Carbon quantum dots (CQDs) are a fascinating class of carbon nanoparticles with sizes around 10 nm. The unique properties of CQDs are low toxicity, chemical inertness, excellent biocompatibility, photo-induced electron transfer and highly tunable photoluminescence behaviour. Sustainable raw materials are commonly used for the fabrication of CQDs because they are cost-effective, eco-friendly and effective to minimise waste production. CQDs can be fabricated using laser ablation, microwave irradiation, hydrothermal reaction, electrochemical oxidation, reflux method and ultrasonication. These methods undergo several chemical reactions such as oxidation, carbonisation, pyrolysis and polymerisation processes to produce CQDs. Due to small particle sizes of CQDs, they possess strong tunable fluorescent properties and highly photo-luminescent emissions. It also contains oxygen-based functional groups and highly desired properties as semiconductor nanoparticles. Therefore, CQDs are promising nanomaterials for photo-catalysis, ions sensing, biological imaging, heavy metal detection, adsorption treatment, supercapacitor, membrane fabrication and water pollution treatment. This review paper will discuss the physical and chemical properties of CQDs, raw materials and methods used in the fabrication of CQDs, the stability of CQDs as well as their potential applications in wastewater treatment and biomedical field.

碳量子点（CQD）是一类引人入胜的碳纳米粒子，尺寸约为10 nm。CQD的独特特性是低毒性，化学惰性，出色的生物相容性，光诱导的电子转移和高度可调的光致发光行为。可持续原材料通常用于制造CQD，因为它们具有成本效益，生态友好且有效地减少了废物产生。可以使用激光烧蚀，微波辐射，水热反应，电化学氧化，回流方法和超声处理来制造CQD。这些方法会经历多种化学反应，例如氧化，碳化，热解和聚合过程，以生成CQD。由于CQD的粒径小，它们具有很强的可调荧光特性和高度的光致发光发射。它还包含基于氧的官能团和作为半导体纳米颗粒的高度期望的性能。因此，CQD是用于光催化，离子感测，生物成像，重金属检测，吸附处理，超级电容器，膜制造和水污染处理的有前途的纳米材料。本文将讨论CQD的物理和化学性质，用于制造CQD的原料和方法，CQD的稳定性以及它们在废水处理和生物医学领域中的潜在应用。膜制造和水污染处理。本文将讨论CQD的物理和化学性质，用于制造CQD的原料和方法，CQD的稳定性以及它们在废水处理和生物医学领域中的潜在应用。膜制造和水污染处理。本文将讨论CQD的物理和化学性质，用于制造CQD的原料和方法，CQD的稳定性以及它们在废水处理和生物医学领域中的潜在应用。