KCS

Recently, in electrochemical CO₂ reduction studies, copper catalysts have been noted as major studies because they could form C-C bonds. To promote the formation of this C-C bond, researchers changed the shape of the copper catalyst surface to induce local pH changes, or to introduce copper oxide as a catalyst. However, in copper oxide-based catalysts not only complexly synthesizes the catalyst, it is not clear why the oxide catalyst shows better C-C coupling performance. Therefore, in this study, a simple anodization method was introduced to synthesize the catalyst in the Cu(OH)₂ state. This catalyst was distinguished from the Cu₂O or CuO present in the traditional native oxide layer, and showed a 40% ethylene selectivity, which was twice as good as copper foil, stable for 40 hours. On the other hand, uniquely selectivity of CH₄ increased slightly over time in the long-term bulk electrolysis. This means that the C1/C2 generation ratio changes with changes in surface conditions of Cu(OH)₂ catalyst. Therefore, we introduced pre-treatment process, which is high negative potential reduction and low negative potential reduction to adjust the Cu²⁺/Cu⁺/Cu⁰ ratio of the surface. At this time we observed that while ethylene production was stable for a long time for samples with a high ratio of Cu²⁺, samples with missing Cu²⁺ decreased ethylene production and increased methane production rapidly within hours. Not only could the cause of C-C bond formation of copper catalyst be identified through this study, it could present a new strategy to maintain stability in oxide-derived copper catalyst in the future.