The electrical energy storage becomes necessary as there is an ever-increasing need to rapidly provide an enormous amount of energy mainly in hybrid vehicles and portable consumer electronic devices. Currently, electrochemical energy storage primarily depends on metal-based components; however, they suffer from the high cost of material synthesis, shortage of metal-rich materials, and high toxicity inhibiting their wide-spread use as a sustainable energy storage materials. Therefore, it is necessary to develop a novel renewable cathode made from earth-abundant, low-cost materials. By gaining inspiration from Nature, we propose an alternative application for the valuable biopolymers found in wood, wherein redox-active tannins from the bark are used as electrode-active materials for clean and low-cost energy storage. Tannins can be grouped among the most abundant and versatile redox active biopolymers found in Nature and can be extracted from bark. The charge storage mechanism of tannin is based on the redox active phenol moiety, and it has the highest phenol content among all natural phenolic biopolymers. In addition, to produce a sustainable electrochemical device, we used carbonized wood as an electrode substrate that dramatically improves the performance of the freestanding electrode. The unique porous structure of the wood-derived substrate with well-aligned channels provides high surface area and facilitates high mobility of ions and electrons in the carbonized cell walls.<br/>In addition, we utilized the well-aligned carbonized wood channels as a substrate to support the in-situ vertical growth of metallic molybdenum disulfide (MoS2) as a catalyst for hydrogen evolution. Nowadays, MoS2 nanosheets gained severe attention due to their catalytic activities, however, the limitation lies in their poor electronic conductivity. These nanosheets also suffer from a limited number of active sites since they tend to restack due to the van der Waals force. The well-aligned long channels of carbonized wood with vertically grown metallic MoS2 maximizes the exposition of active catalytic sites and increases the electrolyte and hydrogen transport by providing a low tortuous pathway. Furthermore, plasma treatment of the carbonized wood aids the dissipation of generated hydrogen, thus reducing the proton transport barrier at the surface. The MoS2 nanosheets grown on carbonized wood displays notable electrocatalytic activity.

Energy storage and energy generation based on the materials and structures derived from wood

255th National Meeting (2018)

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