Dft-guided investigation on the photothermal DMC synthesis mechanism from CO2 and CH3OH over tetragonal ZrO2(101) with oxygen vacancies

Abstract

In the context of global carbon neutrality, “green chemistry” has spurred the conversion of CO₂ into high-value-added dimethyl carbonates (DMC). Nevertheless, the theoretical exploration for the reaction pathway on ZrO₂ catalyst surface is still in the early stages, and several fundamental mechanisms remain unclear to hinder further development of DMC reaction. This study employs theoretical calculations to scrutinize the photothermal catalytic mechanism on tetragonal ZrO₂(101) and Vo-ZrO₂(101) surfaces from the perspective of CH₃OH dissociation. Under illumination conditions, CH₃OH is oxidized via photogenerated holes on the ZrO₂ surface, generating *CH₂OH radicals. These radicals subsequently couple with *CO₂ to form the reaction intermediate *CH₃OCOO, revealing a new photothermal catalytic reaction mechanism. The oxygen vacancies reduce the bandgap of ZrO₂, enhancing its visible light responsiveness to promote CO₂ activation, and more importantly lower the energy barrier of the rate-determining step (215.5 kJ/mol vs. 188.9 kJ/mol), thereby facilitating the DMC synthesis. Furthermore, as guided by theoretical prediction, our experimental results demonstrate that ZrO₂ catalyst with abundant oxygen vacancies can achieve the higher DMC yield of 3.87 mmol·g⁻¹. Under photothermal conditions, the DMC yield can be further elevated to 4.26 mmol·g⁻¹. This work provides new theoretical insights into the DMC synthesis mechanism from CO₂ and CH₃OH.