Preparation And Property Of BaCe_0.8Y_0.2O_3-α、Ba₃Ca_1.18Nb_1.82O_9-α And Composite Material

With the rapid development of the global economy,energy and environmental protection have become major issues that must be faced in sustainable development.Perovskite-type proton conductors have broad application prospects in the fields of hydrogen sensors,fuel cells,aluminum liquid dehydrogenation,atmospheric synthesis of ammonia and catalysts.In traditional perovskite-type proton conductor materials,there are mainly two structures:ABO3 and A3(B’B"2)O9.In the ABO3 structure,BaCeO3 matrix The material has the highest conductivity,but its chemical stability in CO2 and water vapor is poor,and the number of proton migration rapidly decreases at 500℃;in the A3(B’B"2)O9 structure,Ba3Ca1.18Nb1.82O9-α has the highest conductivity.In this paper,BaCe0.8Y0.2O3-α(BCY),Ba3Ca1.18Nb1.82O9-α(BCN),and(1-x)BCYxBCN(BCY-BCN,x=0.01、0.05、0.15、0.20)with different molar ratios were prepared by solid-phase synthesis composite proton conductor.The phase composition and microscopic morphology were studied by XRD and SEM characterization methods.The Nyquist diagrams of the prepared proton conductor samples in the range of 400～800 ℃ under different oxygen partial pressures of pH2O=3.17 and 0.61 kPa were measured by AC impedance spectroscopy.The conductivity,pre-finger factor and conductivity activation energy were calculated by fitting,and the number of carrier migration of the sample was calculated.Finally,its stability in CO2 atmosphere was tested.Research indicates:(1)The BCY,BCN and BCY-BCN composite proton conductors were prepared by solidphase synthesis.Analysis of XRD results showed that the samples after sintering at 1600℃ for 10 h can form characteristic peaks of the perovskite phase without other impurity peaks;SEM results It shows that the synthesized material has uniform grain size,compact surface and no pores.(2)The analysis of the results of electrochemical impedance spectroscopy shows that:the conductivity of BCY gradually increases with the increase of temperature under different oxygen partial pressures at 400～800 ℃,and the conductivity can reach 3×10-2 S·cm-1 in pHf2O=3.17 kPa,50%O2 at 800℃;Under different oxygen partial pressures at 400～800 ℃,the conductivity of BCN gradually increases with temperature,and the conductivity can reach 2.28×10-3 S·cm-1 in pH2O=3.17 kPa,50%O2 at 800 ℃;BCY-BCN composite proton conductor,its conductivity gradually decreases with the increase of BCN content,and the conductivity activation energy gradually increases.(3)BCY,BCN and BCY-BCN composite materials can reach 0.9 proton transfer number at 400℃,which is characterized by proton conductivity.With the increase of temperature,the proton transfer number of the proton material gradually decreases,which is expressed as protonoxygen ion Electronic mixed conductor.The electron mobility of BCY is low,and the oxygen ion mobility of BCN is low;with the increase of BCN content,the proton mobility of the composite material gradually increases,and the oxygen ion and electron mobility gradually decrease.(4)According to XRD analysis,BCY has poor stability in CO2 atmosphere and will react with CO2 to form BaCO3 and CeO2;BCN can remain stable in CO2 atmosphere without reaction;BCY-BCN composite proton conductor increases with the increase of BCN content,The stability under CO2 atmosphere is gradually enhanced.