Co-doped Graphitic Carbon Nitride Research Articles

Shining bright: B@S-codoped graphitic carbon nitride nanorods illuminate enhanced catalytic C-N bond formation under visible-light

Graphitic carbon nitride as a photocatalyst seeking attention nowadays, due to its thermal stability, band structure, and chemical properties. Herein, we reported a boron sulfur co-doped graphitic carbon nitride (B@S-g-C3N4) photocatalyst synthesized by a one-pot thermal polycondensation mechanism. However, it was observed that due to co-doping in native carbon nitride structure the photocatalytic behavior and the band structure enhanced which was capable of fascinating the demand of organic transformations i.e. photocatalytic and charge transfer capability. The synthesized B@S-g-C3N4 photocatalyst was characterized by UV–vis DRS, FT-IR, XRD, SEM, EDX, HR-TEM, XPS and electrochemical properties. In addition, the synthesized B@S-g-C3N4 photocatalyst is a metal-free carbon nitride photocatalyst proven to be highly effective in performing organic transformations (conversion yield 98 %) like C-N bond formation under visible light source.

One pot synthesis of multi-functional B doped g-C3N4-praseodymium oxide nanocomposites for colorimetric detection of Hg2+ ion and solar photocatalytic removal of toxic water pollutants

A novel praseodymium oxide-boron co-doped graphitic carbon nitride composite was synthesized via one-step solid-state thermal condensation of urea, orthoboric acid and praseodymium nitrate precursors. The prepared composites were characterized by various methods. All the prepared composites demonstrated multi-functional activities towards peroxidase-mimetic based colorimetric detection of Hg2+ ions and superior photocatalytic efficiency towards photodegradation of textile colorants, photoreduction of hexavalent chromium and nitro aromatics like para-nitro phenol (PNP) and para-nitro aniline (PNA). The superior photocatalytic activity can be attributed to the formation of type II heterojunction which facilitates charge separation and increases the lifetime of photogenerated charge pairs. As evident from the scavenger studies, these charge pairs are involved in the formation of superoxide and hydroxyl radicals. The superior activity of the optimum composite can be attributed to the porous flaky morphology, decreased optical band gap, heterojunction mediated charge separation, and praseodymium oxide's conductive nature. A linear range of about 0.25–800 nM of Hg2+ ions can be detected with a limit of detection (LOD) of 42.4 nM using the colorimetric strategy. The as-synthesized composite is thus a unique, efficient, economically viable, and excellent candidate for detecting and degrading various hazardous water pollutants.

Adsorption behavior of gas molecules on B and Mo co-doped graphitic carbon nitride: A first-principles study

Adsorption mechanism studies of toxic gases (CH2O, SO2, NH3, CO, NO, and NO2) on pristine, one B-atom and Mo-atom (1B/Mo) and two B-atom and Mo-atom (2B/Mo) co-doped g-C3N4 were investigated based on the density functional theory. It is shown that gases adsorbed on the 1B(2B)/Mo-g-C3N4 surface exhibit a variety of bandgap types such as magnetic half-metal, magnetic metal, and magnetic semiconductor, and the magnetic properties change considerably. The partial density of states suggests strong hybridization between gas molecules with Mo-4d (B1-2p and B2-2p) and C-2p (N-2p). NH3 gas adsorbed on the 1B(2B)/Mo-g-C3N4 surface acts as a donor and the remaining five gas molecules act as acceptors. CH2O gas adsorbed on 1B/Mo-g-C3N4 has suitable adsorption energy, large charge transfer, short recovery time, and large conductivity change. Therefore 1B/Mo-g-C3N4 can be used as a good sensor to detect CH2O. Lower sensitivity, long recovery times, or insignificant conductivity changes make 1B/Mo-g-C3N4 unsuitable for the detection of CO, NO, NH3, and SO2 gases. However, 1B/Mo-g-C3N4 can be used as a one-time detection for NO2 gas. The recovery time of gases adsorbed on the surface of 2B/Mo-g-C3N4 ranges from 1.93 × 1020 h to 6.43 × 1068 h. However, the large adsorption energies (−2.12 eV to −4.99 eV), the high sensitivity, and the high electrical conductivity allow the use of 2B/Mo-g-C3N4 as a disposable assay for gas molecules.

