Overdoping Strategy for Preparing a Two-Phase Oxide Electrocatalyst to Boost Oxygen Evolution Reaction

The oxygen evolution reaction is of great significance to the production of hydrogen from high efficiency electrolytic water, hydrogen oxygen fuel cell and other energy conversion devices, but there are many challenges such as high cost, low efficiency and poor stability of catalysts. Among non-precious metal catalysts, oxide has its unique advantages. We used overdoping strategy to prepare two-phase oxide electrocatalyst SrCo_0.9 Fe_0.05 Mo_0.35 O_x (SCFM_0.35 ) containing double perovskite and Co₃ O₄ with excellent OER electrocatalytic activity and stability in alkaline solution. It required an overpotential of 361.7 mV to reach a 10 mA cm^-2 current density and its performance only degrades by 3.48% after 1000 CV cycles accelerated stability tests, whose electrochemical performance is superior to that of single-phase double perovskites and undoped perovskites. SrCo_0.9 Fe_0.1 O₃ (SCF) ordinary perovskite is doped with slightly molybdenum (Mo), and then the ordinary perovskite turns into double perovskite because of the polyvalence characteristics of Mo. When Mo is overdoped, Co₃ O₄ phase was precipitated while Mo entered perovskite phase. This process causes lattice distortion and makes the surface electronic structure benign changes. Furthermore, the microscopic morphology of the material surface and the valence state of cobalt element are changed, thereby improving the microenvironment of the electrochemical process.