Thermal Copolymerization Research Articles

Application of Ion - Imprinted Polymer Synthesized as New Sorbent for Preconcentration and Separation of Thallium (I) and Its Determination by Electrothermal Atomic Absorption Spectroscopy

At this study, thallium (I) ion-imprinted polymer, as a novel sorbent for Tl (I) and comparison with Tl(III) ion-imprinted polymer has been synthesized. This sorbent for preconcentration and solid-phase extraction of Tl(I) ions from aqueous solutions, used. Through preparing the binary complex of Tl(I) ions with 5, 7-dichloroquinoline-8-ol (DCQ) the particles of thallium (I) Ion-Imprinted Polymer (IIP) have synthesized. In the presence of 2-methoxyethanole (porogen) and 2, 2o-azobisisobutyronitrile (initiator, AIBN) Thermal copolymerization of methyl methacrylate (functional monomer, MMA) and ethyleneglycoldimethacrylate(cross-linkingmonomer, EGDMA) have done. The imprinted ion has removed from the polymer by removing the above particles with 1 mol/L HNO3 to obtain the leached IIP particles. Similarly, Control Polymer (CP) particles, have prepared without thallium (I) ions. The characterization of unleached and leached IIP particles was done by, Fourier-Transform InfraRed (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET), surface area analysis, and X-Ray Diffraction (XRD). As a function of pH, the preconcentration of thallium (I) has studied during rebinding with the leached IIP particles, for determination of thallium in aqueous solution, the weight of the polymer material, the elution and preconcentration times, the concentration of eluent(nitric acid), the volume of the aqueous phase and the volume of an eluent. ElectroThermal Atomic Absorption Spectrometry (ETAAS) has utilized. The method's Detection limit was 0.1 mg/ mL, while the relative standard deviation for five times repeat was 3.5%.

Oxygen self-enriched single-component "black carbon nitride" for near-infrared phototheranostics.

Single component agent-based near-infrared phototheranostics has captivated researchers in cancer treatment over recent decades. However, the current single-component agents rarely alleviate the hypoxic microenvironment in tumor cells, which severely limits the development of photodynamic therapy. Here, we report a new phototheranostic agent, single-component black graphite carbon nitride nanoparticles (named CN-B NPs), synthesized through thermal copolymerization. Compared with unmodified graphitic carbon nitride (g-C3N4), the absorption of CN-B NPs in the near-infrared region was enhanced. Through in vitro and in vivo studies, we demonstrated that CN-B NPs can be used as a near-infrared phototheranostic agent in both normoxia and hypoxia, simultaneously allowing infrared thermal/photoacoustic imaging and photodynamic/photothermal co-therapy, thereby resulting in remarkable inhibition of tumor growth. This approach could provide a new method to achieve multimodal phototheranostics using a single-component material.

High-efficiency photocatalytic water splitting by a N-doped porous g-C3N4 nanosheet polymer photocatalyst derived from urea and N,N-dimethylformamide

N-Doped porous g-C3N4 nanosheets for high-efficiency photocatalytic water splitting were prepared by mixing the precursor of N,N-dimethylformamide and urea through a simple one-step thermal copolymerization method.

Degradation of antibiotics in water by salicylic acid modified carbon nitride photocatalytic material

The misuse and abuse of antibiotics lead to water environment problems in many countries including China all over the world. There are many deficiencies in traditional ways of antibiotics degradation such as high cost, low removal efficiency, low degradation rate etc. In this paper, the modified carbon nitride was synthesized from urea and salicylic acid with thermal copolymerization. The XRD, FT-IR and TEM were used to characterize the structure and optical properties of the material. From the radical sacrificial test, the super oxide radicals were examined as the major radicals in the degradation process. The material provides a good application prospect for the photocatalyst treatment of antibiotic wastewater.

