Cu/ZnV 2 O 4 Heterojunction Interface Promoted Methanol and Ethanol Generation from CO 2 and H 2 O under UV-Vis Light Irradiation.

Adopting the concurrent reduction of Cu 2 O during hydrothermal preparation of ZnV 2 O 4 , metal-semiconductor heterojunction Cu/ZnV 2 O 4 nanorods were synthesized and applied to the catalytic generation of methanol and ethanol from CO 2 aerated water under UV-vis light irradiation. 10Cu/ZnV 2 O 4 obtained from 10 wt % composite amount of Cu 2 O exhibited a total carbon yield of 6.49 μmol·g -1 ·h -1 . The yield of CH 3 OH and C 2 H 5 OH reached 3.30 and 0.86 μmol·g -1 ·h -1 , respectively. 2.5Cu/ZnV 2 O 4 displayed the highest ethanol yield of 1.58 μmol·g -1 ·h -1 due to the strong absorption in the visible light. Cu/ZnV 2 O 4 was characterized using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-vis) spectra, photoluminescence (PL) spectra, transient photocurrent response, and electrochemical impedance spectroscopy (EIS). Results showed that composite Cu 0 -ZnV 2 O 4 increased the surface area and tuned the energy band position, which matches the reaction potential toward methanol and ethanol. The photocatalytic activity toward CH 3 OH and C 2 H 5 OH on Cu/ZnV 2 O 4 is attributed to faster transmission and a slow recombination rate of photogenerated carriers at the heterojunction interface. Multielectron reactions for the production of CH 3 OH and C 2 H 5 OH are promoted. Free radical capture experiments indicated that the active species boost the reaction in the order of • OH > e - > h + .