Interfacial Electrochemical Polymerization of PEDOT@Polyoxometalates Thin Films As Electroactive Material for Energy Storage Devices

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The urgent need for a decarbonized power sector has been one of the most important motivations to get a full transition from the fossil-fuel energy sources to a sustainable energy future based on renewable energy alternatives. In this regard, energy conversion and storage devices, such as batteries, fuel cells and supercapacitors, play a key role in supplying steady power and energy densities in order to guarantee the current energy demand [1]. Among the different alternatives, the design and synthesis of advanced functional nanostructured materials provide an important route to obtain efficient energy devices with high power densities, stability and remarkable energy densities [2].Conducting polymers (CP) have been extensively exploited in a wide application range as result of their remarkable charge-mobility, electrical conductivity, and the scalable synthesis processes. Additionally, the storage of charge, which occurs by a doping process, has been ideal for application as electrochemical supercapacitors [3]. In addition, the CPs network have provided an interesting electrode material in which other active materials (i.e., graphene, MOF) and redox species can be incorporated to induce additional pseudocapacitive processes in the electrode, enhancing the charge stored. The polyoxometalates (POMs), inorganic heteropolyanions received great attention due to their multielectron redox processes in aqueous media [4].Herein, we have explored the electrosynthesis of composite materials based on PEDOT and polyoxometalates (POMs) employing the electrochemical polymerization at a polarized organic | aqueous liquid | liquid interface (L|L), in which the POM acts as oxidizing agent of EDOT and electroactive specie incorporated in the polymer chain network as dopant. The polymerization process was based on the ion migration-controlled by the potential biasing of the water-oil interface. The resulting thin films show the presence of Mo and W within the polymer as well as the presence of different redox processes associated with the POM incorporated in the PEDOT. The induced pseudocapacitive processes in the composite materials have shown high stability in acid media, making it a good candidate as an electrode material in symmetric supercapacitors.