Facile and One Pot Synthesis of Gold Nanoparticles Using Tetraphenylborate and Polyvinylpyrrolidone for Selective Colorimetric Detection of Mercury Ions in Aqueous Medium

Abstract

In this work, we reported for the first time, a facile and one step synthesis of gold nanoparticles from HAuCl4, employing tetraphenylborate as the reducing agent. The synthesis is not only facile but also yields “dumb-bell-shaped”particles. This shape appears to arise from a possible emulsion of the products of oxidation/decomposition of tetraphenylborate by HAuCl4, surrounding the particle. The size and shape of the AuNPs were characterized by Transmission electron microscopy (TEM) and UV-visible Spectroscopy. Interestingly, the addition of polyvinylpyrrolidone (PVP) during the synthesis was found to enhance the stability of the nanoparticle dispersion. The particles synthesized under these conditions assume “spherical” shape with the appearance of only transverse surface plasmon resonance band. The highlight of the observations is that the gold nanoparticles synthesized using tetraphenylborate as reducing agent and PVP as stabilizer are highly stable in alkaline medium, in contrast to the synthesis wherein borohydride is used as reducing agent. The AuNPs synthesized using tetraphenylborate and PVP show their mercury sensing behavior only in the alkaline medium. The color of the nanoparticle dispersion undergoes distinct color change from pink to blue with the addition of mercury ions. They also show dramatic selectivity to mercury ions in presence of other interfering ions, Pb2+, Zn2+ and Ca2+.

Synthesis of colloidal nanomaterials through femtosecond laser ablation

“…Figure 5.6 shows the calculated extinction coefficient of as-produced samples. Again, the surface plasmonic peak (transverse surface plasmon resonance) can be clearly recognized, as well as a secondary small shoulder at wavelengths below 400nm, in agreement with the literature [196].…”

Radiation synthesized poly(n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles as LSPR-based optical sensor for mercury ions estimation

“…ions, while keeping all other reaction parameters identical. This is probably because highly alkaline conditions favor displacement of the PVP molecules from the surface of Au-NPs (Boopathi et al 2012). In the process, carbonyl groups of the lactam rings of PVP, which were earlier interacting with the Au atoms, get exposed and instead bind with the Hg 2?…”

“…ions in aqueous media by PVP-Au-NPs is based on the selective complexation of Hg 2? ions with PVP (Boopathi et al 2012;Guner et al 1998). Guner et al reported that compared to anions and cations, such as Hg 2?…”

Synthesis and characterization of gold/water nanofluids suitable for thermal applications produced by femtosecond laser radiation

“…Again, the surface plasmonic peak (transverse surface plasmon resonance) can be clearly recognized, as well as a secondary small shoulder at wavelengths below 400 nm, in agreement with the literature. 45 The small features at around 965 and 1157 nm are probably due to instrumental artifacts, as the contingent presence of nonspherical particles exhibiting longitudinal surface plasmon resonances in this spectral region 46 could be ruled out by TEM analyses. The difference in the absolute value of the extinction coefficient for the different samples can be ascribed to the different particle size distribution and polydispersion, and distribution of NPs concentration, as mentioned above.…”