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The strategy proposed herein employs the scanning electrochemical microscope in generation/ collection mode to clarify the mechanism involved in the electrosynthesis of metal oxide nanoparticles, NPs. It offers simultaneously both generation of the precursors of the NPs and electroanalysis at a single NP level by nanoimpact coulometry. The former process is operated under controlled fluxes within the wide field of precursor diffusion in the inter-microelectrode gap, thus forming a tunable reaction layer allowing the growth of a size gradient of NPs within this gap. The latter process exploits the much slower diffusion of NPs, spatially frozen, in the near field of a collecting microelectrode. This then makes it possible to dynamically monitor the modes of growth of NPs in situ without perturbing their synthesis. As a proof of concept, the synthesis of Ag2O nanocubes, NCs, is described, using an Ag microelectrode to generate Ag+ ions while a facing Au microelectrode both electrogenerates HO− and collects the resulting Ag2O NCs. Dynamic analysis of the NCs’ reductive electrochemical impacts provides insights into their growth and stability. In particular, it suggests a two-step growth mechanism starting from the quasi-instantaneous nucleation of a > 260 nm nuclei followed by mass-transfer-driven crystallization over the nuclei.

A global strategy to prepare a versatile and robust reactive platform for immobilizing molecules on carbon substrates with controlled morphology and high selectivity is presented. The procedure is based on the electroreduction of a selected triisopropylsilyl (TIPS)-protected ethynyl aryldiazonium salt. It avoids the formation of multilayers and efficiently protects the functional group during the electrografting step. After TIPS deprotection, a dense reactive ethynyl aryl monolayer is obtained which presents a very low barrier to charge transfer between molecules in solution and the surface. As a test functionalization, azidomethylferrocene was coupled by "click" chemistry with the modified surface. Analysis of the redox activity highlights a surface concentration close to the maximum possible attachment considering the steric hindrance of a ferrocenyl group. [ABSTRACT FROM AUTHOR]