Cyclic Control of the Surface Properties of a Monolayer‐Functionalized Electrode by the Electrochemical Generation of Hg Nanoclusters

Abstract

Hg(2+) ions are bound to a 1,4-benzenedimethanethiol (BDMT) monolayer assembled on a Au electrode. Electrochemical reduction of the Hg(2+)-BDMT monolayer to Hg(+)-BDMT (at E degrees =0.48 V) and subsequently to Hg(0)-BDMT (at E degrees =0.2 V) proceeds with electron-transfer rate constants of 8 and 11 s(-1), respectively. The Hg(0) atoms cluster into aggregates that exhibit dimensions of 30 nm to 2 microm, within a time interval of minutes. Electrochemical oxidation of the nanoclusters to Hg(+) and further oxidation to Hg(2+) ions proceeds with electron-transfer rate constants corresponding to 9 and 43 s(-1), respectively, and the redistribution of Hg(2+) on the thiolated monolayer occurs within approximately 15 s. The reduction of the Hg(2+) ions to the Hg(0) nanoclusters and their reverse electrochemical oxidation proceed without the dissolution of mercury species to the electrolyte, implying high affinities of Hg(2+), Hg(+), and Hg(0) to the thiolated monolayer. The electrochemical transformation of the Hg(2+)-thiolated monolayer to the Hg(0)-nanocluster-functionalized monolayer is characterized by electrochemical means, surface plasmon resonance (SPR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact-angle measurements. The Hg(0)-nanocluster-modified surface reveals enhanced hydrophobicity (contact angle 76 degrees ) as compared to the Hg(2+)-thiolated monolayer (contact angle 57 degrees ). The hydrophobic properties of the Hg(0)-nanocluster-modified electrode are further supported by force measurements employing a hydrophobically modified AFM tip.

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

“…Linear sweep voltammetry (LSV) was run around ± 100 mV between hydrogen evolution and oxidation, and the potential of zero current was recorded. The potential of zero current was around 0.2198 V (including pH correction of 0.3 × 0.0591 = 0.0177 V) for Ag/AgCl electrode and 0.3306 V (including pH correction) for Ag wire electrode, resulting in a calibration of E Ag/AgCl(KCl, sat) + 0.1108 V = E Ag wire , which is the same as the previous reported value 57 . The windows were then screwed onto the cell forming an air-tight electrolyte chamber of ∼ 1 mm height.…”

Probing Kinase Activities by Electrochemistry, Contact‐Angle Measurements, and Molecular‐Force Interactions

“…[21] Particularly interesting are systems in which the surface properties are reversibly controlled by means of external signals such as electrochemical, [22] photochemical, [23] or chemical [24] stimuli. The use of enzymes to reversibly control surface properties is, however, rare.…”

Photochemical and Electrochemical Encoding of Erasable Magnetic Patterns

“…Similar kinetic results were observed for the electrochemically induced nanoclustering of Ag 0 or Hg 0 nanoparticles on monolayers and for their electrochemical breakdown on the monolayer-functionalized electrodes. [22] The electrochemical reduction of the Co 2+ ions to Co 0 NPs and the re-oxidation of the nanoclusters to the Co 2+ ions is fully reversible, showing that the Co 2+ ions as well as the Co 0 NPs are confined to the monolayer, and they do not dissociate into the electrolyte solution.…”

“…[21,22] Also, a photoisomerizable monolayer has been used for optically addressing of Ag + ions to the nitromerocyanine photoisomer state of the monolayer. [23] The electrochemical reduction of the Ag + ions associated with the monolayer generated Ag 0 nanoclusters that could be re-oxidized to the Ag + ions, and by the photoisomerization of the nitromerocyanine monolayer to the nitrospiropyran state, the Ag + ions could be washed off from the electrode surface.…”