparticles which could be used in biological and catalytic systems. A simple one-pot two component and three component reaction using formyl quinoline, 2-aminothiophenol, thiosemicarbazone and trifluoromethylbenzaldehyde as a reactant to synthesise quinoline, pyridine and pyran based bioactive small molecules; these products are a quinoline type bearing a benzothiazole moiety, quinoline thio semicarbazone ligand, fluorine substituted dihydro pyridine, fluorine substituted dihydropyran and fluorine substituted pyridine derivatives. In total, fifteen compounds were synthesized eleven of which were novel; all compounds were characterized by spectroscopic techniques. In vitro anti-bacterial activities of the synthesized compounds were investigated against a representative panel of pathogenic strains. Compounds 6, 7, 8, 11 and 13 exhibited excellent anti-bacterial activity compared with first line drugs. Potent p53–MDM2 interaction inhibitors 2-thio-1,2-dihydroquinoline-3-carbaldehyde thiosemicarbazone and fluorine substituted new pyridine scaffold were successfully identified by structure-based design. An efficient one-pot four component route to the synthesis of trifluorinated pyrrolophenanthroline and fluoroquinoline pyrrolophenanthrolines was designed. In this reaction 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ionic liquid (DMTIL) was used as a reaction medium; no catalyst was required. The structure of the pyrrolophenanthrolines was deduced by IR and NMR analysis. These compounds were studied with Bovine Serum Albumin (BSA) through molecular docking. Hydrophopic, electrostatic and hydrogen bonding interaction played a crucial role in the binding to sub domain of BSA. Interaction studies of DMTIL with BSA by emission, absorption, synchronous fluorescence, circular dichroism (CD) and three dimensional emission (3D) spectroscopic techniques were under taken. The results from emission titration experiments revealed the existence of a strong interaction between BSA and DMTIL ionic liquid. It showed that compounds with lesser number of hydrogen bonds are found to be more active which is attributed to hydrophobic interaction and electrostatic interaction which also played a vital role in DMTIL binding to sub domain IB of BSA. A novel copper-loaded boron nitride nanosheet (Cu/BN) catalyst was prepared and fully characterized. It was used as an efficient and chemoselective catalysts for the synthesis of α-aminophosphonates by the Kabachnik-Fields reaction; twenty one α-aminophosphonates were synthesised. The enhanced catalytic activity and product yield was attributed to the increase of surface acidity. Overall, this methodology offered competitive advantages such as recyclability of the catalyst without further purification or without using additives or cofactors, low catalyst loading, broad substrate applicability and high yields. The application of this new nanocatalyst in organic synthesis will provide a novel pathway for the synthesis of pharmaceutically important compounds. Gold nanoparticle surfaces were modified with self-assembled monolayers of important thiol and disulfide bioactive molecules since considerable interest is due to their potential application as anti-cancer agents. Herein, a carbazole was conjugated to lipoic acid by using an amide coupling catalyst HBTU and DIEA reaction. The structure of the carbazole thio octanic acid (CTN) was identified by IR and NMR. CTN was attached to the gold nanoparticles surface and the capping behaviour was characterized by UV-vis spectroscopy, TEM, DLS and FTIR. The cytotoxicity of CTNAuNPs on A549 cell lines was determined using the MTT assay. The results suggest CTN and CTNAuNPs possess anti-proliferative properties in the cancerous A549 cells. Furthermore a dual thiol ligand was synthesized by using equimolar 4-aminothiophenol (4-ATP) and amino oxadiazole thiol (AXT). This dual ligand was attached to the gold nanoparticles surface (DTAu) and the capping behaviour was characterized by UV-vis spectroscopy, TEM, DLS and FTIR. The cytotoxicity of DTAu on A549 cell lines was determined using the MTT assay. The results suggest dual ligands (4-ATP, AXT) and DTAu possess anti-proliferative properties in the cancerous A549 cells. South African indigenous plants and agroforestry waste were also used in the synthesis of silver, gold and palladium nanoparticles (NPs). Green protocols such as the use of environmentally benign solvents and non-hazardous reagents were an added advantage to physical and chemical means. Furthermore these reactions were rapid and the size and shape of the NPs could be manipulated by choosing the correct medium. The formulation of natural medicinal compounds capped onto NPs was assessed for their anti-cancer activity, in A549 lung cancer line, and catalytic reduction of dyes and nitrobenzene derivatives were studied. These NPs displayed: Significant cytotoxicity to lung cancer cells with minimal effect on normal healthy cells. Outstanding catalytic reduction of pharmaceutical and textile waste effluents such as dyes and nitro aromatic compounds. In addition, palladium nanoparticles containing capped Moringa olifera compounds were used effectively in the Suzuki coupling reaction of iodobenzene and phenylboronic acid. The reaction was rapid and was conducted in an aqueous medium.

