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

• Published in: ChemCatChem Vol. 15; no. 12
• Main Authors: Kabiraz, Mrinal Kanti, Choi, Sang‐Il
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 22.06.2023
• Subjects: Atomic properties; Bimetals; Chemical reduction; Coordination numbers; Crystal defects; electrocatalysis; Fuel cells; Grain boundaries; grain boundary; Leaching; Nanocrystals; Noble metals; Oxidation; oxygen reduction reaction; Oxygen reduction reactions; Platinum; Platinum base alloys; reaction mechanism; Surface defects
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.202300454

The 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. This concept review provides a broad overview of the function of grain boundaries (GBs) toward oxygen reduction reaction (ORR). Like, duality symbol of Yin and Yang, presence of GBs on platinum (Pt)‐based nanocatalysts toward ORR has been found to be both beneficial and detrimental.