Simultaneous integration of on-site H2O2 production and in-situ activated fenton-like reaction over Cu-C3N4-on-Mo-BiVO4 photoanodes for rapid pollutant removal

To avoid the potential risks during the transportation and storage of H2O2 as well as its low utilization efficiency in Fenton(-like) systems, we herein report a Cu-C3N4 layer coated Mo-BiVO4 photoanode that allows sunlight-induced on-site H2O2 production and in-situ activated Fenton-like process for pollutant remediation. Wherein Mo6+ serves as a dopant part to substitute V5+ in BiVO4 to enhance PEC two-electron water oxidation reaction to H2O2, and synchronously Cu imbedded in g-C3N4 hosting matrix catalytically activates Mo-BiVO4-evolved H2O2 to generate •OH at neutral condition via a Cu(I)-catalyzed Fenton-like reaction. As a result, the Mo-BiVO4 photoanode achieves on-site H2O2 production rate averaging 0.305 μmol min−1 cm−2 at 2.0 V vs. RHE under AM 1.5G illumination (100 mW cm−2) in 1.5 M KHCO3 solution. The Cu-C3N4/Mo-BiVO4 composite photoanode delivers a removal efficiency of MB up to 93.5 % within 30 min, far superior to the g-C3N4/Mo-BiVO4 (59.8 %) or Mo-BiVO4 (56.4 %) control. Quenching experiments and EPR results prove that •OH and h+ are the primary active species in PEC degradation process. The integrated photoanodes proposed by this work can thereby guide the energy-saving PEC process for the on-site H2O2 evolution and in-situ Fenton system fabrication to boost practical utilization efficiency in environmental remediation.