XPS characterization of the corrosion film formed on the electroless nickel deposit prepared using different stabilizers in NaCl solution

Abstract

X-ray photoelectron spectroscopy (XPS) was used to examine the corrosion films formed on electroless nickel (EN) deposits prepared in an EN solution containing two different types and concentrations of bath stabilizers in Ar-purged and oxygenated neutral 5% NaCl solution. Two distinctive corrosion films were observed after long periods of immersion. An enrichment of elemental phosphorus compared to nickel was observed on the surface of the EN deposit produced with no stabilizer and with maleic acid (MA). By comparison, a high degree of surface oxidation was observed on the EN deposit prepared with thiourea. Trace impurities of sulfur in the EN deposit prepared with thiourea appear to result in enhanced corrosion and, in turn, lead to the build-up of corrosion products on the EN surface. By contrast, a P-enriched chemical passivation layer was formed on the EN deposits prepared either without any stabilizer or with MA present. Copyright INTRODUCTIONThere has been a considerable interest in understanding the nature and properties of the oxide layers formed in aqueous solution on nickel and its alloys because a thin 0.9-1.2 nm film can confer passivity on the material. 1 -12 A bilayer model, composed of a top layer of nickel hydroxide [Ni(OH) 2 ] and a base layer of nickel oxide (NiO), is thought to be present. This model is supported by X-ray photoelectron spectroscopy (XPS) investigations. 1 -5 The XPS data reveal two fairly well resolved O 1s peaks at 529.8 eV and 531.6 eV, and these two peaks correspond well to the positions of oxygen in NiO and Ni(OH) 2 .1 However, these spectral features may also be interpreted differently since Ni 3C can give rise to spectral features very similar to those of Ni(OH) 2 . 6 The atomic structure of thin oxide films on metal surfaces is important in understanding the properties of passive films. 7 The first lateral and vertical atomic resolution ex situ STM imaging of an electrochemically produced passive oxide film on a single crystal Ni(111) electrode revealed it to be crystalline with a mosaic structure of crystallites 2-3 nm in size. 8 On the atomic scale, the film consists of a stepped crystalline lattice with a lattice parameter corresponding to the (111) orientation of NiO in 0.05 M H 2 SO 4 . The lattice mismatch between the oxide Ł Correspondence to: Woo-Jae Cheong, Reactor Chemistry & Corrosion Branch, Atomic Energy of Canada Limited, Chalk River, Ontario, K0J 1J0, Canada. E-mail: cheongw@aecl.ca; cheongw@gmail.com and the substrate resulted in the preferential epitaxial relationship. 7 -9 The atomic structure of the Ni(100) passive film in 1 M NaOH was later imaged with atomic resolution in situ. A well-ordered rhombic structure was identified at low oxidation potentials ( 0.7-0.5 V/Normal Hydrogen Electrode (NHE)), and at higher potentials (>0.18 V/NHE) a quasi-hexagonal structure was observed. 10 The in situ STM observation on single crystal Ni was also studied in acidic solution at pH 3.0.9,11 The first oxide layer on Ni(111) at 0.0915 V/Standard Hydrogen Elec...

Amorphous Ni0.75Fe0.25(OH)2‐Decorated Layered Double Perovskite Pr0.5Ba0.5CoO3‐δ for Highly Efficient and Stable Water Oxidation

“…Despite the relatively low intensities of the peaks representing the decoration elements, i. e., Ni and Fe on the spectra of the two decorated samples, their presence is substantiated by the peaks at 855 eV and 873 eV that represent 2p 3/2 and 2p 1/2 peaks from Ni (Indicated by (*) in Figure ) . Moreover, the two additional peaks at 642 eV and 713 eV on the two decorated samples can be ascribed to LMMa and LMMb signals from Ni . The signature peak of Fe that is normally present at 710 eV cannot be confidently distinguished due to the major overlapping with the other peaks.…”

“…[5] Moreover, the two additional peaks at 642 eV and 713 eV on the two decorated samples can be ascribed to LMMa and LMMb signals from Ni. [41] The signature peak of Fe that is normally present at 710 eV cannot be confidently distinguished due to the major overlapping with the other peaks.…”

Ni2P Nanoparticles Embedded in Mesoporous SiO2 for Catalytic Hydrogenation of SO2 to Elemental S

“…Cheong et al give a binding energy of 856.7 eV for Ni(OH) 2 and state that the small binding energy difference between Ni(OH) 2 and Ni 3 (PO) 4 makes it difficult to distinguish between these two chemical states. 26 Considering that Ni 3 (PO) 4 has been identified from the P 2p peaks and the binding energies observed also correspond to Ni(OH) 2 , it is reasonable to expect that Ni(OH) 2 is the dominant species on the Ni catalyst surface and Ni(OH) 2 and Ni 3 (PO) 2 are present on the Ni 2 P oxidized surface. This is in agreement with the interpretation given by Sawhill et al for the oxidized surface of Ni 2 P catalysts.…”

“…This peak corresponds to the oxidized surface of Ni 2 P and can be attributed to Ni 3 (PO) 4 in accordance with other references. 7,23,24,26 The strongest Ni 2p 3/2 peak for all Ni 2 P and Ni catalyst samples occurs at binding energies between 856.7 and 857.2 eV. Cheong et al give a binding energy of 856.7 eV for Ni(OH) 2 and state that the small binding energy difference between Ni(OH) 2 and Ni 3 (PO) 4 makes it difficult to distinguish between these two chemical states.…”

The role of Bi3+‐complex ion as the stabilizer in electroless nickel plating process

“…A number of sulfur‐containing chemicals, such as thiourea in particular, were proposed to replace lead as the stabilizer in ENP solution. However, the participation of sulfur species in the ENP layer has been a concern for its deteriorative effect on the corrosion resistance of ENP deposits 7–12…”