Study On The Performance Of NdBaFe_2-xCo_xO_5+? Double Perovskites Decorated With Co-Fe Alloy Nanoparticles As Anode Materials For Solid Oxide Fuel Cells

Solid oxide fuel cells(SOFC),which can be considered as the most promising electrochemical devices for direct conversion of chemical energy of fossil fuels into electrical energy,offer an novel solution to the looming environment and energy environment crisis.SOFC has various special advantages,including high energy conversion efficiency,environmental friendliness and low pollution,so it has attracted more and more attention.Most importantly,SOFC can operate on most hydrocarbon fuels.In this work,a new cobalt-doped pre-reduced PR-NdBaFe_2-xCo_xO_5+?(x=0,0.1,0.2,PR-NBFC0,PR-NBFC10,PR-NBFC20)double perovskite anode material was prepared.Co-Fe alloy nanoparticles are precipitated on the anode substrate under a reducing atmosphere.This anode material is expected to exhibit higher electrochemical performance under hydrocarbon fuels.In order to promote the precipitation of alloy nanoparticles from the perovskitelattice,adefectPR-Nd Ba_xFe_1.8Co_0.2O_5+?(x=0.02,x=0.04,PR-0.02NBFC20,PR-0.04NBFC20)was introduced in the Ba site.The effect of site defects on the morphology and quantity of alloy nanoparticles,and the effect of nanoparticles on the performance of anode materials is analyzed.The double perovskite PR-NdBaFe_2-xCo_xO_5+?anode material with precipitation of Co-Fe alloy was prepared by the sol-gel method under 5%H₂/Ar reduction conditions.The XRD results of this material indicate that cobalt is successfully doped into the double perovskite host material,and Co-Fe alloy nanoparticles are precipitated.The electron microscope image proves that the surface of the sample is evenly embedded with Co-Fe alloy nanoparticles with a diameter of about 50nm.XPS results prove that the sample has elemental Fe and Co in a reducing atmosphere,and the quantitative analysis elemental ratio is about Co_0.72Fe_0.28.Conductivity analysis proves that this series of materials is higher than the requirement of SOFC anode material conductivity.The maximum power density values of single cell of PR-NBFC0,PR-NBFC10 and PR-NBFC20 at 850? are 842,1110 and 1247 m W cm^-2,respectively.Stability tests show that this series of anode materials exhibit stable performance within 100 h of operation.The double perovskite PR-Nd Ba_1-xFe_1.9Co_0.2O_5+?(x=0.02,0.04)based material was prepared by the sol-gel method.Through the Ba site defect and Fe site doping,the aim is to prepare SOFC anode materials with excellent performance.XRD results showed that the main structure of the sample did not change,and there was a peak of Co-Fe alloy nanoparticles.Scanning electron microscopy results show that a large number of nanoparticles are deposited on the surface of the sample,with a particle size of about 40nm.As the degree of A-site defects increases,both conductivity and electrochemical impedance first decrease and then increase.The maximum power density of the sample PR-NB_xFC20(x=0.02,0.04)/SDC/LSGM/NBCFC single cell using hydrogen as fuel at 850? is 1378 and 1114 m W cm^-2,respectively.