A review on hollow nanostructures, its derived composites: Preparation, structural control, alterations, and their utilization as an electrode for supercapacitors, rechargeable batteries and electrocatalysis

Hollow nanostructures are highly advantageous for electrochemical reactions due to its internal voids and rapid transport paths. Carbon-based materials, comprising pure carbon, heteroatom-doping, and composites with transition metal nanoparticles are widely recognized for their exceptional conductivity and structural stability. Among these materials, the combination of hollow carbon-based nanomaterials has emerged as a major area of interest in the energy storage and electrocatalysis fields. Researchers have been actively investigating different template-based strategies to synthesize hollow carbon-based nanomaterials and capitalize on their unique properties. This review gives a comprehensive analysis of synthesis approaches for hollow carbon-based materials, highlighting the distinctive properties of every technique. It also examines the various applications of these materials, including oxygen evolution and reduction reactions, hydrogen evolution reactions, CO2 reduction reactions, lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, lithium-sulfur batteries, and supercapacitors. Finally, the article proposes future research directions to further advance the development of hollow carbon-based materials.