Band Gap Of g-C3N4 Research Articles

Cobalt-doped graphitic carbon nitride: A multifunctional material for humidity sensing, electrochemical water splitting and environmental remediation applications

Graphitic carbon nitride (g-C3N4) has emerged as a promising eco-friendly material for catalysis and sensing applications due to their unique properties. However, limitations like low specific surface area, insufficient light absorption, and poor conductivity hinder their broader usability. Elemental doping has been established as an effective approach to modify the electronic structure and bandgap of g-C3N4 thus significantly expanding its light-responsive range for enhanced charge separation. This work reports on the fabrication of cost-effective and stable g-C3N4 and cobalt-doped g-C3N4 (Co@g-C3N4) via a simple one-step calcination process. The humidity sensing performance of both g-C3N4 and Co@g-C3N4 was evaluated across a broad humidity range (7 % - 94 % RH) at various testing frequencies. The results demonstrated good reversibility with Co@g-C3N4 exhibiting superior performance compared to pristine g-C3N4. Furthermore, the synthesized materials were assessed for their suitability as photoelectrochemical water splitting catalysts for hydrogen production, representing a step towards energy-efficient fuel cells. Notably, Co@g-C3N4 displayed enhanced performance with a lower onset potential (420 mV) and a lower Tafel slope (65.4 mV dec-1) for the hydrogen evolution reaction (HER) compared to undoped counterparts. Additionally, Co@g-C3N4 nanorods exhibited remarkable performance for the oxygen evolution reaction (OER), showcasing a lower onset potential (1.505 V) and a considerably low overpotential (270 mV), surpassing numerous reported electrocatalysts and even rivaling precious-metal-based ones. Finally, enhanced photocatalytic activities for organic dyes degradation were recorded for the mentioned materials. Therefore, g-C3N4 and related materials have great potential for their industrial electrochemcial applications.

Polydopamine Coating of Graphitic Carbon Nitride, g-C3N4, Improves Biomedical Application.

Graphitic carbon nitride (g-C3N4) is an intriguing nanomaterial that exhibits photoconductive fluorescence properties under UV-visible light. Dopamine (DA) coating of g-C3N4 prepared from melamine was accomplished via self-polymerization of DA as polydopamine (PDA). The g-C3N4 was coated with PDA 1, 3, and 5 times repeatedly as (PDA@g-C3N4) in tris buffer at pH 8.5. As the number of PDA coatings was increased on g-C3N4, the peak intensity at 1512 cm-1 for N-H bending increased. In addition, the increased weight loss values of PDA@g-C3N4 structures at 600 °C from TGA thermograms confirmed that the coating was accomplished. The band gap of g-C3N4, 2.72 eV, was reduced to 0.87 eV after five coatings with PDA. A pristine g-C3N4 was found to have an isoelectric point (IEP) of 4.0, whereas the isoelectric points of 1PDA@g-C3N4 and 3PDA@g-C3N4 are close to each other at 3.94 and 3.91, respectively. On the other hand, the IEP of 5PDA@g-C3N4 was determined at pH 5.75 assuming complete coating with g-C3N4. The biocompatibility of g-C3N4 and PDA@g-C3N4 against L929 fibroblast cell lines revealed that all PDA@g-C3N4 coatings were found to be biocompatible up to a 1000 mg/mL concentration, establishing that PDA coatings did not adversely affect the biocompatibility of the composite materials. In addition, PDA@g-C3N4 was screened for antioxidant potential via total phenol content (TPC) and total flavonoid content assays and it was found that PDA@g-C3N4 has recognizable TPC values and increased linearly with an increased number of PDA coatings. Furthermore, blood compatibility of pristine g-C3N4 is enhanced considerably upon PDA coating, affirmed by hemolysis and the blood clotting index%. Additionally, α-glucosidase inhibitory properties of PDA@g-C3N4 structures revealed that 67.6 + 9.8% of this enzyme was evenly inhibited by 3PDA@g-C3N4 structure.

