Novel Bi, BiSn, Bi2Sn, Bi3Sn, and Bi4Sn Catalysts for Efficient Electroreduction of CO2 to Formic Acid

Electrochemical reduction of CO2 to useful low-carbon fuels can not only mitigate global warming problems but also be used for energy storage. For efficient CO2 electrochemical reduction in mild conditions, high-performance catalysts are required. In this work, the electrodeposition of bismuth, tin, or both on copper sheets to fabricate Sn/Cu, BiSn/Cu, Bi2Sn/Cu, Bi3Sn/Cu, Bi4Sn/Cu, and Bi/Cu electrodes was conducted, and the electrodes were used as catalysts in CO2 reduction. Experimental results show these electrodes have high activity, stability and selectivity toward CO2 reduction to formic acid. A maximum Faraday efficiency of 90.4% for formic acid production can be achieved when using a Bi/Cu electrode. The mechanism catalyzed by such electrodes is also proposed for fundamental understanding and is clearly explained on the basis of DFT calculations. The results in this paper demonstrate that electrodeposition can be a faster and easier to operate industrial technology for the fabrication of catalyst electrodes, compared with other technologies.