Regulating The Performance Of Nickel Based Electrocatalyst For Oxygen Evolution Reaction By Non-metal-elemental Doping

Oxygen evolution reaction?OER?involves many important energy conversion systems,such as:rechargeable metal-air batteries,electrocatalytic carbon dioxide reduction,electrocatalytic nitrogen fixation,and water decomposition.Since the oxygen evolution reaction involves the transfer of multi-proton coupled electrons resulting in a slow kinetic process,an efficient catalyst is required to reduce the reaction potential energy and improve the catalytic efficiency.However,noble metal catalysts with high catalytic activity,such as iridium and ruthenium,have greatly limited their use due to their expensive costs.Therefore,the development of a cheap and efficient oxygen evolution reaction catalyst is an important research direction to reduce the application cost of energy conversion systems and energy storage systems.In this paper,based on the metal foam,a variety of doped nickel-based materials were obtained by pyrolysis,hydrothermal method and electrochemical oxidation,and the effect of doping composition on the oxygen evolution activity of nickel-based materials was discussed.The specific work is as follows1.Ni₃S₂ and N-Ni₃S₂ were prepared by"one-step"strategy and using the metal foam as the substrate.Nitrogen doping effectively improves the oxygen evolution activity of Ni₃S₂.and the corresponding potential of N-Ni₃S₂ at a current density of 10 m A cm^-2 was only 1.551 V vs.RHE,and its Tafel slope was 54.6 m V dec^-1.2.An cheap and high efficient electrocatalyst N-?Ni Fe?₃S₂ was prepared by a simple"one-step"synthesis method using transition metal sulfide?Ni Fe?₃S₂ that has been Fe-doped to optimize performance.Electrochemical tests show that the potential corresponding to N-?Ni Fe?₃S₂ at a current density of 10 m A cm^-2 was only 1.475 V vs.RHE,and its Tafel slope was35.3 m V dec^-1.The analysis of N-?Ni Fe?₃S₂ and?Ni Fe?₃S₂ through XPS,Raman and other characterization found that the structure of nickel sulfide has been converted into the structure of nickel oxyhydroxide during the oxygen evolution reaction process,and the S content has been almost observed in XPS.However,the N content is still quite high and the valence state of the N anion during oxygen evolution has also increased to negative divalent,and partially replaced the oxygen position in the nickel oxyhydroxide structure.Combined with the electrochemical test results,the actual oxygen evolution active site is derived from:N-?Ni Fe?₃S₂formed by in-situ oxidation of nitrogen-doped nickel iron oxyhydroxide.3.In order to further verify the effect of non-metallic element doping on the oxygen evolution performance of nickel oxyhydroxide formed by electrochemical oxidation.We introduce a kind of sulfur and selenium doped nickel oxyhydroxide prepared by electrochemical in-situ oxidation.We use high specific surface area nickel iron hydroxide as a precursor to dope non-metallic elements such as sulfur and selenium,and electrochemically oxidize it in situ to obtain Ni Fe OOH?S,Se?,Ni Fe OOH?Se?,Ni Fe OOH?S?,Ni Fe OOH.Electrochemical analysis shows that the catalytic activity is improved by doping sulfur and selenium,and the electrode performance and intrinsic performance are greatly improved when sulfur and selenium are co-doped.The potential at a current density of 10 m A cm^-2 Only 1.425 V vs.RHE,lower than the potential of many reported excellent oxygen evolution catalysts,and its Tafel slope is only 31.99m V dec^-1.And in the constant current stability test at a current density of 10 m A cm^-2for up to190 hours,Ni Fe OOH?S,Se?showed very excellent stability.