Electrocatalytic Water splitting step terrace 1.4 1.4 12 C -S atom site S(001) 1.0 Ni atom site 20 4.92 456 0,U=0V Bond site OOH 0.8 -Ring site Ni(001) 2.98 0.6 NiS(210) b200i) 0 S2(210) b4210) 0.4 R(210) 1.17 087 0.2 OH 0.52n 0 H'+e ⅓H -0.06 =1.23W 0.0 0.0 *+2H,0 02 -0.64 -0.64 02 -0.87 Reaction coordinate -2.32U=1.81V (210)surface (0.58) HER Mi111) ● 000m 0.91 OER 0.90 Ni/CeO-(111) 0.5 0.13 0 Ni4Ce0(111) Cu surface: 0.5 Ca02.(111) 1 H,O TS H+HOTheoretical Calculations HER OER Electrocatalytic Water splitting