Reconstructing oxygen electrocatalysts for hydrogen energy applications

Developing hydrogen economy significantly relies on water electrolyzers and fuel cells, where electrocatalysts towards the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) play pivotal roles. For generating unusual catalyst species and preventing detrimental catalyst degradations, manipulating catalyst reconstructions is gaining intensive interest. This work reviews current understandings and modulations of reconstructions of representative OER/ORR electrocatalysts for water electrolyzers and fuel cells, covering platinum group metal- (PGM) based and PGM-free ones. By rigorously discussing the most recent progress, we distinguished catalyst reconstruction from self-optimization or electrochemical activation, and emphasized that (engineered) reconstruction does not necessarily yield improved catalytic performance. More importantly, we highlighted the strategy of rationally designing the physicochemical properties of catalysts and managing the electrochemical conditions to achieve superior control of catalyst reconstructions. Through discussing the advances, challenges, and perspectives, this work contributes to rationally reconstructing oxygen catalysts by managing their reconstructions for high-performance hydrogen energy applications.