Simultaneous construction of dual-site phosphorus modified g-C3N4 and its synergistic mechanism for enhanced visible-light photocatalytic hydrogen evolution

Band structure regulation and the improvement of the carrier separation efficiency represent two important factors in relation to photocatalytic activity. Thus, the simultaneous construction of the structure and the surface of a photocatalyst would serve to address both issues. In light of the special redox property of ammonium hypophosphite, dual-site phosphorus-modified graphitic carbon nitride (g-C3N4) photocatalysts were designed in the present study. In contrast to pristine g-C3N4 and to traditional single-site phosphorus doping, the dual-site phosphorus-modified g-C3N4 showed an apparent increase in photocatalytic H2 evolution. The characterization results showed that the P modification existed in two forms, namely substitution of P atoms for C atoms and the surface PN bond. In-depth analyses of the structure–activity relationship suggested that dual-site doping can regulate the band structure of g-C3N4, promote the charge-transfer rate, and further, improve the separation efficiency of photogenerated carriers. The findings of this study could provide new insights concerning the design of dual-site phosphorus-modified photocatalysts with a regulated band structure and surface state, which could represent a promising strategy for use in the field of solar energy conversion.