Hydrothermal synthesis of carbon quantum dots from Citrus limetta peels: Exploration of pH sensing, non-hemolytic activity and thermoluminescent properties

•Carbon quantum dots (CQDs) were prepared using Citrus limetta peels as a carbon source.•CQDs have low crystallinity and an average size of 3 nm, ranging from 1 to 6 nm.•They have biocompatible properties, making them suitable for developing pH sensors.•Quantum dots increase up to 37 °C under light irradiation of 808 nm. This study introduces a novel hydrothermal green method for synthesized carbon quantum dots (CQDs) using dried powders of Citrus limetta peels as a carbon source. The synthesized CQDs were evaluated for their photothermal response, pH sensing under various conditions and biocompatibility through non-hemolytic activity. CQDs had low crystallinity and an average size of 3 nm, ranging from 1 to 6 nm. CQDs have biocompatible properties, which makes them suitable for developing pH sensors. The study also revealed that the temperature of CQDs increases up to 37 °C under laser light irradiation of 808 nm, which might have potential applications in the biomedical field.