Electrodeposition of NieCoeSn alloy from choline chloride-based deep eutectic solvent and characterization as cathode for hydrogen evolution in alkaline solution 5 J. Vijayakumar, S. Mohan*, S. Anand Kumar, S.R. Suseendiran, S. Pavithra Electroplating and Metal Finishing Technology Division, Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu, India article info Article history: Received 2 April 2013 Received in revised form 24 May 2013 Accepted 16 June 2013 Available online 14 July 2013 Keywords: Electrodeposition Alloys NieCoeSn Deep eutectic solvent Hydrogen evolution reaction abstract The electrodeposition of NieCoeSn alloy were carried out at room temperature from the chlorine chloride (ChCl)eethylene glycol (EG) deep eutectic solvent (DES). For comparison of properties, NieSn and CoeSn alloys were also deposited using the same solvent. Deposition mechanism, microstructure, and electrochemical properties of the deposits in 1 M KOH solution were investigated. The deposition of Ni, Co, Sn, NieSn, CoeSn and NieCo eSn on platinum electrode were also studied using cyclic voltammetry. Interestingly, the electrochemical stability of DES is observed to be increased in the presence of Sn 2þ ions. The X-ray diffraction (XRD) patterns showed only Ni phases indicating that the other el- ements get incorporated inside the nickel matrix and the lattice constant have linear relation with Sn content in alloy. The morphologies of NieSn and NieCoeSn alloys were observed to be almost same with fine grains, the XRD studies confirm this. The potentio- dynamic polarization measurements showed that the NieCoeSn alloy exhibits the lowest corrosion current density ( j corr ), noblest corrosion potential (E corr ) and highest exchange current density ( j c ) value than the other two binary alloys, indicating that the ternary alloy is a good candidate for Hydrogen Evolution Reaction (HER). Copyright ª 2013, The Authors. Published by Elsevier Ltd. All rights reserved. 1. Introduction Electrodeposition of Ni-based alloys such as NieCo, NieSn, etc., are gaining greater attention of the researchers because of its various applications such as an active material for hydrogen evolution reaction as well as for oxygen evolution reaction in water electrolysis [1e4] and as anode materials for lithium batteries [5e7]. In the past decade sustained efforts have been made to overcome the usage of toxic chemicals to conserve environment. This has led to the development of “Deep eutectic solvent” or DES. It is a type of ionic solvent consisting of a eutectic mixture of quaternary ammonium salts such as choline chloride or choline iodide and hydrogen bond donor species such as carboxylic acids, glycols or amides 5 This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. * Corresponding author. Tel.: þ91 4565 241241/261 (office); fax: þ91 4565 227713; mobile: þ91 9442126765. E-mail addresses: mohan40159@cecri.res.in, sanjnamohan@yahoo.com (S. Mohan). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 38 (2013) 10208 e10214 0360-3199/$ e see front matter Copyright ª 2013, The Authors. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2013.06.068