In this study, nickel oxide–Y₂O₃-doped ZrO₂ (NiO-YSZ) composite powder as an anode material was synthesized using a cost-effective combustion method for high-temperature solid oxide fuel cell (SOFC). Further, the effects of sintering temperatures (1200, 1300, and 1400 °C) were studied for its properties in relation to the SOFC performance. The prepared and sintered NiO-YSZ materials were characterized for their surface morphology, composition, structure, and conductivity. The cubic crystalline nature of NiO and YSZ was sufficed by X-ray diffraction, and SEM images revealed an increase in the densification of microstructure by an increase in the sintering temperature. EDX spectrum confirmed the presence of nickel, yttrium, and zirconia without any impurity. Conductivity measurements, under a hydrogen environment, revealed that NiO-YSZ, sintered at 1400 °C, exhibits better conductivity compared to the samples sintered at lower temperatures. Electrochemical performance of button-cells was also evaluated and peak power density of 0.62 Wcm⁻² is observed at 800 °C. The citrate combustion method provided peak performance for cells containing anode sintered at 1200 °C, which was previously reported at higher sintering temperatures. Therefore, the citrate combustion method is found to be a suitable route to synthesize NiO-YSZ at low sintering temperature.

Perovskite materials have gained a lot of interest in solid oxide fuel cell (SOFC) applications owing to their exceptional properties; however, ideal perovskites exhibit proton conduction due to availability of low oxygen vacancies, which limit their application as SOFC electrolytes. In the current project, Sm was doped at the B-site of a BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ perovskite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ electrolytes were synthesized through a cost-effective coprecipitation method and were sintered at a low sintering temperature. The effects of samarium (Sm) doping on the electrochemical performance of BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ were investigated. X-ray diffraction (XRD) analysis confirmed that the BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ electrolyte material retained the perovskite structure. The secondary phase of Sm₂O₃ was observed for BaCe_0.4Sm_0.3Zr_0.2Y_0.1O_3-δ. Scanning electron microscopic (SEM) imaging displayed the dense microstructure for all the compositions, while prominent crystal growth was observed for composition x = 0.3. The formation of the perovskite structure and the presence of the hydroxyl groups of metal oxides for all the compositions were confirmed by Fourier transform infrared spectroscopy (FTIR). An increased symmetrical disturbance was also observed for the increased doping ratio of the Sm. Thermogravimetric analysis (TGA) of all the compositions showed no major weight loss in the SOFC operating temperature range. It was also noted that the conductivity of BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ gradually decreased with the increased contents of the Sm metal. The maximum power density of 390 mW cm⁻², and an open-circuit voltage (OCV) of 1.0 V at 600 °C, were obtained, showing that BaCe_0.7-xSm_xZr_0.2Y_0.1O_3-δ, synthesized by a cost-effective method and sintered at a low temperature, can be used as a proton-conducting electrolyte for IT-SOFCs.