Добірка наукової літератури з теми "Ru Nanocrystal"

A novel nanozyme comprised of graphene encapsuled Ru nanocrystals (Ru@G) with effective and stable peroxidase-like activity prepared using a chemical vapor deposition (CVD) method was used for the colorimetric detection of glutathione (GSH) at near-physiological pH.

Ultrafine (∼2 nm) mono-disperse Ru nanocrystals on N-doped graphene (Ru@NG) shows Pt-like catalytic activity towards HER in the both alkaline and acid media with zero onset potential and better current density as compared to Pt/C.

Sodium-ion batteries (SIBs) are considered a potential replacement for lithium-ion batteries in the area of low-cost large-scale energy storage. Due to its low operating voltage, high capacity, non-toxicity and low production cost, titanium dioxide is now among the anode materials under investigation and shows the most promise. However, its poor electrical conductivity is one of the main reasons limiting its large-scale application. Herein, we designed a ruthenium-doped anatase-type VTi2.6O7.2 ultrafine nanocrystal (Ru-VTO). As the anode of SIBs, Ru-VTO delivers a high specific capacity of 297 mAh g−1 at 50 mA g−1, a long cycle life of 2000 cycles and a high rate capability (104 mAh g−1 at 1000 mA g−1). The excellent performance may be related to the solid-solution interatomic interactions and the enhanced conductivity after ruthenium doping. These studies demonstrate the potential of Ru-VTO as an anode material for advanced SIBs.

Pd-coated Ru nanocrystals supported on N-doped graphene (Pd–Ru@NG) are obtained via electroless deposition of Pd on Ru nanocrystals which shows efficient bifunctional HER and ORR electrocatalytic activity.

Solar energy is by far the most abundant renewable resource available to mankind. However, it is diffused and intermittent, and often geographically separated from that of the production results in underwhelming utilization of this resource. Inspired by photosynthesis, various efforts were made to store solar energy in form of chemical bonds than can be used when the sun is not shining. A promising approach is to produce hydrogen, a carbon-neutral energy carrier is via water splitting which requires electrocatalysts to accelerate the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The state-of-art catalysts used for HER is Pt and for OER is IrO2/RuO2 that are prohibitively expensive. We have developed new synthesis methodologies for various earth-abundant electrocatalysts supported heteroatom-doped carbon nanostructures and exploited for water splitting. An in-situ solid state route was developed to integrate ruthenium nanoparticles with N-doped graphene sheets which exhibited an HER activity rivalling state-of-art Pt/C over a wide pH range. In order to find further cost-effective materials, we sought inspiration from NiFe-hydrogenase (the most efficient catalyst for HER) to develop a general solid state method for bimetallic MFe@ N-doped carbon core-shell nanostructures (M = Ni, Cu, Co, Zn, Mn) as efficient total water splitting catalyst. Thereafter, a new, phosphine-free, solid state method to hybridize Co2P with N, P co-doped CNTs was developed which could also be extended to synthesize Fe2P, Ni2P and Cu3P. Moreover, glucose oxidation was attempted as a possible replacement for the kinetically sluggish OER half-cell reaction, wherein Co2P/N, P-CNTs were demonstrated to be an efficient non-enzymatic glucose sensor for the first time. Thereafter, Co-imidazolate frameworks (ZIF-67) were transformed into hierarchal Co-N-Se nanosheets via a simple selenization method. Investigations were carried out to establish a structure-property correlation between the nanostructures evolved over various interval of time along with their OER activity. Finally, an in-situ strategy was developed to hybridize N-doped graphitic carbon seets with Ni and MoxC (Mo2C and MoC) nanoparticles which exhibited resilient HER activity besides effectively accelerating OER, thereby resulting in overall water splitting that can be attributed to favorable electronic modulation between various strongly coupled components.

Yes
The fabrication of precious metal (ruthenium, osmium, gold, and iridium) nanocrystals from single atoms has been studied in real-time. The dynamics of the first stage of the metal nanocrystallisation on a doped (B,S)-graphitic surface are identified, captured, and reported.
We thank the Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), the ERC (Grant No. 247450 to PJS), EPSRC (EP/F034210/1 to PJS).

