A mechanistic investigation into the covalent chemical derivatisation of graphite and glassy carbon surfaces using aryldiazonium salts

Abstract

Modification of carbon materials such as graphite and glassy carbon in bulk quantities using diazonium salts is developed. We used both 4-nitrobenzenediazonium tetrafluoroborate and 1-antharaquinonediazonium chloride to modify graphite and glassy carbon surfaces. Experiments were carried out in the presence and absence of hypophosphorous acid and the mechanism involved in both cases were studied using cyclic voltammetry. The observed peak potentials for both the 4-nitrophenyl and 1-anthraquinonyl modified materials were found to differ depending on whether or not the hypophosphorous acid reducing agent was used. In the absence of hypophosphorous acid the derivatisation reaction was inferred to go through a cationic intermediate, whilst in the presence of the hypophosphorous acid the mechanism likely involves either a purely radical intermediate or a mixture of radical and cationic species. Derivatisation experiments from 5 to 70°C allowed us to determine the optimum derivatisation temperature for both cases, in the presence and absence of hypophosphorous acid. Optimum temperature was 20°C for the former and 35°C for the later

Carbon Nanoparticle Surface Electrochemistry: High‐Density Covalent Immobilisation and Pore‐Reactivity of 9,10‐Anthraquinone

“…New types of nanocarbon materials such as nanotubes [5], nanoonions [6], graphene flakelets [7], nanodiamond [8], and hydrothermal [9] or pyrolytic [10] carbons are now widely investigated and employed as a substrate for surface modification and optimisation [11]. Methods for covalent surface attachment to carbon have been developed based, for example, on diazonium chemistry [12], Kolbe attachment [13], photografting of olefins [14], silane attachment [15], and "click-coupling" [16,17].…”

Grafting of Quinones on Carbons as Active Electrode Materials in Electrochemical Capacitors

“…40 The grafting reaction was achieved by spontaneous reduction using in situ generated corresponding diazonium ions, 11,12,14,16 a reducing agent such as H 3 PO 2 41 and an acid-assisted diazotization. 42,43 For these modifications, the carbon substrate (e.g., carbon powder, carbon felt) was left to react in a solution containing the diazonium ions.…”

Anthraquinone modification of microporous carbide derived carbon films for on-chip micro-supercapacitors applications

“…While chemical routes have been extensively used for carbon modification [13], the electrochemical grafting is faster and provides higher grafting loadings [27]. Two methods were used to graft AQ molecules on microporous on-chip CDC film.…”

“…The reduction of the diazonium cation proceeds through a concerted mechanism in which an electron transfer and dinitrogen loss lead to the formation of an aryl radical. The resulting radical species further react with the surface to form a covalent bond with active sites on the electrode [13][14][15][16]. Delamar and coworkers were the first to take advantage of the electrochemical reduction of diazonium cations to modify carbon electrodes [17,18].…”