Energy harvesting by neutralization pseudocapacitor obtained from phosphomolybdic acid and poly(3,4-ethylenedioxythiophene)

Neutralization Pseudocapacitors: An Acid–Base Machine

“…Considering that the anion concentration is kept constant after the neutralization, and that this concentration consequently does not contribute to the work performed in the acid–base machine, we first investigated the PMA/PAH/​PEDOT-PSS LbL film as a function of pH (0.0, 2.2, 3.4, 4.3, 5.0, and 6.0) for the electrolytic solution. The anodic and cathodic peak potentials in the cyclic voltammograms (Figure ) differed slightly, indicating low irreversibility associated with proton electroinsertion/​electrodeinsertion in this electrode, in agreement with electrochemical impedance spectroscopy measurements . Moreover, these voltammograms revealed that the peak potentials and potential window shifted as a function of pH, indicating that it might be possible to store energy (to perform work) with the addition of base.…”

“…The anodic and cathodic peak potentials in the cyclic voltammograms (Figure 2) differed slightly, indicating low irreversibility associated with proton electroinsertion/electrodeinsertion in this electrode, in agreement with electrochemical impedance spectroscopy measurements. 10 Moreover, these voltammograms revealed that the peak potentials and potential window shifted as a function of pH, indicating that it might be possible to store energy (to perform work) with the addition of base. In fact, the harvesting energy normalized by the amount of electroinserted protons corresponds to a change in the potential, associated with electroreduction in more acid medium and its electrooxidation in less acid medium, multiplied by the Faraday constant (eq 9).…”

“…Electrodes consisting of phospho­molybdic acid (PMA), poly­(3,4-ethylene­dioxy­thiophene/​poly­(styrene­sulfonate) (PEDOT-PSS), and poly­(allylamine chloride) (PAH) have been investigated in acidic and neutral (or less acidic) medium and have been found to display suitable properties for use in acid–base machine, e.g., low practical irreversibility, selectivity for proton electroinsertion/electrodeinsertion, and high proton and polaron conductivity. − We have used the Layer-by-Layer (LbL) method to grow thin self-assembled films, promoting low diffusion overpotential and Ohmic drop as well as synergistic effects associated with the intimate contact between their components . Considering a full three-electrode electrochemical cell where the negative electrode is PMA/PAH/​PEDOT-PSS and the positive electrode has overpotential tending to zero, we have simulated an acid–base machine with efficiency close to the maximum efficiency provided by the thermodynamic formalism shown below.…”

Electrochemical Systems for Renewable Energy Conversion from Salinity and Proton Gradients

“…Energy conversion to work stems from controlled mixing between a solution containing high proton concentration (or low pH values) and a solution containing low proton concentration (or high pH values). 23,39 NB can be understood as an idealized acid-base machine, which is similar to the concept of thermal machines. 40 In an ideal acid-base machine, matter flows between the acidic and the basic reservoirs, to provide maximum work.…”

“…Moreover, the intimate contact between the materials promoted by the LbL method elicited a synergistic effect that improved the specific capacity and ensured the practical reversibility of the electrochemical process. 23,39,40 An experimental proof of concept of the acid-base machine was carried out by using a three-electrode cell consisting of PMA/PAH/PEDOT-PSS as the working electrode, a platinum sheet as the counter electrode, and an Hg/Hg 2 SO 4 electrode as the reference electrode. Figure 10a shows the electroreduction, at pH 0, and the electrooxidation, at several pHs, of the PMA host matrix in a process that simulated H 2 SO 4 neutralization with KOH.…”