Rapid Screening of Bimetallic Electrocatalysts for Oxygen Reduction in Acidic Media by Scanning Electrochemical Microscopy

Abstract

Additional bimetallic electrocatalysts for the oxygen reduction reaction (ORR) in acidic media were designed using a previously reported thermodynamic selection guide. The electrocatalyst mixtures were prepared in large arrays on glassy carbon substrates and the electrocatalytic activity was screened using scanning electrochemical microscopy (SECM). Activities were measured for a range of bimetallic combinations that showed a synergetic electrocatalytic effect during screening, including Au–V, Ag–V, Pd–Mn, and Pd–V. Upon initial screening, a highly active electrocatalytic combination consisting of 60:40 Pd–V was identified. Using rotating disk electrode (RDE) experiments, the high activity of this combination for the ORR in acidic media was confirmed when the electrocatalysts were supported on Vulcan carbon. The electrocatalytic activity of Pd–V was close to that exhibited by Pt, the electrocatalyst of choice for the ORR in acidic media, and thus is another example of a nonplatinum catalyst with high activity that follows the previous strategy for catalyst design.