Strategies for Surface Modification with Ag-Shaped Nanoparticles: Electrocatalytic Enhancement of Screen-Printed Electrodes for the Detection of Heavy Metals

Abstract

Screen-printed carbon nanofiber electrodes (SPCNFEs) represent an alternative with great acceptance due to their results, as well as their low impact on the environment. In order to improve their performance, in the present work they were modified with silver nanoparticles (Ag-NPs) and electrochemically characterized by using anodic stripping voltammetry. From the Ag-NP synthesis, silver seeds (Ag-NS) and silver nanoprisms (Ag-NPr) were obtained. The Ag-NP formation was confirmed by micrographs, where Ag-NPs with diameters of 12.20 ± 0.04 nm for Ag-NS and 20.40 ± 0.09 nm for Ag-NPr were observed. The electrodes were modified by using three different deposition methods—drop-casting, spin-coating, and in situ approaches—that offer different nanoparticle distribution and electrode modification times. It was observed that the last methodology showed a low amount of Ag-NS deposited on the electrode surface and deep alteration of this surface. Those facts suggest that the in situ synthesis methodology was not appropriate for the determination of heavy metals, and it was discarded. The incorporation of the nanoparticles by spin-coating and drop-casting strategies showed different spatial distribution on the electrode surface, as proved by scanning electron microscopy. The electrodes modified by these strategies were evaluated for the cadmium(II) and lead(II) detection using differential pulse anodic stripping voltammetry, obtaining detection limit values of 2.1 and 2.8 µg·L−1, respectively. The overall results showed that the incorporation route does not directly change the electrocatalytic effect of the nanoparticles, but the shape of these nanoparticles (spherical for seeds and triangular for prisms) has preferential electrocatalytic enhancement over Cd(II) or Pb(II).

Recent Trends in the Improvement of the Electrochemical Response of Screen-Printed Electrodes by Their Modification with Shaped Metal Nanoparticles

“…In addition, triangular-shaped nanoparticles were synthesized for the voltammetric determination of heavy metal ions. Torres-Rivero et al [ 5 , 42 ] synthesized silver nanoparticles (Ag-nanoseeds and Ag-nanoprisms) by the seed mediated approach [ 84 , 85 ]. SEM and TEM images showed that the Ag-nanoprisms had triangular morphology with a size between 14.25 and 16.46 nm ( Figure 5 A).…”

“…SPEs composed of carbon nanoallotropes (e.g., carbon nanotubes, nanofibers, or graphene) represent a versatile sensing tool due to their suitability for incorporation in portable instrumentation [ 1 , 2 , 3 ]. Additionally, it has been reported how modifying their surface with metal nanoparticles (MNPs) leads to the enhancement of the electrochemical reactivity and sensitivity for specific analytes [ 4 , 5 , 6 ].…”

Direct As(V) Determination Using Screen-Printed Electrodes Modified with Silver Nanoparticles

“…The SPCNFEs were modified with Ag-NS or Ag-NPr using the drop-casting method described in [ 18 , 21 ]. Briefly, 40 µL of the solution of Ag-NS or Ag-NPr were dropped onto the working electrode surface and dried in an oven at 50 °C for 30 minutes.…”

“…Regarding the substrate, nanotechnology has become a powerful tool to develop new sensing devices [ 19 , 20 ]. In particular, intrinsic characteristics of electrochemical sensors can be enhanced by modifying their surface with metal nanoparticles that confer better electrocatalytic properties compared with the non-modified sensors [ 21 ]. On the other hand, in terms of support, more classical bulk or film silver electrodes require tedious cleaning and polishing procedures to achieve good reproducibility.…”

“…Thus, in this work, a direct method for the voltammetric determination of As(V) is proposed based on the use of carbon-nanofiber-based screen-printed electrodes (SPCNFEs) modified by drop-casting with two different shaped silver nanoparticles (Ag-NPs) previously synthesized: nanoseeds (NS) and nanoprisms (NPr) [ 21 ]. The resulting modified sensors were microscopically and analytically characterized, and carbon-nanofiber-based screen-printed electrode modified with silver nanoseeds (Ag-NS-SPCNFE), as the optimal carbon-nanofiber-based screen-printed electrode modified with silver nanoparticles (Ag-NP-SPCNFE), was applied to the direct determination of As(V) ion in water samples by differential pulse anodic stripping voltammetry (DPASV).…”