Modification of WO3 photoanode with NiFe-LDHs nanosheets array for efficient Photoelectrocatalytic removal of tetracycline

Abstract

A novel WO3@NiFe-LDHs photoanode was successfully synthesized by electrochemical depositing NiFe-LDHs nanosheets array on the surface of nanoplate WO3 photoanode, in which NiFe-LDHs nanosheets formed a hetero-junction with WO3 and offered mass transfer sites to improve the bulk and interfacial charge separation of WO3@NiFe-LDHs photoanodes. In addition, TC was captured by NiFe-LDHs nanosheets, which not only facilitated the direct charge transfer for TC degradation, but also induced TC to be photo-sensitizer to enhance the light absorbance of WO3@NiFe-LDHs photoanode. Moreover, NiFe-LDHs nanosheets acted as surface catalytic sites for accelerating the water activation to generate highly oxidizing •OH. Therefore, the optional WO3@NiFe-LDHs2.5 photoanode displayed the highest PEC removal of TC with a degradation percentage of 92.3% and total organic carbon removal of 70.4% at 0.6 V (vs Ag/AgCl) bias, and showed higher photocurrent density compared with pristine WO3 photoanode. Furthermore, WO3@NiFe-LDHs photoanode showed favorable stability in the PEC degradation process, and TC was finally mineralized into CO2, H2O and some small molecular products. This work provides a deep insight on the modification of interfacial reaction to enhance the PEC degradation performance, which offered a potential route for designing PEC system with the concept of treating pollution with pollution.