Phase-Controllable Growth Ni x P y Modified CdS@Ni 3 S 2 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 (Ni 3 P and Ni 12 P 5 ) modified CdS@Ni 3 S 2 heterojunction electrocatalysts. It is found that Ni 3 P modified CdS@Ni 3 S 2 (CdS@Ni 3 S 2 /Ni 3 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@Ni 3 S 2 /Ni 3 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@Ni 3 S 2 /Ni 3 P delivers an advantaged photoassisted electrocatalytic water splitting property. The champion electrical to hydrogen and solar to hydrogen energy conversion efficiencies of CdS@Ni 3 S 2 /Ni 3 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 H 2 production from water splitting.