Electrochemical synthesis of p-Cu2O/n-TiO2 heterojunction electrode with enhanced photoelectrocatalytic activity

Abstract

A uniform p-Cu2O/n-TiO2 heterojunction electrode was synthesized using electrochemical anodization and pulse electrodeposition. The nucleation and growth of Cu2O nanoparticles under pulse potential were investigated and controlled. Energy-dispersive X-ray spectroscopy analysis showed that Cu2O nanoparticles (NPs) were uniformly dispersed on the TiO2 nanotube (TiO2 NT) surface. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicated the formation of Cu2O. The electrodeposition of Cu2O on the TiO2 NT surface enhanced visible light response. The current–voltage curve of the Cu2O/TiO2 electrode revealed the formation of the Cu2O/TiO2 p–n heterojunction. The Cu2O/TiO2 electrode exhibited reduced charge transfer resistance and enhanced charge separation, as indicated by the photoluminescence emission spectra, transient photocurrent response, and photovoltage measurements. The uniform Cu2O/TiO2 heterojunction electrode exhibited enhanced photoelectrocatalytic (PEC) activity toward the degradation of chloramphenicol (CAP) compared with the pristine TiO2 NT electrode. The Cu2O/TiO2 electrode under electrodeposition cycles of 400 displayed the highest PEC activity. The enhanced activity is due to the synergistic effect between the uniform p-Cu2O/n-TiO2 heterojunction and the small bias potential. The radical species that play a major role in the PEC degradation of CAP are •OH radicals. A possible PEC mechanism of the uniform Cu2O/TiO2 heterojunction electrode was proposed.