| As environmental problems and the energy problem becoming global issues and getting worse, hydrogen is being paid more and more attention for its own characteristics of efficiency, renew-ability, energy conservation and environmental protection. Water electrolysis is a cheap way to obtain hydrogen with large-scale, but its cell voltage grows during the manufacturing process because of the existence of the over-potential, then energy consumption increases. So it is very important and necessary to develop a cheap hydrogen electrode material with high catalytic properties. The technics of foamed Ni/Ni-Mo prepared by electro-deposition was studied in this paper, and its hydrogen evolution behavior and hydrogen electric catalytic performance were discussed in30%KOH solution. Then the electrodes were characterized by SEM and EDS, which were prepared by adding LaCl3·7H2O into the solution.The ultraviolet spectrophotometry analysis was studied, and the influence of change of its working condition on the test results was discussed. The determined working conditions were as follows:X=470nm; V(H2SO4)=8.00mL; V((H4N)2S)=7.00mL; V(NH4SCN)=6mL; t=35min. Under these conditions, the concentration of molybdenum ion C had a good linear relationship with spectropho-tometry A, and the linear equation was as follows:A=0.00424+0.11691C (C:0.00μg·mL-1～5.00μg·mL-1), and correlation coefficient R was0.9997.A foamed Ni/Ni-Mo electrode was prepared by electro-deposition, and its technics of electro-deposition were preliminarily determined by the orthogonal experiment. The relationship between the concentration of NiSO4·6H2O, Na3Cit·2H2O and Na2MoO4·2H2O, the electrodeposition current density, and the electro-deposition time on the catalytic activity of hydrogen evolution of the foamed Ni/Ni-Mo electrode and the relationship between these conditions and the content of Mo in film were studied. The results showed that the electrodes had good hydrogen evolution activity when the content of Mo in the coating was20%, and the best electro-deposition conditions were:NiSO4·6H2O90g·L-1, Na2MoO4·2H2O35g·L-1, Na3Cit·2H2O150·g·L-1, current density90mA·cm-2NaCl10g·L-1, butynediol0.1g·L-1, saccharin0.5g·L-1, temperature50℃, time30min, pH=11～12and medium mixing speed. The hydrogen evolution behavior of Ni-Mo alloy electrode was studied with the application of Steady-state Polarization curve and A.C. impedance spectra in30%KOH solution, and the relationship between the process conditions and hydrogen evolution performance of foamed Ni/Ni-Mo electrode was discussed. The Steady-state Polarization curves of foamed Ni/Ni-Mo electrode were analyzed in30%KOH solution, and it was found that under the current density of200mA·cm-2, the over-potential of electrode was244mV, and its Tafel slope b was0.311V, and exchange current density io was3.2×10-2A·cm-2, then it was concluded that its hydrogen evolution mechanism was slow discharge mechanism approximately on the over-potential of250mV by analyzing its Tafel slope. SEM and EDS results showed that the electrodeposited foamed Ni/Ni-Mo electrode coating was made up of micron grade grain and the surface of electrode was very coarse,and atom composition of the alloy was Ni86.09M013.91LaCl3·7H2O was added into the solution which was prepared for electrodepositing foamed Ni/Ni-Mo electrode. Then the relationship between the hydrogen evolution performance of alloy electrode and the change of the concentration of LaCl3·7H2O, Na2MoO4·2H2O, NiSO4·6H2O and the current density of electro-deposition with hydrogen evolution performance and the content of Mo in coatings of electrodes was studied. The results showed that the best technics of preparing foamed Ni/Ni-Mo-La electrode by electro-deposition were as follows:NiSO4·6H2O90g·L-1, LaCl3·7H2O5g·L-1,Na2MoO4·2H2O35g·L-1, Na3Cit·2H2O150g·L-1, current density90mA·cm-2, NaCl10g·L-1, butynediol0.1g·L-1, saccharin0.5g·L-1, temperature50℃, time30min, pH=11～12and medium mixing speed. SEM and EDS results showed that the electrodeposited Ni-Mo-La alloy coating was made up of micron grade grain and the surface of electrode was very coarse, and atom composition of the alloy was Ni82.84Mo16.42La0.74. Contrasting with foamed nickel electrode and the foamed Ni/Ni-Mo electrode, the foamed Ni/Ni-Mo-La electrode had an optimal performance of hydrogen evolution. |
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