Bottom-up fabrication of graphitic carbon nitride nanosheets modified with porphyrin via covalent bonding for photocatalytic H2 evolution

In order to broaden the absorption range of graphitic carbon nitride, one of the common methods is to couple the well-known photosensitizer porphyrin with graphitic carbon nitride through van der Waals weak interactions. To date, to combine porphyrin with graphitic carbon nitride through covalent interactions has not been settled. In this work, through rational molecular design, we successfully incorporated porphyrin into the matrixes of graphitic carbon nitride by covalent bonding via one-pot thermal copolymerization. The resultant material not only can widen the absorption range but also possess the enlarged specific surface area and construction intramolecular heterojunctions which can contribute to improve electron-holes separation efficiency. The resultant photocatalyst exhibited enhanced H2 production rate (7.6 mmol·g−1·h−1) and with the apparent quantum efficiency (AQE) of 13.3% at 450 nm. At the same time, this method opens a way to fabricate graphitic carbon nitride nanosheets via bottom-up strategy.

Modified carbon nitride as an efficient adsorbent for ammonia nitrogen with low concentration

AbstractThe adverse effects of excessive ammonia on aquatic ecosystem have provoked the development of efficient methods for its removal. Here, we present a thermal copolymerization of melamine and sodium hydrogen carbonate and successfully introduce oxygen groups into the structure of g‐C3N4, which is applied to low‐concentration ammonia removal. Oxygen groups are introduced into g‐C3N4 and increase its surface electron negativity. When the initial concentration of ammonia nitrogen is 18.74 mg L−1, the lowest concentration of it after adsorption is 1.43 mg L−1, and the ammonia nitrogen removal efficiency is 92.3%. The main reason for our material high performance on adsorption ammonium may be ascribed to deprotonated carboxylic acid, which has the ability to adsorb positively charged ammonium ions.

Preparation and Characterization of Functional Ophthalmic Polymer Containing Nanoparticles Using Heat Treatment Method After Polymerization

The functional hydrogel lens containing HEMA (2-hydroxyethylmethacrylate) was manufactured by thermal polymerization and heat treatment method after room temperature polymerization, respectively. In this study, HEMA, EGDMA (ethylene glycol dimethacrylate) and the initiator AIBN (azobisisobutyronitrile) were used for thermal copolymerization and the mixture was heated at 100 °C for 1 hour. And also, HEMA, EGDMA, the initiator and distilled water were used for heat treatment method after room temperature copolymerization and the mixture was heated 80 °C for 1 hour and then treated at 100 °C for 1 hour to produce the hydrogel ophthalmic lens by cast mold method. To make the functional hydrogel lens, ZnPC and platinum octaethyl porphyrin were used as additives. The measurements of the physical characteristics of the copolymerized material showed that refractive index and contact angle of sample was in the range of 1.4010∼1.4585 and 21.46∼87.28°, respectively. In case of heat treatment method after room temperature copolymerization, the refractive index and wettability of sample was higher than that of thermal polymerization. And also, the addition of ZnPC nanoparticles allowed the hydrogel lens to block UV-light. The absorbance value of solution in which the lens prepared by the heat treatment method was immersed were much lower than that of thermal polymerization, so it can be judged that the stabilization of produced polymer maintained well. Based on the results of this study, the produced optical lens can be considered to satisfy the basic requirements of optical lens and can be used effectively as an additive for functional ophthalmic lens material with high refractive index and wettability.

In-depth study of the key factors affecting the degradation of antibiotics by carbon nitride and its modified photocatalytic materials

In this paper, the method of thermal copolymerization is used to synthesize graphite phase carbonitride with urea as precursor, and thermal copolymerization of urea and salicylic acid to form modified carbon nitride. Through a series of experiments to explore the influencing factors of photocatalytic degradation of antibiotics by carbon nitride and its modified photocatalytic materials under different conditions, the suitable experimental and applied catalytic conditions were proposed to provide theoretical support for scientific research and practical application.

Preparation of Phosphorus and Oxygen Co-Doped With Graphite Carbon Nitride and Its Application in Photodegradation of Methylene Blue

In this study, phosphorus and oxygen co-doped graphite carbon nitride has been successfully prepared by simple thermal copolymerization. The as-prepared materials were characterized by SEM, XRD, XPS and UV-vis-DRS. The results showed that phosphorus and oxygen were successfully doped on the structure of graphite carbon nitride. Photocatalytic degradation of MB in solution by the catalyst has been studied, POCN-1 has the best photocatalytic activity among of the as prepared materials, photocatalytic degradation rate of MB is 10.6 times higher than that of g-C3N4. The main reason for its enhanced photocatalytic performance is that the co-doped of phosphorus and oxygen elements would change the electronic structure of g-C3N4, reduce the forbidden band width of the photocatalyst. At the same time, can extend the absorption boundary of visible light.