Peroxymonosulfate Activation by Bi-Fe Oxide Co-Doped Graphitic Carbon Nitride for Degradation of Sulfamethoxazole: Performance and Mechanism

Graphite carbon nitride (g-C3N4) has been employed as an emerging metal-free catalyst in heterogeneous catalysis. However, the catalyst has a poor activation property for peroxymonosulfate (PMS). In this study, Bi-Fe oxide co-doped g-C3N4 (Bi@Fe/CN) was synthesized for PMS activation to degrade sulfamethoxazole (SMX). In particular, Bi@Fe/CN-3 presented remarkable catalytic performance with 99.7% removal of SMX within 60 min in the PMS system. Additionally, Bi@Fe/CN-3 presented good stability and recyclability through the cycling experiments. Moreover, it was shown that free radicals (O2•−, •OH, and SO4•−) and non-free radicals (1O2) were the primary active species in the Bi@Fe/CN-3/PMS system. Bi, Fe, and surface lattice oxygen were confirmed to be the main contributors to the active species. This work elucidates the mechanism of activation of PMS by Bi@Fe/CN-3, which is beneficial to promote the application of bimetallic oxide-modified g-C3N4/PMS systems in wastewater treatment.

Photoluminescent Self-Healable Waterborne Polyurethane/Mo and S Codoped Graphitic Carbon Nitride Nanocomposite with Bioimaging and Encryption Capability.

Creating polymers that combine various functions within a single system expands the potential applications of such polymeric materials. However, achieving polymer materials that possess simultaneously elevated strength, toughness, and self-healing capabilities, along with special properties, remains a significant challenge. The present study demonstrates the preparation of S and Mo codoped graphitic carbon nitride (g-C3N4) (Mo@S-CN) nanohybrid and the fabrication of self-healing waterborne polyurethane (SHWPU)/Mo@S-CN (SHWPU/NS) nanocomposites for advanced applications. Mo@S-CN is an intriguing combination of g-C3N4 nanosheets and molybdenum oxide (MoOx) nanorods, forming a complex lamellar structure. This unique arrangement significantly improves the inborn properties of SHWPU to an impressive degree, especially mechanical strength (28.37-34.11 MPa), fracture toughness (73.65-140.98 MJ m-2), and thermal stability (340.17-348.01 °C), and introduces fluorescence activity into the matrix. Interestingly, a representative SHWPU/NS0.5 film is so tough that a dumbbell of 15 kg, which is 53,003 times heavier than the weight of the film, can be successfully lifted without any significant crack. Remarkably, fluorescence activity is developed because of electronic excitations occurring within the repeating polymeric tris-triazine units of the Mo@S-CN nanohybrid. This fascinating feature was effectively harnessed by assessing the usability of aqueous dispersions of the Mo@S-CN nanohybrid and photoluminescent SHWPU/NS nanocomposites as sustainable stains for bioimaging of human dermal fibroblast cells and anticounterfeiting materials, respectively. The in vitro fluorescence tagging test showed blue emission from 365 nm excitation, green emission from 470 nm excitation, and red emission from 545 nm excitation. Most importantly, in vitro hemocompatibility assessment, in vitro cytocompatibility, cell proliferation assessment, and cellular morphology assessment supported the biocompatibility nature of the Mo@S-CN nanohybrid and SHWPU/NS nanocomposites. Thus, these materials can be used for advanced applications including bioimaging.

Synthesis of selenium and fluorine co-doped graphitic carbon nitride for photodegradation of toxic organic pollutants and hydrogen peroxide photoproduction

Science is developing every day to race against the factual growth of industrial pollution in order to redeem the environment. In this study, modification of graphitic carbon nitride via selenium and fluoride doping was successfully conducted. Specifically, the process of co-calcination was conscripted using organic precursors, whilst the foreign elements were obtained from ammonium fluoride and selenium dioxide. The morphological assessment revealed the treated-graphitic carbon nitride possessed a flaky sheet form with high porosity and great crystalline uniformity. Photochemical investigation showed the co-doping of selenium and fluorine elevated the optical properties, including the decrement of bandgap and diminishing the recombination rate of electrons and holes. With interesting improvement in photocatalytic activity, the material was applied in persistent organic compound degradation and hydrogen peroxide production. The treatment improved the degradation percentage, in which the methylene blue removal achieved 99.96 % while the tetracycline removal reached 86.38 %. Moreover, high compatibility and great reusability over 4 cycles were also recorded. When applying the material for the generation of hydrogen peroxide, the co-doped material performance was observed to reach 3307 μM/g.h. The results concluded the advancement in material modification with great application in various aspects.

Preparation and characterization of sulphur and zinc oxide Co-doped graphitic carbon nitride for photo-assisted removal of Safranin-O dye.

