Regulation of spin state and oxygen evolution reaction mechanism in cobalt-based catalysts

The application of cobalt-based catalysts in the oxygen evolution reaction (OER) has garnered widespread attention. Despite demonstrating excellent catalytic performance in experiments, the specific mechanisms remain not fully elucidated, particularly regarding the dynamic regulation of spin state and coordination environment and their impacts on catalytic activity and stability. This paper, based on coordination field theory, reveals the essence of the performance differences of cobalt-based catalysts in acidic and alkaline environments. In acidic conditions, the low-spin Co3+ in octahedral strong field coordination enhances stability by suppressing proton attack and lowering the d-band center. In contrast, in alkaline environments, the high-spin Co3+ induced by weak field coordination optimizes the occupancy of the eg orbitals and facilitates spin-polarized charge transfer, thereby reducing the overpotential. The results indicate that the precise regulation of the synergistic effects of coordination field strength and spin structure is key to enhancing the performance of cobalt-based catalysts. We also envision the integration of advanced characterization techniques with artificial intelligence and machine learning to construct a dynamic mechanism of spin-coordination field-reconstruction-catalysis for cobalt-based catalysts, aiming to achieve efficient and stable catalytic performance and promote their scalable application.