Photocatalytic Applications of Carbon Quantum Dots

Carbon quantum dots (CQDs) have emerged as a versatile class of metal-free nanomaterials characterised by strong ultraviolet–visible light absorption, tunable energy levels, high photostability and facile, low-cost synthesis. In photocatalysis, CQDs serve as both light harvesters and charge mediators, capturing photons to generate electron–hole pairs and shuttling these carriers to reactant molecules. Their surface functionalities and doping strategies enable precise control over electronic structure and interfacial charge transfer. CQD-based systems have been demonstrated in solar-driven hydrogen evolution, carbon dioxide reduction, nitrogen fixation, photochemical synthesis and the degradation of organic pollutants. By forming composites with semiconductor oxides, metal chalcogenides or molecular catalysts, CQDs enhance light harvesting through up-conversion photoluminescence, suppress charge recombination via heterojunction formation and improve overall quantum efficiency. These attributes, combined with low toxicity and aqueous processability, render CQDs highly attractive for sustainable energy conversion and environmental remediation.

Research from Nature Portfolio

Recent studies have exploited nitrogen incorporation to toggle CQDs between luminescent probes and effective photocatalysts. By varying the amount and chemical environment of nitrogen dopants, researchers achieved domains favouring graphitic sites for enhanced light emission or edge-site localisation to attract photogenerated electrons, substantially boosting photocatalytic hydrogen generation from water. Another landmark report described the synthesis of CQDs from fruit-derived precursors by a simple solvothermal route. These biomass-derived dots exhibited efficient visible-light-driven degradation of dye pollutants, achieving over 99 % removal of methylene blue within two hours. Detailed mechanistic investigations revealed that abundant surface oxygen groups and rapid charge separation underpinned the high degradation rates.

Photocatalytic Applications of Carbon Quantum Dots publication trend

The graph below shows the total number of articles in photocatalytic applications of carbon quantum dots across all publications each year (not limited to Nature Index journals).

Technical terms

Carbon Quantum Dots (CQDs): Carbon-based nanoparticles below 10 nm in size with tunable optical and electronic properties.

Photocatalysis: Acceleration of a chemical reaction by a material upon light absorption, generating reactive species.

Photosensitiser: Substance that absorbs light and transfers energy or electrons to initiate photocatalytic processes.

Charge Separation: Spatial separation of photogenerated electrons and holes to prevent recombination and enable redox reactions.

Heterojunction: Interface between two materials with differing energy band structures, promoting charge transfer and separation.

References

1. Effect of nitrogen atom positioning on the trade-off between emissive and photocatalytic properties of carbon dots. Nature Communications (2017).
2. Biomass-derived Carbon Quantum Dots for Visible-Light-Induced Photocatalysis and Label-Free Detection of Fe(III) and Ascorbic acid. Scientific Reports (2019).
3. Carbon Dots Based Photoinduced Reactions: Advances and Perspective. Advanced Science (2023).
4. Photocatalytic Degradation of Methylene Blue Using N‑Doped ZnO/Carbon Dot (N-ZnO/CD) Nanocomposites Derived from Organic Soybean. ACS Omega (2023).
5. Recent Progress on Carbon Quantum Dots Based Photocatalysis. Frontiers in Chemistry (2022).