f-p-d coupling-induced bonding covalency boosts CC coupling in electrocatalytic CO2 reduction over ErOCu sites

Abstract

The copper-based electrocatalysts feature attractive potentials of converting CO₂ into multi-carbon (C₂₊) products, while the instability of CuO often induces the reduction of Cu⁺/Cu⁰ catalytic sites at the cathode and refrains the capability of stable electrolysis especially at high powers. In this work, we developed an Erbium (Er) oxide-modified Cu (ErOCu) catalyst with enhanced covalency of CuO and more stable active sites. The f-p-d coupling strengthens the covalency of CuO, and the stability of Cu⁺ sites under electroreduction condition is critical for promoting the CC coupling and improving the C₂₊ product selectivity. As a result, the ErOCu sites exhibited a high Faradaic efficiency of C₂₊ products (FE_C2+) of 86 % at 2200 mA cm⁻², and a peak partial current density of |j_C2+| of 1900 mA cm⁻², comparable to the best reported values for the CO₂-to-C₂₊ electroreduction. The CO₂ electrolysis by the ErOCu sites was further scaled up to 100 cm² to achieve high-power (∼200 W) electrolysis with ethylene production rate of 16 mL min⁻¹.