Colloids and Surfaces A: Physicochem. Eng. Aspects 400 (2012) 73–79 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces A: Physicochemical and Engineering Aspects jo ur nal homep a ge: www.elsevier.com/locate/colsurfa Facile synthesis of silver nanoparticles with high concentration via a CTAB-induced silver mirror reaction Xiuyan Li, Jun Shen ∗ , Ai Du, Zhihua Zhang, Guohua Gao, Huiyu Yang, Jiandong Wu Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Pohl Institute of Solid State Physics, Tongji University, Shanghai 200092, China a r t i c l e i n f o Article history: Received 25 November 2011 Received in revised form 1 February 2012 Accepted 2 March 2012 Available online 10 March 2012 Keywords: Silver nanoparticles High Ag + concentration Ag + –CTAB complex Shape evolution a b s t r a c t Silver colloidal nanoparticles were synthesized via an analogous silver mirror reaction process with- out the traditional Tollens reagent. Instead of ammonia, cetyltrimethylammonium bromide (CTAB) was employed to coordinate with Ag + . The silver nanoparticles and reaction process were characterized by UV–vis spectrometer, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that the silver concentration in the colloid reached 0.05 mol/l and the colloid could keep stable for over 45 days. The halogen in CTAB is used as surfactant counterion to form a CTABr - Ag + complex, which can be reduced by glucose to Ag nanoparticles. Besides, the apparent impact on the dispersion and shape of silver nanoparticles induced by the molar ratio of CTAB to Ag is also discussed. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The noble metal nanoparticles have attracted tremendous inter- est owing to their dramatically different properties as compared to the bulk [1]. The unique electrical and optical properties of noble metal nanoparticles confer them with the ability to function as potential structural blocks for a new generation of electron- ics [2], photonics [3], and sensor materials [4]. The intrinsic properties of a metal nanostructure can be tailored by con- trolling its size, shape, composition, and crystallinity. Among these parameters, shape-control has been proved to be as effec- tive as size-control in fine-tuning the properties and functions of metal nanostructures [5]. Recently, various methods of mor- phology and size control were proposed to obtain the good performance of metal nanostructure using surfactant, which have been attracted in surface and colloid chemistry [6–11]. Surfac- tant can be employed to form a microemulsion, which has been widely used to prepare metal nanoparticles [7] since Bouton- net et al. [8] successfully synthesized platinum nanoparticles. It also can be used as reverse micellar template in the preparation of silver and gold nanoparticle, nanorods and nanowires [9,10]. Besides, surfactant, as a kind of dispersant, was directly used to pre- vent nanoparticles from aggregating in chemical reduction method [11–13]. ∗ Corresponding author. Tel.: +86 21 6598 2762; fax: +86 21 6598 6071. E-mail addresses: shenjun67@tongji.edu.cn, xyli0605@yahoo.com.cn (J. Shen). Most recently, a cationic surfactant, CTAB, as a dispersant arose much concern for preparing shape-control silver nanoparticles. Sihai and David [5] have fabricated two dimension silver nanoplates via chemical reduction method in the presence of appropriate concentrations of CTAB. Sau and Murphy [14] have synthesized multiple shapes of gold nanoparticles in the presence of CTAB. Yu and Yam [15] reported a modified silver mirror reaction method, which was used to synthesize silver nanoparticles of various mor- phologies by adjusting the concentrations of CTAB and the Tollens reagent, Ag (NH3) 2+ . Here we describe an analogous modified silver mirror reaction process that enabled us to prepare silver colloidal nanopar- ticles with good dispersion, relatively high concentration and ideal stability. It was found that CTAB not only act as disper- sant but also play as complexant for forming an CTABr - Ag + complex, which can be reduced by glucose, a green and cheap reductant. The complexation reaction was studied through mul- tidisciplinary approaches. Besides, the effect of molar ration of CTAB to Ag + on the shape and dispersion was observed and dis- cussed. 2. Experimental 2.1. Raw materials AgNO 3 (99.95%), NaOH (99.996%), CTAB (99%), and glucose (99%) were obtained from Sinopharm Chemical Reagent Co., China. All reagents were dissolved in deionized water under vigorous mag- netic stirring to form aqueous solution. 0927-7757/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfa.2012.03.002