چكيده به لاتين
The non-renewable and polluting nature of fossil fuels may create an energy power crisis in the future. Solid oxide fuel cells (SOFC) are one of the most efficient technologies to address this challenge in the energy industry. The anode, as one of the key components of the solid oxide fuel cell, plays a crucial role in its performance. Strontium titanate perovskite is one of the most important materials widely used as the anode in SOFCs. Doping and optimizing the calcination conditions are two critical approaches for improving anode performance in SOFCs. Among various elements, zinc has received less attention from researchers. In this study, strontium titanate precursor was synthesized via the sol-gel method. The dried gel was calcined at seven different temperatures: 550°C, 700°C, 900°C, 1000°C, 1050°C, 1100°C, and 1150°C, and an optimal calcination temperature was selected. In the next step, the calcined sample at the optimal temperature was impregnated with a zinc nitrate solution, and after drying, it underwent calcination at 1250°C. During this calcination step, the dwell time was chosen as a variable with three values of one, two, and four hours. Phase analysis and the examination of phase and chemical transformations were carried out using X-ray diffraction (XRD) and differential thermal and thermogravimetric analyses (DTA and TGA). The microstructure of zinc-doped samples and their comparison with reference samples were investigated using scanning electron microscopy (SEM). Finally, the electrochemical performance of some samples was measured using electrochemical impedance spectroscopy (EIS). According to the XRD results, 1150°C is the optimal temperature for the initial calcination of the gel to form the desired crystalline phase. It was also found that the incorporation of zinc into the strontium titanate structure is highly dependent on the calcination time, as zinc doping did not occur at dwell times of one and two hours, and the evidence pointed to doping only at a four-hour dwell time. Additionally, the incorporation of zinc into the perovskite structure prevents excessive grain growth at a calcination temperature of 1250°C. The EIS results also showed that the addition of zinc, whether as a dopant in the structure or as an impurity phase, leads to a decrease in electrochemical performance at room temperature.
