The synthesis of carbon-based quantum dots: A supercritical fluid approach and perspective

Carbon-based quantum dots (QDs) have attracted significant attention since their discovery. Supercritical fluids (SCFs) with unique gas- and liquid-like properties offer an alternative to existing technologies in realising the commercialisation and production of high-quality QDs. A comprehensive review featuring recent works on the synthesis of carbon-based QDs facilitated by SCFs technologies, with emphasis on SCF-assisted exfoliation and continuous hydrothermal fluid synthesis processes has been conducted. The mechanisms and properties of carbon-based QDs are described to understand the influence of precursors types and synthesis routes on the characteristics of the as-produced QDs. A summary of both the synthesis methods and types of carbon-based QDs produced are included. Recent applications of carbon-based QDs in biomedical and pharmaceutical, electronics and energy storage, as well as materials engineering are also summarized to provide insights into the future potential of carbon-based QDs. • Comprehensive review on synthesis of carbon-based QDs via supercritical fluid. • Critical discussion on SCF-aided exfoliation and hydrothermal treatments. • Advances and challenges of synthesis mechanism and QDs characterisation.