H4,4,4-graphyne with double Dirac points as high-efficiency bifunctional electrocatalysts for water splitting

In the light of ultrahigh atom utilization, high catalytic activity and low cost, single-atom catalysts (SACs) have been garnering extensive attention in the field of electrochemistry. In recent studies, however, bifunctional SACs for water splitting are rare, and face the challenge of high overpotential. In this work, a series of transition metal (TM) atoms supported on two-dimensional (2D) H4,4,4-graphyne monolayer were verified to be bifunctional SACs for HER/OER and OER/ORR by first-principles calculations. It is interesting that Co@H4,4,4-GY and Pt@H4,4,4-GY could be applied as high-efficiency catalysts for water splitting with low overpotentials of 0.04/0.45 and 0.17/0.69 V for HER/OER, respectively. In addition, Ni@H4,4,4-GY as bifunctional SACs also exhibits desirable catalytic activity for OER/ORR with low overpotentials of 0.34/0.29 V, even superior to commercial IrO2 and RuO2. Our results reveal that TM–substrate coordination and local electronic property show significant effects on the catalytic properties for HER/OER/ORR, and the d band center as an effective descriptor could be adopted to optimize the catalytic performance of the catalysts.