Highly efficient p-type Cu3P/n-type g-C3N4 photocatalyst through Z-scheme charge transfer route.

Graphical abstract Highlights • The Cu 3 P/g-C 3 N 4 nanosheets composites catalyst was prepared via chemical deposition and phosphorization. • The Cu 3 P has both promoting charge spatial separation and lowering the overpotential of H 2 production function. • The photogenerated electron is confirm to keep at Cu 3 P site and hole stays at g-C 3 N 4 site. • Z-scheme was proposed to understand the charge transfer route in the catalyst. Abstract Phosphides exhibit relatively low overpotential for electrical hydrogen evolution reaction (HER), thus they have great potential to be used for cocatalyst for photocatalyst. Cu 3 P, as a p-type semiconductor, tends to form a p-n junction with an n-type photocatalyst. Typically, it is treated as a sensitizer to extend the light absorption. However, its function and work mechanism are not fully understood in the catalyst system. In this report, we synthesized g-C 3 N 4 and loaded Cu 3 P nanoparticle on its surface. The photoluminescence (PL) spectra, photocurrent and electrochemical impedance spectra confirm the Cu 3 P greatly enhance the charge separation process. Electrochemical HER results indicate that the composites have lower over-potential for HER. These results confirm the Cu 3 P works as a cocatalyst in the system, not a sensitizer. Further, we tracked the photogenerated electron transfer direction via photodeposition of Pt nanoparticles. The Pt nanoparticles tend to deposit near the Cu 3 P nanoparticles. That illustrates the photogenerated electron will be left on Cu 3 P nanoparticles. On the other hand, the photocatalytic decomposition of Rhodamine B (RhB) illustrates that the holes are left on the g-C 3 N 4 due to both g-C 3 N 4 and Cu 3 P/g-C 3 N 4 have similar decomposition rate, but the Cu 3 P cannot decompose RhB. Based on these, we proposed the photogenerated electron of g-C 3 N 4 recombine with the hole of Cu 3 P, the photogenerated electron of Cu 3 P will be left for HER. That reasonably explain the cocatalyst function of Cu 3 P in the composite catalyst system. [ABSTRACT FROM AUTHOR]