Scalable one-step template-free synthesis of ultralight edge-functionalized g- C 3 N 4 nanosheets with enhanced visible light photocatalytic performance (original) (raw)
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Diamond and Related Materials, 2021
In this work, we focus on synthesizing g-C 3 N 4 nanosheets with a large surface area for enhanced solar light photocatalytic performance via a simple thermal polymerization of a low-cost urea precursor in enclosed conditions. The effects of annealing duration on the phase formation, structure, and optical and photocatalytic properties of the g-C 3 N 4 nanosheets were investigated. The characterization analysis revealed that g-C 3 N 4 nanosheets with different textures, including stacked-layer, porous and ultrathin morphologies, were obtained by controlling the annealing time. The prepared g-C 3 N 4 samples offer a large specific surface area, narrow band gap and efficient separation of photogenerated electron-hole pairs with increasing annealing duration. The photocatalytic properties of the as-synthesized g-C 3 N 4 samples were examined by measuring the degradation of rhodamine B (RhB) under simulated solar irradiation. With a 100% RhB solution (10 ppm) decomposed by exposure to solar irradiation for 60 min, ultrathin g-C 3 N 4 shows considerable potential in practical applications concerning environmental remediation, especially in large-scale applications in industry.
Applied Catalysis A: General, 2011
Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C 3 N 4 /TiO 2 ) catalyst films has been demonstrated in this present work. The g-C 3 N 4 /TiO 2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO 2 nanoparticles in Ar gas flow. The g-C 3 N 4 contents in the g-C 3 N 4 /TiO 2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO 2 with g-C 3 N 4 and the best degradation performance of $70% was obtained from 50 wt% g-C 3 N 4 loading content. Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interfacial electron transfer between TiO 2 and g-C 3 N 4 of the g-C 3 N 4 /TiO 2 composite film. Based on the obtained results, the possible MB degradation mechanism is ascribed mainly to the generation of active species induced by the photogenerated electrons.
Ag loaded B-doped-g C3N4 nanosheet with efficient properties for photocatalysis
Journal of Environmental Management, 2019
Three material engineering strategies in the form of doping (Boron-doping), nanostructuring (nanosheet (NS) formation) and decorating with plasmonic nanoparticles (loading with Ag metal), were integrated to improve the photocatalytic activity of graphitic carbon nitride (gC 3 N 4). Concentrations of B-doping and Ag-loading were optimized to maximize the catalytic performance in the final nanocomposite of Ag-loaded B-doped gC 3 N 4 NS. Combined effect of all three strategies successfully produced over 5 times higher rate towards degradation of organic dye pollutant when compared to unmodified bulk gC 3 N 4. Detailed characterization results revealed that incorporation of B in gC 3 N 4 matrix reduces the band gap to increase the visible light absorption, while specific surface area is significantly enhanced upon formation of NS. Decoration of Ag nanoparticles (NPs) on B-doped gC 3 N 4 NS assists in fast transfer of photogenerated electrons from gC 3 N 4 to Ag NPs owing to the interfacial electric field across the junctions and thus reduces the recombination process. Investigations on individual strategies revealed that decoration of Ag NPs to induce better charge separation, is the most effective route for enhancing the photocatalytic activity.
Journal of Chemical Sciences, 2019
Herein we report the synthesis and photocatalytic evaluation of heterostructure WO 3 /g-C 3 N 4 (WMCN) and CeO 2 /g-C 3 N 4 (CMCN) materials for RhB degradation and photoelectrochemical studies. These materials were synthesized by varying the dosages of WO 3 and CeO 2 on g-C 3 N 4 individually and were characterized with state-of-the-art techniques like XRD, BET surface area, FT-IR, UV-Vis DRS, TGA, SEM, TEM and XPS. A collection of combined structural and morphological studies manifested the formation of bare g-C 3 N 4 , WO 3 , CeO 2 , WO 3 /g-C 3 N 4 and CeO 2 /g-C 3 N 4 materials. From the degradation results, we found that the material with 10 wt% WO 3 and 15 wt% CeO 2 content on g-C 3 N 4 showed the highest visible light activity. The first order rate constant for the photodegradation performance of WMCN10 and CMCN15 is found to be 5.5 and 2.5 times, respectively, greater than that of g-C 3 N 4. Photoelectrochemical studies were also carried out on the above materials. Interestingly, the photocurrent density of WMCN10 photoanode achieved 1.45 mA cm −2 at 1.23 V (vs.) RHE and this is much larger than all the prepared materials. This enhanced photoactivity of WMCN10 is mainly due to the cooperative synergy of WO 3 with g-C 3 N 4 , which enhanced the visible light absorption and suppresses the electron-hole recombination.
