Degradation of phenol in high-salt wastewater by three-dimensional FeCu co-doped materials: Interaction of FeCu with g-C3N4–rGO and synergistic catalytic mechanism

In order to solve the problem of low activity of advanced oxidation processes (AOPs) in degrading high-salt organic wastewater. This study demonstrates a strategy to improve catalyst activity by co-doping with FeCu between the reduced graphene oxide (rGO) and graphitic carbon nitride (g-C3N4) layers. The g-C3N4-FeCu-rGO (GR-FeCu) reaction system achieved a phenol degradation rate of >96% in high-salinity wastewater, with a pH range of 2–8. After six cycles, the phenol degradation rate reached 100%. Electron spin resonance analysis identified·OH and·O2- as the primary active species in phenol degradation. The high activity of the catalyst in high-salt environments is attributed to the synergistic effect of FeCu and rGO-g-C3N4: The introduction of FeCu suppressed the formation of g-C3N4, leading to more defect structures and active groups (CO and C-N = C) in the catalyst. These structures provided active sites for H2O2 activation, enhanced H2O2 activation. The doping of Cu in the catalyst not only accelerates the accelerated Fe (III) reduction in the Fenton reaction, but also enhances the activity of N in g-C3N4. The three-dimensional interlayer structure with FeCu co-doping stabilized the metal ions and provided abundant active sites and metal anchoring structures, presenting a new approach to improve catalytic activity.