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 H 2 evolution during photocatalytic water splitting. In this work, Ni 2 P/g-C 3 N 4 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 Ni 2 P nanoparticles , as well as the stable interface contact between Ni 2 P and g-C 3 N 4 , the Ni 2 P/g-C 3 N 4 exhibit greatly enhanced H 2 evolution performance during photocatalytic water splitting . The optimized H 2 evolution rate can reach 3344 μmol h −1  g −1 over 17.5 wt% Ni 2 P/g-C 3 N 4 , which is 68.2 times greater than that of pure g-C 3 N 4 and even much greater than that of 15 wt% Pt/g-C 3 N 4 . 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 H 2 evolution.