Efficient exfoliation of g-C₃N₄ and NO₂ sensing behavior of graphene/g-C₃N₄ nanocomposite

Hang, Nguyen Thuy,Zhang, Shaolin,Yang, Woochul Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.248 No.-

<P><B>Abstract</B></P> <P>In this work, graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) nanosheets were prepared and employed to improve the gas sensitivity performance of graphene. g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets (NS-CN) were exfoliated from bulk powder using a proton-enhanced liquid-phase exfoliation method, where the co-ordinate bonds between nitrogen of g-C<SUB>3</SUB>N<SUB>4</SUB> and proton H<SUP>+</SUP> of HCl benefit the swelling of bulk and improve the delamination process. The thickness and size of the exfoliated nanosheets were about ∼4nm and 1–2μm, respectively. A slight increment of the bandgap of g-C<SUB>3</SUB>N<SUB>4</SUB> was observed after exfoliation. It was found that the proton functionalization of g-C<SUB>3</SUB>N<SUB>4</SUB> powder before exfoliation facilitates the production of uniform nanosheets. A certain amount ranging from 0% to 90% of as-prepared g-C<SUB>3</SUB>N<SUB>4</SUB> was added to a graphene solution and ultrasonically mixed to prepare a graphene/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposite (G/NS-CN). The performances of pure graphene-based and nanocomposite-based sensors in sensing NO<SUB>2</SUB> gas were systematically investigated and compared. We found compositing g-C<SUB>3</SUB>N<SUB>4</SUB> with graphene significantly enhanced the sensing performance of the graphene sensor. A trade-off effect on sensing response was observed as the weight ratio of NS-CN to graphene in the nanocomposite sensor was changed, suggesting the specific roles of g-C<SUB>3</SUB>N<SUB>4</SUB> and graphene in sensing behavior. It was found that the nanocomposite sensor with 15wt% of NS-CN exhibited the best sensing response. The sensor in this optimized composition presented a linear and stable response as well as good recovery toward NO<SUB>2</SUB> gas. The sensing mechanism of the nanocomposite sensor was also proposed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The protonation treatment facilitates the production of g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets with uniform size. </LI> <LI> g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets were employed to improve the gas sensing properties of graphene. </LI> <LI> Optimal composite sensor containing 15% of g-C<SUB>3</SUB>N<SUB>4</SUB> exhibited the best sensing performance. </LI> <LI> g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets play as an active adsorption site and graphene provides a charge pathway. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Construction of g/C3N4-ZnO composites with enhanced visible-light photocatalytic activity for degradation of amoxicillin

Shuhan Sun,Shiling Li,Yibing Hao,Xiao Yang,Xiaomin Dou 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

g/C3N4-ZnO composite catalysts were synthesized through surface hybridization of the delocalized conjugated- structure of g/C3N4 with the closely contacted surface of ZnO via a successive and simultaneous calcinationprocedure, and two kinds of photocatalysts, g/C3N4-ZnO1 and g/C3N4-ZnO2, were obtained. Heterojunctions wereformed between the two components, which promote the separation of photogenerated carriers efficiently, and thenenhanced the degradation of 100mg/L of AMX. The degradation rate of g/C3N4-ZnO1 was 1.54, 11.33, and 2.52-foldthat of g/C3N4-ZnO2, g/C3N4, and ZnO, respectively, at a 3.5-h reaction period, with the dosage of 0.3 g/L, and solutionpH at 7.0±0.2. The recycle and reuse ability was excellent and 90.5% of AMX mitigation was achieved in the fifthcycle. For g/C3N4-ZnO1, electrons migrated from the conduction band of g/C3N4 to that of ZnO via the heterojunction. ·OH and h+ were the main active species for AMX degradation, compared to ·O2 dominated for g/C3N4. Twelveintermediate products were identified, and two degradation pathways were inferred for g/C3N4-ZnO1 and g/C3N4-ZnO2, respectively. Finally, transformation products without lactam rings were achieved, which lost most of the antibacterialpotencies, and the ecotoxicity was also dramatically decreased as indicated by the ECOSAR program.

