Carbon dots (CDs), as a new type
of carbon-based nanomaterial,
have attracted broad research interest for years, because of their
diverse physicochemical properties and favorable attributes like good
biocompatibility, unique optical properties, low cost, ecofriendliness,
abundant functional groups (e.g., amino, hydroxyl, carboxyl), high
stability, and electron mobility. In this Outlook, we comprehensively
summarize the classification of CDs based on the analysis of their
formation mechanism, micro-/nanostructure and property features, and
describe their synthetic methods and optical properties including
strong absorption, photoluminescence, and phosphorescence. Furthermore,
the recent significant advances in diverse applications, including
optical (sensor, anticounterfeiting), energy (light-emitting diodes,
catalysis, photovoltaics, supercapacitors), and promising biomedicine,
are systematically highlighted. Finally, we envisage the key issues
to be challenged, future research directions, and perspectives to
show a full picture of CDs-based materials.