Preparation And Electrochemical Performance Study Of Nickel-based Sulfide Electrode Materials

Energy crisis and environment pollution are the most serious problem that the development of social is facing.The exploitation of the energy storage devices for intermittent renewable such as energy solar and wind energy etc.and new style energy is the effective way to solve those problems.Supercapacitors stand out various energy storage devices because of high energy density,long working time,wide potential range and so on.In the aspect of new style energy exploitation,hydrogen energy with various advantages of high calorific value,carbon free emission,green and safe possess bright research potential.Achieving H₂ produce through water electrolysis is one of the commonly used methods to obtain hydrogen energy.However,electrode material plays an important role on the performance of supercapacitors and electrocatalysis.Up to now,the development of non-noble metal-based nanomaterials is one of the hottest research fields.Among,nickel sulfides have multiple phases,high capacitance and show great potential in the fields of supercapacitors and electrocatalysis.The paper started from the idea of green and simple synthesis of nanomaterials.Regulated the electronic structure by the strategy of hetro-element doping.A series of material characterizations,electrochemical tests and density functional theory calculation（DFT）were carried out.The supercapacitor and electrocatalytic properties of nickel sulfide-based materials were summarized.Revealed the internal mechanism of performance improvement.The main content was as follow:（1）Novel and speedy pulse laser liquid-phase ablation（PLAL）was adopted to synthesize Co doped Ni/Ni S/Ni₃S₄ by one step.Electrochemical tests and DFT calculation showed that Co doping moderated the electronic structure,improved the electron transfer capacity,so the supercapacitor and electrocatalytic performance of nickel sulfide materials are greatly improved.The specific capacitance of Co doped Ni/Ni S/Ni₃S₄ was 1940 F g^-1when the current density was 1 A g^-1.Asymmetric supercapacitor was assembled by Co doped Ni/Ni S/Ni₃S₄ as positive electrode and activated carbon as negative carbon,showed outstanding energy density,power density and potential of practical.Meantime,when Co doped Ni/Ni S/Ni₃S₄ used as urea oxidation reaction（UOR）electrocatalyst,only a voltage of 1.35 V was needed to achieve a current density of 10 m A cm^-2.（2）Mo doped Ni S_1.97/Co₃S₄ was prepared by simple hydrothermal method,which showed the structure of nanoflower assembled by nanosheets.The opened structure ensures the penetration of electrolyte and the diffusion of N₂ and CO₂.On the one hand,the doping of Mo can adjust the electronic structure of nickel cobalt sulfides,improve the conductivity and the intrinsic activity of Ni S_1.97/Co₃S₄.On the other hand,it can also optimize the chemisorption between the reactant and catalysis active site of UOR,leading to improved catalytic reaction kinetics.At the vulcanizing temperature of 200℃,Mo-Ni S_1.97/Co₃S₄ processed outstanding UOR catalytic activity.When the current density up to 10 m A cm^-2,the needed potential was only 1.35 V,Tafel was 23.53 m V dec^-1.Urea electrolysis NCS-Mo//Pt/C device also had good performance.