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The selective ion transport characteristics of a conducting polymer electrode, based on poly(3,4-ethylenedioxythiophene) (PEDOT), is evaluated with respect to its electrocatalytic performance, specifically targeting redox switching of quinone couples. Employing model organic redox quinones, here, the novel phenomenon of ion-selective electrocatalysis (ISEC) is conceptualized. The effect of ISEC is studied and evaluated using two forms of PEDOT electrodes, which differ in their ion-exchange characteristics, by comparing the redox transformations of catechol and tiron. It is rationalized that the choice of the specific redox couple and the ion selectivity characteristics of the conducting polymer electrode impacts the activation losses in aqueous organic redox-flow batteries. By carefully selecting and designing the conducting polymer electrodes, high conversion efficiency on acid-resistant electrodes is obtained. As far as it is known, this is the first redox flow battery to include conducting polymer electrodes operating in both the posolyte and negolyte configurations, thus the first "all-organic" RFBs., Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Energy harvesting from photosynthetic membranes, proteins, or bacteria through bio-photovoltaic or bio-electrochemical approaches has been proposed as a new route to clean energy. A major shortcoming of these and solar cell technologies is the underutilization of solar irradiation wavelengths in the IR region, especially those in the far IR region. Here, a biohybrid energy-harvesting device is demonstrated that exploits IR radiation, via convection and thermoelectric effects, to improve the resulting energy conversion performance. A composite of nanocellulose and the conducting polymer system poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is used as the anode in biohybrid cells that includes thylakoid membranes (TMs) and redox mediators (RMs) in solution. By irradiating the conducting polymer electrode by an IR light-emitting diode, a sixfold enhancement in the harvested bio-photovoltaic power is achieved, without compromising stability of operation. Investigation of the output currents reveals that IR irradiation generates convective heat transfer in the electrolyte bulk, which enhances the redox reactions of RMs at the anode by suppressing diffusion limitations. In addition, a fast-transient thermoelectric component, originating from the PEDOT:PSS-nanocellulose-electrolyte interphase, further increases the bio-photocurrent. These results pave the way for the development of energy-harvesting biohybrids that make use of heat, via IR absorption, to enhance energy conversion efficiency., Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research; Onnesjo Foundation; Research Institutes of Sweden; Swedish MSCA Seal of Excellence program; Swedish MSCA Seal of Excellence program (Vinnova) [2017-03121]

We demonstrated an asymmetric aqueous supercapacitor made of p- and n-type conducting polymer electrodes. We used the high electron affinity (EA) n-type polymer poly(benzimidazobenzophenanthroline) (BBL) as the anode conducting material, and the low ionization potential (IP) p-type polar polythiophene p(g(4)2T-T) as the cathode material. EA(BBL) matches IPp(g42T-T), enabling the fabrication of all-organic asymmetric p/n-supercapacitors that function in aqueous electrolytes. The devices operate in a voltage window up to 1 V, yielding areal capacitances of 90 mF cm(-2) and specific capacitances of 33 F g(-1) as well as excellent cycling stability with almost 100% capacitance retention over 10 000 cycles., Funding Agencies|Swedish Research Council; Swedish Foundation for Strategic Research; Knut and Alice Wallenberg Foundation; AForsk; VINNOVA; Swedish Government Strategic Research Area in Materials Science on Functional Materials at LinkOping University [SFO-Mat-LiU 2009 00971]; Finnish Cultural Foundation

Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer?polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g?1.

Lignin is one of the most abundant biopolymers, constituting 25% of plants. The pulp and paper industries extract lignin in their process and today seek new applications for this by-product. Here, it is reported that the aromatic alcohols obtained from lignin depolymerization can be used as fuel in high power density electrical power sources. This study shows that the conducting polymer poly(3,4-ethylenedioxythiophene), fabricated from abundant ele-ments via low temperature synthesis, enables efficient, direct, and reversible chemical-to-electrical energy conversion of aromatic alcohols such as lignin residues in aqueous media. A material operation principle related to the rela-tively high molecular diffusion and ionic conductivity within the conducting polymer matrix, ensuring efficient uptake of protons in the course of proton-coupled electron transfers between organic molecules is proposed.