Optical, structural, catalytic and electrochemical properties of the Au nanoparticles synthesized using CTAB based gels Ravi Kant Upadhyay 1 • Sujit Deshmukh 2 • Susmita Saha 3 • Anjan Barman 3 • Susanta Sinha Roy 2 Received: 14 May 2015 / Accepted: 20 June 2015 Ó Springer Science+Business Media New York 2015 Abstract Gold nanoparticles (Au NPs) were synthesized using Au containing CTAB gel as a precursor. The effect of concentration of NaBH 4 on the structural, optical, catalytic and electrochemical properties of the Au NPs was also investigated. With the increase of NaBH 4 concentration from 0.1 to 0.15 M, an increase in the particle size and change in the morphology from spherical to elliptical was observed. Absorption and emission properties of the Au NPs were also probed using UV–Vis and photolumines- cence spectroscopy respectively. Synthesized Au NPs samples were explored as catalyst for the reduction of 4-nitrophenol to 4-aminophenol. Catalytic activity of Au NPs samples prepared using 0.1 and 0.15 M concentration of NaBH 4 were also compared. It was found that Au NPs prepared using lower concentration of NaBH 4 (Au-0.1) exhibits better catalytic activity compared to the other Au NPs sample (Au-0.15). Synthesized Au NPs were also utilized as electrode material for the detection of Pb 2? ions, results show that Au NPs modified glassy carbon electrode can detect very low concentration of Pb 2? ions (2 lM). Au-0.1 sample exhibited better electrochemical perfor- mance compared to the Au-0.15 sample. 1 Introduction Surfactant self-assemblies have been widely explored as template, reaction medium and matrix for the growth of nanoparticles of various materials. In particular for metals (Au, Ag, Pt and Pd etc.) nanoparticles synthesis, surfactant self-assemblies are preferred candidates of choice as a reaction medium since capping of surfactants not only endows control over the particle size but also gives free- dom to tailor the shape of the nanoparticles [1–4]. A diverse class of surfactant self assemblies including micelles, reverse micelles, wormlike micelles and liquid crystals have served as molds for the growth of metal nanoparticles with different sizes and shapes [5–8]. Au nanoparticles (Au NPs) always remain an amiable topic of research owe to wide range of application domain credited to it. Au NPs exhibit several peculiar physical, chemical, optical and magnetic properties which have been exploited for different types of applications including catalysis, drug carrier, electrical and optoelectronic devices etc. [9–11]. Numerous preparation approaches are in practice for obtaining Au nanoparticles, out of which surfactant aided preparation is most frequently utilized [12]. Surfactants of different chemical nature e.g. cationic, anionic and non- ionic have been adopted as surface passivating agents in the Au NPs synthesis. Out of several available surfactants cationic surfactant cetyltrimethylammonium bromide (CTAB) has proven to be highly efficient for size and shape selective synthesis of Au NPs [13–15]. Au NPs have been extensively explored as catalyst for the reduction of several nitroarenes. Most of the nitroarenes are extremely toxic molecules and exert several harmful effects on the living beings [16]. These molecules are found to be anthropogenic and inhibitory in nature therefore degradation or conversion of nitroarenes into safer molecules is very & Susanta Sinha Roy susanta.roy@snu.edu.in 1 Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar 203207, Uttar Pradesh, India 2 Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar 203207, Uttar Pradesh, India 3 Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098, India 123 J Mater Sci: Mater Electron DOI 10.1007/s10854-015-3387-3