Functionalized Gold Nanoparticles Decorated Reduced Graphene Oxide Sheets for Efficient Detection of Mercury

Functionalized gold nanoparticles decorated reduced graphene oxide (RGO) sheets were used as an electrical sensing platform for highly selective and sensitive Hg
²⁺
detection. RGO sheets were synthesized by reduction of graphene oxide (GO) produced by well-known Hummer's method. RGO sheets were further decorated with thioglycolic acid (TGA) functionalized gold nanoparticles (GNPs) by simple chemical approach. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Ultraviolet-visible (UV-Vis) absorbance analysis were done to confirm the presence of gold nanoparticles being attached to the RGO sheets. Transmission electron microscopy (TEM) was performed to analyze the shape and size distribution of gold nanoparticles on RGO sheets. TGA functionalization of GNPs was confirmed by Fourier transform infrared (FTIR) spectroscopic analysis. The RGO sheets as fabricated were observed to impart n-type nature to the sensing characteristics which was supported by Hall measurements. The sensor performance towards Hg
²⁺
was investigated electrically in presence of other competitive contaminants. The sensor was found to be highly selective towards Hg
²⁺
in presence of Pb
²⁺
, Cd
²⁺
and As
⁵⁺
. The interaction of Hg
²⁺
with the sensing layer was also studied using UV-Vis spectrophotometer. Our work suggests that RGO-GNP-TGA (RGT) hybrid structures are promising for low-cost, portable and real-time room temperature heavy metal ion detectors.