Academic literature on the topic 'Photocatalytsts'

Titanium dioxide (TiO2) photocatalyts doped with copper metal at different metal loadings were successfully prepared and characterized. Photocatalytic oxidative desulfurization of model oil containing dibenzothiophene as the sulfur compound (100 ppm) was investigated using the prepared photocatalyst. The photocatalyst with 2.0 wt% Cu metal loading showed the best sulfur removal at 66.25%.

Titanium dioxide (TiO2) photocatalyts doped with iron metal at different metal loadings were successfully prepared and characterized. The doped photocatalyst were characterized using diffuse reflectance spectroscopy (DR-UV-Vis), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM).Photooxidative extractive desulfurization of model oil containing dibenzothiophene as the sulfur compound (100ppm) was investigated using the prepared photocatalyst. The photocatalyst with 0.20 wt% Fe metal loading showed the best sulfur removal at 61.13%.

The different molar ratios of La/Ti (0.025, 0.050, 0.075 and 0.100) photocatalytic electrodes use in this study were synthesized by sol-gel method and dip-coating method. The XRD pattern of TiO2/ITO presents only anatase phases, [1] but for La-TiO2/ITO presents both anatase and rutile phases. The SEM image of the La-TiO2/ITO showed particles of regular shapes with smaller size (＜10nm) compared to the TiO2/ITO, which presented uniform particles of spherical structure and larger size （20nm）.The La-TiO2/ITO photocatalytic electrode with molar ratio 0.050 shows the best ability both on the absorbtion and photocatalytsis. Applied potential 2.0V would effectively increase the photoelectrocatlaytic activity under visible light irradiation.

This review focuses on our research findings about efficiency of different nano materials synthesized by us for photocatalytic hydrogen production from industrial wastes. Lab-scale photocatalytic reactors were fabricated for hydrogen production from liquid phase alkaline waste streams and gaseous phase hydrogen sulfide. The effects of operating parameters namely pH, flow rate, light intensity, liquid depth, sulfide and sulphite concentration were investigated for for 7 photocatalysts viz., CuGa2-xFexO4/RuO2, Fe2O3-CdS/ZnS, Pd-Cr2O3/CdS, Ce-TiO2, CdS-ZnS/TiO2, CdS/ZnS, Ti-Cr-MCM-48. Among the photocatalysts used, CdS/ZnS nanosized photocatalyts have a much greater surface area and thus give a better hydrogen yield.

AbstractWe theoretically and numerically demonstrate that the spontaneous parity-time (PT) symmetry breaking phase transition can be realized respectively by using two independent tuning ways in a tri-layered metamaterial that consists of periodic array of metal-semiconductor Schottky junctions. The existence conditions of PT symmetry and its phase transition are obtained by using a theoretical model based on the coupled mode theory. A hot-electron photodetection based on the same tri-layered metamaterial is proposed, which can directly show the spontaneous PT symmetry breaking phase transition in photocurrent and possesses dynamical tunability and switchability. This work extends the concept of PT symmetry into the hot-electron photodetection, enriches the functionality of the metamaterial and the hot-electron device, and has varieties of potential and important applications in optoelectronics, photodetection, photovoltaics, and photocatalytics.

