Studies On The Electrocatalytic Hydrogen Evolution Of Ni Based Ni-Mo Alloy Electrodes

Hydrogen has attracted much attention as a kind of efficient, clean, ideal secondaryenergy. In particular, water electrolysis technique is able to generate clean hydrogenefficiently with high purity, which is one of the most promising alternatives to fossilfuels. Currently, the cathode materials used in industrial water electrolysis are mainlyRany Ni, low-carbon steel materials and so on. However, these cathode materialsdisplay some obvious shortages such as high over-potential, excessive energyconsumption and corrosion, which has restricted the development of water electrolysisand chlor-alkali industry. Therefore, to design and prepare a novel cathode with highelectrocatalytic activity, long-term stability and inexpensive has been of great practicalsignificance and practical value. In recent years, Ni-based alloy electrodes have drawnmuch attention due to their good activity for hydrogen evolution reaction （HER） andsufficient corrosion resistance in the alkaline solution. In present work, Ni-Mo-P/Nielectrodes were prepared by pulse electrodeposition method, and Ni-Mo/Ni electrodesobtained by magnetron sputtering method. The preparation conditions andelectrocatalytic performance of these electrodes were also systematically studied.Ni-Mo-P/Ni electrode was prepared by pulse electrodeposition method in theelectrolyte, mainly consisting of nickel sulfate, ammonium molybdate, and sodiumphosphite. Characterization technologies including X-ray diffraction （XRD）, scanningelectron microscopy （SEM）, energy-dispersive spectrometry （EDS）, and someelectrochemical test methods were used to scrutinize the surface composition,microstructure, and morphology of the electrodes, as well as their electrocatalyticactivity for HER. XRD and EDS results indicate that the structure of Ni-Mo-P alloy hasalready gradually presents amorphous after introduction of the molybdenum species,which increase the specific surface area of the electrode and enhance the electrocatalyticactivity of HER. When the content of Mo was30wt%in the catalyst, Ni-Mo-P/Nielectrode reveals the best electrocatalytic activity of HER. The onset potentials of HERfor Ni-Mo-P/Ni electrode shift towards the positive direction nearly270mV and100mV, respectively, compared with that of the pure Ni substrate and Ni-P electrode. Inaddition, Ni-Mo-P/Ni electrode shows long-term stability in alkaline condition.Ni-Mo alloy thin film was deposited on the Ni substrate by magnetron sputteringmethod. The thickness, morphology and element composition of Ni-Mo alloy thin film can be regulated by changing the sputtering power, sputtering pressure, reaction timeand temperature. And the electrocatalytic performance of the electrode for HER wasalso investigated. When the pressure of sputtering chamber was4Pa, the sputteringpowers of Ni target and Mo target were80W and180W, respectively, and the substratetemperature was500℃, Ni-Mo alloy electrode shows the best electrocatalytic activityof HER. At the current density of100mA·cm^-2, its potential for HER shifts towards thepositive direction nearly281mV in6M NaOH electrolyte, compared with that of thepure Ni substrate. The reason is mainly that the type of Ni-Mo alloy was nanocrystalline,dispersed well on the substrate with smaller grain diameter, which would result inincreasing specific surface area of the electrode. At the same time, Ni-Mo alloyelectrode displays lower resistance than the pure Ni substrate. The overall results is thusto improve the electrocatalytic performance of the electrode for HER.