Preparation Of Ion-doped Transition Metal Phosphide/carbon Matrix Composites And Their Electrocatalytic Hydrogen Precipitation Performance

Hydrogen energy is considered as an ideal alternative to fossil energy because of its high energy density and clean and non-polluting characteristics.Electrolytic water hydrogen production has received increasing attention due to its production safety and high product purity.However,the overpotential generated in the electrolytic water reaction process leads to the excessive energy consumption,so the catalyst needed to improve the energy conversion efficiency.At present,Pt-based catalysts have excellent electrocatalytic performance for HER,but their high cost and scarcity limit their applications.Thus,it is very important to develop transition metal-based catalysts with high catalytic activity,low cost and high stability.In recent years,transition metal phosphates have attracted extensive attention due to their excellent catalytic activity,abundant reserves and good chemical stability,but these phosphides at the nanoscale still face problems such as low intrinsic catalytic activity,less desirable conductivity and narrow applicable p H range.In this paper,transition metal phosphates doped with different elements have been prepared on different carbon substrates,and the effect of element doping on their hydrogen evolution performance was studied.The main research contents are as follows:(1)Preparation of carbon-cloth-loaded three-dimensional selenium-doped Ni Co bimetallic phosphide nanoarrays composites and their electrocatalytic performance study.Using carbon cloth as the conductive substrate material,Ni Co precursors were grown in situ on carbon cloth fibers by hydrothermal method,and Se doped Ni Co P nanoarrays were obtained by chemical vapor deposition with selenium powder and sodium hypophosphite as the selenium and phosphorus sources.Nanorods with diameters of about 60 nm are interconnected and form nanosheet arrays grown vertically on carbon cloth fibers.The highly open network structure and multi-level array structure not only facilitates the contact between electrodes and electrolyte,but also increases the diffusion rate of electroactive components and generated bubbles.XPS and TEM results show that the Se doping can effectively modulate the electronic structure of Ni Co P and increase the intrinsic catalytic activity of the material.Optimized Se-Ni Co P-2/CC has higher HER activity and efficient performance for overall water splitting under alkaline conditions than undoped Ni Co P/CC.(2)Preparation of nitrogen-doped iron phosphide/graphene composites and study of their electrocatalytic properties.N-Fe P/r GO composite electrocatalysts were synthesized by chemical co-precipitation and chemical vapor deposition using reduced graphene oxide as the conducting substrate and urea and sodium hypophosphite as the nitrogen and phosphorus sources.N-doped Fe P nanoparticles can expose more active sites,and the reduced graphene oxide can not only prevent the nanoparticles from losing activity due to agglomeration,but also effectively improve the conductivity of the catalyst.X-ray photoelectron spectroscopy analysis shows that the nitrogen doping can effectively modulate the electronic structure of Fe P,which effectively improves the intrinsic catalytic activity of the electrode.The N_0.08-Fe P/r GO composite exhibits excellent HER activity in both acidic and alkaline media,with overpotentials of 85 m V and 208 m V at a current density of 10 m A cm^-2and Tafel slopes of 69 m V/dec and 97.5 m V/dec,respectively.After working continuously under acidic conditions for 75 h,the electrode shows no significant decay in current density and exhibited good stability.