In situ synthesis of Cu+ self-doped CuWO4/g-C3N4 heterogeneous Fenton-like catalysts: The key role of Cu+ in enhancing catalytic performance

[Display omitted] •Novel Cu+ self-doped CuWO4/g-C3N4 composites were in situ synthesized.•Cu+ self-doped CuWO4/g-C3N4 was first applied to Fenton-like catalytic reaction.•Abundant Cu+ in the catalyst played an important role in the Fenton-like reaction.•Singlet oxygen was dominant reactive species in CuWO4/g-C3N4/H2O2 process.•A possible reaction mechanism was proposed in CuWO4/g-C3N4/H2O2 system. In this work, novel Cu+ self-doped CuWO4/g-C3N4 composites were in situ synthesized through a simple hydrothermal method. The CuWO4 nanoparticles with the size of about 10 nm were dispersed uniformly on the surface of g-C3N4 nanosheets. The Fenton-like catalytic results showed that the 30 wt% CuWO4/g-C3N4 composite exhibited the best catalytic activity for the degradation of organic dyes. The enhanced Fenton-like catalytic activity could be ascribed to the promoted redox cycle of Cu+/Cu2+ in the presence of abundant Cu+ as well as the synergistic effect between CuWO4 and g-C3N4 in the CuWO4/g-C3N4 composites. In addition, the highly efficient catalysts could be used repeatedly to treat variety of organic pollutants in a wide pH range at room temperature without external energy input (light, electricity and ultrasound). The reactive species quenching experiments showed that singlet oxygen played the major role in the Fenton-like reaction for the degradation of organic dyes. Based on the above results, a possible reaction mechanism was proposed in the Cu+ self-doped CuWO4/g-C3N4/H2O2 system.