Co–O<sub>3</sub>–Zn Electron Transfer\nGenerated Electron-Rich Zn to Promote Hydrogen Desorption for CO<sub>2</sub> Methanolation over Oxygen Vacancies

In order to strengthen the electron-donating–accepting\nbehavior\nof ZnZrO<sub><i>x</i></sub> catalysts to produce methanol\nwith CO<sub>2</sub> hydrogenation, Co was doped in a ZnZrO<sub><i>x</i></sub> catalyst through coprecipitation to generate Co–O<sub>3</sub>–Zn electron transfer to promote hydrogen desorption\non electron-rich Zn sites for CO<sub>2</sub> methanolation. The electron-rich\nstate of Zn species weakened the Zn–H bond to promote desorption\nof H* species, which was favorable to exposure of Zn species for further\nhydrogen dissociation. Co was incorporated into the ZnZrO<sub><i>x</i></sub> crystal lattice to create more oxygen vacancies\nto facilitate CO<sub>2</sub> adsorption on catalysts for methanol\nproduction. DFT calculations showed that the binding energy of active\nhydrogen species on CoZnZrO<sub><i>x</i></sub> catalysts\nwas lower than that of ZnZrO<sub><i>x</i></sub> catalysts.\nHAADF-STEM and XANES/EXAFS clarified that atomic Co with +2.3 valence\nwas dispersed with an average Co–O coordination number of 3.1\nin CoZnZrO<sub><i>x</i></sub> catalysts. XPS confirmed that\nZn accepted electrons donated from Co to generate electron-rich Zn\nspecies. H<sub>2</sub>-TPR revealed that the low-temperature reduction\npeak of the CoZnZrO<sub><i>x</i></sub>-1% catalyst shifted\nto 305 °C, which was lower than that (378 °C) of the ZnZrO<sub><i>x</i></sub> catalyst. This promoted methanol yield by\n58% at 5 MPa, 310 °C, H<sub>2</sub>/CO<sub>2</sub>/Ar = 80:8:12,\nand GHSV = 12,000 mL g<sub>cat</sub><sup>–1</sup> h<sup>–1</sup>.