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Voltammetric behaviour of cationic redox probes at mesoporous silica film electrodes

Abstract : The effect of vertically aligned silica nanochannels on the electrochemical response of various cationic redox probes has been investigated. To this end, an oriented mesoporous silica thin film has been generated by electro-assisted self-assembly onto a fluoride-doped tin oxide (FTO) electrode, which was then used to characterize the voltammetric behaviour of redox cations of different nature, size and charge. Methylene Blue (MB +), paraquat (PQ 2+), diquat (DQ 2+), ruthenium trisbipyridine (Ru(bpy)3 2+) and ruthenium hexamine (Ru(NH3)6 3+) were selected for that purpose. Multisweep cyclic voltammetry experiments showed significant accumulation of these cations thanks to favourable electrostatic interactions with the negatively-charge silica surface, but the enhancement of the votammetric signals compared to the bare FTO electrode was strongly dependent on the probe type, according the following trend: MB + > PQ 2+ > DQ 2+ > Ru(bpy)3 2+ > Ru(NH3)6 3+. The accumulation processes were very fast owing to the vertical orientation of the mesopore channels ensuring fast diffusion from the solution to the electrode surface. Operating at various potential scan rates and different probe concentrations enabled to quantify the relative ratio between surface-confined and diffusion-controlled processes, the adsorption phenomena being clearly more prominent in diluted media and also accentuated at high potential scan rates. The mesoporous silica film electrodes exhibited higher sensitivities at lower concentrations, which can give benefits for sensor applications at trace levels.
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https://hal.univ-lorraine.fr/hal-02484251
Contributor : Grégoire Herzog <>
Submitted on : Thursday, November 26, 2020 - 4:39:00 PM
Last modification on : Wednesday, December 9, 2020 - 3:40:39 PM
Long-term archiving on: : Saturday, February 27, 2021 - 7:56:00 PM

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Deomila Basnig, Neus Vilà, Grégoire Herzog, Alain Walcarius. Voltammetric behaviour of cationic redox probes at mesoporous silica film electrodes. Journal of Electroanalytical Chemistry, Elsevier 2020, pp.113993. ⟨10.1016/j.jelechem.2020.113993⟩. ⟨hal-02484251⟩

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