The Modification And Hydrogen Evolution Performance Study Of Ni-Co-P Electrocatalyst

As the cost of producing clean electricity continues to fall,it is imperative to find an economical and reliable way to store and convert idle power.Hydrogen is an environment-friendly energy source with high energy density and it can not only be used as fuel for direct combustion,but also be converted into other high-value chemicals as chemical raw materials.Therefore,among electric energy storage methods,electrocatalytic hydrogen evolution has been widely concerned by researchers.Transition metal phosphides are considered as ideal materials for electrocatalytic hydrogen evolution because of good conductivity and low production cost.However,the common preparation method of transition metal phosphides usually produces toxic and inflammable substances such as PH₃ and white phosphorus,in addition,a very high preparation temperature is needed.In order to overcome the above shortcomings,this paper prepared and modified transition metal phosphide self-supporting electrode under the condition of room temperature and atmospheric pressure with electrodeposition and chemical deposition methods,and obtained a transition metal phosphide electrocatalyst with an excellent HER performance.The specific research contents of this paper are as follows:（1）The amorphous Ni-Co-P uniform nanospheres with hierarchical structure have been grown on copper foil substrates by the simple one-step electrodeposition method.The optimal preparation conditions of Ni-Co-P were obtained by designing single factor variable experiments by adjusting the metal principal salt ratio of the bath,the amount of sodium hyphite,the pH value of the bath,the deposition voltage and the deposition time.The Ni-Co-P/CF self-supported electrocatalyst showed good electrocatalytic performance for hydrogen evolution in alkaline electrolyte,and only needed 96 mV and190 mV at the current density of 10 mA cm^-2 and 100 mA cm^-2.（2）Self-supported electrocatalyst,PSS-PPy/Ni-Co-P/CF,was prepared by coating polypyrrole-polystyrene sulfonate（PSS-PPy）on the surface of Ni-Co-P electrodeposition and chemical deposition method.The conductive polymer PSS-PPy formed a typical core-shell structure on the surface of Ni-Co-P,which enhanced the electrical conductivity and hydrophilicity of the material.Meanwhile,PSS-PPy introduced a large number of active sites on the surface of Ni-Co-P.First-principle calculations showed that PSS-PPy took away a part of electrons from the Ni-Co-P surface,which led to the hydrogen adsorption free energy closer to zero on the Ni-Co-P surface.Meanwhile,the introduction of PSS-PPy accelerated the decomposition of water molecules,and accelerated the reaction kinetics of electrocatalytic hydrogen evolution.The overpotential of PSS-PPy/Ni-Co-P/CF in neutral electrolyte is 106 mV,and it is only 67 mV in alkaline electrolyte.PSS-PPy/Ni-Co-P/CF showed excellent stability in neutral electrolyte,alkaline electrolyte and even seawater,showing good practical application value.The electrocatalytic hydrogen evolution performance of the above materials is at the forefront of similar materials reported before,and the whole preparation process is under normal temperature and pressure conditions,the raw materials are cheap and easy to obtain,and the preparation process is simple and easy to operate,which provides a new idea for the development of efficient and low-cost electrocatalytic hydrogen evolution technology.