The surface of gold can be modified with alkyl groups through a radical crossover reaction involving alkyliodides or bromides in the presence of a sterically hindered diazonium salt. In this paper, we characterize the Au-C(alkyl) bond by surface-enhanced Raman spectroscopy (SERS); the corresponding peak appears at 387 cm close to the value obtained by theoretical modeling. The Au-C(alkyl) bond energy is also calculated, it reaches -36.9 kcal mol similar to that of an Au-S-alkyl bond but also of an Au-C(aryl) bond. In agreement with the similar energies of Au-C(alkyl) and Au-S-(alkyl), we demonstrate experimentally that these groups can be exchanged on the surface of gold.

Energy storage provides flexibility to an energy system and is therefore key for the incorporation of renewable energy sources such as wind and solar into the grid. Aqueous Zn–MnO2 batteries are promising candidates for grid‐scale applications due to their high theoretical capacity (616 mAh g–1) and the abundance of their components in the Earth's crust. However, they suffer from low cyclability, which is probably linked to the dramatic pH variations induced by the electrochemical conversion of MnO2. These pH variations are known to trigger the precipitation/dissolution of zinc hydroxide sulfate (Zn4(OH)6SO4 . xH2O, (ZHS)), which might have an influence on the conversion of MnO2. Herein, optical reflectometry is used to image and quantitatively monitor the MnO2 electrode's charge and discharge in situ and under operation. It emphasizes how solid‐phase ZHS rules the dynamics of both charge and discharge, providing a comprehensive picture of the mechanism at play in aqueous Zn–MnO2 batteries. If the precipitation of ZHS might impede the MnO2 electrode's discharge, it is a crucial pH buffer delaying the occurrence of the competing oxidation of water on charge.

The spontaneous grafting of diazonium salts on gold may involve the carbocation obtained by heterolytic dediazonation and not necessarily the radical, as usually observed on reducing surfaces. The mechanism is addressed on the basis of DFT calculations and experiments carried out under conditions where the carbocation and the radical are produced selectively. The calculations indicate that the driving force of the reaction leading from a gold cluster, used as a gold model surface, and the carbocation to the modified cluster is higher than that of the analogous reaction starting from the radical. The experiments performed under conditions of heterolytic dediazonation show the formation of thin films on the surface of gold. The grafting of a carbocation is therefore possible, but a mechanism where the cleavage of the Ar-N bond is catalyzed by the surface of gold cannot be excluded.

The degradation of Prussian blue (PB) during H2O2 reduction is investigated by scanning electrochemical microscopy (SECM). Coupling SECM with optical microscopy allows quantitative assessment in situ of the effect of HO− on the dissolution of PB in lithographic experiments. The local production of HO− in the vicinity of PB is an easy way to pattern a PB layer; Such PB dissolution during H2O2 reduction leads to the release of soluble ferrocyanide and Fe2+. In the presence of H2O2, the latter initiate the Fenton reaction and the generation of highly reactive hydroxyl radicals HO.. This is revealed by the degradation of an organic layer immobilized on an ultramicroelectrode held in the vicinity of a PB layer during H2O2 reduction. The formation of such reactive species is of great importance to further understand the possible origin of the activity loss of sensors, batteries, and photovoltaic cells when composite materials based on PB or on its derivatives are used as catalysts for H2O2 or O2 reduction.

Optical modeling coupled to experiments show that a microscope operating in reflection mode allows imaging, through solutions or even a microfluidic cover, various kinds of nanoparticles, NPs, over a (reflecting) sensing surface, here a gold (Au) surface. Optical modeling suggests that this configuration enables the interferometric imaging of single NPs which can be characterized individually from local change in the surface reflectivity. The interferometric detection improves the optical limit of detection compared to classical configurations exploiting only the light scattered by the NPs. The method is then tested experimentally, to monitor in situ and in real time, the collision of single Brownian NPs, or optical nanoimpacts, with an Au-sensing surface. First, mimicking a microfluidic biosensor platform, the capture of 300 nm FeOx maghemite NPs from a convective flow by a surface-functionalized Au surface is dynamically monitored. Then, the adsorption or bouncing of individual dielectric (100 nm polystyrene) or metallic (40 and 60 nm silver) NPs is observed directly through the solution. The influence of the electrolyte on the ability of NPs to repetitively bounce or irreversibly adsorb onto the Au surface is evidenced. Exploiting such visualization mode of single-NP optical nanoimpacts is insightful for comprehending single-NP electrochemical studies relying on NP collision on an electrode (electrochemical nanoimpacts).

A gold surface immersed in an aprotic iodonium salt solution containing a photosensitizer is patterned by irradiation with a blue light through a mask. The photochemical behavior of three photosensitizers in the presence of (4-nitrophenyl)(2,4,6-trimethylphenyl)iodonium triflate I is fully characterized [luminescence quantum yield Φ L and lifetime τ L , quenching rate constant (k q), ΔG° and quantum yield (Φ R)]. The key species for the surface modification are aryl radicals formed under irradiation through reduction of the iodonium salt by the excited state of the photosensitizer. The pattern consists of a polyaryl film obtained from aryl radicals that react with the surface and also with the first grafted aryl groups. The modified surface is characterized by IR, XPS, AFM and electrochemistry. The submillimetric pattern is observed by condensation and Scanning Electrochemical Microscopy. This method permits to obtain strongly bonded patterns with variable substituents on the aryl ring; it allows preparing various patterns of multifunctional surfaces that can be used for sensors and diagnostics, or to limit hydrophilic paths within hydrophobic films for surface tension confined microfluidic devices.

The surfaces of poly(methyl methacrylate) and polyethylene are modified either (i) by a two-step process including the thermal reaction of alkyl radicals derived from bromohexanoic acid in a mixture of 2,6-dimethylbenzene diazonium salt and neat isopentyl nitrite at 60 °C, followed by reaction with p-nitroaniline, anthraquinone, neutral red, and polyethylene glycol moieties, or (ii) by reaction of a previously anthraquinone-modified bromohexanoic acid. The modified surfaces are characterized by IR, XPS, UV, and water contact angles. A mechanism is proposed to rationalize the results. This approach is an efficient way to modify and pattern polymer surfaces with different organic groups and chemical functionalities under mild conditions.

Alkyl chains are covalently attached onto metal surfaces by indirect reduction of the bromoalkyl derivative (RBr). This indirect reaction involves the formation (by spontaneous or electrochemical reduction of the 2,6-dimethylbenzenediazonium salt) of a sterically hindered aryl radical that abstracts a Br atom from RBr but does not react with the surface. This crossover reaction furnishes an alkyl radical that reacts with the surface. Starting from 6-bromohexanoic acid, carboxylic functionalized gold surfaces are prepared. "Layer-by-layer" assemblies are built from these surfaces and present some ionic selectivity.