Molecular approach about the effect of water on the electrochemical behaviour of Ag + ions in urea-choline chloride-wate
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ORIGINAL PAPER
Molecular approach about the effect of water on the electrochemical behaviour of Ag+ ions in urea-choline chloride-water mixture João R. Bezerra-Neto 1 & Lucas L. Bezerra 1 & Natalia G. Sousa 1 & Luis P. M. dos Santos 1 & Emmanuel S. Marinho 2 & Norberto K. V. Monteiro 1 & Adriana N. Correia 1 & Pedro de Lima-Neto 1 Received: 27 March 2020 / Accepted: 25 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The water influence on electrochemical behaviour of Ag+ ions in urea and choline chloride mixture was investigated by cyclic voltammetry technique, while the molecular insights about the investigated systems were obtained from molecular dynamic (MD) simulation. The water content was variated from 0 up to 10% (v/v). Cyclic voltammetry technique showed that the peak potential for Ag+/Ag redox couples shifted in direction to more positive potentials with the gradual increase of water content in solution, indicating that the addition of water electrocatalyses the kinetics of the reduction of Ag+ ions. The MD simulations demonstrated that water molecules do not interact strongly with Ag+ ions but induce a small reduction in the number of urea molecules around of the ion and that the water molecules adjust to free spaces in the mixture. Keywords Deep eutectic solvents . Reline . Molecular dynamic . Cyclic voltammetry . Ag+ ions
Introduction Silver electrodeposited coating has high corrosion resistance; it presents good electric conductivity and it is bright [1, 2]. These properties allow its use as cover coating in electronic devices to protect the metals against corrosion and, furthermore, it improves the final appearance of the industrial product. In electroplating industries, silver coating is traditionally obtained from aqueous plating solution containing cyanide as complexing agent, which is one of the top toxic chemicals. The necessity of this chemical, or other non-environmentally friendly chemicals, is the main disadvantage related to the silver industrial plating process since a non-environmental safety industrial wastewater need to be discharged [3]. Therefore, it is relevant to investigate alternative electroplating formulations that come to allow the silver
* Pedro de Lima-Neto [email protected] 1
Departamento de Química Analítica e Físico-Química, Centro de Ciências, Universidade Federal do Ceará, Campus do Pici, Bloco 940, Fortaleza, CE 60440-900, Brazil
2
Departamento de Química/FAFIDAM, Universidade Estadual do Ceará, Limoeiro do Norte, CE 62930-000, Brazil
electrodeposition, and the electrodeposition of others noble metals, from plating solutions formulated with environmentally friendly chemicals. In this direction, it is increasing the use of the named deep eutectic solvents (DESs) to electrodeposit metal and alloys, since they have interesting chemical and physical properties, such as good ionic conductivity, high thermal stability, the metal salts are soluble in them, they are non-toxic and biodegradable, their production is of low cost and, finally, the
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