Band structure engineering of graphitic carbon nitride via Cu2+/Cu+ doping for enhanced visible light photoactivity

Cu doped g-C3N4 nanosheets are synthesized by a facile process of calcining dicyandiamide, ammonium chloride (NH4Cl) and copper chloride (Cu(II)Cl-2) at N-2 environment. XRD, FTIR and XPS results indicate that the Cu species coordinated in the pore among three tri-s-triazine units at the states of Cu2(+/)Cu(+), expanding visible light absorption and narrowing the bandgap of g-C3N4. The degradation rate is about 2.3 times higher than that of pristine g-C3N4. DFT calculations show that the doped Cu2+ ion acts as the strong reduction site, while the doped Cu+ as the strong oxidation site. Thus the Cu2+/Cu+ doping facilitates the photoinduced charge transfer by forming the S-S Z-scheme heterojunction of photosystem Cu2+ doped g-C3N4 (PSI) and Cu+ doped g-C3N4 (PSII). (C) 2018 Elsevier B.V. All rights reserved.