All-Solid-State C3N4/NiXP/Red Phosphorus Z-Scheme Heterostructure for Wide-Spectrum Photocatalytic Pure Water Splitting

Z-scheme photocatalysts encouraged by natural photosynthesis have received increasing attention for pure water splitting. However, there have been only a few instances of effective Z-scheme nanosystems utilizing nonmetal photocatalysts for both water reduction and oxidation. In this study, we used carbon nitride (CN), metallic NixP, and crystalline red phosphorus (RP) to build a solid-state Z-scheme photocatalytic system, which worked as reduction sites, an electron mediator, and oxidation sites, respectively. The light absorption capability up to similar to 600 nm enabled the photocatalyst to realize water splitting under broad-spectrum illumination. Detailed analysis suggested that the photocatalytic hydrogen production rate was apparently enhanced on account of effective spatial separation of light-induced charges owing to the intimate contact between the NixP mediator and photocatalyst components as well as the suitable energy band alignment. Meanwhile, hydrogen peroxide instead of oxygen was generated from water oxidation, which can solve the separation and safety issues of the synchronized production of hydrogen and oxygen and thus facilitated the feasible application of photocatalytic hydrogen production.

Automated summary

In this study, a solid-state Z-scheme photocatalytic system was built using carbon nitride (CN), metallic NixP, and crystalline red phosphorus (RP) as reduction sites, an electron mediator, and oxidation sites, respectively. The photocatalyst was capable of absorbing light up to 600 nm, enabling water splitting under broad-spectrum illumination. The effective spatial separation of light-induced charges, facilitated by the close contact between the NixP mediator and photocatalyst components as well as the suitable energy band alignment, significantly enhanced the photocatalytic hydrogen production rate. Additionally, the generation of hydrogen peroxide instead of oxygen from water oxidation addressed the separation and safety issues of synchronous hydrogen and oxygen production, promoting the practical application of photocatalytic hydrogen production.