Oxygen vacancy enhanced photocatalytic activity of Cu2O/TiO2 heterojunction

In this study, a method was developed to create oxygen vacancies in Cu 2 O/TiO 2 heterojunctions. By varying the amounts of ethylenediaminetetraacetic acid (EDTA), sodium citrate, and copper acetate, Cu 2 O/TiO 2 with different Cu ratios were synthesized. Tests on CO 2 photocatalytic reduction revealed that Cu 2 O/TiO 2 ’s performance is influenced by Cu content. The ideal Cu mass fraction in Cu 2 O/TiO 2 , determined by inductively coupled plasma (ICP), is between 0.075% and 0.55%, with the highest CO yield being 10.22 μmol g −1 h −1 , significantly surpassing pure TiO 2 . High-resolution transmission electron microscopy and electron paramagnetic resonance studies showed optimal oxygen vacancy in the most effective heterojunction. Density functional theory (DFT) calculations indicated a 0.088 eV lower energy barrier for ∗CO 2 to ∗COOH conversion in Cu 2 O/TiO 2 with oxygen vacancy compared to TiO 2 , suggesting that oxygen vacancies enhance photocatalytic activity.