A photocatalytic and electrochemical study of gold nanoparticles synthesized by a green approach

Abstract

Quasi-spherical gold nanoparticles mixed with a controlled amount of gold nano triangles were obtained through a green chemical method using leaf extract of Loeselia mexicana. Moreover, the influence of the extract and HAuCl 4 solution concentration in the morphology of the nanoparticles was studied. The nanoparticle preparation was performed by varying the concentration of the extract and precursor salt. The catalytic activity of the as-prepared nanoparticles was studied by the reduction of methylene blue, rhodamine B, and gentian violet organic dyes. Also, cyclic voltammetry profiles were obtained in order to analyze the electrochemical response of the nanoparticles. The morphology and structural characterization were analyzed by UV-vis, SEM, TEM, FTIR, and XRD. The SEM analysis reveals gold nanoparticles with spherical and triangular morphologies. The UV-vis spectra revealed that the extract concentration influenced the morphology and amount of the obtained gold nanoparticles. The XRD and TEM analysis showed that gold nanoparticles presented a face-centered cubic lattice structure. The cyclic voltammetry analysis confirms a high-sensitivity electrochemical response and stability corresponding to the gold nano triangles. Finally, the presence of gold nano triangles shapes influenced the efficiency of the degradation of the dyes due to their high specific surface area.

Electrochemical Properties of Phytosynthesized Gold Nanoparticles for Electrosensing

“…Compared with physical methods of synthesis, chemical ones are quite simple, labor-saving, and inexpensive. However, reagents and solvents used in chemical synthesis, as well as reaction byproducts, can have a harmful impact on the human body and the environment [ 2 , 3 ]. Recently, alternative methods of nanoparticle synthesis, based on the “green” chemistry approach, have emerged.…”

“…The distinctive features of phytosynthesized gold nanoparticles (phyto-AuNPs) are their high catalytic ability in the process of organic dye degradation [ 2 , 7 ]; antibacterial [ 8 ], anticancer [ 9 ], and antioxidant activity [ 8 , 9 , 10 ]; and biocompatibility and low cytotoxicity [ 5 ], which makes phyto-AuNPs very attractive for biomedical applications, including theranostics, diagnostic studies, cell imaging, photodynamic therapy, as well as drug, protein, and gene delivery [ 5 , 11 ]. In electrosensing, phyto-AuNPs have not been frequently used yet, which is primarily due to the lack of knowledge about their electrochemistry.…”

Estimation of the Real Area of Au Nanoparticles Over Hopg Using Electrochemical Techniques

“…Lo mismo observó Laffont et al [18] al modificar carbón vítreo con nanopartículas de Au utilizando voltamperometría de extracción anódica de onda cuadrada incluyendo un paso de desorción de cloruro para la detección de trazas de mercurio (II). En cambio, no ocurrió lo mismo cuando Herrero-Calvillo et al [19] obtuvieron nanopartículas de oro sobre carbón vítreo utilizando la química verde, esto es extracto de hoja de Loeselia mexicana.…”

“…4. Diferentes autores [17][18][19][20] obtuvieron resultados similares a los nuestros cuando estudiaron la estabilidad de nanopartículas de oro sobre soportes carbonosos. La forma característica de los voltamogramas de oro se vuelve más definido a un tiempo de deposición de 180 s, esto podría estar relacionado con la reconstrucción de las nanopartículas a geometrías más estables.…”

Ag@Au bimetallic nanoparticles: an easy and highly reproducible synthetic approach for photocatalysis

“…In both cases, the oxidation-reduction processes are irreversible, similar to those reported in the literature. 42,43 These differences could be attributable to the ion's diffusion dependence from the electrode/dissolution interphase posterior to the metallic ion oxidation. In this sense, the rate observed for the ions when migrated from the electrode to the bosom of the dissolution (oxidation) is different from that observed for the inverse process (reduction), when the scanning sense is inverted, promoting a signal decrease in each cycle (see Fig.…”