Arginine‑polyaniline@g‑C3N4 for outstanding retention of Orange G dye from water

Hamid Zouggari,Fatima‑Zahra Mahir,Abdelaziz Imgharn,Abdelghani Hsini,Nouh Aarab,Mohamed Laabd,Abdallah Albourine 한국탄소학회 2023 Carbon Letters Vol.33 No.6

An eco-friendly material was synthesized through interfacial polymerization of aniline on particles of g-C3N4 with arginine, resulting in Arg-PANI@g-C3N4 composite. The as-synthesized composite was characterized by the Brunauer, Emmett, and Teller (BET) surface area, X-ray energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The adsorption capability of as-synthesized composite towards Orange G (OG) dye has been evaluated under several experimental conditions, such as the adsorbent dosage, initial dye concentration, contact time under agitation, pH of dye solution and temperature. Thermodynamics parameters such as free energy (ΔG°), entropy (ΔS°), and enthalpy (ΔH°) were also calculated and suggested that the adsorption process is spontaneous and endothermic in nature. The kinetics data revealed that the adsorption of OG dye onto Arg-PANI@g-C3N4 follows the pseudo-second order kinetics model. The maximum adsorption capacity was found to be 80.54 mg·g?1. Furthermore, the Arg-PANI@g-C3N4 surface exhibited a Langmuir-like adsorption isotherm in contrast to a Freundlich isotherm due to homogeneous active site distribution. Regeneration investigation showed the excellent reusability of Arg-PANI@g-C3N4 composite during the cleaning up of solution containing OG dye molecules.

An S-scheme photocatalyst constructed by modifying Ni-doped Sn3O4 micro-flowers on g-C3N4 nanosheets for enhanced visible-light-driven hydrogen evolution

Dandan Wang,Zhaoxin Lin,Chun Miao,Wei Jiang,Hongji Li,Chunbo Liu,Guangbo Che 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

Carbon nitrides (g-C3N4) is considered to be the prospective semiconductor photocatalyst for photocatalytic H2 evolution. Nevertheless, it suffers from low charge transfer efficiency and fewer metal active sites. Thereby, Ni-Sn3O4/g-C3N4 photocatalysts were constructed by anchoring Ni-doped Sn3O4 micro-flowers on g-C3N4 via a feasible and straightforward solvothermal treatment. The prepared Ni-Sn3O4/g-C3N4 S-scheme heterojunction could improve the transfer and separation efficiency of photo-generated electron-hole pairs by facilitating the electrons transfer from Ni-Sn3O4 to g-C3N4. Moreover, the photocatalytic H2 production performance was ameliorated due to the established internal electric field and the energy band bending in Ni-Sn3O4/g-C3N4 S-scheme heterojunction. Meanwhile, the doping Ni in Sn3O4 exposed more active sites in Ni-Sn3O4/g-C3N4 heterojunction for producing H2. As a result, Ni-Sn3O4/g-C3N4-5 photocatalyst exhibited outstanding H2 yields of 1961 µmol h−1 g−1 under visible light irradiation in comparison with pure Ni-Sn3O4 (12 µmol h−1 g−1) and bared g-C3N4 (1391 µmol h−1 g−1). Furthermore, the S-scheme mechanism in Ni-Sn3O4/g-C3N4 heterojunction for producing H2 by oxidizing H2O was proposed. This study provides helpful guide for developing efficient g-C3N4-based photocatalytic systems.

Effect of g-C₃N₄ precursors on the morphological structures of g-C₃N₄/ZnO composite photocatalysts

Jung, Haewon,Pham, Thanh-Truc,Shin, Eun Woo Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.788 No.-

