Defective High-Crystallinity g-C3N4 Heterostructures by Double-End Modulation for Photocatalysis

Photocatalytic overall water splitting is difficult due to the limitations of band structure, solar absorption efficiency, and carrier recombination. Rich nitrogen vacancies containing g-C3N4 nanosheets were prepared by spark plasma sintering. By modifying highly crystalline graphitic carbon nitride (g-C3N4) with rich nitrogen vacancies as the hydrogen- and oxygen-producing ends and building a Z-scheme heterostructure, overall water splitting can be achieved. Hydrogen and oxygen evolution rates (λ > 320 nm) of 1.51 and 0.75 mmol g–1 h–1 with the reported highest solar-to-hydrogen efficiency of 1.39% for pure g-C3N4 catalyst with cocatalysts under an AM1.5G filter (100 mW cm–2) are reached. The double-ended modulation method improves the overall photocatalytic overall water splitting efficiency of high-crystallinity defect-rich g-C3N4.