Phase‐Controllable Growth NixPy Modified CdS@Ni3S2 Electrodes for Efficient Electrocatalytic and Enhanced Photoassisted Electrocatalytic Overall Water Splitting

The rational design and construction of cost-effective nickel-based phosphide or sulfide (photo)electrocatalysts for hydrogen production from water splitting has sparked a huge investigation surge in recent years. Whereas, nickel phosphides (Ni_x P_y ) possess more than ten stoichiometric compositions with different crystalline. Constructing Ni_x P_y with well crystalline and revealing their intrinsic catalytic mechanism at atomic/molecular levels remains a great challenge. Herein, an easy-to-follow phase-controllable phosphating strategy is first proposed to prepare well crystalline Ni_x P_y (Ni₃ P and Ni₁₂ P₅ ) modified CdS@Ni₃ S₂ heterojunction electrocatalysts. It is found that Ni₃ P modified CdS@Ni₃ S₂ (CdS@Ni₃ S₂ /Ni₃ P) exhibits remarkable stability and bifunctional electrocatalytic activities in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory results suggest that P-Ni sites and P sites in CdS@Ni₃ S₂ /Ni₃ P, respectively, serve as OER and HER active sites during electrocatalytic water splitting processes. Moreover, benefiting from the advantageous photocatalyst@electrocatalyst core@shell structure, CdS@Ni₃ S₂ /Ni₃ P delivers an advantaged photoassisted electrocatalytic water splitting property. The champion electrical to hydrogen and solar to hydrogen energy conversion efficiencies of CdS@Ni₃ S₂ /Ni₃ P, respectively, reach 93.35% and 4.65%. This work will provide a general guidance for synergistically using solar energy and electric energy for large-scale H₂ production from water splitting.