Characterization of Pulse Plated Ni and NiZn Alloys

Abstract

Nickel, zinc and nickel-rich NiZn alloys were formed on platinum by galvanostatic pulse plating from aqueous sulfate baths. The alloys were formed in three steps, first in anomalous deposition by a current pulse, secondly by dissolution and oxidation during the open circuit potential in each cycle and finally by anodic stripping of the fully plated sample. The treatment leaves a stable phase with an alloy composition of Ni 0.8 Zn 0.2 . The potential-time curves during the plating procedure were used to qualitatively describe the nucleation and growth processes. For Zn a fully covered surface was obtained after one pulse while for Ni and NiZn three-dimensional clusters were obtained in the first pulse. Further growth of these layers involves nucleation on the substrate and deposited clusters. The films were characterized with optical microscopy, SEM/EDX, AFM, XPS, TEM and by electrochemical methods. XPS revealed that the surfaces become gently oxidized by the stripping in the plating solution. For Ni a bi-layer of NiO/Ni(OH) 2 was found on the surface while for NiZn mainly the hydroxide was detected. The electrocatalytic properties of the layers toward oxygen reduction in alkaline solution were explored and the NiZn alloy was proven to be an excellent catalyst for hydrogen peroxide production.

Fabrication of Tapered Microtube Arrays and Their Application as a Microalgal Injection Platform

“…The Ni 2p XPS region after Ni PCD (Figure b) shows characteristic peaks for metallic Ni at 851.7 and 868.9 eV with little or no oxide present . This contrasts with the previous work by Göransson et al, who report the presence of NiO and Ni­(OH) 2 species in their Ni PCD sample . We attribute this discrepancy to the difference in the PCD parameters: the work by Göransson et al used longer pulse durations and lower current density then what we applied in our study.…”

“…54 This contrasts with the previous work by Goransson et al, who report the presence of NiO and Ni(OH) 2 species in their Ni PCD sample. 55 We attribute this discrepancy to the difference in the PCD X-ray diffraction (XRD) of the Ni layer electrodeposited by PCD confirms the deposition of polycrystalline Ni (Figure 3d). This sample was prepared by 20 000 cycles of PCD on a Cu foil substrate to ensure sufficient thickness for the XRD experiment.…”

Epitaxial Growth of Au–Pt–Ni Nanorods for Direct High Selectivity H2O2 Production

“…The H 2 O 2 selectivity for H 2 O 2 production varied between 4% and 8% on Au NRs (Figure S8, Supporting Information) and was ≈40% on Ni (Figure S9, Supporting Information). Goransson et al also reported a low selectivity of ≈20% on Ni catalyst in the same electrolyte . Thus, the previously mentioned high selectivity of the prepared NRs can be attributed to the synergetic effect between Au and Ni via epitaxial growth.…”

Phenformin Effect on the Anodic Dissolution of Nickel in Acid Media

“…Among other transition metal-based systems (e.g. nickel, zinc and nickelrich NiZn alloys) [8], polycrystalline nickel electrodes have been the subject of extensive studies in acidic aqueous media [9][10][11][12][13][14][15], where dissolution and passivation processes are observed [16][17][18][19][20][21][22]. Both phenomena were postulated through reaction schemes which begin with two common electrochemical steps, reactions 1 and 2, where an intermediate Ni(II) species is produced from water adsorption on the metal surface.…”