Confinement of Ultrasmall Cu/ZnO_<i>x</i> Nanoparticles in Metal–Organic Frameworks for Selective Methanol Synthesis from Catalytic Hydrogenation of CO₂

Abstract

The interfaces of Cu/ZnO and Cu/ZrO 2 play vital roles in the hydrogenation of CO 2 to methanol by these composite catalysts. Surface structural reorganization and particle growth during catalysis deleteriously reduce these active interfaces, diminishing both catalytic activities and MeOH selectivities. Here we report the use of preassembled bpy and Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 sites in UiO-bpy metal–organic frameworks (MOFs) to anchor ultrasmall Cu/ZnO x nanoparticles, thus preventing the agglomeration of Cu NPs and phase separation between Cu and ZnO x in MOF-cavity-confined Cu/ZnO x nanoparticles. The resultant Cu/ZnO x @MOF catalysts show very high activity with a space–time yield of up to 2.59 g MeOH kg Cu –1 h –1, 100% selectivity for CO 2 hydrogenation to methanol, and high stability over 100 h. These new types of strong metal–support interactions between metallic nanoparticles and organic chelates/metal-oxo clusters offer new opportunities in fine-tuning catalytic activities and selectivities of metal nanoparticles@MOFs.