Robust cobalt-free perovskite type electrospun nanofiber cathode for efficient electrochemical carbon dioxide reduction reaction

Abstract

Solid oxide electrolysis cell (SOEC) is a very competent device for cleanly and efficiently electrochemical carbon dioxide reduction reaction (CO2RR) to high-value added carbon monoxide (CO). However, the low specific surface area and the three-phase boundary (TPB) as the disadvantages of traditional powdery cathode hinder the development of SOEC. Herein, a cobalt-free perovskite oxide Sr2Fe1.5Mo0.5O6-δ nanofiber (SFM-NF), synthesized by the electrospinning technique, is explored as the cathode for CO2RR. The cathode polarization resistance measured by the symmetric cell is reduced from 2.01 Ω cm2 for nanoparticle (SFM-NP) cathode to 1.61 Ω cm2 for SFM-NF cathode at 800 °C in CO:CO2 (2:1) atmosphere. In addition, the corresponding current density of the single cell is greatly increased from 0.732 to 1.173 A cm−2 under 2.0 V and 800 °C. These results all indicate the enhancement of CO2RR catalytic activity. The distribution relaxation of times analysis results for the electrochemical impedance spectra reveal that the increase of surface oxygen species at the interface for SFM-NF cathode allows for a more rapid oxygen ion transport path, and accelerates the CO2RR in a SOEC. This work provids an insightful way for the optimization mechanism of electrode, guiding the development of robust and efficient CO2RR device.