碩士
臺灣大學
化學研究所
98
In this work, three-dimensional branched Au nanomaterials were produced at high yield by reacting an aqueous solution of sodium tetrachloroaurate with a tea extract at ambient temperature and pressure. By varying the tea concentrations at a constant amount of sodium tetrachloroaurate, different size and shape of Au nanomaterials were separately prepared. We also synthesized other noble metal nanoparticles such as Ag, Pt and Pd by tea extract. UV-vis absorption, energy dispersive X-ray, X-ray diffraction, and transmission electron microscopy measurements were conducted to characterize the as-prepared Au nanomaterials. The results revealed that the branched Au nanomaterials (50 nm) were formed through the self-assembly of short nanorods (8 nm in width and 12 nm in length). According to the experiments, we find out that the polyphenols in tea extract play an important role of reducing Au3+ ion to Au and stabling the branched Au nanomaterials. By conducting Raman measurements, we found that the branched Au nanomaterials was useful on enhanced signal further than 10 times through surface-enhanced Raman scattering (SERS) effect and Ag nanoshells when adopting 4-mercaptobenzoic acid as report. We believe the Au/Ag nanomaterials have the potential to be good SERS substrates because of the stable signal and clean surface. Through the interaction of polyphenol and Titanium metal (ligand to metal charge transfer), the branched Au nanomaterials were easily deposited on the surface of TiO2 nanomaterials. On the photocatalysis, we have found the photodegradation of the methylene blue is further enhanced in TiO2(P25) about 2.50 folds and TiO2(P210) about 2.05 folds through the deposition of the branched Au nanomaterials. Consequently, we believe the branched Au materials have the potential to be good SERS substrates and photocatalysis enhancers because of the stable signal and clean surface.

In this work the catalytic activity of nanodiamond particles with different dopants and surface terminations and of diamond nanomaterials funtionalized with ruthenium-based photocatalysts was investigated, illustrating materials application in photoredox chemistry and the photo(electro)catalytic reduction of CO2. Regarding the application of diamond nanomaterials in photocatalysis, methods to fabricate and characterize several (un)doped nanoparticles with different surface termination were successfully developed. Various photocatalysts, attached to nanodiamond particles via linker systems, were tested in photoredox catalysis and the photo(electro)catalytic reduction of CO2
In dieser Arbeit wurde die katalytische Aktivität von Nanodiamant-Partikeln mit unterschiedlichen Dotierungen und Oberflächenterminierungen, sowie von Diamant-Nanomaterialien, die mit Photokatalysatoren auf Rutheniumbasis funktionalisiert wurden, untersucht. Die Verwendung der Materialien in Photoredox-Experimenten und in der photo(elektro)katalytischen Reduktion von CO2 konnte verdeutlicht werden. Für die Verwendung von Diamant-Nanomaterialien in der Photokatalyse wurden erfolgreich Methoden zur Herstellung und Charakterisierung zahlreicher (un)dotierter Nanopartikeln mit unterschiedlicher Oberflächenterminierung entwickelt. Verschiedenartige Photokatalysatoren, die mit Hilfe von Linker-Systemen an Nanodiamant-Partikel angebunden wurden, wurden in der Photoredox-Katalyse und der photoelektrokatalytischen Reduktion von CO2 untersucht

