An effective strategy to enhance cathodic performance of low-temperature solid oxide fuel cells through Mo-doping

This article focuses on the improvement of molybdenum doping on the cathode performance of Ba0.6Sr0.4Co0.85Nb0.15O3-δ (BSCN) based perovskite materials. The original BSCN material and three modified materials Ba0.6Sr0.4Co0.85Nb0.1Mo0.05O3-δ (BSCNM0.05), Ba0.6Sr0.4Co0.85Nb0.05Mo0.1O3-δ (BSCNM0.1), and Ba0.6Sr0.4Co0.85Mo0.15O3-δ (BSCM) with different Mo doping amounts (5mol%,10mol%, and 15mol%) are successfully prepared by the sol-gel process. The effects of Mo doping on the crystal structure, conductivity, thermal expansion coefficient, oxygen reduction reaction (ORR) activity, and electrochemical performance of the material are systematically evaluated through techniques such as X-ray diffraction analysis, thermal induced characterization, electrochemical impedance spectroscopy analysis, and single cell performance evaluation. Experimental data analysis shows that Mo doping can improve the conductivity and suppress thermal expansion effects, and the electrochemical performance has also been significantly improved. Based on surface chemical state analysis using X-ray photoelectron spectroscopy (XPS), 5mol% Mo doping can lead to higher adsorbed oxygen concentration, which is beneficial for enhancing ORR activity. Density functional theory (DFT) calculations further confirm the promoting effect of Mo doping on ORR reaction. At an operating temperature of 600℃, the BSCNM0.05 cathode material exhibits significantly optimized electrochemical impedance characteristics, with an area specific resistance (ASR) reduced to 0.048 Ω cm2, which is 32.39% lower than the undoped BSCN matrix material. At the same temperature, the anode supported single cell assembled with this cathode achieves a peak power density (PPD) of 1477 mW cm-2, which is 30.71%, 56.30%, and 171.50% higher than BSCN, BSCNM0.1, and BSCM respectively. The better ORR activity and electrochemical performance indicate that BSCNM0.05 has considerable potential as a cathode material for low-temperature solid oxide fuel cells (LT-SOFCs).