In-situ Fabrication Of Alloy Nanoparticles Decorated Solid Oxide Fuel Cell Composite Anode

Solid oxide fuel cell(SOFC)is a new type of energy conversion device with whole solid structure,which can directly convert chemical energy into electric energy.It has the advantages of low emission and wide fuel adaptability.In SOFCs,hydrogen is the main fuel with high catalytic performance property and no pollutants.But at the same time,the drawbacks of using hydrogen as fuel are obvious,such as high production cost and storage risk.At present,researchers are actively exploring effective ways to replace H₂fuels with carbon-containing fossil fuels.The conventional nickel cermet anode,such as Ni-YSZ(8mol%Y₂O₃stable Zr O₂),is difficult to obtain desirable fuel catalytic properties when using carbon-containing fuels due to carbon deposition.Mixed conducting perovskite-based anode generally exhibit coking resistance to carbon-containing fuels.However,these alternative perovskite based anodes typically show insufficient electrocatalytic activity for fuel oxidation.Loading nanocatalysis on the surface of electrode materials is a traditional modification method,which can effectively improve the catalytic activity of electrode materials.The in situ exsolution technique of perovskite oxides provides a more effective way to prepare electrode materials with uniformly supported nanocatalysts on the surface.Compared with the other loading method,the process of nanoparticles prepared by this method is simpler,and the size distribution is more uniform.In this study,we did systematically research on the basis of Pr_0.5Sr_0.5Fe O_3-?(PSF)perovskite materials.The exsolution process,structure,morphology evolution and catalytic mechanism were studied in detail by doping the perovskite with transition metal elements Ru,Nb and introducing A-site deficiency.Firstly,Pr_0.5Sr_0.5Fe O_3-?(PSF)and Pr_0.5Sr_0.5Fe_0.9Ru_0.1O_3-?(PSFR)were prepared.After high temperature reduction,nano-metal particles were exsolved on the surface of perovskite materials.The results showed that the ABO₃cubic perovskite structure gradually transformed into A₂BO₄layered perovskite structure(R-PSF,R-SPFR)after the exsolution of metal nanoparticles during the reduction process.The metal nanoparticles exsolved on the reduced PSF surface are consist of Fe,while Fe Ru alloy particles were found on the surface of reduced PSFR.The specific surface area of the Fe Ru alloy nanoparticles is larger than that of the Fe single metal particles,which effectively promotes the chemoadsorption and dissociation process of H₂and expands the three-phase region of the reaction.Subsequently,to investigate the effect of A site deficiency on the metal exsolution and material stability,(Pr_0.5Sr_0.5)_1-yFe_0.9Ru_0.1O_3-?(PSFR_y,0?y?0.2)perovskite precursor powders were prepared.The experimental results showed that a small amount of A site deficiency can inhibit the formation of heterogeneous phases generation in the formation of R-PSFR_y.The R-PSFR_0.1single cell reached a maximum powder density(P_max)of 0.747 W cm^-2at 800?C.To further obtain the anode materials with high catalytic performance and long-term stability,Pr_0.5Sr_0.5Fe_0.8Ru_0.1Nb_0.1O_3-?(PSFRN)material was synthesized by combustion method.Experimental results showed that Nb doping can enhance the morphology of exsolved metal nanoparticles,and maintain the ABO₃cubic structure of reduced PSFRN(R-PSFRN)during reduction process.The single cell based on R-PSFRN anode material reached a maximum power density of 0.809 and 0.548 W·cm^-2at 800°C with H₂and C₃H₈as fuel,respectively.Besides,a stable output of the single cell was obtained during the long turn tests.