Electrochemical Characterization and Electrocatalytic Application of Gold Nanoparticles Synthesized with Different Stabilizing Agents

Abstract

Gold nanoparticles (AuNPs) have unique properties, making them attractive for electronic and energy‐conversion devices and as (electro)catalysts for electrochemical sensors. In addition to the size and shape of AuNPs, the electrocatalytic properties of AuNP‐sensors are also determined by the stabilizing agent used in their synthesis. Here, AuNPs were synthesized with citrate, alginate and quercetin, obtaining spherical and negatively charged nanoparticles. The AuNPs were used to modify glassy carbon electrodes (AuNPs/GCE), which were characterized by scanning electron microscopy and electrochemical techniques. The AuNPs/GCE showed aggregates of different sizes and degrees of dispersion on the electrode surface depending on the stabilizing agent. The AuNP's aggregates affect the homogeneity of the film, the reproducibility of the electrodes and their response in buffer solution. Finally, to evaluate the electrocatalytic ability of the AuNPs/GCE, we studied the oxidation of two analytes with opposite charges: (1) sunset yellow (negative) and (2) hydrazine (positive). Compared with GCE, the AuNPs/GCE showed good electrocatalytic properties for hydrazine, increasing the current up to 50 % and shifting the potential by almost 400 mV, depending on the AuNP used. For the negatively charged analyte, the current decreased up to 50 % and no shift in potential was observed. Thus, the electrocatalytic properties of the AuNPs showed to be highly dependent on the nature of the analyte.

One-step preparation of multifunctional alginate microspheres loaded with in situ-formed gold nanostars as a photothermal agent

“…The aggregation and precipitation of Au NPs were also avoided by such a template effect. [32][33][34][35] As shown in Fig. 2c, EDX analysis of Au@CA-10 microspheres verified the existence of elements C, O, Ca and Au in the matrix of alginate.…”

“…Therefore, alginate is also used as an excellent stabilizer and soft template to synthesize various metal/metal oxide nanocomposites, such as Au, Ag and CeO 2 . [32][33][34][35] Additionally, as a green and mild reducing agent, alginate is capable of reducing HAuCl 4 to Au(0) or AgNO 3 to Ag(0) due to the presence of hydroxyl groups. [36][37][38][39][40] But these as-synthesized Au or Ag nanoparticles (NPs) were in spherical shape without NIR photothermal conversion properties.…”

Thiolated DAB Dendrimers-Gold Nanoparticles as Self-Assembled Layers for the Direct Electrochemistry of HRP

“…The voltammetric profile of the first layer (electrodeposited AuNPs, red line) displays two anodic peaks at 0.829 V and 0.986 V, and a cathodic peak at 0.443 V corresponding to the formation and subsequent reduction of the Au oxides at pH 7.0. 23,52 The feature of anodic region, including the broad peak at −0.05 V, is characteristic and it is assigned to a truncated octahedral structure. 53,54 The total Au surface area could be estimated from the coulombic integration of the reductive waves of gold oxide using the widely accepted conversion factor of 390 μC/cm 2 .…”

Simple immunosensor for ultrasensitive electrochemical determination of biomarker of the bone metabolism in human serum

“…As seen, a remarkably increased capacitive current (~7 fold increasing) is observed on AuNPs/CS-G/GCE compared with that of GCE, suggesting an enlarged ECSA owing to the decoration of AuNPs. In addition, two apparent redox peaks at ~1.1 and ~0.55 V are observed on AuNPs/CS-G/GCE attributing to the decorating of AuNPs (Sierra-Rosales et al, 2018). At the same time, AuNPs/CS-G/GCE demonstrates larger decomposition currents and reduced decomposition potentials for both the anodic and cathodic limits, indicating an improved electroanalytical reactivity.…”