NH2-MIL-101(Fe)/Ni(OH)2-derived C,N-codoped Fe2P/Ni2P cocatalyst modified g-C3N4 for enhanced photocatalytic hydrogen evolution from water splitting

Constructing appropriate cocatalysts to modify semiconductors while maintaining tight interface for charge separation facilitation is important for improving photocatalytic hydrogen production. Thus, in this work, C,N-codoped Fe2P/Ni2P (CN/FeNiP) polyhedrons derived from NH2-MIL-101(Fe)/Ni(OH)2 were used as cocatalysts to modify graphitic carbon nitride (g-C3N4) for photocatalytic hydrogen production from water splitting under visible-light irradiation. The highest evolution rate observed over CN/FeNiP/g-C3N4 was 13.81 mmol g−1 h−1 under 1.0 mmol L−1 of Eosin Y (EY) sensitization (compared to 0.196 mmol g−1 h−1 without EY sensitization), which was about 10 and 5 times higher than that of g-C3N4 (1.33 mmol g−1 h−1) and CN/FeP/g-C3N4 (2.73 mmol g−1 h−1). The apparent quantum yield at 420 nm reached 45.8%. A detail analysis of the mechanism revealed that the improved photocatalytic activity can be ascribed to highly efficient spatial separation of photo-induced charges from the excited EY and g-C3N4 to CN/FeNiP with tight interface, staggered band energy between g-C3N4, CN/Fe2P and Ni2P as well as accelerated surface reaction by CN/FeNiP cocatalysts. This work demonstrates that MOF-derived hybrid hollow metal phosphide can be good substitutes for noble metal catalysts for photocatalytic hydrogen production.