La pollution de l'air intérieur est une cause importante de divers problèmes de santé pour les occupants tels que des maladies respiratoires, des symptômes allergiques... De nos jours, les gens passent 80 à 90 % de leur temps à l'intérieur, d'où l'importance de comprendre les principales causes de la pollution de l'air intérieur et de trouver des solutions appropriées pour améliorer la qualité de l'air intérieur (QAI). L'Organisation Mondiale de la Santé (OMS) a signalé en 2009 que la pollution biologique était l'une des principales causes de la dégradation de la QAI. Sous certaines conditions (humidité élevée), les fungi peuvent se développer sur presque tous les matériaux de construction. Ils produisent alors des particules telles que des spores, des toxines ou des composés organiques volatils (COV) et d'autres métabolites pouvant être aérosolisés. La libération de particules par les surfaces dépend de différents facteurs, notamment du type et de l'âge des micro-organismes, des propriétés des matériaux et des conditions environnementales (température, humidité, vitesse de l'air). En fonction de leur taille et de leur disponibilité dans l'air intérieur, elles peuvent être inhalées par les occupants, ce qui entraîne de graves risques pour la santé car elles peuvent pénétrer plus ou moins profondément dans le système respiratoire. Pour répondre à cette problématique, ce travail visait à étudier les relations qui peuvent éventuellement exister entre les micro-organismes, en particulier les fungi, présents sur les surfaces et les particules en suspension dans l'air qui contaminent l'air intérieur (in situ et en laboratoire). L'objectif étant d'avoir une vision plus claire de la contamination fongique dans l'environnement intérieur, permettant ainsi une meilleure gestion des risques pour la santé des personnes exposées. En outre, une étude sur les performances de photocatalyseurs et d'esters de glycérol en tant que produits antimicrobiens pour les matériaux de construction ont été réalisées. Dans un premier temps, une campagne d'échantillonnage in situ a été réalisée dans une maison avec présence fongique visible dans le sud de la France. Des échantillons de surface et d'air intérieur ont été prélevés et analysé pour identification des organismes présents. L'objectif de cette partie était de vérifier la relation, s'il y en a une, entre la contamination fongique sur les surfaces et la contamination aérienne. Ensuite, des expériences sur les activités antimicrobiennes de produits photocatalytiques et d'esters de glycérol ont été réalisées dans différentes conditions expérimentales. L'objectif de cette partie était de tester leur efficacité en tant que produits antimicrobiens pouvant être utilisés comme additifs dans les peintures ou les revêtements. Les tests effectués dans cette partie étaient des tests préliminaires en solutions aqueuses et l'impact des différentes conditions sur l'efficacité de chaque produit a été évalué. L'efficacité de trois photocatalyseurs (TiO2, ZnO, AuZnO) en tant que produits antimicrobiens a été évaluée à des intensités lumineuses proches des conditions intérieures réelles. L'efficacité de l'Acide Undécylénique (AU) et de trois esters de glycérol en tant que produits antifongiques a également été évaluée. La dernière partie de cette étude visait à étudier la relation entre la prolifération sur matériaux et la concentration en spore dans l'air dans des conditions contrôlées (principalement le flux d'air et l'humidité relative). Un dispositif expérimental innovant a été développé. La conception et la validation d'un protocole expérimental permettant d'observer des corrélations quantitatives entre la prolifération sur matériaux et la contamination de l'air ont été effectuées. L'impact de différents paramètres sur l'aérosolisation des particules a été évalué. La validation de ce banc expérimental est encourageante et permettra de poursuivre différents essais dans un avenir proche
Indoor air pollution is an important cause of diverse health problems for occupants including respiratory diseases, allergic symptoms, cancers, and cardiovascular problems. People spend 80-90% of their time indoors emphasizing the importance of understanding the main causes of indoor air pollution and finding suitable solutions to improve indoor air quality. The World Health Organization (WHO) reported in 2009 that biological pollution is one of the main causes of the degradation of indoor quality. In humid indoor environments, fungi can grow and develop on almost all building materials. Upon their development on surfaces, they produce particles such as spores, toxins or volatile organic compounds, and other metabolites that can be aerosolized. The release of particles from surfaces as well as their characteristics is dependent on different factors including the type and age of microorganisms on the surface, material properties, and environmental conditions (temperature, humidity, air velocity). Based on their sizes and their duration of availability in the indoor air, they can be inhaled by occupants, leading to serious health risks as they may penetrate different depths in the respiratory system. To respond to these issues, this work aimed to investigate the relations that may exist between microorganisms, especially fungi, present on surfaces and airborne particles contaminating the indoor air (In situ and in the lab). It would provide a clearer vision of fungal contamination in the indoor environment and would be helpful during investigating methods for controlling the growth of fungi indoors. In addition, investigations on the performances of selected photocatalysts and glycerol esters as antimicrobial products for reducing microbial contamination on surfaces in the laboratory were achieved. Initially, an In situ sampling campaign was held in a visibly contaminated house in Southern France. Surface sampling from contaminated materials and indoor airborne sampling were carried out. Then, DNA analysis for samples was carried out by Toulouse Biotechnology Institute (TBI). This part aimed to check the relationship, if any, between fungal contamination on surfaces and airborne contamination. Then, experiments on the antifungal and antibacterial activities of photocatalytic products and the antifungal activity of glycerol esters were carried out under different experimental conditions. This part aimed to test their efficiency as antibacterial/antifungal products that may be applied as additives in paints or coatings. The tests carried out in this part were preliminary tests in aqueous solutions and the impact of different conditions on the efficiency of each product was evaluated. The efficiency of three photocatalysts (TiO2, ZnO, Au-decorated ZnO) as antimicrobial products under light intensities close to real-life indoor conditions. The efficiencies of Undecylenic Acid (UA) and of three glycerol esters, formed upon esterification of Glycerols with UA, as antifungal products were evaluated. The last part of this study aimed to investigate the relationship between surface contamination and airborne contamination under controlled conditions (mainly airflow and relative humidity). A new experimental device was settled, design and validation of an experiment protocol that permit to determine the quantitative correlation between surface contamination and airborne contamination were carried out. The impact of different experimental parameters on the aerosolization of particles from contaminated surfaces into air was evaluated. The validation of this experimental protocol was important and brought attention to different tests that will be investigated in the near future

