Preparation of trimetallic electrocatalysts by one-step co-electrodeposition and efficient CO₂ reduction to ethylene

Use of multi-metallic catalysts to enhance reactions is an interesting research area, which has attracted much attention. In this work, we carried out the first work to prepare trimetallic electrocatalysts by a one-step co-electrodeposition process. A series of Cu-X-Y (X and Y denote different metals) catalysts were fabricated using this method. It was found that Cu₁₀La₁Cs₁ (the content ratio of Cu²⁺, La³⁺, and Cs⁺ in the electrolyte is 10 : 1 : 1 in the deposition process), which had an elemental composition of Cu₁₀La_0.16Cs_0.14 in the catalyst, formed a composite structure on three dimensional (3D) carbon paper (CP), which showed outstanding performance for CO₂ electroreduction reaction (CO₂RR) to produce ethylene (C₂H₄). The faradaic efficiency (FE) of C₂H₄ could reach 56.9% with a current density of 37.4 mA cm⁻² in an H-type cell, and the partial current density of C₂H₄ was among the highest ones up to date, including those over the catalysts consisting of Cu and noble metals. Moreover, the FE of C₂₊ products (C₂H₄, ethanol, and propanol) over the Cu₁₀La₁Cs₁ catalyst in a flow cell reached 70.5% with a high current density of 486 mA cm⁻². Experimental and theoretical studies suggested that the doping of La and Cs into Cu could efficiently enhance the reaction efficiency via a combination of different effects, such as defects, change of electronic structure, and enhanced charge transfer rate. This work provides a simple method to prepare multi-metallic catalysts and demonstrates a successful example for highly efficient CO₂RR using non-noble metals.