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 (eta(OER)) volcano curve can be plotted as a function of Delta G(O)* - Delta G(HO)*. RhIr-COF shows the best OER catalytic activity with a eta(OER) value of 0.29 V, followed by CoNi-COF (0.33 V), RuRh-COF (0.34 V), and Nilr-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.