Copper nanoparticles supported on metal-organic framework with topological defects for CO₂ hydrogenation to methanol

The catalytic hydrogenation of CO₂ to methanol represents a promising strategy to reduce CO₂ emissions and mitigate the energy crisis. For this conversion, reoUiO-66 with topological defects was synthesized through acid etching, and a novel Cu-based catalyst (Cu@reoUiO-66) was prepared by incorporating active Cu onto reoUiO-66. The introduction of topological defects enhanced the specific surface area (892.2 m² g^-1) and CO₂ capture capacity (35.1 cm³ g^-1) of reoUiO-66, surpassing those of UiO-66 (718.3 m² g^-1, 30.9 cm³ g^-1), thereby facilitating mass transfer during the reaction. Regarding CO₂ hydrogenation, Cu@reoUiO-66 achieved a CO₂ conversion rate of 6.1 % and a methanol selectivity of 53.1 %. Moreover, the methanol space-time yield of the Cu@reoUiO-66 reached 336.1 mg_MeOH g_Cat^-1h^-1 and almost no decreased after continuous reaction for 70 h, which is nearly ten times that of traditional Cu/ZrO₂ catalysts and better than many reported metal-organic framework (MOF)-based catalysts. The characterization results showed that the abundant exposed active sites induced by topological defects facilitated the fixation of active metals and reactants, thereby accelerating the activation of reactants. This study demonstrated that structural defects in the support significantly influence catalyst behavior and catalytic activity. Furthermore, it highlighted that MOFs with tunable structures serve as an ideal platform for catalyst design and structure-activity relationship studies.