Ternary CoAuPd and binary AuPd electrocatalysts for methanol oxidation and oxygen reduction reaction: Enhanced catalytic performance by surface reconstruction

Abstract

Two kinds of ternary cobalt gold palladium (CoAuPd) and three kinds of binary AuPd alloy nanocatalysts are synthesized by co-reduction and successive reduction method. The CoAuPd nanocatalysts obtained by the successive reduction method possess a hollow structure with some solid nanospheres, nanodendrites and show much better catalytic activity for methanol oxidation reaction (MOR) (1.26 mA cm−2) than another CoAuPd NCs (1.14 mA cm−2) and binary AuPd nanocatalysts (0.85 mA cm−2). CO adsorption and electrochemical dealloying method can restructure nanocatalyst surface and improve MOR and oxygen reduction reaction (ORR) activities. Electrochemical dealloying reconstructs the hollow CoAuPd alloy to a CoAuPd@AuPd core-shell structure with pinholes and the dealloyed NCs exhibits better MOR (1.92 mA cm−2) and ORR (6.3 mA cmGEO−2) catalytic activities than the initial CoAuPd nanocatalysts (1.26 mA cm−2 for MOR and 3.4 mAcmGEO−2 for ORR). Accelerated durability tests (ADT) quantify the changes of stability before and after the surface reconstruction. The ternary CoAuPd nanocatalysts have excellent durability before and after surface reconstruction (current density decrease 14.04% for MOR and 0.3 mA cmGEO−2 for ORR) in alkaline medium.