Zobrazení zdroje stránky Conwayrowland9172

Ultra-small and monodispersed Pt nanoparticles (NPs) have been successfully synthesized in polymer electrolyte membrane fuel cells. The process normally involves the use of capping agents, organic species, templates, and substrates and is thus complex. Hence, obtaining Pt NPs with a clean surface is challenging. In this study, a method for preparing stable and highly dispersed Pt NPs with clean surfaces is proposed. The method involves the use of a modified Na3C6H5O7 reduction process assisted by NaNO3 stabilization. The specific complexations of NO2- ions possibly alter the reaction kinetics and lower the growth rate of Pt NPs by retarding the reduction reaction. The optimized Pt/carbon nanotube (CNT) catalysts exhibit high mass activity and moderate activity decay after 10,000 times of potential cycling compared with commercially available Pt/C catalysts. Then, membrane electrode assemblies based on the resultant catalysts are characterized. The cell performance of 744&nbsp;mW&nbsp;cm-2 (maximum power density) is achieved after the optimized Pt/CNT catalysts are used in carbon black. CoAl-LDH and ZnxCd1-xS (ZCS) were successfully assembled. [https://www.selleckchem.com/products/tiplaxtinin-pai-039.html selleck chemical] By studying the microstructure of the catalysts, it was found that the agglomerated ZCS nanoparticles were equably dispersed on the hexagonal plate-like CoAl-LDH surface. The increase of the specific surface area of the composite catalyst further proves that the agglomeration state of ZCS nanoparticles has been improved. When the mass of the introduced CoAl-LDH is 20% of the ZCS, the maximum hydrogen production after the optimization is 1516&nbsp;μmol/5h, which is about 6.9 times that of pure ZCS. UV-vis DRS in the range of 250-800&nbsp;nm proved that the visible light absorption intensity of the composite is enhanced compared to pure materials. Electrochemical and photoluminescence experiments proved that the heterostructure formed between ZCS and CoAl-LDH accelerates photoelectron transfer and inhibits the recombination of electrons and holes. In addition, possible mechanisms of the sample were explored by UV-vis DRS and Mott-Schottcky. Hybridization has become a powerful toolbox for developing ultrafiltration membranes with superior properties. However, it remains challenging to give full play to the utility of nanofillers because of poor bonding strength between polymers and inorganic nanomaterials. Herein, hydroxyapatite nanotubes (HANTs) were modified via bio-inspired polydopamine (PDA) and polyethylenimine (PEI) co-deposition. Meanwhile, polysulfone with carboxylation degree of 30% (PSF-COOH-30%) was synthesized by nucleophilic substitution reaction and employed as the membrane matrix. The results showed that when 0.3&nbsp;wt% HANTs@PDA/PEI was incorporated, the pure water flux of the hybrid membrane achieved about 3.2 times that of the unfilled membrane and the rejection rate of bovine serum albumin (BSA) and humic acid (HA) remained 94.5% and 97.8%, respectively. Meanwhile, the flux recovery ratio for BSA and HA solutions (1&nbsp;g/L) reached 90.8% and 93.7%, respectively. Specifically, the superiority of UF performance benefited from the synergistic effect of both the carboxylated polymer and the nanofiller. On one hand, the incorporation of HANTs@PDA/PEI promoted the formation of more porous membrane structure and improved the hydrophilicity of the membrane. On the other hand, due to the existence of COOH, the electrostatic repulsion between the membranes and contaminants enhanced the fouling resistance for BSA and HA. Conspicuously, the ease and versatility of co-deposition provide new ideas in the construction of nanohybrid and the favorable improvement renders that appropriate combination of polymer and additive is an effective way for developing future ultrafiltration membranes. A global water pollution on account of organic dye waste poses serious heath threat to human beings. Graphene-based micromotors have recently attracted considerable attentions for efficient water remediation. However, a secondary catalytic degradation is required for completely destroying persistent organic dyes after their adsorption by graphene and its derivatives. Here, we immobilized ferroferric oxide (Fe3O4) nanoparticles (NPs) with reduced graphene oxide (rGO)-based micromotors in order to synthesize heterogeneous Fenton Fe3O4-rGO/Pt composite microjets and to improve their catalytic performance. The as-prepared composite microjets are well propelled in contaminated waters by Pt catalyzing hydrogen peroxide. Combining the attractive properties of reduced graphene oxide (rGO) and Fe3O4 NPs along with fascinating motor movement, the composite microjets offer an efficient removal of methylene blue in short time. This outstanding catalytic performance is ascribed to the synergistic effect of Fe3O4 and rGO during the heterogeneous Fenton-like reaction and the enhanced localized mixing effect during the motion. Moreover, the Fenton composite microjets are able to magnetically recovered and reused for further decontamination processes. Our proposed Fenton composite microjets with extraordinary catalytic capability and good recyclability holds considerable promise for diverse environmental applications. Structural design, doping, and construction of heterojunctions are effective strategies for producing highly efficient photocatalytic materials. Herein, N-doped TiO2 was formed on hexagonal C3N4 tube through in-situ hydrolysis of a Ti source on a supramolecular precursor, followed by thermal treatment. As a result, a double-shell microtube, C3N4@TiO2 heterostructure was fabricated. It was worth noting that the supramolecular precursor was prepared from melamine and cyanuric acid, which not only served as a template for the double-shell tubular structure, but also provided nitrogen for the doping of TiO2. The photocatalytic efficiency of C3N4@TiO2 was investigated by conducting hydrogen production experiments. The hydrogen production rate of C3N4@TiO2 was measured to be 10.1&nbsp;mmol&nbsp;h-1&nbsp;g-1, which is 4 times and 15 times that of C3N4 and TiO2, respectively. The improved photocatalytic activity of C3N4@TiO2 can be ascribed to (1) the tubular structure that provides a large number of reaction sites and enhances mass transport, (2) the heterojunction that is beneficial to charge separation, and (3) doping of TiO2 with nitrogen which extends its optical absorption range to visible light.