Revealing the stability of CuWO4/g-C3N4 nanocomposite for photocatalytic tetracycline degradation from the aqueous environment and DFT analysis.

Graphitic carbon nitride (g-C3N4) is an emerging metal-free photocatalyst, however, engineering the photocatalytic efficiency for the effective degradation of hazardous molecules is still challenging. An unstable and low bandgap CuWO4 was composited with g-C3N4 to achieve synergistic benefits of tuning the visible light responsiveness and stability of CuWO4. CuWO4/g-C3N4 nanocomposite exhibited a relatively high visible light absorption region and the bandgap was modified from 2.77 to 2.53 eV evidenced via UV-DRS. Moreover, the fast electron transfer rate was observed with CuWO4/g-C3N4 nanocomposite as confirmed using PL and photocurrent studies. XRD, FT-IR, and HR-TEM analyses signified the formation of CuWO4/g-C3N4 nanocomposite. CuWO4/g-C3N4 nanocomposite showed enhanced photocatalytic degradation of Tetracycline (TC) about ∼7.4 fold greater than pristine g-C3N4 in 120 min. Notably, the OH• and •O2- radicals played a most significant role in photocatalytic TC degradation. Furthermore, the energy band structure, density of state, and Bader charge analyses of these molecules were performed.

rGO supported self-assembly of 2D nano sheet of (g-C3N4) into rod-like nano structure and its application in sonophotocatalytic degradation of an antibiotic.

Graphitic carbon nitride (g-C3N4) is an analog of graphite due to its unique electronic structure. g-C3N4 based materials have been used in photocatalytic applications. However, pure g-C3N4 suffers from major shortcomings which include poor disparity, low surface area and a high recombination rate of photo generated electron-hole pairs that significantly reduce its photocatalytic activity. In this work, self-assembly of g-C3N4 sheet into rod shaped g-C3N4 was developed via a simple polymerisation method. A composite made of g-C3N4 nanorods and rGO (rGO-RCN) was also prepared. The band gap g-C3N4 was shifted from 2.77 to 2.6 eV evidented by UV-DRS data. As a result, rGO-RCN showed a relatively high absorption in the visible region. Moreover, a fast electron transfer rate was observed with rGO-RCN composite as conformed from PL analysis and photocurrent measurement. The formation of nanorod and sheet morphologies was confirmed via TEM analysis. The photocatalytic activities of prepared sheet-g-C3N4 (SCN), Rod g-C3N4 (RCN), reduced graphene oxide supported sheet-g-C3N4 (rGO-SCN) and reduced graphene oxide supported Rod-g-C3N4 (rGO-RCN) were evaluated using a commonly used antibiotic (tetracycline). Among these catalysts, rGO-RCN nanocomposite showed sonophotocatalytic activity 3 times higher compared to pure g-C3N4. This superior sonophotocatalytic activity could be due to enhanced visible light absorption of the material, active sites generated by ultrasound, and the high electron transport property of rGO.

Reduced graphene oxide (rGO) supported electron deficient B-doped TiO2 (Au/B-TiO2/rGO) nanocomposite: An efficient visible light sonophotocatalyst for the degradation of Tetracycline (TC).

Incorporation of electron deficient boron atoms along with Au doped TiO2 in the presence of rGO support was synthesized by hydrothermal method and demonstrated for the sonophotocatalytic degradation of TC under visible light illumination. The successful incorporation of electron deficient boron atoms and Au on TiO2 was considerably enhanced the optical absorption towards visible region due to the formation acceptor energy levels below to the conduction band of TiO2 by boron doping and surface plasmonic effect of Au. Moreover, formation of acceptor energy levels and introduction of reduced graphene oxide (rGO) support significantly improved the electron-hole pair separation and transportation which were supported by UV-vis-DRS, photo-current and photoluminescence measurements. The individual effect of photocatalysis and ultrasound for the TC degradation was found to be 45% and 12%, respectively. Importantly, a complete degradation (100%) of TC was achieved with 1.3 folds synergistic effect when ultrasound coupled with photocatalysis in 1 h. The enhanced degradation activity was mainly attributed to combined effect of rapid electron-hole pair separation facilitated by electron deficient B-atoms and rGO support and physical forces of ultrasound as well. In addition, ∼74% of Total Organic Carbon (TOC) removal was achieved within 1 h which further confirmed the effective demineralization of TC by the Au/B-TiO2/rGO composite.