Bis(4-cyanophenyl) phenyl phosphate as viscosity reducing comonomer for phthalonitrile resins

Bis(4-cyanophenyl) phenyl phosphate (CPP) is introduced for the first time as a viscosity reducing comonomer for phthalonitrile resins. In comparison to the common phthalonitrile resins, the blends of CPP with 4,4′-[benzene-1,3-diylbis(oxy)]diphthalonitrile demonstrated advanced processing properties suitable for cost-effective injection processing (η as low as to 180 mPa∙s at 100 °C). Thermal copolymerization was performed indicating complete inclusion of bis-benzonitrile CPP into the phthalonitrile network resulting in formation of thermosets with great thermal performance. Hydrolysis of CPP at pH 4, 7, and 10 was studied to confirm its suitability as a reactive diluent for phthalonitrile. Conversion vs. time plots were obtained via HPLC analysis, and pseudo-first order rate constants were determined in the range of 25–80 °C. The activation parameters were calculated from the Arrhenius equation.

Enhanced photodegradation of toxic organic pollutants using dual-oxygen-doped porous g-C3N4: Mechanism exploration from both experimental and DFT studies

Novel visible-light-driven dual-oxygen-doped porous g-C3N4 (OPCN) photocatalysts were synthesized by a facile thermal copolymerization of urea and ammonium oxalate. The introduced O atoms were preferable to synchronously substitute for two sp2-hybridized N atoms in the para-positions (i.e., N1′ and N4′ sites) of the melem unit by forming dual-O-doped g-C3N4. Together with porous structures, OPCN exhibited enlarged specific surface area, narrowed band gap and expanded visible light response. The photocatalytic activity of the optimal OPCN was approximately 9 times higher than that of pure g-C3N4 for bisphenol A (BPA) removal under visible light irradiation, and efficient removal rates for various chlorophenols, phenols and dyes were also observed. Combined with experiments and DFT calculations, this dual-O-doped structure resulted in effective charge transfer and separation of OPCN under visible light irradiation by forming e− and h+-related conjugated delocalized systems on the surface, which contributed to its interfacial contact with organic pollutants and adsorbed O2. As a result, the degradation of BPA was readily induced by photoinduced h+ and then thoroughly mineralized by O2−. On the other hand, more O2− radicals were generated, which could also oxidize BPA directly due to their strong oxidation power. The superior stability and reusability of OPCN catalysts were also revealed during photoreaction. This work provides a novel viewpoint to fabricate high-performance nonmetal photocatalysts for wastewater treatment.

Facile fabrication of phosphorus-doped g-C3N4 exhibiting enhanced visible light photocatalytic degradation performance toward textile dye

Phosphorus-doped graphitic carbon nitride (P-g-C3N4) was facilely fabricated by in situ thermal copolymerization of urea and triphenylphosphine source materials. The P-g-C3N4 exhibited an enhanced photocatalytic performance than pristine g-C3N4 counterpart for the degradation of rhodamine B and acid blue D-2BR textile dye under visible light irradiation. X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms, X-ray photoelectron spectra (XPS), and diffuse reflection spectroscopy (DRS) techniques were used to characterized the structure and property of P-g-C3N4 photocatalyst. The phosphorus doping enhanced visible light harvesting and surface area, but also substantially changed the electronic property of g-C3N4 material that could suppress the recombination of photogenerated charge carriers, and thus improved photocatalytic performance.