Halloysite nanotubes (MHNTs) modified S-scheme g-C3N4/γ-Fe2O3 photocatalyst for enhancing charge separation and photocatalytic activity

Photocatalysis is a surface process and an increase in the adsorption of target molecules on the surface of a photocatalyst could be of prime necessity in the photodegradation efficiency enhancement of dyes. To attain such a purpose, this study equips g-C3N4 with pores-modified halloysite nanotubes (MHNTs), then gets it wrapped by γ-Fe2O3 nanoparticles with high specific surface area (SSA) and S-scheme mechanism through a one-pot synthesis and co-precipitation, respectively. Characterization of fabricated photocatalysts is conducted to detect physical, chemical, optical, magnetic, and electrical properties by XRD, FT-IR, XPS, FE-SEM, EDX+MAP, TEM, BET, DRS, PL, VSM, Photocurrent, and EIS analyses. This research introduces a novel, ternary nanocomposite (g-C3N4/MHNTs/γ-Fe2O3) with dual functionality towards adsorption of both anionic and cationic dyes. Modified halloysite nanotubes (MHNTs), due to predominant negative charges (Si-O) on their outer surface, perform a significant role in the separation of holes (h+) from the photocatalysts and higher adsorption in MB photodegradation. In contrast, the inner surface of MHNTs through positive charges of AL-OH is beneficial for the electron (e-) separation and MO treatment. MHNTs with mesopores structure (Mean pore diameter: 10.6 nm) and high specific surface area (76.25 m2/g) contribute to higher adsorption and rapid transfer of photoexcited charges to the surface of ternary photocatalyst (g-C3N4/MHNTs/γ-Fe2O3 – 59.06 m2/g). After adding γ-Fe2O3 to g-C3N4/MHNTs, band gap of g-C3N4/MHNTs/γ-Fe2O3 reduces to 2.70 eV from 2.85 eV of g-C3N4/MHNTs, indicating influential role of γ-Fe2O3 nanoparticles in shifting photocatalytic activity of the ternary photocatalyst towards larger wavelengths (≥ 900 nm), and real world’s application (under illumination of sunlight). Among fabricated photocatalysts, g-C3N4/MHNTs/γ-Fe2O3 excels at degrading both MB and MO with the efficiency of %99.99 in 60 min and %89.1 in 120 min, respectively. To recognize the photocatalytic mechanism of the ternary photocatalyst, a trapping experiment was utilized for detecting oxidizing radicals in the photocatalytic process and then a photocatalytic mechanism was proposed.

Atomic Nickel on Graphitic Carbon Nitride as a Visible Light-Driven Hydrogen Production Photocatalyst Studied by X-ray Spectromicroscopy

The photocatalytic production of solar hydrogen through water splitting by graphitic carbon nitride (g-C3N4) has gained substantial interest due to its advantageous characteristics, such as eco-friendliness, wealth on the earth, favorable bandgap, and easy preparation. Nevertheless, the performance for photocatalytic overall water splitting has been significantly restricted owing to the rapid recombination of charge carriers and slow catalytic kinetics. This investigation demonstrates the utilization of a single-atom Ni-terminating agent to coordinate with the heptazine moieties of g-C3N4, resulting in the formation of a new electronic orbital. g-C3N4 with single-atom Ni-termination can achieve highly efficient photocatalytic overall water splitting into H2 and H2O2 upon visible light irradiation, without requiring the use of any additional cocatalysts. The underlying cause of the enhanced photocatalytic performance of single-atom Ni-incorporated g-C3N4 in hydrogen evolution reaction is identified using synchrotron X-ray spectroscopy and microscopy. The X-ray spectro-microscopic results discover that the new hybrid orbital that is critical for optimizing photocatalysis is associated with carbon defects. The atomic and electronic structures and the band gap of g-C3N4 are adjusted by the new hybrid orbital. Moreover, it synergistically enhances visible light absorption, thereby promoting the separation and transfer of photogenerated charge carriers. The single-atom Ni and the adjacent C atom are recognized as the active sites for water oxidation and reduction, respectively, supporting the efficient photocatalytic splitting of water via a two-electron transfer pathway. This study demonstrated a promising material design for promoting photocatalytic activity in solar energy conversion applications.

