The Electrocatalytic Performance Of Fe,Co,Ni Phosphides/Borides For Water Splitting Synthesized By High Pressure

With the development of society,mankind’s demand for energy is increasing day by day.Hydrogen energy is an ideal clean energy that can achieve zero emissions in a true sense.People have high hopes that it can replace traditional fossil fuels.Up to now,hydrogen production by electrolysis of water is a very environmentally friendly and highly feasible method for large-scale production of hydrogen.The key to this technology is to seek efficient,environmentally friendly,and low-cost electrolysis water catalysts.Due to its diverse crystal structure,unique electronic structure and abundant earth reserves,3d transition metal compounds are suitable candidates for a new generation of electrolyzed water catalysts.In this paper,rapid solid-phase synthesis of 3d transition metal phosphides and borides of Fe,Co,Ni by high temperature and high pressure methods,and a detailed study of their catalytic properties in electrolyzed water.The main research content includes:Using nanometer Fe,Co,Ni and B powder and red phosphorus as raw materials,a series of homogeneous pure phase and high crystallinity Iron/Cobalt/Nickel phosphides and their B-doped samples are synthesized through high temperature and high pressure methods,and After grinding and refining,its electrochemical catalytic performance was tested.At the same time,first-principles calculations are carried out on the electronic density of states and d-band centers of all samples.Combining the experimental results and calculation results,we can get:Ni₂P has the best electrochemical catalytic activity.In the 1 mol/L KOH solution,when the current density is 10 m A/cm²,its OER overpotential and HER overpotential are 307 mV and 191 mV respectively;Ni₂B_0.11P_0.89 doped with B element are at 298 mV and 177 mV,respectively.The electronic interaction between the doping of B element and the P element changes the electronic structure of the d-band of Ni₂P,making the center of the d-band closer to the Fermi surface,which promotes the electrocatalytic performance.Using nanometer Fe,Co,Ni and B powders as raw materials,a series of homogeneous and pure phase Iron/Cobalt/Nickel borides with high crystallinity are synthesized through high temperature and high pressure methods,and their electrochemical catalytic properties are obtained after grinding and refinement carry out testing.At the same time,first-principles calculations are carried out on the electronic density of states and d-band centers of all samples.Combining the experimental results and calculation results,it can be obtained:when the transition metal content is higher,the conductivity of the material is better,and the center of the d-band is closer to the Fermi surface.The Ni₂B sample after high-energy ball milling has the best electrochemical catalytic activity.When the current density is 10 m A/cm² in the 1 mol/L KOH solution,it has an OER overpotential of 297 mV and a HER overpotential of 169 mV.At the same time,ball milling can increase the surface area of the sample and expose more active sites to improve electrocatalytic activity.Compared with before ball milling,the OER overpotential and HER overpotential of Ni₂B after ball milling decreased from 353 mV and 203 mV to 297 mV and 169 mV,respectively.