Enhanced electron separation on in-plane benzene-ring doped g-C3N4 nanosheets for visible light photocatalytic hydrogen evolution

Solar-to-chemical energy conversion by photocatalytic hydrogen evolution (PHE) is critical for reduction of the pollution and storage of clean energy. To improve the solar conversion efficiency, it is highly imperative to accelerate the photocarrier separation and transportation through materials design. Herein, we describe a highly effective PHE catalyst based on in-plane benzene-ring doped g-C3N4 nanosheets heterostructure through the thermal co-polymerization of urea and 4, 4'-sulfonyldiphenol (BPS) followed by a controlled heat-etching step. The solid-state 13C NMR confirms the existence of benzene-ring structure in g-C3N4 nanosheets. Experimental results and theoretical calculations show that the energy and electronic structure of the catalyst are optimally regulated, inducing increased light absorption and effectively accelerated separation of the photo-driven charge carriers. It exhibits enhanced photocatalytic hydrogen evolution efficiency with a PHE rate of 12.3 mmol h−1 g−1 (almost 12 times higher than that of pure g-C3N4 nanosheets) and the quantum efficiency of 17.7% at 420 nm.

Synergistic Effects of Boron and Sulfur Co-doping into Graphitic Carbon Nitride Framework for Enhanced Photocatalytic Activity in Visible Light Driven Hydrogen Generation

During in situ thermal co-polymerization of melamine using boric acid and thiourea as the dopant, graphitic carbon nitride (g-C3N4) co-doped with boron and sulfur has been successfully synthesized....

Carboxylic acid-functionalized cadmium sulfide/graphitic carbon nitride composite photocatalyst with well-combined interface for sulfamethazine degradation

The carboxylic acid-functionalized cadmium sulfide/graphitic carbon nitride (CdS-TGA/g-C3N4) isotype heterojunction was prepared by thermal copolymerization of CdS-TGA/urea, which was formed via the interaction between COO− groups on CdS-TGA NPs and -NH2/-NH groups on urea. It was proposed that the well-developed combined interface between CdS-TGA and g-C3N4 was formed in CdS-TGA/g-C3N4 and consequently improved the stability and separation of the photo-generated charge carriers. As a result, the CdS-TGA/g-C3N4 exhibited significantly enhanced activity for the visible-light photocatalytic degradation of sulfamethazine (SM2) as compared to CdS/g-C3N4. The O2− was found to be the dominant active species for SM2 decomposition and the possible photocatalytic degradation pathway of SM2 over CdS-TGA/g-C3N4 was through sulfonate elimination. This work demonstrated rational design and preparation of CdS-based heterojunction composites via construction of well-combined interface, which could open up a new way for the development of efficient and stable visible-light photocatalysts.

Boron doped g-C3N4 as an effective metal-free solid base catalyst in Knoevenagel condensation

In this paper, boron, sulfur and phosphor doped g-C3N4 materials (defined as CNBF, CNSF and CNPF, respectively) were successfully prepared by thermal copolymerization of dicyandiamide and imidazole ionic liquids. The CNBF catalysts exhibited significantly enhanced activity in various Knoevenagel condensation of aldehyde with malononitrile, which were typical base-catalyzed reactions, comparing with CNSF and CNPF catalysts. The detailed characterizations of Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High angle annular dark field-scanning transmission electron microscopy (HADDF-STEM) and 11B solid-state MAS NMR showed that boron was evenly doped in tri-s-triazine rings of g-C3N4 by substituting the carbon sites. In addition, CO2 Temperature programed desorption (CO2-TPD) characterizations indicated that the basic site concentration of CNBF catalysts was proportional to the doped boron content. Excluding the effect of specific surface area, the catalytic activity of CNBF catalysts followed the order CNBF-0.1 < CNBF-0.3 < CNBF-0.5 < CNBF-0.7, which was the same as that of boron content and basic site concentration. The catalytic performance revealed that boron-doping was an effective strategy to enhance the basicity of g-C3N4. This study will put forward the further application of boron-doped or boron-dominant two dimensional materials towards metal-free heterogeneous base catalysis.

Cross-Linked Graphitic Carbon Nitride with Photonic Crystal Structure for Efficient Visible-Light-Driven Photocatalysis.