Efficient photocatalysis of Cu doped TiO2/g-C3N4 for the photodegradation of methylene blue

The release of dyes into normal water reservoirs has become a tremendous environmental problem and the development of methods to remove such dyes is essential. A novel photocatalyst was fabricated in which Cu doped to TiO2 was coupled with g-C3N4 (Cu-TiO2/g-C3N4) in different weight percentages as 10, 30 and 50%, hydrothermally. Pure TiO2 consisted of both Anatase and Rutile phases where slight lattice distortions were observed in the Cu-doped TiO2 as evidenced by the XRD and Raman analysis. Cu was present at 1.7% by weight respective to TiO2 according to the XRF analysis. Spherical and irregularly shaped aggregated Cu-doped TiO2 nanoparticles in the range of 15–55 nm were heterogeneously distributed on the g-C3N4 matrix as observed by TEM and SEM. The band gap of TiO2 (3.0 eV) was reduced to 2.67 upon doping with Cu. The band gap of g-C3N4 was found to be 2.81 eV and that of Cu-TiO2/g-C3N4 in different weight percentages were in the range of 2.82 to 2.88 eV. Synthesized photocatalysts were tested on the ability to degrade methylene blue under UV and Visible light. Cu-TiO2/50% g-C3N4 showed the highest rate constant (4.4 × 10-3 min−1) which is 5 and 9.8 times greater than TiO2 and g-C3N4, respectively. The rate constant decreased with the introduction of EDTA and Isopropyl alcohol as they scavenge holes and hydroxyl radicals, respectively. The photocatalytic activity of all the nanomaterials increased with the increasing concentration of persulfate due to the increasing concentration of SO4●- and OH● produced. Synthesized nanomaterials effectively adsorb methylene blue under dark conditions following the pseudo-second-order kinetics suggesting that methylene blue molecules were chemisorbed to the adsorbents. The adsorption rate constant resulting in the best-performing photocatalyst was 0.122 g mg−1 min−1. Hence, it is evident that Cu-TiO2/g-C3N4 can effectively degrade methylene blue.

Fabricating transfer channel and charge trap in carbon nitride ultrathin nanosheet for enhanced photocatalytic hydrogen evolution

Fabricating environmental and stable graphitic carbon nitride (g-C3N4) photocatalyst with highly efficient visible light response and charge separation is still a challenging work. Herein, g-C3N4 ultrathin nanosheets are synthesized via oxidation etching method. The as-synthesized samples show improved visible-light response and photogenerated charge separation, which is revealed to be brought from the synergy of hierarchical porous structure and nitrogen vacancies. On one hand, macropores can provide light transport channels for enhanced visible light absorption, meanwhile the photogenerated charge favors to be migrated on two-dimensional ultrathin planes and trapped in mesoporous structure to avoid the recombination. Also, macropore and mesopore promote the transport and adsorption of substrates. On the other hand, DFT calculations verify that nitrogen vacancies are conductive to the rearrangement of charge density distribution and the formation of defect levels in the band gap of g-C3N4, leading to the improvement of carrier mobility and separation. Thus, nitrogen vacancies promote more active sites generation. Consequently, the g-C3N4 ultrathin nanosheet presents a promising photocatalytic hydrogen evolution rate of 1.77 mmol .g−1 .h−1 in a long time run under visible light, which is far higher than that of comparison samples (0.18 and 0.29 mmol .g−1.h−1 respectively).

Unraveling the synergy between oxygen doping and embedding Fe nanoparticles in gC3N4 towards enhanced photocatalytic rates

With graphitic carbon nitride (gC3N4) showing considerable potential for photocatalytic applications, the four significant limitations: surface area, light-harvesting capability, photogenerated charge separation, and charge transfer at the interface, need to be comprehensively addressed. The present work aims to exfoliate the gC3N4 stacking layers and fragment the layers horizontally to form ultra-thin nanosheets (NS) by a facile mixed-acid treatment. The surface area of gC3N4 increased by one order of magnitude (120 m2/g), due to the formation of nanosheets with planar size below ∼50 nm. Moreover, incorporating non-metal (oxygen) anion dopants and metal (iron) nanoparticles enhances the overall reactivity of gC3N4 NS under light irradiation. Co-integration of these strategies led to ∼17 times improvement in the photocatalytic pollutants degradation rate compared to pristine gC3N4. First-principles calculations and experimental evidence suggest the formation of an intermediate band within the bandgap of gC3N4, caused by the hybridization of N-Fe-O, which assists in harvesting a larger number of photons. Nanosheet morphology provides a shorter distance to photogenerated charges towards the surface, while the incorporation of Fe and O together offers the lowest charge transfer resistance at the interface to efficiently degrade the adsorbed pollutant molecules on the surface. With all these promoting features along with cost-effective and stable elements, Fe-O-gC3N4 NS provides an ideal solution for tuning the intrinsic morphological and electronic structure of gC3N4 for its effective application in various photocatalytic reactions.

