Study On Electroless Plating Ni-P-S Function Coating And Its Electrocatalytic Activity

study on electroless plating Ni-P-S function coating and its electrocatalytic activityWith the rapid development of chlorine alkali industry, it becomes an important research subject how to reduce energy consumption, raise economic benefits and improve the technology level. The metal oxides coating of anode ( DSA) and ion-membrane bath can greatly reduce electrolytic energy consumption,so it could be said the cathodic overpotential has already become the decisive factor for reducing electrolytic energy consumptions. In ten years recently, the research of active cathodes has been paid attention to by people.The chlorine alkali industry traditionally adopts the ordinary iron or the low carbon steel as the cathode material. This kind of cathode material not only has high overpotential of hydrogen evolution, but also the stability of the cathode material is bad. So developing a high activity and good stability material will be an important research goal, from previous documents, study many active cathodes including noble metal electrode, Raney Ni electrode, cobalt coating electrode, nickel alloy electrode, etc. have already been studied. In the nickel alloy electrodes, Ni-P and Ni-S materials are widely studied. Because of its excellent corrosion resistance in the high concentration alkaline solution, electroless plating Ni-P coating is widely applied. But its electrocatalytic property is not very ideal. The electrodeposited Ni-S coating has a better electrochemical activation, but the stability need improving. In addition, for industrial application of the kind of cathode there are still some problems.In this thesis,Ni-P-S compond funtion coatings were fabricated on low carbon steel by the technology of electroless plating Ni-P, adding an appropriate amount of thiourea into plating solution. The content and form of sulphur were studied by X -ray . The electrocatalytic activity of the cathode was measured by cathodicpolarization technology. In addition the heat stability of Ni-P-S coating and impurity ions poisoning to the active coating were studied.The content directly affected electrocatalytic hydrogen evolution property of the coating. In the plating solution that the content of thiourea were 4, 8, 10, 20, 40 g/L respectively, the hydrogen evolution potential of the active cathodes were 1.385V, 1.332V 1.243V 1.275V 1.281V respectively (VS Hg/HgO ) at 50, IMNaOH, I=200mA/cm.The experiments showed that at a low content of thiourea, the hydrogen evolution property was raised with the increase of its content. But when the content of thiourea exceeded 10 g/L, the hydrogen evolution property was reduced with the increase of its content. When the content of thiourea was 10 g/L, the hydrogen evolution property was best, which was lower by 250 V than the low carbon steel at 50C, IMNaOH, I200mA/cm.The content of thiourea determined the structure of Ni-P-S coating and influenced its electrocatalytic property. Through analyzing X-ray diffraction of the different coatings.lt was observed that there were the characteristic peaks of NiS2. Experiments indicated the more NiSi was, the better hydrogen evolution property was. Analyzing the polarized electrode and unpolarized electrode from X-ray diffraction, we can observed that with gradually decreasing NiS, the electrocatalytic activity increased. The reason maybe was that the surface area of the coating would be increased after surface atoms were dissolved.The experiment showed that iron ion had no effect on the electrocatalytic activation of compound coating of electrodes. The crystal structure of NiS2 had no change by heated at 473K and 573K in the stove. But after heated at 573K, the hydrogen evolution property decreased slightly .Generally the electroless plating Ni-P-S function coating has better stability and hydrogen evolution activation. So there are better application prospects .