Enhancing the selectivity of CO formation for electrochemical reduction of CO2 on tin(IV) oxide-based catalysts

Abstract

In this work, the relationship between crystal size of SnO2 and CO selectivity (the CO/formate ratio) is investigated and a great enhancement in CO selectivity is achieved by reduction in its crystal size. The crystal size of SnO2 is less than 5 nm by the synthesis of a core-shell-like microstructure of SnO2 on the rutile-phase TiO2 particles (denoted as R-TiO2@SnO2). The faradaic efficiency and CO selectivity are promoted to be over 42% and 1.18, which are two folds of that of pure SnO2 nanocrystals. According to the X-ray photoelectron spectroscopic results, SnO is more active for the CO2ER to generate CO than Sn or SnO2 and the corresponding electrochemical reduction pathway of CO2 on SnOx is proposed. The increase in the electron density on the oxygen atom of SnO may increase the possibility of *COOH formation, favoring the formation of CO.