Template-Free Synthesis of g-C3N4 Nanoball/BiOCl Nanotube Heterojunction with Enhanced Photocatalytic Activity.

There are many reports on g-C3N4 nanosheet and BiOCl nanosheet, but few studies on other morphologies of g-C3N4 and BiOCl. Herein, a g-C3N4 nanoball/BiOCl nanotube heterojunction prepared by a simple one-step acetonitrile solvothermal method is reported. The XRD results prove that the g-C3N4/BiOCl composites can be prepared in one step. SEM results revealed that the g-C3N4 was spherical and the BiOCl was tubular. The HRTEM results indicate that g-C3N4 has an amorphous structure and that the (100) crystal plane of BiOCl borders the g-C3N4. Spherical g-C3N4 has a narrow band gap (approximately 1.94 eV), and the band gap of g-C3N4/BiOCl after modification was also narrow. When the BiOCl accounted for 30% of the g-C3N4/BiOCl by mass, the quasi-primary reaction rate constant of RhB degradation was 45 times that of g-C3N4. This successful preparation method for optimizing g-C3N4 involving simple one-step template-free synthesis may be adopted for the preparation of diverse-shapes and high-performance nanomaterials in the future.

High-energy ball-milling constructing P-doped g-C3N4/MoP heterojunction with Mo[sbnd]N bond bridged interface and Schottky barrier for enhanced photocatalytic H2 evolution

The critical prerequisite for realizing the industrial application of photocatalytic technology lies on developing efficient photocatalyst through reasonable and large-scale modification strategy. Herein, the rapid and solvent-free high-energy ball-milling procedure was adopted to modify graphitic carbon nitride (g-C3N4) on a large-scale by phosphorus (P) atom doping and molybdenum phosphide (MoP) decorating. It is confirmed that P doping can introduce a mid-gap state in the band gap of g-C3N4, broadening the light responsive region and enhancing the electrical conductivity of g-C3N4. The MoN bond at the interface of P-doped g-C3N4 and MoP acting as electrons “delivery channels” facilitates the charge transfer from P-doped g-C3N4 to MoP, while the Schottky barrier promotes the separation of photocarriers. As a result, the optimized P-doped g-C3N4/MoP photocatalyst performs an improved H2 evolution rate of 4917.83 μmol·g−1·h−1 and a favorable H2 production stability. This work offers a replicable prototype on adopting high-energy ball-milling to modify photocatalyst.

Ionic liquid-assisted synthesis of porous boron-doped graphitic carbon nitride for photocatalytic hydrogen production

This work presents a simple way to prepare boron-doped graphitic carbon nitride (B/g-C3N4), exhibiting an enhanced photocatalytic performance to split water for hydrogen production. B/g-C3N4 was synthesized via the pyrolysis of urea and 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4), which was adopted as the boron source. The aggregate of B/g-C3N4 nanosheets shows a porous structure since some bubbles are generated under the heat decomposition of ionic liquids. The porous structure is conducive to the exposure of more active sites. Moreover, B-doping will form some localized electronic energy levels in the band gap of g-C3N4, thereby extending its visible light response. As impacted by the porous structure of B/g-C3N4 aggregate and the narrow the band gap, the photocatalytic hydrogen generation rate (901 μmol h−1 g−1) is increased, almost 3 times faster than g-C3N4 (309 μmol h−1 g−1). This work proposed a simple method to prepare the aggregate of B/g-C3N4 nanosheets exhibiting pores under ionic liquid assistance. It can be a novel method to design porous polymer photocatalysts.

Sunlight-assisted degradation of textile pollutants and phytotoxicity evaluation using mesoporous ZnO/g-C3N4 catalyst.

