Enhanced CO2 electrolysis through modulation of oxygen vacancies

Abstract

Conventional metal and cermet cathodes are easily oxidized during CO₂ electrolysis, which seriously affects the electrolysis performance of electrolysis cells. The excellent durability and low cost of ceramic cathodes make them a promising alternative electrode. However, their catalytic activity is limited. In this work, we prepared a series of perovskite materials La_0.6Sr_0.4Cr_1−xFe_xO_3−δ (LSC_1−xF_x, x = 0–1) by synergistic doping at the B site to improve the catalytic activity. Replacing Cr with Fe can increase the concentration of low-valent Fe ions linked to oxygen vacancies, which leads to an increase in oxygen vacancies and thus improves the activity of CO₂ electrolysis. Among the LSC_1−xF_x (x = 0–1) cathode materials, the LSC_0.25F_0.75 sample exhibits the highest electrochemical catalytic activity with a CO production rate of 5.32 mL min⁻¹ cm⁻² at 1.6 V and 850 °C, which is about 5 times that of other LSC cathode materials. In addition, its current efficiency can reach 96.4% during electrolysis of CO₂. The electrolytic performance remained stable during the high temperature test for up to 100 h, further demonstrating its excellent thermal stability.