Oxygen deficient yolk-shell structured CoO microspheres as an oxygen evolution reaction electrocatalyst for anion exchange membrane water electrolyzers

Anion exchange membrane water electrolyzers (AEMWEs) are a promising next-generation technology for producing clean hydrogen using cost-effective, non-platinum group metal (non-PGM) based electrocatalysts. Despite their potential advantages, their low energy conversion efficiency presents a significant obstacle to their commercialization. Herein, we developed an oxygen deficient yolk-shell structured Co 3 O 4 as the oxygen evolution reaction electrocatalyst for AEMWEs. The yolk-shell structure provided a large surface area, and the introduction of oxygen vacancies to the yolk-shell structured Co 3 O 4 modulated the electronic structure and enhanced the OER activity. The abundant voids in the yolk-shell structure facilitated mass transport and effectively reduced mass transport loss in the AEMWE, resulting in excellent performance at high current density. This work suggests that the yolk-shell structured electrocatalysts can effectively improve the performance of AEMWEs, thereby addressing the major obstacle that is currently delaying their commercialization. A yolk-shell structured Co 3 O 4 , with abundant voids and large surface areas, facilitated efficient mass transport and enabled the implementation of high-performance anion exchange membrane water electrolyzer at high current density.