Accessibility of adequate safe and fresh water for human consumption is one of the most significant issues throughout the world and extensive research is being undertaken to resolve it. Nanotechnology is now an outstanding medium for water treatment and remediation from microorganisms and organic dyes, as compared to conventional treatment methods. For this task graphitic carbon nitride (g-C3N4) is a potential nanomaterial for environmental remediation, but its photogenerated charge carrier recombination rate restricts its use in practical applications. Hence, in the current study, we used a simple one-step calcination method to synthesize various ratios of ZnO/g-C3N4 binary nanocomposites. The band gap of g-C3N4 is 2.70 eV, but it is shifted to 2.60 eV by the 0.75 : 1 ZnO/g-C3N4 binary nanocomposite. Moreover, phase structure, morphology, thermal stability, oxidation state, elemental analysis, and surface area were evaluated using XRD, SEM, TEM, TGA, XPS, and BET analysis. The optimal ZnO loading content was determined and the mechanism of enhanced photocatalytic activity was studied in detail. The photocatalytic efficiency of the best catalyst was employed for the degradation of textile effluent followed by phytotoxicity evaluation using methylene blue (MB), and rhodamine B (RhB) as a model substrate was tested. Furthermore, the textile effluent treatment analysis discovered that the 75 mg concentration of 0.75 : 1 ZnO/g-C3N4 catalyst degraded up to 80% within 120 min and significantly reduced the concentrations of different physico-chemical parameters of textile effluents. These treated effluents have no phytotoxic effects on fenugreek plants, according to a pot study. It was found that the mesoporous 0.75 : 1 ZnO/g-C3N4 catalyst can be used as an effective and low-cost technique for the degradation of azo dyes in textile wastewaters.

Efficient promotion and transfer of excited charge carriers in phosphorus doped and Ni complex modified g-C3N4

Solar hydrogen energy generation via photocatalysis can play a vital role in reducing global warming, environmental pollution, and the ever-increasing energy demand. Herein, phosphorus and Ni complex modified g-C3N4 were prepared by a hydrothermal method. The bonding of electron-rich phosphorous heteroatom to the g-C3N4 changed the morphology of the g-C3N4 from nanosheets into nano-rods and significantly altered the electronic structure, as evident by the shift in the conduction band edge and bandgap of g-C3N4. FTIR and XPS measurements revealedthat the triazine ring is oxygen functionalized and the P atom bonded to g-C3N4 via PN bond. Furthermore, EPR, UPS, and UV-DRS measurements revealed that the P and Ni complex reduced the localized π-conjugated structure defects of g-C3N4 and extended the light absorption into the near IR region. The Ni complex in the photocatalysts provided the additional charge transfer band of IMCT and OMCT. EDS color mapping revealed that the Ni complex is distributed uniformly on the P-g-C3N4 surface. These surface embedded Ni complex acts as an electron trap state, thereby suppressing the charge pair recombination rate which was confirmed by the PL and TRPL measurements. The synergetic effect of Ni complex and P resulted in 86 % tetracycline degradation in 20 min. and 3272 μmol/g of H2 production in 4 h. Compared to bulk g-C3N4, 818 times higher H2 production activity was achieved for the P and Ni complex modified g-C3N4.

Application of a calcined animal bone to synthesis of graphitic carbon nitride composite

ABSTRACT Graphitic carbon nitride (g-C3N4) is a polymeric organic semiconductor that has been extensively developed for various applications. In this study, composites of g-C3N4 and calcined animal bone (CAB) were facilely synthesized by calcining a mixture of urea and CAB at different temperatures. The results revealed that the calcination temperature influenced yield, crystallinity, and band gap of g-C3N4. In addition, ultraviolet–visible diffuse reflectance spectroscopy indicated a shift in absorption edge to the high wavelength side in the presence of CAB, implying that CAB promoted thermal condensation of urea. However, thermogravimetric measurements revealed that g-C3N4 yield decreased as the calcination temperature increased in the presence of CAB. This is because the amount of g-C3N4 was scarce when the mixture was calcined at 823 K. Furthermore, the results of differential thermal analysis indicated that g-C3N4 and its intermediates were oxidatively decomposed by CAB at 823 K.

Ionic liquid assisted preparation of phosphorus-doped g-C3N4 photocatalyst for decomposition of emerging water pollutants

Phosphorus doped g-C3N4 (P/g-C3N4) polymer has been prepared by using ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate providing the P source. P/g-C3N4 shows a high photoactivity for photodecomposition of methylene blue and tetracycline hydrochloride as an emerging water pollutant. The photocatalytic activity of optimized 3%-P/g-C3N4 sample (3% in mass ratio of P) is 3 times improved compared to g-C3N4. This improvement in activities attribute to the new generated energy levels in the bandgap of g-C3N4 that originates from the doping of phosphorus. Photoelectrochemical and photoluminescence results confirmed the high charge separation rates and low charge recombination rates after P doping in g-C3N4. The present study showed a simple method of preparation of non-metal ions doped porous g-C3N4 photocatalysts for the decomposition of antibiotics in polluted water.

