Producing hydrogen by electrocatalytic water splitting is considered to be an effective solution to optimize the energy structure and promote the development of clear energy.The development of efficient and stable OER catalysts is the key to improve the efficiency of electrocatalytic water splitting for hydrogen production.The flexible valence states of transition metal elements in perovskite oxides enables them to exhibit excellent electrocatalytic OER performance,and their highly tunable elemental structure and composition also provide room for further improvement of electrocatalytic performance.In this work,through the element substitution and calcination temperature control,perovskite oxides PrxSr1-xCoyFei-yO3-δ with different Pr doping ratios were synthesized,the crystal structure and morphology were studied,and the internal factors which involved the change of electrocatalytic performance were also investigated,respectively.(1)A series of perovskite oxides PrxSr1-xCoO3-δ(x=0.1,0.3,0.5,0.7,0.9)were synthesized by the sol-gel method,and the crystal structure and morphology of PrxS1-xCoO3-δ calcined at 950℃ and 700℃were studied.The crystal structure of Pr0.1Sr0.9CoO3-δ,Pr0.3Sr0.7CoO3-δ,Pr0.5Sr0.5CoO3-δ calcined at 950℃(denoted as PSC19-950,PSC37-950,PSC55-950,respectively)are both cubic,while PSC73-950 and PSC91-950 exhibited orthorhombic phase,The particle size of PrxSr1-xCoO3-δ calcined at 700℃ is significantly smaller than that at 950℃,but only PSC55-700,PSC73-700,PSC91-700 are pure phase,and its crystal structure are as same as that of 950℃.The samples with Pr doping ratio of 0.1 and 0.3 are composed of cubic Pr0.5Sr0.5CoO3-δ and hexagonal SrCoO3-δ.The electrocatalytic performance of those perovskite oxides were both test in 1M KOH,among these,PSC55-700 exhibited the best catalytic activity.The results of TEM and electrochemical tests show that the increase of specific surface area contributed to the improvement of OER performance between 950℃and 700℃.XPS show that the optimization of surface Co valence state and the increase of O22-/O-by Pr substitution leads to the improvement of catalytic activity.(2)A series of perovskite oxides Pr0.5Sr0.5CoxFe1-xO3-δ(x=0.7,0.8,0.9)were synthesized to investigate the changes in structure and OER catalytic performance.XRD shown Pr0.5Sr0.5Co0.7Fe0.3O3-δ(denote as PSCF5573),Pr0.5Sr0.5Co0.8Fe0.2O3-δ(denote as PSCF5582),Pr0.5Sr0.5Co0.9Fe0.1O3-δ(denote as PSCF5591)are both in cubic phase.Electrochemical test results show that PSCF5582 calcined at 700℃ exhibited the best OER catalytic performance with an overpotential of 320 mV.The deep research shows that the improvement comes from a larger surface area,stronger charge transfer ability and optimized eg obit electron filling.Besides,DFT calculations show that the O p band center of PSCF5582 is closer to the Fermi level than SCF82,which promotes the OER catalytic performance. |