Study On Preparation And Properties Of Ni-Based Carbon Nanotube Composite Coatings

With the development of science and technology,people have higher requirements on the properties of materials.Composite materials have attracted attention because of their many excellent properties.There are many preparation methods of composite materials,among which electrodeposition method is a commonly used method,which has the advantages of simplicity and convenience.As a common coating,nickel-based composite coating has the advantages of good catalytic performance,low price and abundant sources.It has been used in the field of electrocatalytic hydrogen production.On the other hand,it is found that carbon nanotubes have excellent mechanical and electrical properties in carbon materials.Therefore,it has important meaning to prepare nickel-carbon series composite coatings by adding carbon nanotubes to the nickel base plating solution for composite co-deposition.In this paper,pretreated carbon nanotubes were introduced into the plating solution,and Ni-CNTs composite coatings and Ni-Mo-CNTs composite coatings were prepared by electrodeposition.The main research contents are as follows:?1?Through the pretreatment of carbon nanotubes,the precipitation test shows that the dispersion property of the pretreated carbon nanotubes in aqueous solution is significantly improved compared with that of the untreated carbon nanotubes.The acidified carbon nanotubes can be dispersed stably in aqueous solution for more than one month,while the untreated carbon nanotubes all sink to the bottom of colorimetric tube after more than ten minutes,forming obvious delamination with the aqueous solution.The morphology of carbon nanotubes before and after treatment was analyzed,and it was found that impurities on the surface of carbon nanotubes were removed obviously after pretreatment.?2?The effects of trisodium citrate concentration,carbon nanotube concentration,p H,current density,and temperature on the Ni-CNTs composite coating were studied.On this basis,the optimum preparation condition of Nickel-carbon nanotube composite coating was obtained.It was shown that the composite coatings prepared under optimal conditions have good binding power and catalytic hydrogen evolution potential is lower than pure nickel coatings;which plating rate is 64.75 mg·cm^-2·h^-1.?3?The effects of sodium molybdenum concentration,carbon nanotube concentration,p H,current density,and temperature on nickel-molybdenum-carbon nanotube composite coating were investigated.Orthogonal experiments were used to optimize the preparation conditions of nickel-molybdenum-carbon nanotube composite coatings,and parallel experiments were carried out under the optimal conditions.It was found that the coating performance and morphology were better.The composite coating is placed in 1 mol/L Na OH solution for LSV test.When the scanning speed is 10 m V/s;the calomel electrode is used as reference electrode,average result of test corresponds to hydrogen evolution potential is-1.30 V when the current density is 50 m V/dm².The average plating speed of the coating is equal to 1.363 mg·cm^-2·h^-1.By observing the surface morphology of coating,it was found that the surface of coating was covered a rough substance with carbon nanotubes as the core,which can provides a larger effective catalytic area and enhances the catalytic hydrogen evolution ability of composite coating.EDS test shows that the mass fractions of C,Mo and Ni in the composite coating are 4.848%,42.145%and 53.007%,which proves that molybdenum,nickel and carbon nanotubes have been co-deposited on the copper substrate surface.?4?The nickel-molybdenum-carbon nanotube composite coatings prepared under the optimal technological conditions were compared with the pure nickel,nickel-carbon nanotube and nickel-molybdenum-carbon nanotubes coatings prepared under similar technological conditions.It is found that these four kinds of different coatings are different in color and good in appearance.No charring,uniform color,strong binding force.Through LSV test,it was found that Ni-Mo-CNTs composite coating had the best catalytic hydrogen evolution performance;and the results showed that the plating rate of Ni-Mo-CNTs composite coating was significantly higher than that of Ni-Mo coating,which indicated that the addition of carbon nanotubes could improve the plating rate.