NiCo-Based Electrocatalysts for the Alkaline Oxygen Evolution Reaction: A Review

Electrocatalytic water splitting is a sustainable way to produce hydrogen energy, but the oxygen evolution reaction (OER) at the anode has sluggish kinetics and low energy conversion efficiency, which is the major bottleneck for large-scale hydrogen production. The design and synthesis of robust and low-cost OER catalysts are crucial for the OER. NiCo-based electrocatalysts have suitable atomic and electronic structures, and show high activity and stability during the OER process. Recently, significant progress has been made in regulating the structure and composition of NiCo-based catalysts and understanding the nature of catalysis, especially the OER mechanism, catalytic active sites, and structure–activity relationship. In this work, we summarized and discussed the latest development of NiCo-based electrocatalysts in the OER, with particular emphasis on catalyst design and synthesis, strategies for boosting OER performance, and understanding the nature of catalysis from experimental and theoretical perspectives. The OER mechanism, some activity descriptors, and atomic and electronic structure–activity relationships based on NiCo-based electrocatalysts are unveiled. Finally, some challenges and futuristic outlooks for improving the performance of NiCo-based electrocatalysts are proposed, and we hope this review can provide guidance for the design of more efficient NiCo-based electrocatalysts.