Incorporation of Engineered Cu0/Cu+ Interfaces in Metal-Organic Frameworks for Boosting CO2 Hydrogenation to Methanol.

The Cu-based materials are an important category of catalysts for CO2 hydrogenation to methanol, in which Cu0 and Cu+ species have been widely acknowledged to play key roles in the reaction. Herein, a series of metal-organic frameworks (MOFs), namely UiO-66(n) with exposed ─COOH groups, are fabricated by employing both terephthalic acid and 1,2,4-benzenetricarboxylic acid linkers. Following by introducing Cu nanoparticles, Cu@UiO-66(n) are synthesized. By regulating the amount of exposed ─COOH groups on the MOF pore wall, the interaction between Cu and the MOF support is regulated. This ─COOH microenvironment regulates the overall Cu0/Cu+ ratio in the supported Cu species, thereby tuning the Cu0/Cu+ interfacial descriptor, which is closely associated with the CO2 hydrogenation performance. The Cu@UiO-66(25) featuring the longest Cu0/Cu+ interface achieves a methanol space-time yield of 694 g kgcat -1 h-1 and methanol selectivity of 92.8% at 250 °C and 4 MPa, far surpassing other counterparts. This work provides a deep understanding of the synergistic effect between Cu0 and Cu+ species in catalytic CO2 hydrogenation.