The self-assembly process of metal nanoparticles has aroused wide attention due to its low cost and simplicity. However, most of the recently reported self-assembly systems only involve two or fewer metals. Herein, we first report a successful synthesis of self-assembled Ag@AuCu trimetal nanoplates in aqueous solution. The building blocks of multibranched AuCu alloy nanocrystals were first synthesized by a chemical reduction method. The growth of Ag onto the AuCu nanocrystals in the presence of hexadecyltrimethylammonium chloride (CTAC) induces a self-assembly process and formation of Ag@AuCu trimetal nanoplates. These nanoplates with an average side length of over 2 μm show a porous morphology and a very clear boundary with the branches of the as-prepared AuCu alloy nanocrystals extending out. The shape and density of the Ag@AuCu trimetal nanoplates can be controlled by changing the reaction time and the concentration of silver nitrate. The as-assembled Ag@AuCu nanoplates are expected to have the potential for wide-ranging applications in surface-enhanced Raman scattering (SERS) and catalysis owing to their unique structures.Keywords:trimetal;self-assemble;nanoplates;AuCu alloy
Deli Jiang,Yimeng Zhou,Qianxiao Zhang,Qi Song,Changjian Zhou,Xiangli Shi,Di Li
Photocatalytic reduction of CO2 toward eight-electron CH4 product with simultaneously high conversion efficiency and selectivity remains great challenging owing to the sluggish charge separation and transfer kinetics and lack of active sites for the adsorption and activation of reactants. Herein, a defective TiO2 nanosheet photocatalyst simultaneously equipped with AuCu alloy co-catalyst and oxygen vacancies (AuCu-TiO2–x NSs) was rationally designed and fabricated for the selective conversion of CO2 into CH4. The experimental results demonstrated that the AuCu alloy co-catalyst not only effectively promotes the separation of photogenerated electron–hole pairs but also acts as synergistic active sites for the reduction of CO2. The oxygen vacancies in TiO2 contribute to the separation of charge carriers and, more importantly, promote the oxidation of H2O, thus providing rich protons to promote the deep reduction of CO2 to CH4. Consequently, the optimal AuCu-TiO2–x nanosheets (NSs) photocatalyst achieves a CO2 reduction selectivity toward CH4 up to 90.55%, significantly higher than those of TiO2–x NSs (31.82%), Au-TiO2–x NSs (38.74%), and Cu-TiO2–x NSs (66.11%). Furthermore, the CH4 evolution rate over the AuCu-TiO2–x NSs reaches 22.47 μmol·g–1·h–1, which is nearly twice that of AuCu-TiO2 NSs (12.10 μmol·g–1·h–1). This research presents a unique insight into the design and synthesis of photocatalyst with oxygen vacancies and alloy metals as the co-catalyst for the highly selective deep reduction of CO2.
Gang Wang,Zhitong Jin,Meirong Zhang,Zhong-Sheng Wang
Controlling the electronic structure of a catalyst has become an important approach to tune and optimize its antipoisoning ability and catalytic efficiency for a chemical reaction. Using d -mannitol as a structure-directing agent to induce size transformation and twinned defects in copper particles, penta-twinned Cu elongated pentagonal bipyramids as supports have been synthesized, and HAuCl 4 is reduced in situ to form an AuCu alloy on the surface of Cu, generating a self-supporting AuCu@Cu core–shell structure for application as a glucose sensor in a neutral medium. The AuCu@Cu elongated pentagonal bipyramids with 0.42 at% Au show activities comparable with the Au and Pt catalyst but are more tolerant toward Cl − than Au and more tolerant toward H 3– x PO 4 x − than Cu. The mass activity of AuCu@Cu reaches 0.10 A mg −1 of Au at 0.6 V versus Ag/AgCl (3 m KCl) in a pH 8.0 buffer. The self-supporting AuCu@Cu elongated pentagonal bipyramids are promising catalysts for glucose sensing in a neutral medium. This work offers an effective way to design antitoxic and durable catalysts with ultralow content of noble metal for glucose sensing.
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