Continuous electroreduction of carbon dioxide to formate on Tin nanoelectrode using alkaline membrane cell configuration in aqueous medium

Using electrochemical reduction to convert CO 2 into useful small molecule fuels represents a value-added approach to the simultaneous generation of alternative fuels and environmental remediation of carbon emissions from the continued use of conventional fuels. Here, we report a novel flow cell design for CO 2 electroreduction. The alkaline ion-exchange membranes are used to separate anolyte from aqueous catholyte, and the commercial Sn particles are deposited over a carbon support, which serves as the cathode. Various influence factors on the electrochemical reduction of gaseous CO 2 into fuel are investigated, including a selection of different alkaline-exchange membranes, time duration of the electrolysis, current density and flow rate of electrolyte on the produced formate as a target fuel. Three alkaline membranes (A901, FAD and Yichen) and an acidic membrane (Naffion 117) are used. The maximum Faradaic Efficiencies (FE) of formate formation are 82.8% (Yichen), 79.2% (A901) and 90.1% (FAD), which are comparable to and even higher than that of Nafion 117 membrane (89.2%). In particular, the FAD alkaline membrane showed an applicable prospect with cell voltage of 2.85   V, lower than when using Nafion 117 membrane. We also successfully achieve the formate production rate over 1.47   mmol   m −2   s −1 at a working current density of 50   mA   cm −2 over 60   min continuous’ operation, allowing the formate concentration up to 1.9   g   L −1 . These encouraging results reveal that different ion-exchange membranes have obvious impact on the electrochemical reduction of carbon dioxide (ERC).