Carbon Quantum Dots Based Nanocomposite for Selective Mercury Detection

The emergence of 2D carbon-based materials has a profound impact on various research areas, such as biosciences, electronics, optics, environmental protection, and monitoring. Mercury, a highly toxic pollutant, can cause severe health complications such as neural toxicity, insomnia, cognitive dysfunction, muscle atrophy, peripheral vision impairment, and emotional instability. A suitable 2D nanostructural interface is required to effectively monitor mercury levels in the environment. This study presents the use of synergistic nitrogen and sulfur co-doped carbon quantum dots anchored on exfoliated molybdenum disulfide for rapid detection of mercury ions. This process employs a biomass extract that facilitates the exfoliation of bulk molybdenum disulfide and also act as carbon precursor for in situ carbon quantum dot deposition on exfoliated molybdenum disulfide. The nanocomposite provides photo-physical properties and surface functionalities from both organic and inorganic components to bridge the charge transfer, resulting from selective binding of mercury (II) ions. This 2D heterojunction is capable of detecting mercury (II) ions with a response time of ≈90 s, limit of detection of 31pm, and photosensitivity of 16.6A cm^-2 M^-1. The interface is tested on blood samples from Labeorohita fish to detect mercury (II) toxicity in nature.