A reconstructed, surface S-coordinated gas-penetrable Cd hollow fiber for selective CO2 electroreduction to CO at high current density

Abstract

Efficient electrochemical CO₂ reduction reaction (CO₂RR) relies on not only the development of selective/active catalysts but also the smart design of advanced electrode configuration to address the critical issues of poor CO₂ mass transport and sluggish cathodic reaction kinetics. In this work, a reconstructed, surface S-coordinated low-melting-point (LMP) Cd hollow fiber (s-Cd HF) for CO electrosynthesis through CO₂ reduction is developed by partial hydrothermal sulfidation of a porous CdO HF (CdS@CdO HF), followed by in situ electroreduction during the CO₂RR. Attributed to the improved mass transfer, well-established triphasic interfaces, and abundant S-coordinated Cd active sites, the most active s-Cd HF, operated in gas-penetrable configuration, exhibits high electrocatalytic efficiency for CO₂-to-CO conversion with a faradaic efficiency (FE_CO) of over 90% across a wide potential range of 220 mV, and it displays a high CO partial current density (j_CO) of up to −125.1 mA cm⁻² at −1.01 V vs. the reversible hydrogen electrode (RHE). Notably, both FE_CO and j_CO remain constant over a 12 h stability test. This work demonstrates the great potential of employing a LMP metal hollow fiber to reinforce reaction kinetics for efficient CO₂ electroreduction.