Electrochemical Reduction of Carbon Dioxide to Formate by Tin-based Metal-Organic Frameworks

There is an urgent need to develop new technologies for converting greenhouse gas CO2 into useful products to address environmental and energy crises simultaneously. Electrochemical CO2 reduction reaction (eCO2RR) driven by renewable electricity affords a capable route to realizing a carbon-neutral future and combating a global climate predicament. In determining the relationship between synthesis approach, catalyst structure and performance, two Sn-MOF electrocatalysts were produced with a bottom-up hydrothermal method. A two-dimensional catalyst 2D Sn-BDC was prepared by the open hydrothermal synthesis method, while a three-dimensional catalyst 3D Sn-BDC was prepared under the closed hydrothermal method. In CO2-saturated 0.5 M KHCO3 aqueous solution, 2D Sn-BDC catalyst displayed good performance compared with 3D Sn-BDC catalyst for CO2 reduction to formate with Faradaic efficiency of 96.3 %, partial current density of 10.0 mA cm-2 at an overpotential of 0.42 V, TOF of 4887 h-1, charge transfer resistance of 42.98 Ω and over a 10 h stability. It is recognized that the superiority of 2D Sn-BDC is assumed to originate from the ultrathin structure, enhanced surface area and presence of surface vacancies. Consequently, the improvement in mass transport, accessibility of Sn active sites and carrier concentration resulted in high catalytic performance