Synergistic oxidation-induced exsolution–reconstruction enables heterostructured Cu/Zn hollow fibers for high current density syngas electrosynthesis

Abstract

Electrocatalytic CO₂ reduction (CO₂RR) to produce syngas is a highly attractive strategy for achieving carbon neutrality, yet it remains challenging to achieve a tunable CO/H₂ ratio at high current densities due to the lack of low-cost and efficient electrocatalysts and effective electrode working configurations. In this work, a gas-penetrable electrode (GPE) based on heterostructured Cu/Zn hollow fibers (Cu/Zn HFs) is developed through a synergistic oxidation-induced exsolution–reconstruction strategy. Owing to the enhanced mass transfer and the abundance of well-established triphasic reaction interfaces, Cu/Zn HF GPE exhibited an excellent faradaic efficiency (FE) of 100% for syngas electrosynthesis at −1.09 V vs. the reversible hydrogen electrode (RHE) and a high current density of −290.8 mA cm⁻². Additionally, the controllable CO/H₂ ratios of 1 to 3.2 could be obtained over a wide potential window, from −0.63 V to −1.09 V vs. RHE. More importantly, Cu/Zn HF GPE maintained a stable FE_syngas of 85% and a current density of −180 mA cm⁻² for prolonged CO₂RR over a period of 18 h. In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) characterization revealed that the formation of strongly coupled Cu/Zn interfaces is effective for lowering the formation energy of the key *COOH intermediate, promoting the reaction kinetics of CO₂ reduction to CO, and thereby improving the syngas production efficiency. This study provides new insights into the development of heterostructured electrocatalysts via the synergistic engineering of the electrode configuration and active sites for efficient syngas production from CO₂RR.