‘Multipronged’ Approach to Investigate Interfacial Processes on Graphene-Based Hybrid Electrodes at Solid/Liquid Interfaces for Electrochemical Energy Storage

Intense research in alternative sources of renewable and clean energy is stimulated by increasing global demand for electric energy. Electrochemical energy conversion/storage systems (super-/pseudocapacitors and batteries) represent the most efficient and environmentally benign technologies for sustainable advancements. Therefore, there is an urgent need for engineered electrochemical electrodes to enable high-performance next-generation energy storage devices to approach industrially relevant specific energy and power densities and deliver electrical power rapidly and efficiently. Among various nanocarbons, graphene showing its quantum nature continues to promote extensive developments since its inception due to exceptionally rich surface chemistry and tunable physicalchemical properties. In this talk, I will present (a) potent strategies geared towards the rational design of multifunctional graphene-based hybrids with tailorable structural and electrochemical properties. We aimed to create an enhanced function from both atomic-scale interfaces and nanoscale morphology, with a strong emphasis on exploring micro(nano) structure-property-activity relationships using complementary analytical tools. Specifically, we invoked chemical hybridization for mixed dimensional carbons (2D graphene and 1D carbon nanotubes) and molecular bridging nanostructured transition metal oxides via electrostatic assembly and electrodeposition, respectively. (b) Secondly, fundamental insights into the dynamic processes occurring at the electrode-electrolyte interfaces and activity over large electrode areas are gained by utilizing scanning electrochemical microscopy. Finally, (c) identifying the origin of pseudocapacitive behavior and charge storage mechanisms (surface redox, intercalation) was carried out using operando Raman spectroscopy. The experimental findings complemented density functional theory that signified the available density of states in the vicinity of the Fermi level contributing to higher activity. These investigations pave the way for potential application at the grand challenges of clean energy-water-sensing nexus.