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

While the mild production of syngas (a mixture of H and CO) from CO and HO is a promising alternative to the coal-based chemical engineering technologies, the inert nature of CO molecules, unfavorable splitting pathways of HO and unsatisfactory catalysts lead to the challenge in the difficult integration of high CO conversion efficiency with produced syngas with controllable H/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 HO molecules, where their syngas production capacity is regulated by the in situ evolved ligand defects and the plasma-activated intermediate species of CO molecules. Specially, the Cu-based catalyst system achieves 61.9 % of CO conversion and the production of pure syngas with wide H/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 to *COOH and the protonation of HO to *H.