Silver Nanoparticle-Decorated Defective Zr-Based Metal–Organic Frameworks for Efficient Electrocatalytic Carbon Dioxide Reduction with Ultrahigh Mass Activity

Electrochemical reduction is considered to be a fascinating strategy to alleviate CO2 accumulation by converting it into value-added products. In this work, we used silver nanoparticle (Ag NP)-incorporated defective, thiol-functionalized UiO-66 metal–organic frameworks (MOFs) as a catalyst for the electrocatalytic conversion of CO2 to CO. We used a de novo defect engineering technique, coordination modulation, for defect incorporation as well as the functionalization of the MOF, where the introduced thiol moieties act as anchoring sites for the Ag NPs. Ag@UiO-66-SH catalyzed the CO2 reduction reaction to form CO with a Faradaic efficiency (FE) of 74% and a partial current density of 19.5 mA cm–2 at −1.1 V vs a reversible hydrogen electrode. This material showed remarkable catalytic stability, retaining the FE for CO without any significant loss in reduction current over 10 h and an excellent mass-specific activity of 218 A g–1. Density functional theory calculations further establish the enhanced catalytic CO2 reduction reaction (CO2RR) activity of Ag@UiO-66-SH compared to their pristine counterparts based on free energy calculations. This study demonstrates the use of metal NP–MOF composite materials with very less metal loading as an effective catalyst for CO2RR to CO.