Sensing behavior of silica-coated Au nanoparticles towards nitrobenzene

Abstract

In the present work, we report silica-stabilized gold nanoparticles (SiO 2/Au NPs) as a wide-range sensitive sensing material towards nitrobenzene (NB). Surface hydroxyl groups of silica selectively form Meisenheimer complex with electron-deficient aromatic ring of NB and facilitate its immobilization and subsequent catalytic reduction by Au cores. Silica-coated Au NPs were synthesized and characterized for their chemical, morphological, structural, and optical properties. SiO 2/Au NPs-modified electrodes were characterized with impedometric and cyclic voltammetric electrochemical techniques. SiO 2/Au NPs are found to have a higher optical detection window of range, 0.1 M to 1 μM and a lower electrochemical detection window of range, 10 -4 to 2.5×10 -2 mM with a detection limit of 12.3 ppb. A significant enhancement in cathodic peak current, C 1, and sensitivity (102 μA/mM) was observed with modified electrode relative to bare and silicamodified electrodes. The I P pwas found to be linearly corelated to NB concentration (R 200.985). The interference of cationic and anionic species on sensor sensitivity was also studied. Selectivity in the present sensing system may be further improved by modifying silica with specific functional moieties. © The Author(s) 2012.