Theoretical insights into performance descriptors and their impact on activity optimization strategies for cobalt-based electrocatalysts

Abstract

The hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are crucial half-reactions in energy storage and conversion systems. As ideal alternatives to precious metal catalysts, cobalt (Co)-based catalysts have attracted significant attention due to their adjustable oxidation states, multifunctionality, and structural diversity. Nevertheless, because of the complexities in composition, stoichiometry, and structures, fully understanding the microscopic origin of relevant reaction mechanisms and the inherent structural and performance relationships remains a great challenge. Therefore, utilizing the theoretical descriptors to distinguish and reveal the factors that limit the electrocatalytic activities of the Co-based electrocatalysts is thus of great importance, which is very crucial for appropriate adjustment of the synthetic strategies, the structure/composition optimizations, and finally the enhancement of the electrocatalytic performance. In this review, the computational hydrogen electrode and HER, OER, and ORR mechanisms are first introduced. Then, the performance descriptors related to the conductivity, reactivity, and stability were derived and discussed in-depth from density functional theory (DFT) calculations. Inspired by these descriptors, various strategies to comprehensively optimize the structures and electronic properties of the Co-based catalysts are summarized. Finally, current status, challenges, and future prospects of Co-based catalysts in practical Zn-air batteries (ZABs) and water splitting applications were reviewed.