Insight on the Surface Structure Effect of Free Gold Nanorods on Glucose Electrooxidation

Abstract

The physicochemical properties of noble metal such as gold strongly depend on their size, shape, and their surface structure composition. Gold NPs have been studied in electrocatalysis due to their unexpected activity toward the oxidation of organics. The chemical reactions studies on a well-defined shape provide fundamental data on the surface reactivity for understanding and designing novel catalytic materials. Therefore, different gold nanorods (GNRs) were synthesized by chemical growth process. The UV–vis spectroscopy and transmission electron microscopy measurements confirmed their well-defined shape and size distribution. Moreover, the under-potential of lead (UPD), which is a sensitive electrochemical surface characterization tool, has been used to assess GNRs crystallographic structure information. Additionally, the UPD of lead reveals that their crystallographic facets are affected by their growth process. Most importantly, the interaction between GNRs surface and the remaining capping agent (CTAB) adsorbed after cleaning process has a high effect on the lead deposition and also leads to a decrease in the electrochemical activity of GNRs. The activity of different GNRs toward glucose oxidation was also investigated. The correlation between the activity of these materials toward this reaction and their surface structure was established. It shows an enhancement of the electroactivity in the presence of (100) facets.

Shape-dependent electrocatalytic activity of free gold nanoparticles toward glucose oxidation

“…For the electrochemical experiments, the glassware was cleaned according to the methodology described elsewhere [28,35]. Afterwards, the glassware was rinsed with hot water and kept in aqua regia solution for an hour and finally rinsed with ultrapure water (18.2 MΩ cm at 20°C).…”

“…It could therefore allow electrocatalytic reactions with great selectivity. The details of the synthesis process were reported elsewhere [5,14,16,28]. .…”

“…In the literature, the electrocatalytic oxidation of glucose in alkaline medium was studied on Cu, Ag-Au, Au-Pt, Ag, Pt and Au materials [21][22][23][24][25][26][27][28][29][30][31]. In alkaline and neutral media, gold appeared as an excellent electrocatalyst for several saturated oxygenated organic compounds due to its catalytic activity at low potentials compared to the other catalysts in the same conditions [22,25,30].…”

“…lead on gold, are a useful tool for characterizing its surface structure distribution [17,18]. More recently, Hebié et al [28] showed that the contribution of (100) facets on gold nanorods enhances the electroactivity toward the glucose oxidation.…”

Probing the surface oxidation of chemically synthesised gold nanospheres and nanorods

“…In many cases, this can be quite involved and may perturb the shape and size of the nanomaterial in question. Electrochemical cleaning routes are often used which employ oxidation of the surface to remove the capping agent [13,14]. Indeed, repetitive cycling in acidic electrolyte is often used even for bare gold surfaces and nanoparticles to generate a clean sample [15,16].…”