Electrocatalytic Reduction of CO2 to Long-Chain Hydrocarbons on (FeCoNiCu)3O4 Medium Entropy Oxide Nanoparticles

Abstract

Electrocatalytic CO₂ reduction reaction (CO₂RR) to valuable multicarbon (C₂₊) fuels and chemicals presents a promising strategy to mitigate atmospheric CO₂ accumulation and promote the closure of the carbon cycle. However, significant challenges persist in achieving both high product selectivity and sustained stability in the CO₂RR. In this study, the catalytic performance of (Fe,Co,Ni,Cu)₃O₄ medium entropy oxide (MEO) nanoparticles anchored on reduced graphene oxide (rGO) was evaluated for the CO₂RR. The MEO–rGO catalyst exhibited remarkable activity, achieving a cathodic current density of −0.5 A cm^–2 at −1.7 V, significantly outperforming bare nickel foam (−0.15 A cm^–2). Additionally, the catalyst demonstrated a high total Faradaic efficiency (FE) of 60.3% for C₂₊ products, comprising 30.6% C₅H₁₂O and 29.7% C₅H₁₀O. This exceptional selectivity toward long-chain hydrocarbons is attributed to the enhanced C–C coupling on the MEO–rGO surface, facilitated by reduced energy barriers. Density functional theory (DFT) calculations further revealed that the adsorption and reduction of CO₂ on the (Fe,Co,Ni,Cu)₃O₄ MEO surface are energetically favorable processes.