Nanoscale Au–In Alloy–Oxide Core–Shell Particles as Electrocatalysts for Efficient Hydroquinone Detection

Abstract

The presence of hydroquinone (HQ), a phenol, ubiquitous in nature and widely used in industry needs to be monitored due to its toxicity to the environment. Here we demonstrate efficient detection of HQ using simple, fast and non-invasive electrochemical measurements on ITO electrodes modified with nanoparticles comprising bimetallic Au-In cores and mixed Au-In oxide shells. While bare ITO electrodes show very low activity for the detection of HQ, their modification with Au-In core-shell nanoparticles induces a pronounced shift of the oxidation peak to lower potentials, i.e., facilitated oxidation. The response of the different electrodes was correlated with the initial composition of the bimetallic nanoparticle cores, which in turn determined the amount of Au and In stabilized on the surface of the amorphous Au-In oxide shells available for the electrochemical reaction. While adding core-shell nanostructures with different compositions of the alloy core facilitates the electrocatalytic (reduction-) oxidation of HQ, the activity is highest for particles with AuIn cores (i.e., a Au:In ratio of 1). This optimal system is found to follow a single pathway, the two-electron oxidation of the quinone-hydroquinone couple, which gives rise to high oxidation peaks, and is most effective in facilitating the electrode-to-analyte charge transfer and thus detection. The limits of detection (LOD) decreased when increasing the amount of Au exposed on the surface of the amorphous Au-In oxide shells. The LODs were in the range of 10-5-10-6 M and were lower than those obtained using bulk Au.

Electrochemical Sensors Modified with Combinations of Sulfur Containing Phthalocyanines and Capped Gold Nanoparticles: A Study of the Influence of the Nature of the Interaction between Sensing Materials

“…The electrocatalytic properties of gold nanoparticles (AuNPs) are also well established [24,25,26,27], and a variety of uncapped and capped AuNPs have been successfully used to detect phenols [28,29,30].…”

Monitoring the Phenolic Ripening of Red Grapes Using a Multisensor System Based on Metal-Oxide Nanoparticles

“…The responses on MONP-CPEs were consistent with those already reported in bare CPE electrodes (Kilmartin et al, 2001 ), but the presence of MONPs caused shifts in the position of the peaks to lower potentials and/or increases in the intensity of the peaks. This effect could be attributed to the excellent electrocatalytic activity of MONPs due to the mixed valence state found at the nanoparticle surface (Medina-Plaza et al, 2015b ). Depending on the nature of the MONPs used as modifiers, the responses toward a certain compound was more or less enhanced.…”

“…Prior to perform the statistical analysis, the number of variables was reduced using a data reduction technique based on predefined response “bell-shaped-windowing” curves called “kernels” (Medina-Plaza et al, 2015b ). In this method, each voltammogrammetric curve is multiplied by 10 smooth, bell-shaped windowing functions defined as:…”

“…Metal nanoparticles have demonstrated their capability to catalyze the oxidation/reduction of organic acids and phenols commonly present in wines. The oxidation of phenols occurs at lower potentials, whereas the presence of metallic nanoparticles increases the reactivity of acids and enhances the intensity of the anodic wave at negative potentials (Medina-Plaza et al, 2015a , b ). In spite of this interest, metal nanoparticles have rarely been included as sensing materials in electronic tongues (Gutiérrez et al, 2013 ; Sharpe et al, 2014 ; Mercante et al, 2015 ).…”

Novel Method for the Identification of the Variety of Grape Using Their Capability to Form Gold Nanoparticles

“…This is in good correlation with previous studies that have demonstrated that the size of the obtained nanoparticles depends on the concentration of the reducing agent (citrate, nitrite, etc. ), and that this effect can be used to develop colorimetric probes [27,28]. A further observation from analysis of these spectra concerns the broadness of the peaks that are reflecting of a large dispersion of the size of the AuNPs obtained.…”