Abstract
While inorganic materials are currently dominating in energy storage, organic redox active molecules and polymers are sustainable and low-cost alternatives. Thin layer redox active polymers and molecules are often deposited onto high surface area carbonaceous substrates to form high-performance composite electrodes. Layer-by-layer (LbL) deposition has been widely used in such deposition to provide versatile electrochemical properties for specific applications [1, 2]. The advantages of LbL are its easy and effective processes and, more importantly, allowing design and engineering of novel composites. Through simple superimposing and overlapping of organic molecules, combined supplementary effects and even synergies can be achieved.In this study, a composite electrode based on CNT modified with two previously investigated organic layers, a chemically polymerized luminol (CpLum) [3] and a tetraphenylporphyrin sulfonate (TPPS), was developed via an in-situ polymerization/layer-by-layer process. Fig 1 a) depicts the CVs of CNT, CpLum-CNT, TPPS-CNT as well as TPPS-CpLum-CNT electrodes in 1 M H2SO4 electrolyte. TPPS-CNT showed clear increase in capacitive current from CNT baseline due to the redox contribution from TPPS. CpLum-CNT had a much greater faradaic current but with much less “mirror-image” CV profile, indicating a slower kinetics. When combining CpLum and TPPS by LbL deposition, a new pseudocapacitive CV profile with highly reversible redox peaks was obtained. The TPPS-CpLum-CNT composite electrode not only had higher current and capacitance (Fig. 1b) than those of the individual composite electrodes but also a much faster charge transfer kinetics. The synergy within the composite promoted the complementary electrochemical contribution between the CpLum and the TPPS layer with fast surface capacitive charge storage. Detailed analyses of this composite from first-principles adsorption and energy level, vibrational spectroscopy as well as surface and morphology were carried out to understand the origin of the synergistic effect of the TPPS-CpLum-CNT composite and will be presented in the talk.
Published Version
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