Abstract:

The electrocatalytic carbon dioxide reduction reaction can convert the greenhouse gas carbon dioxide into chemical raw materials or organic fuels, providing a feasible way to overcome global warming and the conversion of electrical energy to chemical energy. The main challenge of this technology is the wide product distribution, resulting in low selectivity of a single product, however, modulating the surface properties of the catalyst is an efficient strategy to solve this problem. In this study, the precursors of Cu₂O and Cu₂S were oxidized to the CuO catalysts with different surface properties. The CuO-FS catalyst derived from Cu₂S delivered the improved activity of electro-reduction of carbon dioxide and selectivity for formic acid product. This catalyst exhibited a higher total current density and the Faraday efficiency of formic acid > 70% in a wide test voltage range of -0.8 - -1.1 V; the Faraday efficiency for formic acid could reach a maximum of 78.4% at -0.9 V. The mechanism study indicated that the excellent performance of CuO-FS for electro-reduction of carbon dioxide could be attributed to the large electrochemically active surface area, which provided a large number of surface active sites, resulting in a higher total current density; moreover, the less zero-valent Cu was produced over the surface of CuO-FS during the electrocatalytic process, which reduced the production of ethylene and thus promoted the production of formic acid.

Key words: CO₂ electroreduction, Cu-based catalyst, surface properties, product selectivity, formic acid