Colloquium- A Systematic Study on Hybrids of Graphene Oxide and Silk Carbonization

Hybrid materials are of interest to bring the synergistic effect of the properties of precursor samples especially faradaic properties of transition metal oxides and double layer (EDLC) of high surface area carbon materials for energy storage¹. Rechargeable aqueous Zn-ion batteries (ZIBs) with zinc metal anodes have attracted growing interest as cost-effective, safe solutions for large-scale stationary energy storage. Coupled with pseudocapacitive cathodes, they offer high capacity, fast charge–discharge rates, and long cycle life—making them strong contenders for next-generation grid storage².

Studies in this thesis primarily deal with the preparation and characterization of vanadium pentoxide xerogels (V₂O₅·nH₂O) and their hybrids, which were further analyzed as cathode materials for zinc-ion batteries (ZIBs). The xerogels were prepared via sol–gel and hydrothermal routes and systematically examined with emphasis on preparation strategies, underlying chemical processes, and formation mechanisms. Hybrids incorporating graphene-based materials—graphene oxide (GO) and reduced graphene oxide (rGO)—alongside pristine vanadium pentoxide xerogels were evaluated for their electrochemical performance. These studies revealed the operational potential range for water insertion during cycling, providing mechanistic insights into charge storage. Additionally, hybrids with controlled grain boundary variations were fabricated to probe dielectric properties and electrical conductivity^3,4.

In the next part of this thesis, the biopolymer silk, a natural pyroprotein, was carbonized and subsequently graphitized under varying thermal and pressure conditions. The extent of graphitization and the associated structural evolution were examined to establish processing–structure correlations, enabling the design of bio-derived carbon materials and achieving graphitization at temperatures as low as 1000 °C^5-8. Furthermore, antimony telluride (Sb₂Te₃), a phase-change material, was synthesized via a citrate-mediated soft-solution approach from oxides. Composites of Sb₂Te₃ with reduced graphene oxide (rGO) were also developed to enhance electrical conductivity, with their potential applications identified for future exploration.

Overall, this thesis presents a comprehensive study on the synthesis, structural tuning, and functional evaluation of hybrid materials, providing mechanistic insights into their electrochemical behavior and contributing to the rational design of multifunctional systems for energy storage, as well as the graphitization of a natural pyroprotein under varied processing conditions.