Emerging linear activity trend in the oxygen evolution reaction with dual-active-sites mechanism

Abstract

Developing efficient catalysts for the oxygen evolution reaction (OER) is critical to supplying renewable and clean energy. In heterogeneous catalysis, a strategy with a second active site has been developed to improve OER catalytic performance. Here we propose the design of dual-active sites consisting of two adjacent TMN₄(OH) (TM = Cr/Mn/Fe/Co/Ni/Cu) sites confined to a nanotube and use first-principles calculations to investigate their OER mechanisms. It was found that the OER pathway including the chemical step of O₂ generation from direct O–O coupling (*O + *O → 2* + O₂, ΔG₅) can be carried out on the TMN₄(OH) dual-active sites. It associates with a newly linear OER activity trend function, with ΔG₅ as the descriptor. Importantly, the potential-independent process should occur under mild conditions, which limits ΔG₅ to be relatively negative. This law of thermodynamic feasibility gives an optimal overpotential (0.18 V) for the FeN₄(OH) dual-active sites. Besides, the ΔG₅ descriptor is only related to the binding energy of *O, implying a facile route to achieve optimal activity. Our proposed dual-active-sites catalysis provides new insights into the fundamental understanding of OER mechanisms and theoretical guidelines for the accelerated discovery of efficient OER catalysts.