Study of Capacitive Electrodes for Reverse Electrodialysis Processes

It has been calculated that the energy dissipated wherever the rivers get to the sea this corresponds to an amount of about 2 TW of power [1]. Recovering part of this energy could attenuate the dependency of our economic system from fossil fuels. The techniques conceived to exploit this blue energy are grouped within the family of the salinity gradient technologies, where pressure-retarded osmosis (PRO) and reverse electrodialysis (RED) are regarded as the most established technologies [2]. Nevertheless, their power is limited respectively by various factors including the kinetics of electrodes reactions. Conversely, the use of capacitive electrodes proposed by Brogioli in 2009, does not seem to be affected from these limitations, relying only on ions movement across the electrical double layer [3]. The literature highlights that RED and capacitive electrode can take advantage of their combination, implementing the Capacitive RED (CRED) [4]. In this framework, different electrochemical techniques such as cyclic voltammetry, impedance spectroscopy and chronoamperometry can be used to characterize the performance of the electrodes. These different strategies are here compared and applied to the characterization of novel, super-critical-carbon-dioxide-prepared electrodes.