Molecular-Level Insight into How Hydroxyl Groups Boost Catalytic Activity in CO2 Hydrogenation into Methanol

Exploring how hydrophilicity regulates catalytic properties at the molecular level remains a grand challenge, although it has great potential to offer guidelines for developing highly efficient catalysts and deepen the mechanistic understanding of heterogeneous catalysis. Here, we provide molecular-level insight into the influence of surface hydroxyl groups on hydrophilic SiC quantum dots (QDs) on CO2 hydrogenation. In CO2 hydrogenation into methanol, SiC QDs exhibited higher catalytic activity and lower activation energy than commercial SiC. Mechanistic studies revealed that the surface hydroxyl species on SiC QDs was directly involved in CO2 hydrogenation through the addition of H atoms in hydroxyl groups into CO2 to form HCOO* as the intermediate. The unique reaction path decreased the energy barrier for the formation of HCOO*, facilitating the activation of CO2. Our understanding of surface hydrophilicity directly instructs the development of efficient catalysts toward CO2 hydrogenation.