Dual-metal atoms embedded into two-dimensional covalent organic framework as efficient electrocatalysts for oxygen evolution reaction: A DFT study

The electrochemical oxygen evolution reaction (OER) is a half-reaction of water-splitting for hydrogen generation, yet suffers from its sluggish kinetics and large overpotential. It is highly desirable to develop efficient and stable OER electrocatalysts for the advancement of water-splitting. Herein, by means of density functional theory (DFT) calculations, we systematically investigated a series of two-dimensional (2D) dual-atom catalysts (DACs) on a novel synthesized covalent organic framework (COF) material as potential efficient catalysts toward the OER. The designed 6 homonuclear (2TM-COF) and 15 heteronuclear (TM₁TM₂-COF) DACs all exhibit good stability. There is a strong scaling relationship between the adsorption Gibbs free energies of HO* and HOO* intermediates, and the OER overpotential (η^OER) volcano curve can be plotted as a function of ΔG_O* − ΔG_HO*. RhIr-COF shows the best OER catalytic activity with a η^OER value of 0.29 V, followed by CoNi-COF (0.33 V), RuRh-COF (0.34 V), and NiIr-COF (0.37 V). These four OER DACs exhibit lower onset potential and higher current density than that of the IrO₂(110) benchmark catalyst. Aided by the descriptor identification study, the Bader charge that correlated with the Pauling electronegativity of the embedded dual-metal atoms was found to be the most important factor governing the catalytic activity of the OER. Our work highlights a potentially efficient class of 2D COF-based DACs toward the OER.