Metal-free n/n–junctioned graphitic carbon nitride (g-C3N4): a study to elucidate its charge transfer mechanism and application for environmental remediation

Synergistic effects of the hybridization between boron-doped carbon quantum dots and n/n-type g-C3N4 homojunction for boosted visible-light photocatalytic activity

“…Apart from the gradual decrease in absorbance intensity with time, the peaks shifted gradually towards the blue region (left) of the visible spectrum as the illumination time lengthened. This was in congruent with the reported studies on the photodegradation of RhB catalyzed by g-C 3 N 4 /g-C 3 N 4 homojunction systems, Ag 3 PO 4 nanoparticles and Ag 3 VO 4 /β-Ag 3 VO 4 nanocomposites(Gao et al, 2017;Xu et al, 2017;Phang et al, 2020a). Besides, the left-shifted peaks signi ed the generation of deethylated intermediates as the chromophores and aromatic rings of the RhB dye undergone deconstruction(Li et al, 2008;Chiu et al, 2019) 3.3 Photoelectrochemical and PL analysisTo further study the charge migration behavior and separation of photo-generated electron-hole pairs across the interface of BCQD/CN photocatalyst, transient photocurrent response and Mott-Schottky plots were also constructed.…”

“…The surface structure and morphology of CN, CQD/CN and 1-BCQD/CN were analyzed using FESEM and TEM. The successful fabrication of an n/n-type g-C 3 N 4 homojunction (CN) was reported in our previous work (Phang et al, 2020a). As shown in Fig.…”

“…2.2.2 Synthesis of g-C 3 N 4 /g-C 3 N homojunction (CN) g-C 3 N 4 /g-C 3 N 4 homojunction was prepared by a facile thermal polymerization route following a reported work with slight modi cations (Phang et al, 2020a). Typically, 6 g of each precursor (urea and thiourea) were mixed in 30 ml of distilled water with gentle stirring to obtain a well-mixed solution.…”

“…Among the more effective strategies in enhancing the photocatalytic performance of g-C 3 N 4 is through the formation of a homojunction system, where the difference in conduction band (CB) and valence band (VB) levels between precursors could facilitate the separation of photoinduced charge carriers (Phang et al, 2020b). Several research articles on g-C 3 N 4 homojunction with enhanced photocatalytic performance have been published in literature (Ye et al, 2017;Phang et al, 2020a). For instance, Tan et al successfully fabricated a mesoporous g-C 3 N 4 nanosheets laminated homojunction, which displayed a 12.5-and 6.5-fold improvement in performance as compared to pristine g-C 3 N 4 derived from melamine and amino cyanamide respectively (Tan et al, 2017).…”

“…As presented in Fig.8(a), the transient photocurrent measured were plotted with respect to time for CN, CQ/CN and 1-BCQD/CN with alternate cycles of on-off visible light irradiation to study their photoelectronic properties. The electric current generated by the photo-excited charge carriers were measured via transient photocurrent as the visible light pulse was turned on and decayed promptly with the light shut off(Xiang et al, 2011;Phang et al, 2020a). It is observed that there was a signi cant improvement in the transient photocurrent response exhibited by 1-BCQD/CN.…”