Electrochemical Reduction of Carbon Dioxide to Formate on Tin and Polyaniline-Modified Tin Electrocatalysts

Tin is one of the most efficient electrocatalysts for the carbon dioxide reduction to formate 1 , but the real feature that is responsible for such activity is not yet well-understood 2 . Herein, the carbon dioxide electrochemical reduction to formate ions was studied on Sn and on polyaniline-modified Sn electrocatalysts. The results showed that tin foil electrodes, even having different initial degree of oxidation, as revealed by XPS, exhibited similar faradaic efficiencies, ca . 92%, suggesting that the oxidation state is not the principal factor that control the electrocatalytic activity. Interestingly, when Sn foils and Sn nanoparticles were superficially modified by polyaniline, the rate of formate production was considerably increased, and the faradaic efficiency to formate was maintained close to 92%. In this study, the main features that actually govern the faradaic efficiency of Sn electrodes, and the role of the alkaline nitrogen atoms of polyaniline on detaining CO 2 molecules in the vicinities of the electrode producing an increased reaction rate are discussed. References [1] J. Wu, F. G. Risalvato, F-S. Ke, P. J. Pellechia, X-D. Zhou, J. Electrochem. Soc., 159 (7) (2012) F353-F359. [2] C. Cui, J. Han, X. Zhu, X. Liu, H. Wang, D. Mei, Q. Ge, J. Catal. 343 (2016) 257 - 265. Acknowledgements The authors gratefully acknowledge financial support from FAPESP (2016/13323-0 and 2013/16930-7), CNPq (306469/20162), and Capes.