Preparation And Properties Of Nitrogen-containing Perovskite Catalysts

In order to achieve the commercialization and reduce the cost of the protonexchange membrane fuel cell (PEMFC), tremendous progress has been focused onthe study of non-noble metal electrocatalysts.In this article, La0.7Sr0.3MnO3perovskite nanomaterials is synthesized by sol-gelmethod and the stability of them in NH3is also researched. The results indicate thatLa0.7Sr0.3MnO3perovskite nanomaterials is not nitrated but decomposed in NH3, andthe main phase of the product may be SrMnO2.694, MnO1-xNx,(La0.7Sr0.3)2MnO4-δNδ(0≤δ<4). After heat treated in NH3, their electrochemical activity is also decreasedsignificantly.So we report a method to dope nitrogen into La2Zr2O7nanoparticles which ismore stable in NH3by the sol-gel process combined with ammonolysis. But XRDresults indicate that the structure of N-dopped La2Zr2O7is not changed frompyrochlore structure to perovskite. And XPS results indicate that the nitrogen contentin La2Zr2O7is approximately0.92at.%, with a stoichiometry of La2Zr2O6.85N0.15.Compared to the ORR activity of La2Zr2O7, that of the N-doped La2Zr2O7isconsiderably enhanced, the onset potential reaches0.902V vs.RHE, and the electro-chemical stability is inproved too. Density functional theory (DFT) calculationsindicate that the band gap in LaZrN2O is1.812eV, lower than that in La2Zr2O7pyrochlore, which may be one of the factors that contribute to the improvement.In perovskite-type materials, organic-metal perovskite have recently beenfocused widespread. In this article, CH3NH3PbI3perovskite is also successfullysynthesized by optimizing solution-proccess. The TG spectrum shows that theperovskite crystal is thermally stable when the temperature is less than300℃, butquickly decomposes above this temperature due to the decomposition of the CH3NH3Icomponent in CH3NH3PbI3. On the other hand, the stability of CH3NH3PbI3perovskiteis unstable in polar solvents. It is noteworthy that CH3NH3PbI3will be completely decomposed when contacted with water with the final product of PbI2and I2.