Application of electrodeposited cobalt hexacyanoferrate film to extract energy from water salinity gradients

Abstract

Emission of greenhouse gases and limited amount of fossil fuels lead to the emerging need for renewable and sustainable energy sources. The Gibbs free energy released when river water flows into the sea can be utilized as a source of energy. The Mixing Entropy Battery (MEB) is a novel electrochemical cell which efficiently extracts energy from this natural salinity. It consists of cationic and anionic electrodes. Each of these electrodes interacts selectively with one type of ions. In this work the “MEB” principle is applied. The battery is constructed with two inexpensive and easily prepared electrodes including carbon paste electrode modified by cobalt hexacyanoferrate film (CPE-CoHCF) as cathode, and silver/silver chloride as anode. The feasibility of electrochemical oxidation, reduction and cycling of CoHCF were demonstrated. The AgCl/CPE-CoHCF cell showed the standard cell potential of 0.497 V. A power density of about 24 000 μW g⁻¹ with 65% efficiency was achieved with this system, which is a considerable improvement over previous reported results.