Phosphorus modified Ni-MOF–74/BiVO4 S-scheme heterojunction for enhanced photocatalytic hydrogen evolution

Abstract

Regulating the directional migration of photo-generated carriers is an important strategy for realising high-performance photocatalysts. In this work, nano-particle Ni2P and peanut-like BiVO4 were grown on a rhombic structure Ni-MOF-74 substrate. A composite catalyst Ni-MOF-74/BiVO4/P with excellent performance was prepared by the high-temperature calcination method. Phosphorus modification produces Ni2P as an electron-capture centre while maintaining the basic morphology of Ni-MOF-74, effectively avoiding the accumulation of nanoparticles. The Ni2P nanoparticles not only increase the number of active sites but also introduce negatively charged P that captures more protons for hydrogen evolution. After reasonable modification, the hydrogen production of the Ni-MOF-74/BiVO4/P reached 245.4 μmol in 5 h, 23 times that of pure Ni-MOF-74. An S-scheme heterojunction between Ni-MOF-74 and BiVO4 achieves the directional transfer of carriers thereby inhibiting the recombination of electron-hole pairs. The band structure and density of states of Ni2P and BiVO4 were determined in density functional calculations. This work provides a new way for the regulation of the carrier-behaviour in photocatalysts.