Inhibiting photogenerated electron-hole recombination in double metal phosphides decorated g-C3N4 nanosheets by work function gradient for improved hydrogen production

It is crucial for the inhibition of photogenerated electron-hole recombination that rationally designs the interface electron bridge by regulating the electronic structure of photocatalysts and cocatalysts. In this work, we design a novel double metal phosphides (Ni-CoP3/Fe2P) decorated g-C3N4 nanosheets (Ni-CoFeP/CNNS) heterostructure photocatalyst to form the interface electronic bridge between photocatalysts and cocatalysts by work function gradient, which exhibits the inhibition of photogenerated electron-hole recombination. It is demonstrated that Ni-CoFeP/CNNS heterostructure photocatalyst has lower over-potential, enhanced light absorption, and inhibited photogenerated electron and hole recombination capability. Moreover, due to its unique electronic structure, the optimized Ni-CoFeP/CNNS heterostructure has a photocatalytic activity of 4188.5 mu mol g- 1 h- 1, which is 2.2 times and 6.1 times higher than the CNNS modified by single metal phosphide (Ni-Fe2P or Ni-CoP3), respectively. As supported by DFT calculations and experimental data analyses, the photocatalytic mechanism and charge migration path were enunciated in Ni-CoFeP/CNNS during the photocatalytic reaction. This work affords a new view of the inhibition of photogenerated electron-hole recombination.