Cu ⁺ ‐Cu ⁰ Cluster Pairs in Defective MOFs for Highly Synergistic CO ₂ Hydrogenation to Methanol

Abstract

ABSTRACT Precise arrangement of multivalent Cu sites for the synchronized activation of CO 2 and H 2 in selective methanol synthesis remained challenging. Herein, we designed spatially arrayed Cu + ‐Cu 0 cluster pairs confined within UiO‐66 (U66) to achieve spatiotemporally directed CO 2 hydrogenation to methanol. This architecture was constructed by creating missing‐linker defects within U66 using L‐ascorbic acid (LA), followed by sequential anchoring of high‐density, adjacent Cu + ‐Cu 0 cluster pairs (≈1:1 ratio) to yield a Cu/U66(LA‐Cu) catalyst. Under reaction conditions of 220°C and 3 MPa, this catalyst achieved a methanol space‐time yield of 688.1 mg·g −1 ·h −1 and an ultra‐high methanol selectivity (97.0%). Its unity‐methanol selectivity was 1.06–1.77 times that of high‐stability oxide materials. Meanwhile, catalyst's stability of 200 h was significantly prolonged compared to high‐selectivity MOF‐based catalysts that operated stably for 60–175 h. Mechanistic studies revealed that Cu + ‐Cu 0 cluster pairs within defective U66 not only enabled partitioned synergistic activation of CO 2 and H 2 , but established an efficient electron/hydrogen transfer pathway. This facilitated the migration of active hydrogen species to CO 2 adsorption sites, where adsorbed CO 2 was converted into CO intermediates and underwent deep hydrogenation. This structural design synergistically enhanced compatibility between H 2 dissociation and CO 2 hydrogenation steps, enabling reaction to proceed efficiently along the RWGS + CO‐hydro pathway.