Switching charge transfer process of carbon nitride and bismuth vanadate by anchoring silver nanoparticle toward...

With the aim of exploring and modulating the interfacial charge kinetics, a ternary g-C₃N₄/Ag/BiVO₄ was constructed with excellent photocatalytic performance and preferable stability toward H₂ evolution in absence of cocatalyst. Both density functional theory (DFT) and experimental results implied that the type II g-C₃N₄/BiVO₄ composite can be switched to Z-scheme via Ag nanoparticles as the electron shuttle. The optimal photocatalytic H₂ yield rate achieved for g-C₃N₄/Ag/BiVO₄ was 57.4 µmol·g^-1·h^-1, being far surpassed the H₂ harvest rate of g-C₃N₄/BiVO₄, Ag/g-C₃N₄ and g-C₃N₄, which is 2.9, 14.8 and 1.7 µmol·g^-1·h^-1, respectively. The apparent quantum efficiency of g-C₃N₄/Ag/BiVO₄ photocatalyst was also determined to be 1.23%. Besides, the photocatalytic performance of g-C₃N₄/Ag/BiVO₄ well preserved over 5 runs in 50 h. The improved H₂ production performance is considered as the consequence of promoted segregation of photoexcited charge carriers and SPR effects of Ag nanoparticles. In combination with photocurrent measurement, examination of active species and DFT calculation, it is found that Ag nanoparticles as an electron mediator can highly promote the Z-scheme carrier migration that electrons come from conduction band of BiVO₄ will quickly assemble with the photo-induced holes from valence band of g-C₃N₄, leaving electrons in the conduction band of g-C₃N₄ and holes in valence band of BiVO₄ that could greatly enhance the charge separation efficiency.