Study On Electrocatalysis Of Nickel And Cobalt Based Compounds Grown On Flexible Graphite Felt

With the huge consumption of fossil energy and the rapid deterioration of the living environment,mankind is so urgent to obtain a renewable and environmentally friendly clean energy.Among them,hydrogen energy has become the focus of attention because of its high combustion calorific value and only water as its product.However,the traditional hydrogen production process（hydrogen production from fossil fuels）has some problems,such as high pollution and high energy consumption.In order to solve these problems,hydrogen production by electrolysis has received widespread attention.In this paper,the modification of the substrate material in the catalytic electrode,the morphology control of the catalytic nanomaterials,the influence of the nanomorphology on the electrocatalytic performance,the improvement of electrocatalysis by sulfur active sites introduced by sulfide,and the comparison of double transition metal compounds with single metals has been fully studied.The modification of the surface properties of the base material graphite felt used in the experiment is extremely critical.The method used in this article is high-temperature rapid thermal annealing.By adjusting the temperature and time of thermal annealing,it is found that the effect of graphite felt annealed at 800℃for one minute is the best.On the basis of ensuring the original advantages such as good flexibility and large specific surface area,the surface roughness is increased with many nano-pores generated,and the subsequent growth of the catalytic material is more firmly bonded.In addition,high temperature has further improved the conductivity of graphite felt,laying the foundation for the rapid transmission of electrons in the catalytic electrode.A simple one-step hydrothermal method is used to grow Ni（OH）₂ and Co（OH）₂nanomaterials on the modified graphite felt,and the morphology of the nanomaterials is controlled by changing the hydrothermal temperature.Next,the single metal hydroxide of nickel and cobalt is further sulfided into Ni₃S₂ and Co S.We used a variety of characterization methods to study nickel,cobalt hydroxides and sulfides with different morphologies,and obtained the influence of hydrothermal temperature on the microscopic morphology of the electrode and the difference in morphology between hydroxides and sulfides.The research on hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）of a variety of electrodes displays that the difference in the micro morphology of the catalytic electrode brings about a huge difference in catalytic performance.Besides,the different active sites contained in nickel,cobalt sulfide and hydroxide has its own advantages in electrocatalysis.On the basis of the above research,we have grown Ni Co₂O₄ nanorod arrays with different morphologies by changing the temperature of hydrothermal synthesis and simply sulfide them to obtain nickel-cobalt bimetallic sulfide nanospheres.Full characterization of Ni Co₂O₄ and Ni Co₂S₄ nanostructured electrodes based on graphite felt implied the stability of the synthesis method and the successful synthesis of catalytic materials.The exploration of the HER and OER performance of Ni Co₂O₄ and Ni Co₂S₄ electrodes with different morphologies fully indicates the advantages of Ni Co₂O₄ with spinel structure in the catalytic process for HER,and the superiority of the introduction of sulfur active sites of the Ni Co₂S₄ electrode for OER.