Development of Lanthanum based Perovskite Structured Cathode using Biogas as Fuel

Abstract

World is moving towards renewable energy sources to avoid carbon dioxide emission causing global warming and climate change. Solid oxide fuel cells SOFCs are one of the best alternatives for energy production due to its maximum energy conversion and zero/low emission. To use biogas as a clean and high energy conversion, SOFC is the good option. There are still few challenges which need to be addressed especially, intermediate to lower operating temperature SOFCs with biogas fuel. Perovskite structured has important role to meet the SOFC materials requirement. Therefore, in this project, Lanthanum based perovskite structured cathode materials were synthesized. The proposed materials are Lanthanum strontium cobalt ferric oxide ( La1−xSrxCo1−yFeyO3–δ (LSCF)), where x=0, 0.2,0.4,0.6,0.8 and y=0, 0.2,0.4,0.6,0.8. All samples are prepared by sol gel method. The functionalities of cathode materials ( La1−xSrxCo1−yFeyO3–δ (LSCF)) is investigated in this research. Prominent bands at peak positions 200–500, 464,520,546, 632, 675, 700 and 900 cm−1 wavelengths are observed through Raman spectra of LSCF cathodes, analogous to O-B-O bonds typical vibrations, Co2FeO4 phase, optical phonon mode ,Eg mode characteristics to the structure of R3c, rhombohedral structure of space group R3c vibration mode, A1g mode of a Co3O4 phase and B-O bonds stretching vibrations respectively. LSCF behaves as an excellent cathode material as it generates more oxygen ion vacancies which enhance the oxygen reduction reaction (ORR) at cathode side. Optical band gaps of LSCF samples (2a,2b,2c,2d,2e,2e10) and (2ao,2bo,2co,2do,2eo) are 4.37,4.09,4.22,4.24,4.38,4.26eV and 4.41,4.23,4.36,4.07,4.39eV which are attained by UV-Visible spectroscopy are good to functionalize LSCF cathode materials for solid oxide fuel cell (SOFC). DC Conductivity measurements of LSCF cathode samples are evaluated by four point probe method. The sample 2e- La0.2Sr0.8Co0.2Fe0.8O3–δ (LSCF) from citric acid series has maximum conductivity of 26.04 Scm-1 at 650 °C and 2co- La0.6Sr0.4Co0.6Fe0.4O3–δ (LSCF) and 2eo- La0.2Sr0.8Co0.2Fe0.8O3–δ (LSCF) from oxalic acid series exhibited maximum conductivity values of 22.32 and 31.25 Scm-1 at 650 ˚C temperature respectively. The effects of synthesized LSCF materials on performance for Solid Oxide Fuel Cell (SOFC) cathode were studied. The sample 2e shows maximum OCV of about 1.01 V and power density of about 0.159 mW/cm2 at temperature 650 ˚C while samples 2co, and 2eo shows the maximum OCV about 1.081 V, 1.02 V and power density about 0.184, 0.178 mW/cm2 respectively at temperature 650 ˚C. The results indicate that developed LSCF materials are good cathode for SOFC.