The Synthesis Of Co-based Perovskite And The Study Of Its Electrocatalytic HER And OER Performance

Hydrogen Evolution Reaction（HER）and Oxygen Evolution Reaction（OER）are two key components reactions in water splitting.It is great significance for the overall water decomposition reaction to develop an easy to obtain,efficient and stable dual-function electrocatalyst material at room temperature.In this thesis,Pr Ba1-x Co2O5+δ、Pr0.94Ba Co2-x Fex O5+δand Pr0.48-x Agx Ba Co O3-δperovskite oxide have been synthesized based on mixed ionic and electronic conductor（MIEC）Pr Ba Co2O5+δwith double perovskite structure,through the cation-deficiency and doping strategy.In order to develop new electrocatalyst materials which are easy to prepare and high efficiency,their properties as electrocatalyst materials for hydrogen evolution and oxygen evolution were studied.Pr Ba1-x Co2O5+δ（x=0-0.06）double perovskite oxide were synthezied by a conventional solid-state reaction.Herein,a hierarchical double/simple perovskite heterostructure（PB0.94C-HDSPH）has been successfully synthesized by a facile in situ exsolving from Ba-deficient double perovskite Pr Ba0.94Co2O5+δ.At the current density of10 m A cm^-2,the overpotential of PB0.94C-HDSPH‖Ru O2 electrode is 350 m V,which has higher current density than the most advanced Pt/C‖Ru O2 electrode at the battery voltage of more than 1.85 v,and has long-term stability and superior performance of electrolyzing water.In addition,PB0.94C-HDSPH also has excellent catalytic activity at high current density(>350 m A cm^-2),even better than the commercial Pt/C electrode material.The good charge transfer ability of PB0.94C-HDSPH and its abundant surface oxygen species(adsorbed H2O and O2^2-/O^-)are more conducive to the promotion of catalytic activity.Pr0.94Ba Co2-x Fex O5+δ（x=0-0.3）double perovskite oxide were synthezied by Solution burning.A small amount of Fe doping can improve the thermodynamic stability of electrocatalyst materials.At the current density of 10 m A cm^-2,the overpotential of PBCF-2/Ru O2‖PBCF-2/Ru O2 electrode is 350 m V.When the electrode voltage is more than 1.80 v,its catalytic activity is better than that of Pt/C.The size difference between the doped Fe²⁺and Co⁴⁺ions is small,which will increase the concentration of Co⁴⁺.Co⁴⁺can promote the formation of oxyhydrogen species and facilitate the adsorption of O2 on the surface of the material.And the perovskite catalyst material after introducing Fe²⁺has a larger specific surface area,which can increase the reaction contact surface and promote the mass and charge transfer between the electrode and the electrolyte.Pr0.48-x Agx Ba Co O3-δ（x=0-0.06）single perovskite oxide were synthezied by Sol-gel.The single perovskite electrocatalyst material（e-PABC）with heterogeneous structure and surface silver nanoparticles was prepared by chemical reduction method.In oxygen evolution reaction,when the current density is 10 m A cm^-2,the overpotential of Pr0.43Ag0.05 Ba Co O3-δ（PABC-5）is 370 m V,mainly due to its large surface coefficient and good oxygen surface exchange kinetics.In the hydrogen evolution reaction,when the current density is 10 m A cm^-2,the overpotential of e-PABC is 151 m V.It is because the dissolution of nanometer silver increases the oxygen vacancy concentration and conductivity of the catalyst material,changes the surface properties of its oxide,and further improves HER catalytic activity.