A novel fuel electrode enabling direct CO2 electrolysis with excellent and stable cell performance

Abstract

Solid oxide electrolysis cells (SOECs) can directly convert CO₂ to CO and O₂ that are important building blocks for chemical production and other applications. However, the use of SOECs for direct CO₂ electrolysis has been hampered mainly due to the absence of a stable, highly catalytically active and cost effective cathode (fuel electrode) material. Here we report a ceramic SOEC cathode material of perovskite-structured Sr_1.9Fe_1.5Mo_0.4Ni_0.1O_6−δ for direct CO₂ electrolysis. By annealing at 800 °C in H₂, homogeneously dispersed nano-sized NiFe alloy nanoparticles are exsolved from the Sr_1.9Fe_1.5Mo_0.4Ni_0.1O_6−δ perovskite lattice. The exsolved NiFe nanoparticles significantly enhance the chemical adsorption and surface reaction kinetics of CO₂ with the cathode. SOECs with the novel cathode have demonstrated a peak current density of 2.16 A cm⁻² under an applied voltage of 1.5 V at 800 °C and have demonstrated stable direct CO₂ electrolysis performance during 500 h of operation under current density above 1 A cm⁻² at 800 °C.