HER on NiS/NiSnS 30 NiS2(101)-S NiaS2(101)-Ni 20 量-(101)S Ni3S2(101)-Ni2 10 ◆(101-N3 Ni,S,(101)-Ni3 101-N2 -(101)1 4-(012-NSr ◆-(012外-S1 ◆-012分5 ●-(012外2 NiSn2S2(012)-Ni/Sn NiSn2S2(012)-S1 L .8 -6 4 2 NigSn2S2(012)-Ni Ni3Sn2S2(012)-S2 Sulfur Chemical Potential/eV NigS2(101)-Ni3 and NiSn2S2(012)-Ni/Sn is more stable under the O-rich condition;NiS2(101)-S and NiSn2S2(012)-S2 is stable under the S-rich conditionThe catalytic activity of Ni3S2 and Ni2Sn3S2 toward hydrogen evolution reaction Ni3S2 (101)-Ni3 and Ni3Sn2S2 (012)-Ni/Sn is more stable under the O-rich condition; Ni3S2 (101)-S and Ni3Sn2S2 (012)-S2 is stable under the S-rich condition. Ni3S2 (101)-S Ni3S2 Ni3S2 (101)-Ni2 (101)-Ni3 Ni3S2 (101)-Ni1 Ni3Sn2S2 (012)-Ni/Sn Ni3Sn2S2 (012)-S1 Ni3Sn2S2 (012)-Ni Ni3Sn2S2 (012)-S2 HER on NiS/NiSnS