Vietnam Journal of Chemistry, 2018, 56(4), 473-477 Article DOI: 10.1002/vjch.201800032 473 Wiley Online Library © 2018 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Bismuth nanodendrites deposited on glassy carbon electrode as a sensitive electrochemical sensor for simultaneous detection of Cd 2+ and Pd 2+ ions Nguyen Hoang Anh 1 , Pham Khac Duy 1 , Pham Thi Hai Yen 1 , Vu Hai Dang 1 , Nguyen Quynh Giao 1 , Vu Thi Thu Ha 1,2* 1 Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay district, Hanoi 100000, Viet Nam 2 University of Science and Technology of Hanoi (USTH), VAST, 18 Hoang Quoc Viet, Cau Giay district, Hanoi 100000, Viet Nam Received March 16 th 2018; Accepted for publication June 15 th 2018 Abstract In this study, bismuth nanodendrites (BiNDs) were fabricated on glassy carbon electrode by chronopotentiometric method. The hierarchical structure and high population matrix of BiNDs provides high surface active area to enhance the electrochemical signals of measured Cd 2+ and Pb 2+ ions. The developed bismuth nanodendritic structure was well-observed and characterzied by scanning electron microscopy (SEM). Electrochemical behaviours of developed BiNDs electrodes were studied by the cyclic voltammetric (CV) method. The fabrication conditions for BiNDs such as the applied current and deposition time were optimized as -10 mA and 90 s, respectively. Under this optimized condition, the highest peaks of Cd 2+ and Pb 2+ ions at concentration of 20 ppb were obtained. The Cd 2+ and Pb 2+ signals acquired by BiNDs are almost three times greater than that measured by the Bi film electrode. Keywords. Bi nanodendrite, electrodeposition, surface structure, electrochemical behaviours, cadmium, lead. 1. INTRODUCTION Recently, the electrochemical methods have been strongly developed for simultaneous dectection of heavy metals due to their good selectivity, high accuracy, low expense of instrument, portability and operation simplicity. [1] Among various electrochemically analytical techniques, the anodic stripping voltammetry (ASV) is commonly used for determination of heavy metals at the same time such as zinc, cadmium, lead and copper because of its convenience not only in laboratory condition but also on-site. The conventional working electrode used in the method is mercury film electrodes due to its good reproducibility and high sensitivity. [2] However, many alternative materials have been found to replace mercury beacause of its extreme toxicity of mercury to the environment and human health. Bismuth electrode were first studied by J. Wang in 2000 as the best replacement because of similar electrochemical properties to mercury electrode such as wide potential window; well- defined, good signal-to-background characteristics; forming fused multicomponent alloys with heavy metals. [1] Especially, bismuth is a friendly- environmental material which is employed in many fields including catalysis, photonics, electronics, optoelectronics, energy storage, sensor, superconductive material even in pharmaceutical products. [3] There are many modifications of bismuth on different substrates in order to enhance the electrochemical signals of the heavy metals. Among them, bismuth film electrodes (BiFE) were widely used. [4,5] The differrent forms of bismuth such as nanoparticles, nano rods [6] and nanosheets, [7] microrods on glassy carbon and film were also well studied. [8] Conventionally, the electrochemical deposition method was applied; only few studies reported the chemical method for the fabrication of Bi nanostructure. [9] In this study, the bismuth nanodendrite was succesfully obtained by chronopotentiometric method. The electrodeposition condition of the BiNDs was carefully examined. The obtained BiNDs with hierarchical structure and high