Electrochemistry as a Complementary Technique for Revealing the Influence of Reducing Agent Concentration on AgNPs

Abstract

The synthesis process of AgNPs has been attracting a lot of attention in the fields of biosensors/sensors, diagnostics, and therapeutic applications. An attempt to understand the effect of different concentrations of reducing agents on the synthetic design process has been made. In this paper, we gather information on voltammetry studies and relate it with UV–vis and scanning electron microscopy (SEM) analyses. Given the kinetics, localized surface plasmon absorption (LSPR) band, and narrow size distribution of these methods, it was possible to compare the obtained measurements and clearly distinguish sizes and aggregation. AgNPs measured by SEM showed a statistically significant reduction of the nanoparticle sizes from 65 to 37.5 nm as the reducing agent increased. Well-matched d-spacing data calculated from selected area electron diffraction (SAED) patterns and X-ray diffraction (XRD) were obtained for all of the samples. The UV–vis studies showed that the SPR bands shift toward the blue region as the reducing agent concentration is increased, indicating a decrease in particle sizes. It is worth emphasizing that cyclic voltammetry (CV) and differential pulse voltammetry (DPV) coincide well with SEM on the aggregation of AgNPs at higher concentrations. A 10 mM reducing agent concentration resulted in uniform outcomes for producing AgNPs with the smallest size in terms of full width at half-maximum (FWHM) in all of the methods used in this study, while UV–vis band gaps increase with increasing reducing agent concentration. In agreement with all of the methods investigated, the results suggested that the best concentration of the reducing agents is 10 mM for a target application. These findings suggest the usefulness of voltammetry as a complementary method that can be used as a qualitative guide to identify the size and aggregation of NPs.

The Release of Non-Extractable Ferulic Acid from Cereal By-Products by Enzyme-Assisted Hydrolysis for Possible Utilization in Green Synthesis of Silver Nanoparticles

“…The reduction in the size of AgNPs is perhaps due to additional hydroxyl moieties ensured by the presence of t - iso -FA, which also was directly involved in reducing Ag ions to NPs. This observation is in line with that of Timakwe et al [ 54 ], reporting a substantial reduction of the size of AgNPs from 65 to 37.5 nm achieved by supplementation of working solution with the additional amount or reducing agent.…”

Catecholate Dye-Assisted Decoration of Ag on TiO2 Nanoparticles for Detection of Cancer-Related MicroRNA Biomarkers on a Multiplexed Photoelectrochemical Platform

“…37,38 Our synthesis method took advantage of these properties of HTX to decorate TiO 2 NPs with Ag NPs for later use in creating high-performance photoelectrodes. 43 Photoelectrodes fabricated from the TiO 2 NP samples (Figure 1) were optically and photoelectrochemically characterized (Figure 4). Ultraviolet−visible (UV/vis) spectroscopy of the solid photoelectrode samples (Figure 4A) showed unmodified TiO 2 NP having an optical absorption peak at 319 nm and having comparatively higher light absorption in the UV range (<400 nm) than in the visible range (400−700 nm).…”

“…Catecholate molecules like HTX are known for improving colloidal stability by reducing agglomeration in metal oxides after surface adsorption. , The phenolic hydroxide groups of catechol molecules have also been proven to reduce silver nitrate. Thus, surface-bound HTX acts as the driving force for the nucleation of Ag NPs onto TiO 2 NPs, rather than only precipitating in the solution. , Our synthesis method took advantage of these properties of HTX to decorate TiO 2 NPs with Ag NPs for later use in creating high-performance photoelectrodes …”