Interfacial charge transfer and enhanced photocatalytic mechanisms for Pt nanoparticles loaded onto sulfur-doped g-C3N4 in H2 evolution

C3N4 exhibits great research potential in photocatalytic hydrogen evolution. Herein, sulfur is doped into C3N4 (SCN) by using thiourea as the precursor. The platinum (Pt) nanoparticles (NPs) are photo-deposited onto the surface of S-CN. Photocatalytic activity in H2 evolution for C3N4 is improved from 0 to 56.58 μmol/h/gcat after sulfur doping, and to 742.19 μmol/h/gcat with the modifications of sulfur and Pt NPs. The enhancement in the photocatalytic hydrogen production may be due to the following: (1) the dope of sulfur can optimize the band structure and provide more reactive site for C3N4, (2) the porous morphology of S-CN enhanced the light-harvesting ability of C3N4, (3) Pt NPs with the surface plasmonic resonance effect are capable of absorbing more photons of visible light, and (4) Pt acts as a reservoir of photogenerated charge carriers, inhibiting its recombination. Enhancement mechanism has been deeply explored and comprehensively discussed in this work.