CuMoRu ternary alloy nanorods: synergy effect of metal elements enables efficient electrochemical CO2 reduction towards selective ethanol production

Abstract

Copper (Cu)-based alloy catalysts are promising for converting CO₂ to hydrocarbons and oxygenated compounds through the electrochemical CO₂ reduction reaction (eCO₂RR). However, it remains a great challenge to selectively obtain ethanol among the C₂ products from eCO₂RR. Herein, CuMoRu alloy nanorod catalysts were synthesized by a one-pot wet chemistry method. Compared with Cu, CuRu and CuMo catalysts, CuMoRu is more efficient in converting CO₂ to ethanol in eCO₂RR. Theoretical calculations illustrate that Mo and Ru doping onto a Cu substrate leads to suppressed hydrogen evolution reaction (HER), enhanced *CO production, and the formation of C₂ products occurs via an asymmetrical *CO–*CHO coupling pathway. Additionally, the stabilization of CH₂CHO* and enhanced H₂O dissociation benefit ethanol production by breaking the scaling relationship. In a flow cell, CuMoRu displays a faradaic efficiency of 63.0% and 51.8% for C₂ products and C₂H₅OH at −1.1 V vs. the reversible hydrogen electrode (RHE), respectively, and the corresponding total and C₂ partial current density is 290 and 182.7 mA cm⁻² in an alkaline electrolyte, respectively. In situ Raman spectroscopy demonstrated that the CuMoRu interface exhibits increased CO_b (CO on bridging site) coverage and local pH, and the directly observed vibrational bands from *COCHO confirm the asymmetrical *CO–*CHO coupling mechanism. This work highlights the importance of alloying metal with Cu for the selective production of C₂ products in eCO₂RR.