Facile synthesis of CQD/g-C3N4 as a highly effective metal-free photocatalyst for the degradation of carmoisine and indigo carmine dye

The development of extensive dye pollution in the water ecosystem seriously endangers the health of the living organism. For effectively eradicating dye contaminants from water bodies, photocatalysis is considered an effective, energy-consumption, inexpensive disinfection technique. As an alternative to conventional metal-based catalysts, heterogeneous metal-free photocatalysts are more sustainable and kinder to the environment. Here, we reported the simple hydrothermal chemical production of Carbon Quantum dots (CQD)-doped graphitic carbon nitride (GCN). Analytical instruments such as XRD, SEM, FE-SEM, HR-TEM, EDX, FT-IR, the surface area of BET analysis, photoluminescence, and UV–vis spectroscopy, zeta potential were used to characterize the as-prepared CQD doped GCN (CDCN). The degradation studies reveal that the CDCN catalyst displays the highest rate of degradation performance than pure GCN. Within 60 min, it shows 96 % degradation toward indigo Carmine (IC) and 93 % decomposition towards carmoisine dye (CM). Significant e⁻/h⁺ separation, an increased surface area, and a high redox potential capacity to induce charge bears may all contribute to the CDCN catalyst’s enhanced photocatalytic degradation efficiency. The efficiency of the photocatalytic process was optimized by studying and altering many variables. These include Dye concentration, catalyst concentration, and variation of the pH solution were some of these. The nanocomposite exhibited excellent stability after three successive runs of the photocatalytic procedure. According to the kinetics analysis results indicate that the photocatalytic decomposition of Indigo Carmine (IC) and carmoisine (CM) dye follows pseudo-first-order kinetics. For better photodegradation performance, a potential photocatalytic method employing several pairs of electron-hole acceptor scavengers has been put forth. Based on the positions of the band gap and the result of the characterization, a feasible mechanism pathway for charge carriers was also presented.