Rapid precipitation-reduction synthesis of carbon-supported silver for efficient oxygen reduction reaction in alkaline solution

摘要

Silver has emerged as a promising electrocatalyst for oxygen reduction reaction (ORR) in alkaline membrane fuel cell for its high stability in alkaline solution. However, the electrocatalytic activity of silver-based ORR electrocatalyst is generally poor. This paper presents a rapid precipitation-reduction method to synthesize carbon-supported silver electrocatalysts, which involves precipitating AgBr compound on carbon support, and then transforming it into carbon-supported silver via an in situ electrochemical reduction process. The obtained electrocatalysts show excellent oxygen reduction performances in terms of E-1/2 (0.84 V vs. RHE) and mass specific activity J(m) (9.1 mA mg(Ag)(-1)@0.85 V), outperforming most of recent reported silver-based ORR electrocatalysts. Further experiment indicates that the improved electrocatalytic performances can be assigned to the presence of lattice defects at Ag surface, which can facilitate the adsorption and further reduction of oxygen molecular on the silver surface.