Revisit to Grain Boundary Effect in Pt Nanocrystals toward the Oxygen Electroreduction Reaction

Abstract

AbstractThe effect of catalytic surface defects in the oxygen reduction reaction (ORR) has been extensively studied to enhance the performance of proton‐exchange‐membrane fuel cells. Platinum (Pt)‐based nanocatalysts have been used to overcome the poor performance of ORR, and Sabatier‐type activity plots have been used to identify the optimal adsorption properties for ORR intermediates on the catalytic surface. Grain boundaries (GBs) within the nanostructures have been identified as the optimal active sites for ORR due to their reasonable coordination number and high oxygen residence time. However, oxidation of Pt atoms exposed at GB sites and leaching of non‐noble metals from bimetallic Pt alloys have been identified as the “Achilles Heel” of GB‐containing nanocatalysts. In this concept, we revisit the effect of GBs on nanocatalysts, summarize the mechanism of GBs towards ORR, and suggest outlooks for improving ORR for future design of nanocatalysts.