Preparation and Performance of Nickel-Doped La0.5Sr0.5CoO3-δ Perovskite Materials for Alkaline Oxygen Evolution in Water Splitting

Perovskites exhibit catalytic properties on the oxygen evolution reaction in water electrolysis. Elemental doping by specific preparation methods is a good strategy to obtain highly catalytical active perovskite catalysts. In this work, La0.5Sr0.5Co1-xNixO3-δ perovskite materials doped with different ratios of nickel were successfully synthesized by the sol-gel method. The electrochemical measurement results show that in 1 M KOH solution, La0.5Sr0.5Co0.8Ni0.2O3-δ prepared by the sol-gel method requires only a low overpotential of 213 mV to reach 10 mA cm-2, which is significantly lower than that of La0.5Sr0.5Co0.8Ni0.2O3-δ prepared by the hydrothermal method for the increasing about 45.24 % (389 @ 10 mA cm-2). In addition, La0.5Sr0.5Co0.8Ni0.2O3-δ by the sol-gel method can be kept stable in alkaline medium tested for 30 h without degradation. This indicates that the prepared La0.5Sr0.5Co0.8Ni0.2O3-δ has better OER performance. The SEM results shows that layer structured La0.5Sr0.5Co0.8Ni0.2O3-δ by the sol-gel method has more surface pores with a pore diameter of about 0.362 μm than spherical granular structured La0.5Sr0.5Co0.8Ni0.2O3-δ by the hydrothermal method. XPS results reveal that the crystal lattice of La0.5Sr0.5Co0.8Ni0.2O3-δ by nickel doping is lengthened and the electronic configuration of Co also is changed by the sol-gel preparation process. The improved electrocatalytic performance of La0.5Sr0.5Co0.8Ni0.2O3-δ may be attributed to the pore structure formed with providing more active sites during the sol-gel process and the improved oxygen mobility with Ni doping by the sol-gel method. The doping strategy by the sol-gel method provides valuable insights for optimizing perovskite catalytic properties.