Carbon quantum dots (CDs) are a fascinating class of carbon nanomaterials (less than 10 nm in size) with unique optical, electrical, and physicochemical properties. In addition to these properties, CQDs exhibit the desired advantages of aqueous stability, low toxicity, high surface area, economic feasibility, chemical inertness, and highly tunable photoluminescence behaviour. Recently, graphitic carbon nitride (g-C₃N₄) has appeared as one of the required stable carbon-based polymers due to its varied applications in several fields. In this regard, modification strategies have been made in the g-C₃N₄ semiconductor using CQDs to enhance the adsorptive and photocatalytic activity. In comparison to other semiconductor quantum dots, g-C₃N₄ shows strong fluorescent properties, such as wide excitation spectra, photostability, and tunable photo-luminescent emission spectra. The interaction inside this multicomponent photocatalyst further promotes the photocatalytic activity by improving charge transference, which plays a vital role in electrochemistry. Therefore, CQDs are auspicious nanomaterials in the field of photocatalysis, wastewater treatment and water adsorption treatment. This particular article featured the recent progression in the field of CDs/g-C₃N₄-based photocatalysts focusing on their luminescent mechanism and potential applications in wastewater treatment.

The prevalence of lethal viral infections necessitates the innovation of novel disinfection techniques for contaminated surfaces, air, and wastewater as significant transmission media of disease. The instigated research has led to the development of photocatalysis as an effective renewable solar-driven technology relying on the reactive oxidative species, mainly hydroxyl (OH^●) and superoxide (O₂^●−) radicals, for rupturing the capsid shell of the virus and loss of pathogenicity. Metal-free graphitic carbon nitride (g-C₃N₄), which possesses a visible light active bandgap structure, low toxicity, and high thermal stability, has recently attracted attention for viral inactivation. In addition, g-C₃N₄-based photocatalysts have also experienced a renaissance in many domains, including environment, energy conversion, and biomedical applications. Herein, we discuss the three aspects of the antiviral mechanism, intending to highlight the advantages of photocatalysis over traditional viral disinfection techniques. The sole agenda of the review is to summarize the significant research on g-C₃N₄-based photocatalysts for viral inactivation by reactive oxidative species generation. An evaluation of the photocatalysis operational parameters affecting viral inactivation kinetics is presented. An overview of the prevailing challenges and sustainable solutions is presented to fill in the existing knowledge gaps. Given the merits of graphitic carbon nitride and the heterogeneous photocatalytic viral inactivation mechanism, we hope that further research will contribute to preventing the ongoing Coronavirus pandemic and future calamities.