Carbon-Modified CuO/ZnO Catalyst with High Oxygen Vacancy for CO2 Hydrogenation to Methanol

CO2 hydrogenation to methanol is a prospective approach to alleviate both global warming and energy problems. CuO/ZnO is proven to be an efficient catalyst, in which ZnO carriers prepared by different methods directly affect the catalytic activity. Herein, a novel method is used to apply a zeolite imidazolate framework-8 (ZIF-8)-derived ZnO to the carrier of copper-based catalyst. In the process of thermal transformation from ZIF-8 to ZnO, the carrier ZnO-400 is specially modified by carbon inherited from ZIF-8, and the corresponding CuO/ZnO-400 catalyst still has special carbon modification, which is confirmed by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Meanwhile, the pyrolysis temperature of ZIF-8 affects the surface oxygen defects of ZnO and the CuO/ZnO-400 catalyst has a large oxygen vacancy concentration, which is proven by X-ray diffraction (XRD) and XPS. Consequently, the CuO/ZnO-400 catalyst achieves the best CO2 conversion and methanol selectivity due to more oxygen vacancies and carbon modification.