Improving the performance for direct electrolysis of CO2 in solid oxide electrolysis cells with a Sr1.9Fe1.5Mo0.5O6−δ electrode via infiltration of Pr6O11 nanoparticles

Abstract

Direct CO₂ electrolysis using solid oxide electrolysis cells (CO₂-SOECs) holds promise to efficiently convert carbon dioxide to carbon monoxide and oxygen. Cathodes with desirable catalytic activity and chemical stability play a critical role in the development of direct CO₂-SOECs. Although Sr₂Fe_1.5Mo_0.5O_6−δ (SFM) has exhibited promise for direct CO₂-SOECs due to its redox stability, it suffers from insufficient activity for the CO₂ reduction reaction (CO₂RR). Here we report interface engineering of nanosized Pr₆O₁₁ on the SFM cathode obtained through infiltration to promote the CO₂RR performance for direct CO₂-SOECs. The effect of Pr₆O₁₁ loading on the performance of the CO₂RR is systematically investigated. At 800 °C, the current density of the Pr₆O₁₁ infiltrated SFM cathode with an optimum Pr₆O₁₁ loading of 14.8 wt% reaches 1.61 A cm⁻² at 1.5 V, more than double that of the SFM cathode (0.76 A cm⁻²) under the same operating conditions. X-ray photoelectron spectroscopy (XPS) characterization and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis indicate that the adsorption ability of CO₂ on the SFM cathode has been significantly improved by the formation of Pr₆O₁₁. Temperature-programmed desorption (TPD) of CO₂ measurements further manifest that a 14.8 wt% Pr₆O₁₁-SFM cathode has better CO desorption capacity. In addition, polarization resistance of the SFM cathode has significantly decreased with the addition of Pr₆O₁₁. Three-electrode measurement was used to analyze the improved electrode kinetics. These results demonstrate that the formation of Pr₆O₁₁ in the SFM cathode through infiltration is a promising approach for increasing CO₂RR activity for CO₂-SOECs.