Nucleation and Atmospheric Aerosols, 2021
Ultrathin g-C3N4 (g-CN) nanosheets are prepared by a two-step thermal exfoliation process in an air atmosphere. X-ray diffraction pattern (XRD) shows that ultrathin g-CN nanosheets have the same crystal structure as that of the bulk g-CN with a slight shift in the peak positions due to the reduction of sheet thickness. Field emission scanning electron microscope (FESEM) images show that the bulk g-CN is converted into ultrathin g-CN nanosheets due to thermal oxidation in an atmosphere, which increases the number of reactive active sites for water splitting. Due to a reduction in sheet thickness of g-CN, quantum confinement happened and thereby increase the bandgap from 2.88 (bulk g-CN) eV to 3.10 eV (ultrathin g-CN). Steady-state photoluminescence (PL) shows a blue shift, and time-resolve photoluminescence (TRPL) shows that the average lifetime of photogenerated charge carrier increases when bulk g-CN is converted into ultrathin g-CN nanosheets. Enhancement in photoelectrochemical performance is observed in ultrathin g-CN nanosheets compared to bulk g-CN due to the increased average lifetime of photogenerated charge carriers and a large number of reactive active sites.
ACS Sustainable Chemistry & Engineering, 2017
Exfoliation of bulk graphitic carbon nitride (BCN) into two-dimensional (2D) nanosheets is one of the effective strategies to improve its photocatalytic performance. Compared with BCN, the 2D g-C 3 N 4 nanosheets (CNNS) have larger specific surface areas and more reaction sites. With the etching assistance of anhydrous ethylenediamine, BCN can be successfully peeled off into 2D CNNS with a large lateral size of more than 15 μm which is much larger than that of other works. After appropriate etch by anhydrous ethylenediamine, the specific surface area of g-C 3 N 4 expands from 4.7 to 31.1 m 2 g −1 and the photocatalytic hydrogen evolution rate increases 7.4 times, from 4.8 to 35.3 μmol h −1. In contrast to other reported methods, the strategy to fabricate 2D CNNS in this work is convenient and it is the first time to report the fabrication of 2D CNNS with the assistance of alkaline reagent.
Enhanced visible-light photocatalytic activity of g-C3N4/TiO2 films
2014
Enhanced photocatalytic degradation of methylene blue (MB) using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) catalyst films has been demonstrated in this present work. The g-C3N4/TiO2 composites were prepared by directly heating the mixture of melamine and pre-synthesized TiO2 nanoparticles in Ar gas flow. The g-C3N4 contents in the g-C3N4/TiO2 composites were varied as 0, 20, 50 and 70 wt%. It was found that the visible-light-induced photocatalytic degradation of MB was remarkably increased upon coupling TiO2 with g-C3N4 and the best degradation performance of ~70% was obtained from 50 wt% g-C3N4 loading content. Results from UV-vis absorption study, Electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggest that the improved photoactivity is due to a decrease in band gap energy, an increased light absorption in visible light region and possibly an enhanced electron-hole separation efficiency as a result of effective interf...
Environmental Science and Pollution Research, 2020
Graphitic carbon nitride (g-C 3 N 4 ) is paying attention lately owing to its interesting characteristics and substantial application in improving environmental and energy concerns. Nevertheless, the photocatalytic activity of g-C 3 N 4 is constrained by the inertness of the surface and particle aggregation during photocatalytic activity. Herein, we report the preparation of g-C 3 N 4 with honeycomb-like morphology (HC-C 3 N 4 ) via thermal condensation of prepared SiO 2 templates and dicyandiamide. The etching out of the SiO 2 templates by NH 4 HF 2 created hollow or macropores in the C 3 N 4 matrix resulting in its structural changes. Similar, to the bulk C 3 N 4 , the HC-C 3 N 4 exhibited higher photocatalytic CO 2 reduction in hydrocarbons. This improved photocatalytic achievement is associated with higher specific surface area, excellent visible light absorption capability, higher electron donor density, easy mass diffusion of materials for surface reaction, and effective segregation of photogenerated charge carriers. Furthermore, the HC-C 3 N 4 honeycomb structure was deposited with Ni(OH) 2 clusters which showed remarkable CO 2 reduction activity of 1.48 μmolh -1 g -1 of CH 4 and 0.73 μmolh -1 g -1 of CH 3 OH generation which is 3.5 and 4.3 times higher CO 2 reduction activity compared with bulk C 3 N 4 clustered with Ni(OH) 2 particles. This comprehensive study demonstrated that HC-C 3 N 4 nanostructured polymeric semiconductor is envisaged to have great potential in the application of a variety of fields such as photocatalysis, sensor technology, and nanotechnology.