Microenvironment engineering to modulate the tolerance of Pt/Pd-based electrocatalysts for methanol crossover in oxygen reduction reaction

Abstract

Platinum/palladium (Pt/Pd)-based electrocatalysts are considered the most promising cathode reaction catalysts for direct methanol fuel cell (DMFC) owing to their ability to effectively mitigate the sluggish oxygen reduction reaction (ORR) kinetics. However, the methanol (CH₃OH) crossover phenomenon in DMFC can poison the cathodic Pt/Pd electrocatalyst, resulting in a notable degradation in ORR activity and stability, which in turn disrupts the efficient and stable operation of DMFC. Aiming at the above phenomenon, the present review draws attention to the Pt/Pd-based ORR electrocatalysts with anti-poisoning performance in recent years, and systematically summarizes them from the standpoint of microenvironment engineering regulation. To better understand the mechanisms and manifestations of CH₃OH crossover-induced poisoning of Pt/Pd-based electrocatalysts in DMFC, we begin with a discussion of the mechanisms of DMFC and ORR. Subsequently, the Pt/Pd-based electrocatalyst design strategies (surface modification, morphology control, alloying, and metal–support interaction) based on microenvironmental engineering at the atomic/molecular level are highlighted in detail in terms of their application in DMFC cathode ORR with anti-poisoning property. Finally, the current limitations of the field are summarized and future research directions are discussed from individual standpoints in expectation of broadening research ideas and enriching research directions.