## 3 Design Consideration for g-C\({}_{3}\)N\({}_{4}\)/CQDs-Based Nanocomposites
### g-C\({}_{3}\)N\({}_{4}\)/CQDs-Based Nanocomposites for Different Antibiotic Degradation
[65] Copyright Springer 2019.  
positioned at CQDs and g-C\({}_{3}\)N\({}_{4}\), respectively (Figure 6f). Thus, this lowering of the band energy resulted into wider-range of light absorptivity, along with efficient separation of charge pairs. As a result, the degradation efficacy of the 3 wt% CQDs/g-C\({}_{3}\)N\({}_{4}\) towards sulfradiazine was reached 92.8% than bare g-C\({}_{3}\)N\({}_{4}\) (53.7% in 80 min). Recently, [PERSON] and co-researchers investigated tubular-shaped g-C\({}_{3}\)N\({}_{4}\)-altered CQDs nanocomposite, synthesized by simple polymerization technique for the removal of carbamazepine under light of 400 nm [70]. The photoactivity of the CQDs/g-C\({}_{3}\)N\({}_{4}\) was depicted as being five times greater than the g-C\({}_{3}\)N\({}_{4}\), due to the synergistic effect between the two photocatalysts and strong recyclability for up to four successive cycles. In order to detect the roles of reactive oxidative groups, different scavengers were applied in the experiments, along with electron spin resonance analysis. Here, \({}^{\bullet}\)O\({}_{2}\)\({}^{-}\) and h\({}^{+}\) were the main species in the degradation process while \({}^{\bullet}\)OH radicals had no effect. Basically, the K\({}_{1}\) values decreased by 98% and 86% by potassium iodide (for h\({}^{+}\)) and p-benzoquinone (for \({}^{\bullet}\)O\({}_{2}\)\({}^{-}\)), respectively. On the contrary, only an 8% decrease was observed with the addition of tert-butyl alcohol, employed for quenching \({}^{\bullet}\)OH species. Furthermore, no signal peak was detected in the electron spin resonance spectra of 5,5-Dimethyl-1-pyrroline N-oxide (DMPO)-\({}^{\bullet}\)OH species, indicating no \({}^{\bullet}\)OH formation in the system. Subsequently, DMPO-\({}^{\bullet}\)O\({}_{2}\)\({}^{-}\) group showed a strong peak, revealing \({}^{\bullet}\)O\({}_{2}\)\({}^{-}\) as a main reactant species. In another study, [PERSON] et al., studied highly crystalline g-C\({}_{3}\)N\({}_{4}\)/CQDs nanocomposites, synthesized using calcination techniques, particularly for the degradation of tetracycline [71]. Herein, the possible tetracycline degradation route with product intermediates were recognized using liquid chromatography-mass spectrometry technique. The photoactivity towards tetracycline degradation by g-C\({}_{3}\)N\({}_{4}\)/CQDs nanocomposite reached about 86%  
Figure 6: **(a,b)** Effects of variant scavengers (1 mM ammonium oxalate (AO), 50 \(\mu\)M tert-butyl alcohol, 50 \(\mu\)M, and p-benzoquinone (p-BQ) on the degradation efficiency for diclofenac, (c) fluorescence emission spectrum of CQDs/g-C\({}_{3}\)N\({}_{4}\) and different samples (d) transient photocurrent densities of CQDs/g-C\({}_{3}\)N\({}_{4}\) and different samples, and (e) energy dispersive X-ray spectroscopy of CQDs/g-C\({}_{3}\)N\({}_{4}\) (inset: transmission electron microscopy image of the corresponding region). Reproduced with permission from Refs. [34, 68, 69] with license number 5043061194671, 5043061353580, 5043070650674, Copyright Elsevier 2019, 2020, and 2021.  
within 120 min with the notable photostability of the photocatalyst up to four consecutive cycles with 480 min. Recently, [PERSON] and his peer group studied the integration of CQDs into acidified g-C\({}_{3}\)N\({}_{4}\) and coupling with CdIn\({}_{2}\)S\({}_{4}\) forming g-C\({}_{3}\)N\({}_{4}\)/CQDs/CdIn\({}_{2}\)S\({}_{4}\) photocatalyst and prepared using simple hydrothermal technique [72]. The best photoactivity of hybrid composite towards ibuprofen degradation was found to be 91.0% under 420 nm of visible-light. For optical properties, the strong intense absorption peaks for g-C\({}_{3}\)N\({}_{4}\) and CdIn\({}_{2}\)S\({}_{4}\) at 600 and 680 nm was estimated using UV-visible diffuse reflectance spectroscopy.