Advances in Carbon-Based Nanomaterials: From Graphene to Quantum Dots

Carbon-based nanomaterials have emerged as a transformative class of materials, owing to
their unique structural, electronic, optical, thermal, and mechanical properties. Since the
discovery of two-dimensional graphene and one-dimensional carbon nanotubes, the field has
rapidly expanded to include zero-dimensional carbon quantum dots, graphene quantum dots
(GQDs), and hybrid composites. This review collates recent advances in carbon-based
nanomaterials, tracing the evolution of graphene from nanotubes to quantum dots, and
examines their classification, structure–property relationships, synthesis routes,
characterization modalities, and application landscapes. A historical overview of carbon
allotropes and nanomaterials is initially presented, and the motivation and scope of this
comprehensive treatment is provided. Following the classification of materials into 0D
(fullerenes, CQDs/GQDs), 1D (CNTs), 2D (graphene, graphene oxide, derivatives), and hybrid
composites, the exploration focuses on how their atomic bonding (sp², sp³), defects, doping,
edge effects, and quantum confinement determine their performance. Synthesis strategies
such as exfoliation, chemical vapor deposition (CVD), arc discharge, laser ablation, and top
down/bottom-up approaches for quantum dots have been described. Then, characterization
techniques are detailed, including TEM, SEM, AFM, XRD, Raman spectroscopy,
photoluminescence, UV‑Vis, XPS, FTIR, and advanced time‑resolved methods. Major
applications are examined in energy storage and conversion, sensing, biomedicine, catalysis,
the environment, and optoelectronics. Finally, challenges such as scalability, reproducibility,
stability, toxicity, and integration into devices are critically discussed and future directions
for hybrid systems, computational design, and multifunctional platforms are outlined.
Through this review, major advances and key takeaways are synthesized, offering an outlook
on the next five to ten years of carbon‑based nanomaterial research and implementation.