Porous materials have exhibited some remarkable performances in wide range of applications such as in the field of catalysis, gas adsorption, water treatment, bio- imaging, drugs delivery and energy applications. This is due to the pore characteristic of these materials. In fact, their properties depend mainly on the pore size, pore morphology and pore size distribution. The knowledge of understanding the effect of chemical nature of porous materials on the heterogeneous catalysis has significantly increased since last decades resulting in the increase in the development of innovative porous nano-hybrid materials. Scientists have integrated inorganic and organic materials to generate new structures with unique properties. A significant enhancement in their properties have been observed compared to their single components. This research work focuses on the design and tailoring of innovative hybrid materials with intrinsic porosity based on well studied single components for catalysis and energy applications. The first example is represented by the impregnation technique of gold nanoclusters (Au NCs) inside the pores of mesoporous silica nanoparticles (MSNs). The performance of Au NCs/ MSN as catalyst was evaluated by the epoxidation reaction of styrene. It shows a remarkable catalytic activity, high selectivity towards styrene epoxide (74%) and high conversion of styrene (88%). We have also investigated the self-assembly of polyoxomolybdates (P2Mo5O23) and cyclodextrins (CDs) as molecular building blocks (MBBs) through the bridging effect of counter cations (Na+, K+, and Cs+). This assembly has resulted in the formation of seven different crystals to give seven crystal structures of POM-CD MOFs. These novel porous hybrid frameworks with intrinsic porosity and tunable porosity have been well studied and characterized using different techniques. Interestingly, one of these structures (K-PMo-γ-CD) was obtained in good yield (70 % based on γ-CD), and was therefore selected to further study the catalytic performance of this type of the hybrid organic-inorganic structures (POM-CD MOFs). The ketalization process of cyclohexanone with glycol using K-PMo-γ-CD as catalysts, have been chosed as module reaction for this study. Our results showed that the material give the best catalytic performance, which reached its maximum conversion of 99.94 %, at 100oC. Finally, the scope of our research have been extended by combining another porous macrocycle, a trianglamine (TA), with the metal cluster complex system (polyoxometalate). This hybrid framework (POM-TA) have been well designed and synthesized based on molecular recognition. A detailed characterization shows that the POM-TA material has high surface area that suggests that it can be suitable as catalyst for some industrial processes. Our research on such organic-inorganic hybrid frameworks represents a promising enrichment in the field of heterogeneous catalysis. This is largely due to the possibility of combining different molecular building blocks to form a hybrid framework with improved properties such as intrinsic porosity, large surface area, and tunable structural properties.

碩士
國立臺灣大學
化學研究所
103
A large-area two-dimensional mesostructure with well-ordered mesochannels, especially for supported mesoporous silica thin films (MSTFs) with vertical mesochannels, have drawn lots of attention in potential applications. However, due to dissimilarity of two interfaces, micelle-templating method usually leads to parallel aligned channels on substrates. Herein we introduce an oil agent into synthetic solution for effectively tuning interfacial interaction between the substrate and solution. As a result, the oil agent here serves as two key roles: (i) one is to tune the orientation of mesochannels perpendicular to the substrate. (ii) The other is to controll the mesochannel sizes in the range of 4-6 nm. Thus, a series of pore-size controllable silica thin films can be obtained in the size of 1

碩士
大同大學
材料工程學系(所)
101
Electric catalysts are easily poisoned by CO adsorption in oxidation of methanol and formic acid that will lead to decrease the performances of catalysts. In this study, the metal oxides are introduced and coated on the MWCNTs to prevent CO poison the electro catalysts, and to improve catalyst activity and stability. Hybrid Oxides/ MWCNTs are synthesized by two different methods: chemical reduction method and impregnation method. Noble metals (Platinum, Pt or Palladium, Pd) are synthesized by polyol method to deposit on the MWCNTs or Oxide/MWCNTs. In Pt-series electrocatalysts, the catalytic effect by adding different oxides such as indium oxide (In2O3), tin (IV) oxide (SnO2) and indium tin oxide (ITO) on the surface of MWCNTs are examined. The results of electrochemical analysis that indicate electrocatalytical activity can be enhanced more than that of Pt/MWCNTs by adding metal oxide. In addition, Pt/In2O3/MWCNTs electrocatalysts have the highest catalytic active. In Pd-series electrocatalysts, three different electrocatalysts (Pd/In2O3/MWCNTs, Pd/SnO2/MWCNTs and Pd/MWCNTs) are compared the electrooxidation performance of formic acid. In2O3/MWCNTs are synthesized by chemical reduction method. This method can enhance the dispersion of In2O3 nanoparticles on the surface of MWCNTs. After Pd deposition, InPd2 structure is observed in XRD analysis. The electrochemical results indicate Pd/In2O3/MWCNTs electrocatalysts have higher active than those of Pd/SnO2/MWCNTs and Pd/MWCNTs. Summarize the results of this study, metal catalysts deposited on In2O3 modified MWCNTs have better catalytic property than those other supports. The addition of In2O3 enhances the oxidation of the carbon monoxides that absorb on the surface of Pt electrocatalysts; it can prevent CO poison of electrocatalysts. Thus, it will enhance the efficiency of anode materials in fuel cell applications by adding In2O3.