Highly cross-linked graphitic carbon nitride has been prepared by a thermal copolymerization of dicyanodiamide with tetramethylammonium salts. The cross-linking can be evidenced by (i) increased C/N ratio without new carbon species, (ii) decreased specific surface area, and (iii) Tyndall effect after dissolution in concentrated sulfuric acid. The cross-linked graphitic carbon nitride with photonic crystal structure has highly efficient photocatalytic activity for water splitting under visible light due to the synergistic enhancement by the greatly suppressed photoluminescence, red-shifted absorption edges, strong inner reflections, and effective PCs stop band overlaps. It exhibits an enhanced photodegradation kinetic of methyl orange and a high visible-light-driven hydrogen-evolution rate of 166.9 μmol h-1 (25 times higher than that of the pristine graphitic carbon nitride counterpart). This work presents a facile method for designing and developing high-performance graphitic carbon nitride photocatalysts, providing a broad range of application prospects in the fields of electronics and energy conversion.

Noble metal-free NiS/P-S codoped g-C3N4 photocatalysts with strong visible light absorbance and enhanced H2 evolution activity

Noble metal-free NiS/P-S codoped g-C3N4 (PSCN) nanocomposites were fabricated by combination of thermal copolymerization using ammonium O, O- diethyl dithiophosphate as P-S precursor and ion-exchange precipitation. The optimal H2-generation rate of NiS/PSCN is 30.5μmolh−1, which is 1.9 times higher than that of NiS/pristine g-C3N4. The codoping of P and S into g-C3N4 not only enhances the light harvesting, but also promotes the charge separation. Noble metal-free NiS loaded onto PSCN serves as electron trapping centers and active sites for hydrogen evolution which further enhances the photocatalytic H2 evolution activity of PSCN.

Modified graphitic carbon nitride prepared via a copolymerization route for superior photocatalytic activity

Molecular doping strategy has been applied for regulating the electronic band structure of graphitic carbon nitride (g-C3N4). By incorporating the electron-withdrawing impurity group of N,N′,N″-s-triazine-2,4,6-triyl-tri-p-aminobenzoic acid (H3TATAB) into the network of g-C3N4, a series of H3TATAB-doped g-C3N4 (TABCN) photocatalysts were synthesized via thermal copolymerization at 550 °C for 4 h. H3TATAB doping shifts the VB of TABCN from 1.78 eV (pristine g-C3N4) to a low position (2.07 eV for TCBCN0.8), which enhances the oxidation ability of the VB hole for producing hydroxyl radicals in aqueous solution, and, therefore, the UV photocatalytic activity of TABCN0.8 is estimated to be about twice as high as that of g-C3N4 for the degradation of AO7. Further, doping the H3TATAB impurity group into the g-C3N4 network induces plenty of defect levels below the CB of g-C3N4, which gives a significant absorbance enhancement in the visible region. As a result, the visible light photocatalytic activity of TABCN0.8 is 7.5 times higher than that of g-C3N4 for the degradation of AO7. This work may provide guidance on designing an efficient g-C3N4 polymer photocatalyst with desirable electronic structure.

Phosphorus- and Sulfur-Codoped g-C3N4: Facile Preparation, Mechanism Insight, and Application as Efficient Photocatalyst for Tetracycline and Methyl Orange Degradation under Visible Light Irradiation

Phosphorus- and sulfur-codoped graphitic carbon nitride has been successfully synthesized by in situ thermal copolymerization of hexachlorocyclotriphosphazene and thiourea. The phosphorus doping, together with the sulfur doping, would enhance light trapping, surface area, and charge separation, making it serve as a more efficient photocatalyst than its pure g-C3N4 and single-doped g-C3N4 counterpart for the removal of tetracycline (TC) and methyl orange (MO). The optimum photocatalytic activities of a P-, S-codoped g-C3N4 sample for the degradation of TC and MO were about 5.9 times and 7.1 times higher than that of individual g-C3N4, respectively. Furthermore, the optimum TOC removal reached 70.33% and 55.37% for TC and MO within 120 min, respectively. The introduction of a P atom and S atom could significantly change the electronic property of g-C3N4 and suppress the recombination of photogenerated charges. Moreover, the defects in the framework of samples caused by the doping of P and S could serve as c...