(191e) Strontium Copper Oxide Catalysts for Electrochemical CO2 Reduction Towards C2+ Products

Electrochemical CO₂ reduction (ECR) provides a solution that enables a shift to renewable energy sources and convert CO₂ to more valuable commodities and carbon-based fuels that suit the contemporary fuel structure. ECR produces myriad products, causing selectivity to be a challenge. While state-of-art ECR catalysts can achieve >95% Faradaic efficiency (FE) for CO production, obtaining high FEs for C₂₊ products that hold more economic value and energy density remains a challenge.

Various modifications on copper catalysts, such as facet and surface modification, surface ligand control, alloying and oxidation state modifications, have shown improved C₂₊ selectivity. Copper of higher oxidation state has attracted extensive attention. Cu⁺ species are known to facilitate C-C bond formation to ethylene through *CO_atop species¹, and Cu²⁺ in the form of doped copper oxides promotes ethanol and n-propanol production².

Herein, we report strontium copper oxide (SCO) catalysts that exhibit improved C₂₊ selectivity over copper. Preliminary data shows that SCO catalysts have lower C₂₊ onset potential compared to copper and retain Cu²⁺ species after 1 h of electrolysis. When operating in a gas diffusion electrode cell with 1.0 M potassium hydroxide, SCO catalysts at -0.8 V vs RHE all show three-fold increase in C₂₊ FE compared to copper powder (~1 m) of similar particle size (Figure 1). SCO-B (SrCuO₂) sample has ethylene FE of 25% measured at 5, 28 and 51 min during chronoamperometry, and SCO-C (SrCuO₂ and SrCu₂O₃) sample has 39% C₂₊ FE. SCO-A (SrCuO₂ and Sr₂CuO₃) sample also show higher conversion of CO₂ to ethylene. We also performed X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and X-ray absorption spectroscopy to further investigate the enhancement effect of strontium.