Semiconductor and magnetic nanoparticles hold unique optical and magnetic properties, and great promise for bio-imaging and therapeutic applications. As part of their stable synthesis, the nanocrystal surfaces are usually capped by long chain organic moieties such as trioctylphosphine oxide. This capping serves two purposes: it saturates dangling bonds at the exposed crystalline lattice, and it prevents irreversible aggregation by stabilizing the colloid through entropic repulsion. These nanocrystals can be rendered water-soluble by either ligand exchange or overcoating, which hampers their widespread use in biological imaging and biomedical therapeutics. Here, we report a novel scheme of synthesizing fluorescent PbS and magnetic Fe3O4 nanoparticles using DNA oligonucleotides. Our method of PbS synthesis includes addition of Na2S to the mixture solution of DNA sequence and Pb acetate (at a fixed molar ratio of DNA/S2−/Pb2+ of 1:2:4) in a standard TAE buffer at room temperature in the open air. In the case of Fe3O4 particle synthesis, ferric and ferrous chloride were mixed with DNA in DI water at a molar ratio of DNA/Fe2+/Fe3+ = 1:4:8 and the particles were formed via reductive precipitation, induced by increasing pH to ∼11 with addition of ammonium hydroxide. These nanocrystals are highly stable and water-soluble immediately after the synthesis, due to DNA termination. We examined the surface chemistry between oligonucleotides and nanocrystals using FTIR spectroscopy, and found that the different chemical moieties of nucleobases passivate the particle surface. Strong coordination of primary amine and carbonyl groups provides the chemical and colloidal stabilities, leading to high particle yields (Figure 1). The resulting PbS nanocrystals have a distribution of 3–6 nm in diameter, while a broader size distribution is observed with Fe3O4 nanoparticles as shown in Figure 1b and c, respectively. A similar observation was reported with the pH change-induced Fe3O4 particles of a bimodal size distribution where superparamagnetic and ferrimagnetic magnetites co-exist. In spite of the differences, FTIR measurements suggest that the chemical nature of the oligonucleotide stabilization in this case is identical to the PbS system. As a particular application, we demonstrate that aptamer-capped PbS QD can detect a target protein based on selective charge transfer, since the oligonucleotide-templated synthesis can also serve the additional purpose of providing selective binding to a molecular target. Here, we use thrombin and a thrombin-binding aptamer as a model system. These QD have diameters of 3∼6 nm and fluoresce around 1050 nm. We find that a DNA aptamer can passivate near IR fluorescent PbS nanocrystals, rendering them water-soluble and stable against aggregation, and retain the secondary conformation needed to selectively bind to its target, thrombin, as shown in Figure 2. Importantly, we find that when the aptamer-functionalized nanoparticles binds to its target (only the target), there is a highly systematic and selective quenching of the PL, even in high concentrations of interfering proteins as shown in Figure 3a and b. Thrombin is detected within one minute with a detection limit of ∼1 nM. This PL quenching is attributed to charge transfer from functional groups on the protein to the nanocrystals. A charge transfer can suppress optical transition mechanisms as we observe a significant decrease in QD absorption with target addition (Figure 3c). Here, we rule out other possibilities including Forster resonance energy transfer (FRET) and particle aggregation, because thrombin absorb only in the UV, and we did not observe any significant change in the diffusion coefficient of the particles with the target analyte, respectively. The charge transfer-induced photobleaching of QD and carbon nanotubes was observed with amine groups, Ru-based complexes, and azobenzene compounds. This selective detection of an unlabeled protein is distinct from previously reported schemes utilizing electrochemistry, absorption, and FRET. In this scheme, the target detection by a unique, direct PL transduction is observed even in the presence of high background concentrations of interfering negatively or positively charged proteins. This mechanism is the first to selectively modulate the QD PL directly, enabling new types of label free assays and detection schemes. This direct optical transduction is possible due to oligonucleotidetemplated surface passivation and molecular recognition. This chemistry may lead to more nanoparticle-based optical and magnetic probes that can be activated in a highly chemoselective manner.