Preparation of Nitrogen-Deficient Graphitic Carbon Nitride with a Large Specific Surface Area by Melt Pretreatment and Its Photocatalytic Performance

In this study, nitrogen-deficient graphitic carbon nitride (M-LS-g-C3N4) with a mesoporous structure and a large specific surface area was obtained by calcination after melt pretreatment using urea as a precursor. X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption, X-ray photoelectron spectroscopy (XPS), UV-Vis, ESR and photoluminescence (PL) were used to characterize the structure, morphology and optical performance of the samples. The TEM results showed the formation of a mesoporous structure on the 0.1[Formula: see text]M-LS-g-C3N4 surface. The porous structure led to an increase in the specific surface area from 41.5[Formula: see text]m2/g to 124.3[Formula: see text]m2/g. The UV-Vis results showed that nitrogen vacancies generated during the modification process reduced the band gap of g-C3N4 and improved the visible light absorption. The PL spectra showed that the nitrogen defects promoted the separation of photogenerated electron–hole pairs. In the visible light degradation of methyl orange (MO), the reaction rate constant of 0.1[Formula: see text]M-LS-g-C3N4 reached 0.0086[Formula: see text][Formula: see text], which was 5.05 times that of pure g-C3N4. Superoxide radicals and photogenerated holes were found to be the main active species in the reaction system. This study provides an efficient, green and convenient means of preparing graphitic carbon nitride with a large specific surface area.

Synergetic effect of g-C3N4/ZnO binary nanocomposites heterojunction on improving charge carrier separation through 2D/1D nanostructures for effective photocatalytic activity under the sunlight irradiation

The heterojunction between the two different semiconductors shown to increase the photocatalytic activity due to their ability in improving the photo-generated electron-hole pairs separation. Hence designing and synthesizing such heterojunctions employing different semiconducting materials to improve the photocatalytic efficiency using various methods have gained importance. For this purpose graphitic like carbon nitride (g-C3N4) is a hopeful photocatalytic material for environmental remediation but its photogenerated charge carriers recombination rate limits g-C3N4 for practical applications. Hence, in the present work we synthesized heterojunction of g-C3N4/ZnO binary nanocomposites in 2D/1D by sonication assisted hydrothermal method. X-ray diffraction analysis confirms the formation of g-C3N4/ZnO binary nanocomposites. Transmission electron microscope analysis shows that the binary nanocomposites consists ZnO rods coupled with sheet like structure of g-C3N4. The band gap of g-C3N4 is 2.67 eV; however, the g-C3N4/ZnO binary nanocomposites shifts the band gap to 2.9 eV. Photoluminescence spectral analysis evidently shows the recombination rate of electron-hole pairs in the g-C3N4/ZnO binary nanocomposites is effectively reduced due to the formation of the heterojunction. The photoelectrochemical analysis shows that g-C3N4/ZnO binary nanocomposites enhance the photocurrent to 1.5 μA and effectively separate the electron-hole pairs when compared with that of bare ZnO and g-C3N4. Hence, the g-C3N4/ZnO binary nanocomposites effectively enhanced RhB dye degradation to 99% for 20 min and enhanced the 4-chlorophenol degradation to 90% for 40 min. under the sunlight irradiation.

3D-Printed Grids with Polymeric Photocatalytic System as Flexible Air Filter

Significant concerns regarding nitric oxide removal are related to the difficulty in developing a catalytic system with improved removal efficiency. With the consideration to immobilize efficient photocatalyst, fulfill multilevel hierarchy and involve excellent reusability, 3D printing methodology is adopted to explore the novel photocatalytic system as a flexible and freestanding air filter. The efficient photocatalyst - g-C3N4 serves as starting material, while the Poly-(ethylene glycol) double acrylate is used as both dispersant and matrix to form an optimal ink. By forming newly bonded composite, the band gap of g-C3N4 is reduced by 0.1 eV, led to increasing of photocatalysis efficiency. This photocatalytic system exhibits excellent NO removal capability and durability, indicating that such air filter can be a promising candidate for a real application. Simulation models are also established to study light absorption in the grid geometry as well as the influence of printing parameter like grid spacing.

