Facile strategy to fabricate Ni2P/g-C3N4 heterojunction with excellent photocatalytic hydrogen evolution activity

Transition metal phosphides are considered as the most prospective replacements for noble metal cocatalysts used for H₂ evolution during photocatalytic water splitting. In this work, Ni₂P/g-C₃N₄ composite photocatalyst was synthesized using a simple in-situ hydrothermal method by one step. Benefiting from the excellent light trapping, efficient transfer of charge carriers and strong stability of Ni₂P nanoparticles, as well as the stable interface contact between Ni₂P and g-C₃N₄, the Ni₂P/g-C₃N₄ exhibit greatly enhanced H₂ evolution performance during photocatalytic water splitting. The optimized H₂ evolution rate can reach 3344 μmol h^?1 g^?1 over 17.5 wt% Ni₂P/g-C₃N₄, which is 68.2 times greater than that of pure g-C₃N₄ and even much greater than that of 15 wt% Pt/g-C₃N₄. The apparent quantum efficiency (QE) is about 9.1% under 420 nm monochromatic. The enhancement mechanism was demonstrated in detail by transient photocurrent responses, photoluminescence spectra and electrochemical impedance spectroscopy. This work develops a facile strategy to fabricate transition metal phosphide/semiconductor heterojunction systems with potential application for photocatalytic H₂ evolution.