Carbon quantum dots: Comparative analysis of synthesis strategies and their environmental application

Carbon quantum dots (CQDs) are a novel and noteworthy addition to the nanomaterial family. CQDs are highly promising nanomaterials owing to their distinctive optical, physical, chemical, structural, and electronic properties. Particularly, the exceptional up-converted photoluminescence (PL), remarkable photoinduced electron transfer, tunable PL, extraordinary biocompatibility, notable chemical inertness, and effective light harvesting ability of CQDs have grown significant interest. Consequently, CQDs have been widely employed across diverse fields such as detection, degradation, adsorption, antimicrobial activities, hydrogen production, CO 2 reduction, energy storage and microplastics detection. Currently, numerous CQD synthesis techniques have been established in which there is a significant change in the formation and structure of CQDs while characterized and applied in practical applications. In this regard, the unique and controlled synthesis techniques are still quite difficult task. In this review, we highlighted a comparative analysis of various synthesis approaches towards planned synthesis of CQDs. In addition, explored the obstacles and potential paths for CQDs, with the goal to achieve highly effective and stable CQDs over the long run. Likewise, this review provides insights guidance for the advance of a cost effective and environmentally friendly synthesis technique for CQDs. Consequently, this review also focused on recent studies concerning the removal of environmental pollutants, with a particular focus on the mechanism for depredating pollutants. Additionally, this study examines and talks about the stability and difficulties of CQDs in the environmental domain. • Fundamentals, properties and characteristics of CQDs are briefed. • A detail comparism of synthesis routes of CQDs are specified with environmental application and performance with mechanism. • Offers a direction for the controlled green synthesis and method choice for CQDs.