Cyano group modified carbon nitride with enhanced photoactivity for selective oxidation of benzylamine

Polymeric graphitic carbon nitride (g-C3N4) is a promising photocatalyst but suffers from the high recombination rate of photogenerated carriers. Many strategies for introducing active “sites”, such as heteroatom doping and defect creation, which can hinder recombination by capturing the separated electrons or holes, have been developed to solve the problem. As a polymeric organic material, it is possible to alter the electron structure and improve the charge separation by introducing organic groups with different electronegativities or conjugation properties to the side chains. Herein, we report a facile and efficient CN group modification strategy using the thermal condensation of the thiocyanuric acid (TA) precursor. The sulfur content in the precursor forms CNS and then transforms to CN. The CN group introduced catalyst exhibits enhanced light absorption and a low carrier recombination rate based on optical and photoelectrical measurements. This is due to the formation of a CN group related midgap state between the bandgap of g-C3N4, according to a density functional theory (DFT) calculation. The CN groups can also loosen the stacking texture of g-C3N4 and result in a thinner layer structure during the post-thermal treatment, which can shorten the distance of photogenerated carrier transfer from the bulk to the surface. The CN group introduced photocatalyst is efficient for the selective oxidation of benzylamine to imine, even under green light irradiation. This result demonstrates that the introduction of an electron rich conjugation group such as CN into the edge chain of polymeric carbon nitride is efficient for better photoactivity.

Multifunctional performance of gC3N4-BiFeO3-Cu2O hybrid nanocomposites for magnetic separable photocatalytic and antibacterial activity

Highly active gC3N4-BiFeO3-Cu2O nanocomposites were successfully prepared via a facile, cost effective and eco-friendly method of hydrothermally wet precipitation combined with ultrasonic dispersion process. The prepared samples were characterized by XRD, FTIR, HRSEM, EDS, TEM, UV–Vis DRS, PL, VSM, BET and electrochemical properties. By means of these analysis for examine the crystal phase, nanostructure, band gap and light-harvesting properties were carried out. UV-DRS spectra indicate that the bandgap of g-C3N4 (2.7 eV) reduced to 2.59 and 2.21 eV by mixed with corresponds to BiFeO3 and BiFeO3/Cu2O nanomaterials. The ideal photocatalytic activity of the gC3N4-BiFeO3-Cu2O nanocomposites, where RhB dye under visible light irradiation which was up to 4.36 and 2.52 times as the higher photodegradation ability to compare pristine g-C3N4 and gC3N4-BiFeO3 catalyst. The magnetization was confirmed by VSM studies, and hence, after the photocatalytic reaction, the magnetically separable catalyst can be quickly separated from the water by an external magnetic field. The superior photocatalytic performance is due to the synergistic effect on the interface of BiFeO3/Cu2O in the gC3N4-BiFeO3-Cu2O nanocomposites has reduced the bandgap which enables high separation efficiency of the charge carrier, suppressed recombination rate and their high surface area. Moreover, the chief gC3N4-BiFeO3-Cu2O catalyst can exhibited the lesser charge transfer resistance (impedance), enhances of photocurrent responses, whereas exposed to the development of photocatalytic appearance and more charge carrier ability. Also, the antibacterial activity of the gC3N4-BiFeO3-Cu2O nanocomposite has showing a well deactivation in both G+ (S. aureus) and G− (E. coli) bacteria’s whereas compare to other prepared samples.

Hybrid density functional study on the mechanism for the enhanced photocatalytic properties of the ultrathin hybrid layered nanocomposite g-C3N4/BiOCl

To investigate the origin of the high photocatalytic performance of experimentally synthesized g-C3N4/ BiOCl, we studied its geometry structure, electronic structure, and photocatalytic properties by means of hybrid density-functional theory (DFT). The calculated band alignment of g-C3N4 and few-layer BiOCl sheets clearly shows that g-C3N4/ BiOCl is a standard type-II nanocomposite. The density of states, Bader charge, partial charge density, charge density difference, and the effective masses show that electron-hole pair can be effectively separated in the g-C3N4/BiOCl interface. The calculated absorption coefficients indicate an obvious redshift of the absorption edge. The band gap of g-C3N4/BiOCl can be modulated by external electric field, and a semiconductor-semimetal transition is observed. The type-II vdW heterostructure is still maintained during the changes of external electric field. Especially, when the electric field reaches to +0.7 V/Å, the impurity states have been eliminated with the band gap of 2.3 eV. An analysis of optical properties shows that the absorption coefficient in the visible-light region is enhanced considerably as the electric-field strength increases. Our calculation results suggest that the ultrathin hybrid layered g-C3N4/BiOCl nanocomposite may have significant advantages for visible-light photocatalysis.