银锡双金属催化剂的制备及其对氧还原的催化性能

Synthesis and Electrocatalysis Activity of Silver-Tin Bimetallic Catalysts for Oxygen Reduction Reaction

在乙醇为溶剂和还原剂、碳粉为载体的体系中,采用水热法将Ag+或Ag+-Sn2+还原,形成纳米多孔网状结构的Ag或Ag-Sn双金属纳米颗粒,制备碳粉负载的Ag/C和Ag-Sn/C催化剂。利用循环伏安和线性扫描技术,研究了碱性溶液中这些催化剂对氧还原反应(ORR)的电活性。研究表明,Ag/C和Ag-Sn/C对ORR均表现出强的电催化活性,它们对ORR的起始电位约0.05 V(vs.Ag/AgCl)。在Ag97Sn3/C催化剂上,ORR的电流密度为2.87×10-3A/cm2(800 r/min),高于Ag/C。Levich方程分析表明,在Ag-Sn/C催化剂上,ORR转移电子数明显大于Ag/C,说明在Ag-Sn/C催化剂上,氧气能够较为彻底被还原。此外,在甲醇存在下,Ag/C和Ag-Sn/C对ORR的活性基本保持不变,表明它们对甲醇有较强的耐受力。

Carbon-loaded Ag or Ag-Sn bimetallic nanoparticles were prepared by the hydrothermal process, in which Ag＋ or Ag＋ ＋ Sn2 ＋ dissolved in ethanol were reduced to Ag or binary Ag-Sn nanoparticles by ethanol as the reduction agent. The morphological features of the catalysts show a typical nanoporous structure. Cyclic voltammetry and steady state polarization measurements were used to investigate the electroactivity of the samples for oxygen reduction reaction（ORR）. The results show that both Ag,/C and Ag-Sn/C exhibits a high electrocatalysis activity, with the onset potential of ca. 0. 05 V （ vs. Ag/AgC1） and a high current density for the ORR. Levich analysis shows that the binary Ag-Sn/C possesses a much greater electron number for ORR than Ag/C. Among the prepared samples, the Ag97 Sn3/C catalyst displays the highest current density for oxygen reduction reaction. In addition, the Ag/C and Ag-Sn/C catalysts exhibit strong tolerance towards methanol.