博士
國立交通大學
材料科學與工程學系所
107
This thesis focus on exploring essentially robust and practically efficient photocatalyst platform in order to make significant breakthrough to the ever-challenging fields of environmental sustainability and renewable energy. We developed the intelligent photocatalyst and demonstrated the correlations of their interfacial charge dynamics and photocatalytic activity including typical semiconductor/metal heterostructure photocatalyst system, ZnO/Metal (Ag, Au, Pd), especially for the quantitative analysis on the SPR-induced interfacial charge dynamics of ZnO-Au system. The correlations among plasmonic metal content, surface plasmon resonance-mediated charge transfer and electromagnetic response, and the resultant photoactivity enhancement toward photoelectrochemical (PEC) water splitting provide a solid foundation for creating effective and applicable plasmonic PEC cells. We also introduced Ta, Nb, Zr into TiO2 nanotube system to modify its electronic structures and established a fully depleted quaternary Ti−Nb−Ta−Zr−O (TNTZO) mixed-oxide nanotube arrays to serve as a versatile structural backbone for construction of a sophisticated photoelectrode paradigm. Besides, by coupling the pronounced charge separation and distinctive peroxidase mimic features, an all-day-active photocatalyst, Au@Cu7S4 nanocrystal-decorated TiO2 nanowires, were also successfully synthesized.

碩士
國立交通大學
材料科學與工程學系所
105
Highly ordered TiO2 nanotube arrays are fabricated via electrochemical anodization of high purity titanium metal sheet in fluorine containing electrolytes. The microstructures were characterized by GIXRD, XPS, SEM, synchrotron radiation beam line 17B and beam line 24 analyses. Using a solar simulator measurement, the photocurrent density and photoelectric conversion of the TiO2 nanotubes was evaluated and discussed. The photoconversion efficiency of silver loading TiO2 nanotubes following hydrogenation treatment at 300°C for 3hs was found to be improved comparing with the highly ordered TiO2 nanotubes arrays. With silver loading, the TiO2 nanotubes can achieve 0.64% in efficiency with 0.52 mA/cm2 in photocurrent density for hydrogen production; after the hydrogenation treatment, the efficiency and photocurrent density increase to 0.87% and 0.79 mA/cm2, respectively. The efficiency of the silver-loaded TiO2 nanotubes and hydrogenation treatment also will be discussed.

Interest in photocatalytic disinfection synthesis has increased in recent years with the use of different semiconductor photoreceptors. While much attention has been given to the photocatalytic inactivation process, researchers have shifted to focusing on bio-inspired metal oxide materials for photocatalytic inactivation in recent years. Bio-inspired metal oxide photocatalysts have unique advantages with special emphasis being placed on its highly earth abundance, economic cost of production, eco-friendliness, simple structure and easy to synthesize. Besides that, bio-inspired metal oxide photocatalysts has also been applied extensively for the development of emerging areas, such as environmental as well as energy materials. Today, the development of simple and inexpensive bacterial disinfection technology to addresses the peril of waterborne disease in the emerging areas has grown rapidly. This chapter proposes an analysis of recent research activities that involved the use of bio-inspired photocatalytst for the disinfection of water under light radiation. Various nano-structured photocatalytic materials like titanium dioxide (TiO2), zinc oxide (ZnO), iron oxide (Fe2O3), nickel oxide (NiO), etc., are introduced. Material and various bacterial pathogens, photocatalytic and pathogens disinfection mechanism are described in detail. Finally, the progress of novel bio-inspired photocatalysts for the disinfection applications is discussed at the end of this chapter.