Structural Regulation Of Barium Cobaltate And Its Electrocatalytic Performance For Water Splitting

Hydrogen,which possesses several appealing advantages including clean combustion products and sustainable regeneration,has been regarded as one of the most ideal energy sources to replace traditional energy.Electrocatalytic water splitting is a kind of hydrogen production technology with two electrodes electrolyzer,in which oxygen evolution reaction（OER）is carried out on the anode and hydrogen evolution reaction（HER）is carried out on the cathode.The sluggish kinetics of oxygen evolution reaction and hydrogen evolution reaction seriously reduce the catalytic efficiency of electrocatalytic water splitting.Therefore,it is extremely urgent to develop and design an efficient and stable catalyst for the development of electrocatalytic water splitting technology.Perovskite oxides have become potential catalyst candidates due to the price moderate and tunable electronic configuration.However,perovskite oxides have small specific surface areas,low electrical conductivity,and its inherent activity still cannot meet people’s needs.To solve the above problems,a series of catalyst samples(BCOF_0.1,BCOF_0.2,BCOF_0.4,BCOCl_0.2)with different ratios and different anions were prepared by using F^-or Cl^-anion as heterogeneous ion doping into the O site of BaCoO_3-δ.The phase structure and morphology of the catalysts were characterized by X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The electrochemical test and the overall water splitting test results show that BCOF_0.2 has better electrocatalytic water splitting performance,The OER and HER show an overpotential of 404 and 388 m V at 10 m A·cm^-2,respectively,On the basis of anion doping,the transition metal ions are doped into the B site of BCOF_0.2.The electrochemical test and the overall water splitting performance test shown that BCOF_0.2-Fe_0.5,which Fe ion doping at B-site and doping amount of 0.5,has low overpotential and Tafel slope,and exhibits better overall water splitting catalytic performance.Subsequently,A series of catalyst samples with different proportions of Sr were prepared by introducing Sr element into the A site of BCOF_0.2-Fe_0.5.Among them,the electrocatalytic activity of BCOF_0.2-Sr_0.8Fe_0.5 was further improved.The OER and HER showed an overpotential of 341 and 303 m V at 10 m A·cm^-2,respectively,and the overall water splitting showed a voltage of 1.658 V at 10 m A·cm^-2.When the electrolyte is simulated seawater,there is no difference in the overall water splitting performance of BCOF_0.2-Sr_0.8Fe_0.5.According to XRD,EIS and Density Functional Theory（DFT）calculation,it is proved that the introduction of Sr changes the crystal structure,enhances the electrical conductivity of the catalyst,and greatly increases the oxygen vacancy,which is conducive to the adsorption of reaction intermediates on the catalyst.Therefore,its electrocatalytic water splitting performance is greatly improved.In addition,the catalyst showed excellent durability.After working for 12 h,the overpotential of OER and HER increased by only 10 mV and 2 mV,respectively.