Construction of p-n heterojunction film of Cu2O/α-Fe2O3 for efficiently photoelectrocatalytic degradation of oxytetracycline.

A p-n heterojunction film of Cu2O/α-Fe2O3 was constructed by electrodepositing p-type Cu2O microcubes on liquid phase deposited film of n-type α-Fe2O3. The surface morphology, the crystal phase and composition of Cu2O/α-Fe2O3 heterojunction film were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The enhanced absorption in the visible light region was observed in UV-visible diffuse reflectance spectra. Meanwhile, an efficiently improved separation and faster transfer of photogenerated electrons and holes were revealed by photoluminescence spectra and electrochemical impedance spectra. The Cu2O/α-Fe2O3 p-n heterojunction was applied to photoelectrocatalytic degradation of oxytetracycline at a bias potential of +0.5 V under visible light illumination. After 60-min photoelectrocatalytic treatment, 73.3% of oxytetracycline was removed and the degradation rate constant reached 2.14 × 10-2 min-1. Moreover, the crystal phases and compositions for the used and fresh Cu2O/α-Fe2O3 films were studied, and a possible photoelectrocatalytic mechanism was proposed.