Electrochemical studies of perovskite cathode material for direct natural gas fuel cell

Natural gas is the most promising renewable energy source and its widespread availability ensured its importance for early applications in stationary fuel cells as a reliable and low cost fuel. Therefore it is very important to efficiently utilization of natural gas in low temperature fuel cells. Herein, we demonstrate the synthesis of perovskite material of Yttrium doped Sr_0.92Fe_xTi_1-xO_3-δ (x = 0.25, 0.30) (YSFT) by solid state reaction method and further investigated as a new cathode material for a low temperature solid oxide fuel cell fueled by natural gas. The YSFT is characterized by X-ray powder diffraction, Brunauer-Emmett-Teller and scanning electron microscopy. The perovskite structure is achieved at relatively low temperature (850 °C). The average crystalline size is found 28 nm and 36 nm for x = 0.25 and 0.30 respectively. TGA results showed the lattice oxygen loss of YSFT is about 0.206% in its original weight in the temperature range of 25-1000 °C. The maximum electronic conductivities of 2.3 Scm^-1 and 2.07 Scm^-1 are achieved for x = 0.25 and x = 0.30 at 550 °C in air atmosphere respectively. It is observed that the oxygen reduction is enhanced due to the perovskite crystal structure and oxygen vacancies play an important role in the redox reaction to improve the performance of fuel cell. The YSFT perovskite cathode material based fuel cell with natural gas have achieved the power density of 250 mWcm^-2 for x = 0.25 at 550 °C. The fuel cell device has demonstrated very stable results by running continuously for 5 h with domestic available natural gas.