Boosting the High-Temperature Methanol Selectivity in CO 2 Hydrogenation by Stabilizing the Formate Intermediates at ZnO/MnO-MnCO 3 Interfacial Sites

Zn-based catalysts for CO2 hydrogenation to methanol are typically active yet face the challenge of the key formate (HCOO*) intermediate decomposing into CO at high temperatures, thereby suppressing methanol selectivity. In this work, we designed ZnO/MnO-MnCO3 interfacial sites via the in situ reconstruction of a ZnMn2O4 spinel precursor. The resulting catalyst exhibits enhanced methanol selectivity over 350 °C, significantly outperforming ZnGa2O4, ZnAl2O4, and ZnFe2O4 benchmarks. In situ DRIFTS and DFT studies reveal that the ZnO/MnO-MnCO3 interface markedly enhances the thermal stability of the adsorbed HCOO* species, effectively inhibiting its decomposition and promoting hydrogenation toward methanol. Furthermore, DFT calculations establish a linear correlation between the overall reaction energy for HCOO* decomposition and the experimental methanol selectivity, offering a key descriptor for catalyst design. This work highlights the crucial role of stabilizing formate intermediates at oxide interfaces for achieving high-temperature methanol synthesis and provides fundamental insights into the development of efficient CO2 hydrogenation catalysts.