Regulate the behaviors of photo-generated carriers in CuFe-LDH/TiO2 based on positive bias voltage to enhance the capability of photo-Fenton on nitrobenzene degradation

In this study, we reported a novel positive bias voltage assisted photo-Fenton technology in to solve the low utilization rate of photoelectrons and slow redox cycle of Fe(III)/Fe(II) in traditional photo-Fenton system. The results showed that the CC/TiO2/CuFe-LDH electrode has the best performance on nitrobenzene degradation under simulated sunlight and +0.6 V bias voltage, in 60 min, the removal rate of nitrobenzene was 99.2%, which was 1.2 times of that without bias voltage. Positive bias voltage can cause the conduction band and valence band to bend upward, narrow the band gap, promote the transfer of the photoelectrons, and increase the separation efficiency of photogenerated electron-hole pair. Different from other photoelectric coupling catalysis, photoelectrons of TiO2 in this system are transferred to CuFe-LDH rather than to the external circuit, which promotes the redox cycles of Cu(III)/Cu(II) and Fe(III)/Fe(II) . In addition, positive bias voltage can not only improve the utilization rate of photoelectrons, but also improve the utilization rate of photogenic holes to produce a large number of ·OH for the degradation of organic pollutants. This study provides a new efficient and economical method for the removal of persistent organic pollutants.