New One-Step Thiol Functionalization Procedure for Ni by Self-Assembled Monolayers

Abstract

This article reports on a facile and fast strategy for the self-assembled monolayer (SAM) functionalization of nickel surfaces, employing cyclic voltammetry (CV) cycling of a suitable tailored solution containing the species to be adsorbed. Results are presented for ultrathin films formed on Ni by 1-hexadecanethiol (C16), L-cysteine (L-cys), and the poly{methyl (2R)-3-(2,2'-bithiophen-4-ylsulfanyl)-2-[(tert-butoxycarbonyl)amino]propanoate} (PCT-L) thiophene-based chiral polymer. The effective formation of high-quality ultrathin organic films on the nickel was verified both electrochemically and by exploiting typical surface characterization techniques such as contact angle, ellipsometry, atomic force microscopy (AFM), polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS).

Spin-Dependent Transport through Chiral Molecules Studied by Spin-Dependent Electrochemistry

“…41,42 In particular, Ni (for Co the situation is even worse) forms an oxide layer which can deteriorate the coherence of spin in the current flowing through it. Thus, we developed a method to reduce the oxide film on Ni in situ with the assembly of a monolayer of chiral polymer.…”

Fabrication of ultra-smooth and oxide-free molecule-ferromagnetic metal interfaces for applications in molecular electronics under ordinary laboratory conditions

“…Fabrication methods based on highly controlled ultra-high vacuum (UHV) environments or in situ electrochemical control are available. 4,5,[33][34][35][36] Most electrochemical techniques are based on a two-step procedure involving removal of the native oxide by electrochemical reduction, followed by immediate substrate immersion in alkanethiol containing ethanolic solutions. During transfer of the oxide free Ni surface, metal-oxides can form as the substrates are exposed to air.…”

“…For example, Bengió et al 34 reported the fabrication of n-alkanethiolate SAMs on Ni(111) and polycrystalline Ni surfaces by the electrochemical reduction method in which the electrochemical reduction was performed under either acidic or basic aqueous conditions, while the SAM formation was carried out either in situ or by pulling the substrate through a top layer of neat thiol. Instead of using two separate steps and acidic or basic aqueous electrolyte, Fontanesi et al 35 performed electrochemical removal of the oxide layer with the thiol precursor present in the electrolyte (1 : 0.8, ethanol : water) and reported good quality SAMs. Hoertz et al 14 used three different methods for SAM formation on Ni, Co and Fe substrates, (i) glovebox techniques (freshly evaporated metal transfer to a solution of the SAM precursor without exposure to air), (ii) electrochemical reduction inside a glovebox (oxide removal by electrochemical reduction and SAM formation carried out inside the glovebox), and (iii) deposition of metal via direct metal evaporation followed by a brief exposure in air before immersion into a solution with the SAM precursor.…”

“…[37][38][39][40][41][42] Substrates used for preparation of SAMs on Ni by electrochemical methods have typically a root mean square (rms) surface roughness of 2.5 nm over an area of 2 Â 2 mm 2 which is much higher than the molecular dimensions of the SAMs they support. 35 In addition, electrochemical etching increases the rms surface roughness of, for example, Ni and Co, by about $40%. 14 Although the roughness is usually reported in terms of rms surface roughness, the topography can also be more comprehensively analyzed to include, grain size, width of the grain boundary, presence of pinholes, and whether the grains are located in the same plane or not.…”

Magnetoelectrochemistry and Asymmetric Electrochemical Reactions

“…Using the pulsed mode of the potentiostat and galvanostat techniques gives an interesting chiral system with uniform surface morphology. A prepared Ni surface can be further functionalized for spin dependent electrochemistry [18].…”