A new gold(III)-aminoethyl imidazolium aurate salt as precursor for nanosized Au electrocatalysts

In this work the novel, robust, air- and moisture-stable gold(III)-aminoethyl imidazolium aurate salt [Cl3AuNH2(CH2)2ImMe][AuCl4] (1) has been employed as precursor for the electrosynthesis of gold nanoparticles (AuNPs) onto ITO electrodes in 0.5 mol dm−3 H2SO4 aqueous solution without the use of additional additives and/or stabilizers. The electrode termed ILNH2-AuNPs200 prepared at a fixed electrodeposition time (td) of 200 s was characterized with AFM, SEM, XRD diffraction as well as cyclic voltammetry (CVs) and compared with an electrode in which the AuNPs have been electrodeposited from KAuCl4 in the presence of KI as additive at the same td (AuNPs200). The effect of the td (i.e. 50 s or 500 s; electrodes ILNH2-AuNPs50 and ILNH2-AuNPs500, respectively) was also investigated together with the electrocatalytic activity towards methanol oxidation in alkaline medium of all the prepared electrodes. The comparison with AuNPs obtained with KI as additive shows that the presence of the amino-functionalized imidazolium moiety although not relevant in relation to the particle size, favours the metal electrodeposition process and plays an important role in the enhancement of the following parameters: (i) surface coverage (S.C.), (ii) electroactive particle coverage Φp %, (iii) electroactive surface area σred(exp)/σred(theor) and (iv) catalytic efficiency.