ZnZrOx Nanoparticles Derived from Metal–Organic Frameworks as Superior Catalysts to Boost CO2 Hydrogenation to Methanol

ZnZrOx solid solution is a promising catalyst for the hydrogenation of CO2 to methanol, but precise design of the nanostructure to enhance catalytic performance remains a significant challenge. Herein, a ZnZrOx-based solid solution (ZnZrOx-MD) nanoparticle catalyst with uniform metal dispersion and remarkable CO2 activation ability was developed via calcination of metal–organic frameworks [MOFs, viz., PCN-223(Zn)] with mixed metal (Zr and Zn) as solid precursors. It was found that the ZnZrOx-MD nanoparticle catalyst outperformed its counterparts prepared using a traditional deposition–precipitation method (ZnZrOx-TD). Furthermore, the effects of the micromorphology and crystal composition on the catalytic performance of ZnZrOx-MD were systematically investigated. Comprehensive characterization results reveal that ZnZrOx-MD contained abundant oxygen vacancies, large specific surface area, and uniform metal dispersion, which collectively contributed to its excellent CO2 hydrogenation performance, resulting in a high methanol selectivity of 77.2% at 320 °C. In situ DRIFTS experiments confirm the mechanism for the CO2 hydrogenation to methanol over the ZnZrOx nanoparticle catalysts involved the initial formation of HCOO* species, followed by subsequent hydrogenation to generate CH3O* and ultimately produce methanol. Overall, this work highlights the potential benefits of MOFs as thermal decomposition precursors for the fabrication of solid-state catalysts with unique properties.