Carbon quantum dots (CQDs) are a type of carbon nanomaterial that has
lately received attention as a potential replacement for standard semiconductor
quantum dots (QDs). CQDs feature a quasi-spherical structure and amorphous to
nanocrystalline carbon cores with diameters of 10-20 nm. Based on the carbon core,
CQDs are further classified as graphene quantum dots (GQDs), carbon nanodots
(CNDs), and polymer dots (PDs). CQDs exhibit unique electrical and optical properties
due to their bigger edge effects and quantum confinement; better than graphene oxide
nanosheets, they can also be easily split into electrons and holes due to their high
dielectric constant and extinction coefficient. CQDs are crucial in the sector of energy
storage and transformation because CQDs offer the advantageous properties of low
toxicity, environmental friendliness, low cost, photostability, favourable charge transfer
with increased electronic conductivity, and comparably simple synthesis processes.
Due to their superior crystal structure and surface properties, CQD nanocomposites
often helped to shorten charge transfer paths and maintain electrode material cycle
stability. CQDs provide cost-effective and environmentally friendly nanocomposites
used for supplying high energy density and stable electrodes for energy storage
applications. This chapter provides a summary of the role that CQDs play in energy
transmit technologies, including solar cells, supercapacitors, lithium-ion batteries, and
hydrogen and oxygen evolution reactions.
Keywords: CQDs, Hydrogen and oxygen evolution reactions, Lithium-ion batteries, Supercapacitor.
