Ni-P-based Alloy Coatings Prepared by Direct and Pulsed Electrodeposition for Hydrogen Evolution Reaction in Alkaline Media (original) (raw)
Related papers
2011
Ni-Sn alloy coatings were deposited from the constant composition pyrophosphate-glycine bath at different current densities. Their morphology, composition and phase composition were investigated by SEM, EDS and XRD techniques. It was shown that the morphology of coatings depends on current density, being rougher and more porous with the increase of deposition current density. EDS analysis of the cross sections revealed that the coating composition varies from the substrate surface towards the coating surface, being richer in Ni close to the substrate surface, while the composition on top of the surface was approximately the same for all samples . XRD analysis showed the presence of only one phase in all deposits, NiSn 2 . The increase of Ni-Sn coatings catalytic activity for hydrogen evolution with the increase of deposition current density was shown to be the consequence of their porosity, while the sample with the smooth surface showed lower overvoltage for hydrogen evolution than the commercial De Nora's electrode (DN), indicating synergetic effect of Ni-Sn alloys.
Electrochemical Behavior of Ni-based Alloys for Hydrogen Evolution Reaction in Alkaline Media
*Nickel-based alloys (Ni 0.8 CoO 0.1 Zn 0.05 MnO 0.02 Ti 0.01 Y 0.01 Al 0.01 (M1), NiO 0.8 CoO 0.1 Zn 0.05 MnO 0.02 Ti 0.01 Y 0.01 Al 0.01 (M2) and NiO 0.6 CoO 0.35 Zn 0.025 Ti 0.025 (M3)) were synthesized from high purity powders by means of high-energy mechanical milling. The hydrogen evolution reaction (HER) kinetic-performance of the as-prepared materials was evaluated using linear sweep voltammetry at alkaline conditions and room temperature. According to kinetic parameters calculated from Tafel slopes, the sample M2 showed the better activity in the HER. These results suggest that the electrode surface state in the material play an important role in the proton-adsorption kinetic as demonstrated by SEM, open circuit potential transients and cyclic voltammetry techniques.
Different weights of amorphous NiP alloy with same P contents were electrodeposited on nickel plate with same area used as cathode for hydrogen evolution reaction (HER). The amorphous NiP alloy coatings were characterized for their surface morphology and composition through Scanning electron mi-croscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS) techniques, X-ray photoelectron spec-troscopy (XPS) and X-ray diffraction (XRD) analysis. The electrocatalytic activity for HER in alkaline medium is determined by linear scan voltammetry (LSV) and a relationship between HER activity and capacitance is established. The capacitance varies with the loading of the NiP on Ni plate but the activity for HER is directly proportional to the capacitance in alkaline and vice versa. 3#Ni-P/Ni containing 3.85 mg NiP alloy with highest capacitance performs the best catalytic activity. This work provides direct evidence to explore the capacitance influence on the electrocatalystic activity for the HER.
Studies of the Hydrogen Evolution Reaction on Ni-P Electrodes
Journal of The Electrochemical Society, 1997
The hydrogen evolution reaction (HER) was studied on Ni‐P electrodes containing 8 to 30 atomic percent P prepared by galvanostatic deposition. The electrodes were studied directly after preparation or after pretreatment by heating, leaching in HF solution, anodic oxidation, or potential ...
Electrochimica Acta, 2016
The effect of addition of silver nanoparticle sol (SNS) into NiP plating bath was studied in terms of the variation in electrocatalytic behavior of the developed coatings in 1.0 M KOH. NiP -Ag composite coating was achieved through direct electrolysis by adding a known quantity of the conventionally prepared SNS into NiP bath. NiP -Ag coatings electrodeposited galvanostatically on copper under different conditions of the bath was used as electrode material for alkaline hydrogen evolution reaction (HER). The optimal concentration of the SNS required for maximum electrocatalytic activity towards HER was obtained by adding different volumes of SNS (from 0 to 50 mL L À1) into the bath. The HER efficiency of the test electrodes in 1.0 M KOH medium was examined using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. The kinetics of HER on the alloy and composite electrodes were established through Tafel polarization and electrochemical impedance spectroscopy (EIS) analyses. Energy dispersive spectroscopy (EDS) was used to confirm the incorporation of Ag nanoparticles into the NiP alloy matrix. The microstructure and morphology of the alloy and composite coatings were analyzed by Scanning Electron Microscopy (SEM). A significant improvement in the electrocatalytic property of nano-Ag derived composite coatings was found, and was attributed to the enhanced electroactive sites of Ag particles. Deposition conditions to maximize the electrocatalytic activity of NiP -Ag nanocomposite coatings in relation to traditional NiP alloy coatings was arrived, and results are discussed. 2016 Published by Elsevier Ltd.
Ni–Sn coatings as cathodes for hydrogen evolution in alkaline solutions
2013
In this work the hydrogen evolution reaction (HER) at Ni-Sn alloy coatings, deposited onto Ni 40 mesh at different current densities from the bath containing 0.1 mol dm −3 SnCl 2 + 0.3 mol dm −3 NiCl 2 in the pyrophosphate-glycine solutions, was investigated by polarization and EIS measurements. The morphology and chemical compositions of all samples were investigated by the SEM and EDS techniques. It was shown that their morphologies and chemical compositions depend on the deposition current density. The increase of their catalytic activity for the HER in 6 mol dm −3 KOH and in 1 mol dm −3 NaOH with increasing the deposition current density was shown to be the consequence of the change of both: their chemical composition and morphology.
2014
The hydrogen evolution reaction (HER) has been investigated on two types of electrodeposited, Nibased, non-noble metal coatings: composite coatings with inclusion of MoO2 particles and electrodeposited NiSn alloy coatings, in order to find suitable replacement for noble metal coatings (commercial De Nora's Ni-RuO2 electrode (DN)), as cathodes for industrial application in the zero-gap membrane cell for chlor-alkali electrolysis. Some samples of both types of cathodes showed better catalytic activity for the HER than the DN electrode under the conditions of industrial applications: 32 mass % NaOH at 90 o C and j = -0.3 A cm -2 . Since lower overvoltage for the HER is not the only criteria for successful application in industrial electrolysis, service life test (SLT), simulating long time operation of cathodes, has been applied for both types of cathodes. It has also been shown that certain samples of both types of cathodes could be promising replacement for the commercial DN electrode since they showed better performance during the SLT.
2013
The hydrogen evolution reaction (HER) was studied on Ni, Ni-Ebonex and Ni-(Ebonex-Ru) coatings in 1 mol dm À3 NaOH solution at 25 C. The composite coatings were electrodeposited from a nickel Watts-type bath containing suspended Ebonex (chemical composition mainly Ti 4 O 7 ) or Ebonex-supported Ru(10 wt.%) particles (0e10 g dm À3 ) onto Ni 40 mesh substrate. The electrodes were investigated by cyclic voltammetry (CV), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), electrochemical impedance spectroscopy (EIS) and polarization measurements. These investigations showed that the roughness factor of the Ni-(Ebonex-Ru) and the Ni-Ebonex coating was 29 and 6 times higher than that of a pure Ni coating, respectively. In the whole potential range of the HER only one Tafel slope of about À120 mV was present at the polarization curves of Ni and Ni-Ebonex electrodes, with increased activity of the latter being attributed only to the increase of the electrochemically active surface area. The Ni-(Ebonex-Ru) electrodes exhibited the highest intrinsic catalytic activity with two Tafel slopes, indicating also that the HER takes place exclusively on Ru active sites.