Transition metal atoms (Fe, Co, Ni, Cu, Zn) doped RuIr surface for the hydrogen evolution reaction: A first-principles study

• Transition metal atom doped on the RuIr(1 1 1) surface terminated by Ru atoms is more stable than that by Ir atoms. • Zn-doped RuIr(1 1 1) surface has the best performance for HER reaction. • After doping, the best active sites migrate from Ir to Ru atoms. • Synergistic effect of Ru and Ir atoms promotes the HER activity on the surface. Electrochemical water splitting to produce hydrogen is an effective strategy to solve the energy shortage. Since hydrogen is easier to produce under acidic conditions, the development of electrocatalysts with high activity and stability is particularly important in acidic electrolytes. Based on this, we systematically studied the active sites of transition metal atoms doped RuIr(1 1 1) surface (TM-RuIr(1 1 1), TM = Fe, Co, Ni, Cu, Zn) for hydrogen evolution reaction (HER) through first-principles calculations. We find Zn-RuIr(1 1 1) has the best performance for HER and the Gibbs free energy change of the adsorbed H atom (△ G H* )and exchange current reach −0.03 eV and 1.68 A cm −2 , which is superior than Pt(1 1 1). Crystal Orbital Hamilton Population (COHP) analysis shows the △ G H* of adsorption surface with the same configuration is negatively correlated with calculated bond energy. Further Bader charge analysis reveals the doping transition metal changes the electronic properties of Ru atom and Ir atom near the doping site, thereby activating the Ru adjacent to the doped site so that the best active site migrates from Ir to Ru atom. The synergistic effect of Ru and Ir atoms promotes the HER activity on the surface. Our results help to understand the internal mechanism regulating HER activity on the RuIr surface and guide the design and synthesis of high-activity TM-RuIr catalysts.