Bimetallic Pt or Pd-based carbon supported nanoparticles are more stable than their monometallic counterparts for application in membraneless alkaline fuel cell anodes

Abstract

Alkaline fuel cells (AFCs) are relevant for niche applications, but still require enhanced performance and lifetime. Active and durable hydrogen oxidation reaction (HOR) catalysts must be developed: linking their electrochemical surface area (ECSA) loss to their HOR activity and understanding whether the ECSA loss of carbon-supported platinum group metal-based (PGM/C) HOR catalysts is irreversible (nanoparticles dissolution, detachment, Ostwald ripening) or reversible is pivotal. Using identical-location transmission electron micrographs (IL-TEM) and ECSA characterizations by “CO-like” stripping undertaken pre and post accelerated stress tests (AST), the different degradation mechanisms undergone by monometallic (Pt/C and Pd/C) and bimetallic catalysts (Pd-Pt/C and Pd-Ni/C) are unveiled. Monometallic PGM/C undergo extensive reversible poisoning and irreversible degradation upon operation at low potential, in contrast to bimetallic catalysts, which are less affected. Pd-Ni exhibits the smallest loss of ECSAPGM and HOR activity: it poorly catalyzes carbon corrosion and is hardly poisoned by “CO-like” species.