<P><B>Abstract</B></P> <P>In this study, g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO (CNZ) composite materials were synthesized through a one-step facile method with diverse precursors to investigate the interaction between g-C<SUB>3</SUB>N<SUB>4</SUB> precursors and ZnO and the resultant morphological structures. Thiourea (Thio), urea, and dicyandiamide (DCDA) were used as g-C<SUB>3</SUB>N<SUB>4</SUB> precursors. Several characterization methods were employed to understand the structural and optical properties affected by the interaction variation between g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO nanoparticles during the thermal polycondensation process to the g-C<SUB>3</SUB>N<SUB>4</SUB> structure. Consequently, each composite material resulted in different morphological composite structures. DCDA-CNZ formed a core–shell structure covered with thin g-C<SUB>3</SUB>N<SUB>4</SUB> layers due to an efficient interaction between DCDA and ZnO nanoparticles. Meanwhile, Thio and Urea-CNZ showed a segregated morphology of porous g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO nanoparticles in the composites, which was ascribed to a weak interaction between them and gas generation from thiourea and urea during the thermal polymerization. The core–shell morphology of DCDA–CNZ led to a unique behavior, such as the deficient electron density of Zn and g-C<SUB>3</SUB>N<SUB>4</SUB>-responded photoluminescence emission. Furthermore, DCDA–CNZ exhibited the highest efficiency for the photocatalytic degradation of methylene blue under visible-light irradiation, implying the strong influence of the morphological structure on the photocatalytic performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composites (CNZ) are prepared by a facile method with diverse precursors. </LI> <LI> Urea, thiourea (Thio) and dicyandiamide (DCDA) are utilized as a g-C<SUB>3</SUB>N<SUB>4</SUB> precursor. </LI> <LI> Segregated morphology in Urea and Thio-CNZ is caused by weak interaction with ZnO. </LI> <LI> DCDA-CNZ forms the core-shell structure by efficient interaction of g-C<SUB>3</SUB>N<SUB>4</SUB> with ZnO. </LI> <LI> The different morphologies in the CNZ composites influence photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Interactions between ZnO nanoparticles and amorphous g-C₃N₄ nanosheets in thermal formation of g-C₃N₄/ZnO composite materials: The annealing temperature effect

Jung, Haewon,Pham, Thanh-Truc,Shin, Eun Woo Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.458 No.-

<P><B>Abstract</B></P> <P>In this study, C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite materials were prepared at various annealing temperatures and systematically characterized to investigate the role of ZnO in the thermal formation of graphitic C<SUB>3</SUB>N<SUB>4</SUB> (g-C<SUB>3</SUB>N<SUB>4</SUB>), and to understand effect of annealing temperatures on the interaction between g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO in the composite materials. ZnO nanoparticles in the composite materials facilitated the thermal formation of the g-C<SUB>3</SUB>N<SUB>4</SUB> structure due to the strong interaction between g-C<SUB>3</SUB>N<SUB>4</SUB> and ZnO nanoparticles, resulting in a decrease in thermal polymeric condensation temperatures. Moreover, the morphological structure of g-C<SUB>3</SUB>N<SUB>4</SUB> was significantly influenced by the presence of ZnO nanoparticles with an amorphous g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheet structure in the composite materials and a crystalline interlayered g-C<SUB>3</SUB>N<SUB>4</SUB> structure in g-C<SUB>3</SUB>N<SUB>4</SUB> only. The higher annealing temperatures for composite materials induced the stronger interaction between ZnO nanoparticles and g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets. The strong interaction in a core-shell g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO structure not only gradually decreased the electronic density of ZnO nanoparticles but also proportionally inhibited the recombination of photo-generated electron-hole pairs in the composite materials, with increasing the annealing temperature. The g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite material prepared at 500 °C exhibited the highest photocatalytic reaction rate constant for photocatalytic degradation of methylene blue, which might be caused by the slowest recombination rate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite materials were prepared at various annealing temperatures. </LI> <LI> Non-crystalline g-C<SUB>3</SUB>N<SUB>4</SUB> nanosheets were formed from DCDA over ZnO nanoparticles. </LI> <LI> The strong interaction between ZnO and g-C<SUB>3</SUB>N<SUB>4</SUB> decreased the electron density of ZnO. </LI> <LI> The g-C<SUB>3</SUB>N<SUB>4</SUB>/ZnO composite prepared at 500 °C showed the slowest recombination rate. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Plasmonic Ag nanoparticles decorated NiAl-layered double hydroxide/graphitic carbon nitride nanocomposites for efficient visible-light-driven photocatalytic removal of aqueous organic pollutants

