Plasma-Driven Efficient Conversion of CO 2 and H 2 O into Pure Syngas with Controllable Wide H 2 /CO Ratios over Metal-Organic Frameworks Featuring In Situ Evolved Ligand Defects.

While the mild production of syngas (a mixture of H 2 and CO) from CO 2 and H 2 O is a promising alternative to the coal-based chemical engineering technologies, the inert nature of CO 2 molecules, unfavorable splitting pathways of H 2 O and unsatisfactory catalysts lead to the challenge in the difficult integration of high CO 2 conversion efficiency with produced syngas with controllable H 2 /CO ratios in a wide range. Herein, we report an efficient plasma-driven catalytic system for mild production of pure syngas over porous metal-organic framework (MOF) catalysts with rich confined H 2 O molecules, where their syngas production capacity is regulated by the in situ evolved ligand defects and the plasma-activated intermediate species of CO 2 molecules. Specially, the Cu-based catalyst system achieves 61.9 % of CO 2 conversion and the production of pure syngas with wide H 2 /CO ratios of 0.05 : 1-4.3 : 1. As revealed by the experimental and theoretical calculation results, the in situ dynamic structure evolution of Cu-containing MOF catalysts favors the generation of coordinatively unsaturated metal active sites with optimized geometric and electronic characteristics, the adsorption of reactants, and the reduced energy barriers of syngas-production potential-determining steps of the hydrogenation of CO 2 to *COOH and the protonation of H 2 O to *H.