Study On The Preparation Of Transition Metal Phosphides And Their Electrocatalytic Performance

With the continuous consumption of traditional energy sources and the sharp increase in environmental pollution,the research and development of new energy materials is imminent.Hydrogen energy has high combustion value,environmental friendliness and renewable characteristics,so it is considered to be the most potential sustainable clean energy.Traditional industrial hydrogen production methods sometimes not only need to consume other chemical reagents as raw materials,but also need to pollute the environment.Due to its high purity and low resource consumption,electrocatalysis is considered to be a promising and environmentally friendly hydrogen production method.The hydrogen evolution reaction（HER）on the cathode and the hydrogen evolution reaction（OER）on the anode together form an electrocatalytic total water solution.At present,it has been proved that precious metal catalysts such as Pt/C and lr O₂ can be used for the cathode and anode respectively to reduce the capacity barrier and promote the reaction.However,due to their expensive price and scarcity of production,noble metal catalysts cannot be used in large-scale commercial applications.Therefore,the development of transition metal-based electrocatalysts with abundant reserves,high catalytic efficiency,and low cost has become a key to a green future.Transition metal phosphides have a suitable d-electron configuration,abundant chemical states and similar properties of zero-valent metals,so they are expected to be used as electrocatalysts for large-scale applications.Based on the above considerations,a variety of bimetallic phosphide composites were prepared by designing and regulating the composition,morphology and structure of the two element transition metal phosphides,which were used as electrocatalysts for water electrolysis reaction.The main research contents of this paper are as follows:1.The 3D manganese-cobalt bimetallic phosphide was constructed on the surface of nickel foam by using electrodeposition and chemical vapor deposition methods.By controlling the electrodeposition time and phosphating temperature,an excellent and controllable synthesis method is provided.Due to the integrated design,the active material grows directly on the current collector to ensure close contact with the substrate.At the same time,the interconnected nanosheet structures help electrolyte penetration and more effective utilization of active sites.Engineering design through heteroatom manganese doping can optimize the adsorption of hydrogen on the active site,resulting in good catalytic kinetics.At a current density of 10 m A cm^-2,Mn-Co-P/NF has low HER and OER overpotentials of 63 m V and 310 m V.In addition,when Mn-Co-P/NF is directly used as the anode and cathode to form an electrocatalytic device with a two-electrode system to complete the entire water splitting,only 1.70 V is required to achieve a current density of 20 m A cm^-2.2.A 3D nickel-iron bimetallic phosphide was constructed on the surface of the foam nickel combined with the chemical vapor deposition method after the normal temperature immersion treatment.By controlling the soaking time for comparison,a simple and economical preparation method is provided.Through this controllable synthesis method,the active material grows directly on the substrate and is closely connected with the substrate to enhance conductivity.At the same time,the unique 3D layered sheet structure connects each other and exposes more active sites.The synergy between the bimetallic phosphides reduces the reaction barrier,resulting in good catalytic kinetics and enhanced catalytic performance.When the current density of Ni-Fe-P/NF is 10 m A cm^-2,the over-potential of HER and OER are 62 m V and 297 m V,respectively.Moreover,when Ni-Fe-P/NF is directly used as a two-electrode system to complete the water decomposition,the current density of 10 m A cm^-2 can be generated at only 1.60 V of Ni-Fe-P/NF.3.The ZnCo-LDH nanowires grown vertically on conductive carbon paper were prepared by hydrothermal method as the precursor,and phosphating with Na H₂PO₂?H₂O as the P source at 350℃,the Zn-Co-P coexisting nanosheets and nanowires were obtained.Composite materials.During the preparation process,the nanowire structure of the precursor is completely retained,and the smooth nanosheets intersect the nanowires.It is the structure of the coexistence of the wires that expands the active area and strengthens the contact with the electrolyte,making the HER and OER overpotentials of Zn-Co-P/CP respectively 84 m V and 220 m V at a current density of 10 m A cm^-2.In addition,when the Zn-Co-P/CP is directly used as the positive electrode and the negative electrode in the complete water dissolution device,the total water dissolution test potential at a current density of 10 m A cm^-2 is only 1.57 V.This paper contains 45 figures,4 tables and 110 references.