Promoting intramolecular charge transfer of graphitic carbon nitride by donor-acceptor modulation for visible-light photocatalytic H_(2) evolution

摘要

To satisfy the requirements of substantial green development,it is urgent to explore an innovative eco‐friendly semiconductor photocatalyst to efficiently achieve visible‐light‐driven photocatalytic H 2 evolution(PHE).The strategy of promoting the spatial separation efficiency of photoinduced carriers can essentially enhance the PHE performance of a photocatalyst.Herein,a graphitic carbon nitride(g‐C 3 N 4)‐based donor–acceptor(D‐A)copolymer(CNDM x)is constructed by simple one‐pot thermal polycondensation,using urea and 5,8‐DibroMoquinoxaline(as an electron donor)as precursors.The electron D-A modulation consequently creates an internal electric field to facilitate the intramolecular charge transfer within the copolymer.A series of experimental characterizations and density functional theory calculations are applied to elucidate the variation and correlation of the structure and PHE performance of the as-prepared catalysts.It is found that the best average PHE rate of 3012.5μmolg^(−1) h^(−1) can be achieved over the optimal D-A copolymer under visible‐light(400<λ<800nm)irradiation,which is~3.3 times that of pure urea-derived g-C_(3)N_(4).The corresponding apparent quantum efficiency is 1.3% at 420nm.This study provides a protocol for designing effective visible-light photocatalysts via D-A modulation of polymeric semiconductors.