Deposition of Tin Catalysts from Thiolated Precursor Organic Solutions for CO2 Reduction to Formate: A Potential-Dependent Mechanism Study.

Abstract

The production of efficient catalysts is mandatory to attain superior catalytic performance. Once the catalyst deposition mechanism is clear, one can define the optimal physical and chemical conditions of the deposition process, such as electrolyte composition, reduction potential, current operation mode, result chemical composition of the catalyst, its structure and morphology. Here, we investigate the electrodeposition mechanism of tin catalysts in dimethyformamide of a thiolated tin complex under potential control for CO2 reduction to formate. First, a new synthesis route is presented for a tin thiolate precursor, Bis(1,2-ethanedihiolate)Sn(IV). Second, a potential-controlled deposition process of tin from dimethylformamide solutions of this precursor is discussed, with the intention to deposition of tin catalysts on acid-sensitive substrates, such as carbon-composed gas-diffusion-layers. We expose with scan-rate cyclic-voltammetry, scan-rate mass-potential and chronoamperometry measurements irregular current-potential and mass change phenomena along electrodeposition, which reflect a complicated potential-dependent mechanism composed of redox and chemical reactions. Disproportionation and comproportionation reactions of tin are indicated by the holistic picture of the potential and time -dependent mass measurements and complementary structure and morphology analysis and are suggested to have an important role in the deposition mechanism of tin. The complex mechanism is untied and the deposition conditions are defined accordingly.