Electrocatalytic CO₂ Reduction via a Permeable CNT Hollow-Fiber Electrode Incorporated with SnO₂ Nanoparticles

Abstract

Herein, we introduce a permeable carbon nanotube hollow-fiber electrode incorporated with SnO2 nanoparticles (SnO2–CHE) and propose a new type of gas-phase operational mode. Highly efficient electrochemical syngas production from CO2 is made possible by switching the operating mode from liquid phase to gas phase. The operation of SnO2–CHE in the conventional liquid-phase mode yielded a H2/CO ratio higher than 4.59, and the maximum jCO was only 2.16 mA/cm2 at −0.88 V (vs RHE) due to the low solubility and limited mass transfer of CO2 in liquid electrolytes. On the other hand, SnO2–CHE operated under the newly designed gas-phase mode achieved a H2/CO ratio ranging from 1.22 to 4.11 with a maximum jCO of 7.42 mA/cm2 at −0.76 V (vs RHE), which is proper for direct post-conversion processes. Therefore, this work could offer a new avenue for electrochemical syngas production using a nonprecious metal-based hollow-fiber type electrode, which allows for a large electrode surface area and high CO2 availability in gas-phase operation.