Tonda, Surendar,Jo, Wan-Kuen Elsevier 2018 CATALYSIS TODAY - Vol.315 No.-

<P><B>Abstract</B></P> <P>Ag nanoparticles decorated NiAl-layered double hydroxide/graphitic carbon nitride (Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB>) nanocomposites were synthesized for the first time by an <I>in situ</I> hydrothermal method, followed by photoreduction. The visible-light-driven Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites exhibited enhanced performance for the photocatalytic degradation of aqueous Rhodamine B and 4-chlorophenol. Notably, the Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposite with LDH and Ag contents of 15 wt% and 1 wt%, respectively, showed the highest photocatalytic performance, which was far superior to that observed for pure g-C<SUB>3</SUB>N<SUB>4</SUB>, LDH, and the binary Ag/g-C<SUB>3</SUB>N<SUB>4</SUB> and LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> composites. The enhanced photocatalytic efficiency was mainly attributed to rapid charge transfer at the Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> interfaces and the surface plasmon resonance of the Ag nanoparticles, which promotes the separation efficiency of photogenerated charge carriers and improves optical absorption. Additionally, the Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites exhibited excellent photostability during successive experimental runs, with no significant change in degradation performance. These findings are expected to provide new mechanistic insights into the design and construction of efficient visible-light-driven photocatalysts for application in solar energy conversion and environmental remediation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> were prepared by an <I>in-situ</I> hydrothermal followed by photoreduction. </LI> <LI> Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> exhibits stronger light absorption in the visible light region. </LI> <LI> Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> showed high photocatalytic performance for RhB and 4-CP degradation. </LI> <LI> Rapid charge transfer at interfaces and SPR of Ag contribute to enhanced activity. </LI> <LI> The Ag/LDH/g-C<SUB>3</SUB>N<SUB>4</SUB> nanocomposites exhibited excellent photostability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile preparation of antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic polyvinylidene fluoride membranes for effective removal of rhodamine B

Yanhua Cui,Lili Yang,Minjia Meng,Qi Zhang,Binrong Li,Yilin Wu,Yunlei Zhang,Jihui Lang,Chunxiang Li 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.2

A simplified strategy for facilely fabricating antifouling graphite carbon nitride/silver phosphate (g-C3N4/ Ag3PO4) nanocomposite photocatalytic polyvinylidene fluoride (PVDF) porous membranes was developed for effective removal of rhodamine B (RhB). g-C3N4/Ag3PO4 heterojunction was strongly fixed to the interior of the PVDF membranes via phase inversion method. The membrane structure was analyzed by Fourier transform spectrophotometer (FT-IR). The morphology of the prepared membranes was investigated using scanning electron microscopy (SEM), EDX-mapping and atomic force microscopy (AFM), respectively. All prepared nanocomposite photocatalytic PVDF membranes exhibited a typically porous structure, and g-C3N4/Ag3PO4 nanocomposites were well dispersed inside the membranes. The obtained g-C3N4/Ag3PO4 heterojunction nanoparticle decorated PVDF membrane had a lower water contact angle of 79o and higher porosity of 85% than that of other two control membranes. The nanocomposite photocatalytic PVDF porous membranes had extremely high permeation flux over 1,083 L·m−2·h−1, and could be used for the removal of RhB. The removal efficiency of g-C3N4/Ag3PO4-PVDF membranes towards RhB solution under visible light irradiation reached 97%, higher than that of the pure PVDF membranes (41%) and g-C3N4-PVDF membranes (85%). Remarkably, the flux performance and flux recovery ratio (FRR) of membranes revealed that the g-C3N4/Ag3PO4- PVDF membranes could recover high flux after fouling, which presented better fouling resistance. Furthermore, the fabricated antifouling g-C3N4/Ag3PO4 nanocomposite photocatalytic PVDF porous membranes exhibited excellent recyclability. Therefore, it is expected that g-C3N4/Ag3PO4-PVDF membranes could provide an energy-saving strategy for effective removal of organic dyes wastewater and have a great potential for practical wastewater treatment in the future.

