The Synthesis And Hydrogen Evolution Properties Of Self-supporting Ni-based Amorphous Catalysts

Industrial water electrolysis is a low-cost,high-efficiency hydrogen production technology.At present,noble metal catalysts（such as Pt,Ir,Ru,etc.）are still the best catalysts for hydrogen evolution in water electrolysis,but their rare reserves and high cost limit their large-scale industrial applications.Therefore,the development of low-cost and highly active hydrogen evolution catalysts is of great significance for indus-trial water electrolysis.Ni-based catalysts are currently commonly used materials for industrial electrolysis of alkaline water for hydrogen production.However,there are still problems of low intrinsic activity and high energy consumption for hydrogen production.The intrinsic activity of Ni-based catalysts can be effectively improved by alloying it with d-block metal elements（Mo,W,etc.）.Electrodeposition is considered as a facile,green,and time-saving strategy for material synthesis,and the sample size is not limited,which facilitates the large-scale fabrication of electrodes.In this thesis,NiMo and NiW hydrogen evolution catalysts were prepared by electrodeposition method,and the effect of electrodeposition process on the hydrogen evolution per-formance of catalysts was systematically studied,which provided theoretical guidance for the development of low-cost and high-activity Ni-based non-precious metal cata-lysts.The main research contents and corresponding conclusions are as follows:（1）In this work,the amorphous NiMo coating was successfully prepared on nickel foam in the sodium citrate system by chronopotentiometry electrodeposition.The effects of sodium citrate concentration and p H of electrodeposition solution on the microstructure and catalytic performance of the coatings were studied.NiMo_{（p H10）}prepared in solution（p H=10）exhibits excellent catalytic activity for hydrogen evolu-tion in alkaline solution,with overpotentials of 64 m V and 157 m V at-10 m A cm^-2and-100 m A cm^-2 current densities in 6 mol L^-1 KOH solution,respectively.It can run stably for 100 h at-100 m A cm^-2,and the composition of the coating remains ba-sically unchanged,suggesting good stability of this catalyst.The electrons were trans-ferred from Nito Mo in the coating,which induces a synergistic effect and improves the hydrogen evolution catalytic activity significantly.（2）In the sodium citrate-boric acid electrodeposition system,NiW alloys with ef-ficient hydrogen evolution catalytic activity were successfully prepared at low current density,which further reduced the current density during electrodeposition(deposi-tion current density decreased by 70 m A cm^-2 compared with that of NiMo system),and provided a theoretical guidance for the industrial preparation of samples.The ef-fects of the molar ratio of Niand W and current density on the phase and catalytic properties of the coatings were also studied.NiW-60 prepared at-60 m A cm^-2 has ex-cellent catalytic activity,with the overpotentials of 100 and 199 m V at-10 and-100m A cm^-2 in 6 mol L^-1 KOH.After stability test at-100 m A cm^-2 for 100 h,the coating was bonded with the substrate firmly,thus leading to the excellent stability.The in-corporation of W plays the role of tuning the electronic structure of Nias well as bal-ancing the adsorption/desorption energy of hydrogen on the catalyst surface,which contributes to the efficient water electrolysis.