Beyond hydrogen, helium, and oxygen, the fourth most prevalent element traversing the cosmos is carbon. It is not the most abundant element in the Earth's crust, since elements such as iron, silicon, and titanium are found in larger quantities. Nevertheless, carbon materials are universal as it constitutes the very fundamental cornerstone of life, and unique in forming σ and π covalent bonds across diverse hybridization states such as sp, sp 2 and sp 3 , interlinking neighbouring carbons or non-metallic elements, often termed as heteroatoms. This characteristic brings out a variety of carbon allotropes, naming from single molecules to layered structures and to tortuous mesoporous frameworks. The recognition of carbon traces back nearly two millennia when its presence was discerned within organic molecules, serving as the foundational constituents of biomolecules. As time progressed, carbon unveiled itself in various natural forms, including the illustrious trio of diamond, graphite, and amorphous carbon. Among these, diamond emerges as a tetrahedral arrangement of sp 3 carbon atoms, acclaimed for its exceptional hardness and transparent nature, rendering it an adept electrical insulator while proficiently conducting heat. Contradictorily, graphite is soft, opaque, and having substantial electrical conductivity. Graphite is hexagonally packed lattice of sp 2 carbon atoms, stacked-up by an atomically thin (0.335 nm) graphene layers, that are bonded by weak Vander Waals forces, allowing them to be readily stacked upon one another. Evidently, the realm of carbon allotropes unveils a myriad of possibilities, where distinct atomic arrangements give rise to diverse allotropic structures of carbon, each endowed with unique physical, and functional properties. The dimensions of these carbon structures play a pivotal role in conferring distinct intrinsic physicochemical properties, a fact that has stimulated the innovation of novel nanostructured carbon allotropes, leading to a wide array of functional applications that been documented thus far. Specifically, the industrial significance of carbon materials in electrochemical applications spans over a century, which are largely made possible by the excellent physical and chemical attributes inherent to carbon-based materials . These particularly incorporate the capability of carbon materials to seamlessly conduct substantial electrical currents, withstand elevated temperatures without compromise, facilitate rapid heterogeneous electron transfer, and exhibit excellent mechanical resilience even when subjected to the aforementioned extreme conditions. This section will be discussing different dimensions of various carbon nanostructures.