Fabrication of heterostructured vanadium modified g-C3N4/TiO2 hybrid photocatalyst for improved photocatalytic performance under visible light exposure and antibacterial activities

Shanmugam Vignesh,Sanjeevamuthu Suganthi,Jeyaperumal Kalyana Sundar,Vairamuthu Raj 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-

Improving visible-light active photocatalytic performance of the heterostructured g-C3N4-V-TiO2 (g-C3N4-Vanadium-TiO2) hybrid catalyst has been synthesized via facile calcination and ultrasonicdispersion facilitated hydrothermal techniques were considered. The phase composition, morphology,surface area, chemical structure as well as optical properties were systematically characterized. HR-TEMimages were exposed good crystallinity of g-C3N4-10% V-TiO2 nanocomposite (size~35–40 nm) with VTiO2porous discrete on g-C3N4 nanosheets. Too occurred in high pore volume and large surface area(91.5 m2 g 1) of g-C3N4-10% V-TiO2 hybrid catalyst compared than pristine g-C3N4. The 10% g-C3N4-V-TiO2photocatalyst shows substantial photocatalytic activity, 5.7 and 4.8 times higher that pristine g-C3N4nanosheets and TiO2 under visible light with the degradation efficiency over 99.5% for 60 min. Besides,the recycling test specified that the g-C3N4-10% V-TiO2 photocatalyst had admirable stability up to 5sequential cycles. The trapping assessments which authorize that OH radicals and h+ plays an activerole in the degradation process and the separation of photoinduced charges transversely theheterostructure boundary reserved electron-hole recombination they were good agree with PL studies. Moreover, g-C3N4-10% V-TiO2 composite catalyst show high catalytic antibacterial activity againstEscherichia coli (G ) and the Staphylococcus aureus (G+) bacteria.

Efficient Fe₂O₃/C-g-C₃N₄ Z-scheme heterojunction photocatalyst prepared by facile one-step carbonizing process

Kang, Myung Jong,Yu, Hyejin,Lee, Wonjoo,Cha, Hyun Gil Elsevier 2019 The Journal of physics and chemistry of solids Vol.130 No.-

<P><B>Abstract</B></P> <P>Photocatalytic water purification has emerged as new effective ways for an environment preserve and purification in few decades. As a part of studies on photocatalytic water purification, constructing heterojunction structured compounds with different photocatalysts for efficient organic pollutant degradation is regarded as key-strategy. Herein, facile one-step carbonizing process was introduced for synthesizing Fe<SUB>2</SUB>O<SUB>3</SUB>/C-g-C<SUB>3</SUB>N<SUB>4</SUB> based Z-scheme heterojunction photocatalyst. The two times of photocatalytic organic pollutant degradation rate of Fe<SUB>2</SUB>O<SUB>3</SUB>/C-g-C<SUB>3</SUB>N<SUB>4</SUB> based Z-scheme heterojunction photocatalyst was enhanced comparing with pristine Fe<SUB>2</SUB>O<SUB>3</SUB>/g-C<SUB>3</SUB>N<SUB>4</SUB> heterojunction photocatalyst through rhodamine B (RhB) degradation under AM 1.5G (100 mWcm<SUP>−2</SUP>, 1 sun) illumination. The reasons for enhanced photocatalytic RhB degradation efficiency of Fe<SUB>2</SUB>O<SUB>3</SUB>/C-g-C<SUB>3</SUB>N<SUB>4</SUB> based Z-scheme heterojunction photocatalyst were revealed to efficient charge transfer during light induced RhB degradation reaction by constructing junction structures among Fe<SUB>2</SUB>O<SUB>3</SUB>, amorphous carbon layer and g-C<SUB>3</SUB>N<SUB>4</SUB>, which proved by fluorescence spectroscopy, XPS, SEM, TEM and UV–Vis analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe<SUB>2</SUB>O<SUB>3</SUB>/g-C-<SUB>3</SUB>N<SUB>4</SUB> (Fg) and Fe<SUB>2</SUB>O<SUB>3</SUB>/C-g-C<SUB>3</SUB>N<SUB>4</SUB> (FCg) heterojunction photocatalysts synthesized via simple solid-state reaction. </LI> <LI> Z-scheme heterojunction between Fe<SUB>2</SUB>O<SUB>3</SUB> and g-C<SUB>3</SUB>N<SUB>4</SUB> was constructed by insertion of amorphous carbon layer. </LI> <LI> Photocatalytic activities of double charge transfer or Z-scheme heterojunction between Fe<SUB>2</SUB>O<SUB>3</SUB> and g-C<SUB>3</SUB>N<SUB>4</SUB> was studied. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>