Preparation And Study On The Raney Ni-Mo Active Cathode

In order to prepare an active cathode for the sea-water electrolysis system,Ni-Mo-Zn alloy was electrodeposited and leached in hot alkaline solution to obtain Raney Ni-Mo electrode with high specific area and good electro-catalytic ability.Factors in electro-deposition,such as the content of nickel sulfate,sodium molybdate and zinc sulfate in the solution and current density were investigated in terms of their effects, which exhibits by polarization curves,on the activity of prepared electrodes.It was found that the content of zinc sulfate matters the most that means leached electrodes' surface morphology is closely related with its electro-catalytic ability.The best condition for electrode preparation was established:nickel sulfate 100g/L,sodium molybdate 40g/L,zinc sulfate 10g/L and current density 0.03A/cm~2.The influence of Ni-Mo interlayer on the component and morphology of surface layer was studied with SEM and EDX.It turned out to be that Ni-Mo-Zn electrodeposited on the interlayer has multi-layered,loose surface structure.A special structure that numerous tiny particles were wrapped in bigger particles was formed after leaching,which enabled the Raney Ni-Mo electrode to have much better performance than Ni-Mo electrode.In addition, different electro-deposition durations of interlayers affected electrodes' surface morphology, and in turn influenced the activity of electrode towards hydrogen evolution.The optimal thickness of interlayer electro-deposition is 18μm.EIS spectrums of Ni electrode and Raney Ni-Mo electrode in NaOH solution under different voltages were compared and contrasted to discover the origin of Ni-Mo alloy's good electro-catalytic performance toward hydrogen evolution.Absorption of H and formation of a subsurface hydride weakens the adsorptive power of the bare Ni surface and causes "deactivation" of the Ni surface.On the contrary,the "deactivation" of the electrode by the excessive coverage of adsorbed hydrogen can be reduced by the fast recombination rate achieved on Mo,while the high electrochemical activity of Ni for hydrogen adsorption makes Ni a source of hydrogen for Mo.Interval electrolysis experiment showed that Raney Ni-Mo electrode was not deactivated in long-time interval electrolysis.The polarization curves in NaCl solution exhibited its less possibility of corroding in sea-water than Ni and carbon steel.Its EIS spectrums in NaCl solution indicated that its ability of anti-corrosion decreased in long-period immersion testing. The interlayer of the Raney Ni-Mo electrode prevented the permeation of electrolyte into substrate that accounts for the electrode's good ability of anti-corrosion.