Fabrication of NiWO4/g-C3N4 S-scheme heterojunction photocatalyst for enhanced H2 evolution

Photocatalytic H2 production is a desired route to obtain green H2 for its cleanness and sustainability properties. It is still essential to explore the highly active photocatalysts in this field. Herein, a facile solvent evaporation strategy to fabricate a NiWO4/g-C3N4 heterojunction photocatalyst was employed. The research demonstrates that NiWO4/g-C3N4 hybrids can achieve an obviously enhanced H2 evolution actively, although they have poor activity individually. The H2-releasing rate of 10 % NiWO4/g-C3N4 can reach 2546 mu mol & sdot;h- 1 & sdot;g- 1 under 300 W artificial light source illumination in 20 vol.% TEOA. Further investigations indicate that NiWO4 and g-C3N4 can form S-scheme heterojunction according to band structure analysis and photoelectrochemical tests, which leads to an effective charge separation for the energy band bending, coulomb force and interfacial electric field between g-C3N4 and NiWO4, making reserved charges with higher redox activity. In addition, NiWO4 can reduce the H2 evolution overpotential, favoring fast surface H2-releasing kinetics.