Recently, there has been significant interest in photocatalytic reactions involving graphitic carbon nitride (g-C3N4) due to its sp2-hybridized carbon and nitrogen content and it is an ideal candidate for blending with other materials to enhance performance. Here, we have synthesized and analyzed both doped and undoped g-C3N4 nanoparticles. Specifically, we co-doped sulfur (S) into g-C3N4, integrated it with ZnO particles, and investigated the photocatalytic potential of these nanocomposites to remove Safranin-O dye. The initial step involved the preparation of pure g-C3N4 through calcination of urea. Subsequently, S-g-C3N4 was synthesized by calcining a mixture of urea and thiourea with a 3 : 1 ratio. Finally, the ZnO-S-g-C3N4 composite was synthesized using the liquid exfoliation technique, with distilled water serving as the exfoliating solvent. These samples were characterized by advanced techniques, including UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), energy dispersive X-ray (EDX) and scanning electron microscopy (SEM), to assess their crystallinity, morphology, optical properties, and phase purity. Subsequently, these nanocomposites were employed in catalytic and photocatalytic processes to remove the Safranin-O dye (SO). The results highlighted the formation of Z-scheme junction responsible for ZnO-S-g-C3N4's significant performance improvement. The comparison of results demonstrated that S-g-C3N4 and ZnO-S-g-C3N4 composites revealed an effective removal of Safranin-O dye in the presence of UV-light as compared to pure g-C3N4, as it was attributed to the phenomenon of improved separation of photogenerated charge carriers as a result of heterojunction formation between S-g-C3N4 and ZnO interfaces. In addition to improving photocatalytic performance, this study presents a facile route for producing ZnO-S-g-C3N4 composite with superior adsorption capabilities and selectivity.

Electrocatalytic quantification of quinol in cosmetic samples using Co-doped graphitic carbon nitride @biomolecule assisted electrochemically reduced graphene nanosheets

A bio-nanocomposite “Co-doped-g-C3N4@ biomolecule assisted electrochemically reduced graphene nanosheets (Co-g-C3N4@GNbme)” was prepared by electrochemical exfoliation of GO from graphite anode in the presence of amino acid ‘l-cysteine’ followed by its association with Co-g-C3N4. The preparation of material has been confirmed by characterizations with FTIR, XRD, XPS and Raman spectroscopy. The morphology was investigated with TEM and SEM. Further, Co-g-C3N4@GNbme modified GC electrode was utilized for detecting and quantifying the ‘Quinol’ (a skin lightning agent) in cosmetic samples electrochemically. Quinol is a fundamental constituent utilized in various industries such as pharmaceuticals, oil refineries, textiles, and dyes. In the realm of cosmetics, it is utilized as a skin-lightning agent to inhibit the production of melanin in the skin. However, prolonged use of this component often results in allergic reactions among individuals. Furthermore, the effluents discharged from its manufacturing units pose a significant threat to the environment and human health due to its slow degradation. The detection limit was calculated to be 2.4 nM (S/N = 3).

Visible light driven hydrogen peroxide production by oxygen and phosphorus co-doped CoP-C3N4 photocatalyst

Photocatalytic hydrogen peroxide (H2O2) by oxygen and phosphorus co-doped graphitic carbon nitride (C3N4) with cobalt phosphate (CoP) cocatalyst is investigated. The photocatalyst powder of CoP-C3N4 1:n, n = 0–4, n is the weight ratio of cyanuric acid added) was synthesized by melamine cyanurate template method. Characterization of the catalyst was performed by X-ray diffraction analysis, and scanning electron microscopy, X-ray photoemission spectra, and fluorescence decay spectra. Oxygen doping was performed by the melamine and cyanuric acid template method, followed by phosphorus doping of the C3N4 backbone by the introduction of CoP. Co-doping of O and P atom facilitated charge transfer on the C3N4 backbone, while CoP facilitated charge separation at the C3N4 interface. The CoP-C3N4 (1:4) photocatalyst increased H2O2 production rate by 293 % compared to that of the cyanuric acid-free photocatalyst and also achieved the photocatalytic oxygen evolution from water. These results indicate that O,P co-doped CoP-C3N4 can perform sacrificial agent-free hydrogen peroxide under visible light irradiation.

Integrating K and P co-doped g-C3N4 with ZnFe2O4 and graphene oxide for S-scheme-based enhanced adsorption coupled photocatalytic real wastewater treatment

Recently, there has been a significant increase in the interest of using photocatalysis for environmental clean-up applications. In this research, potassium, and phosphorus co-doped graphitic carbon nitride (KPCN) photocatalyst modified with graphene oxide (GO) and heterostructured with ZnFe2O4 was synthesized via the hydrothermal method (KPCN/GO/ZnFe2O4). The photoactivity of KPCN/GO/ZnFe2O4 photocatalyst was examined for the photocatalytic degradation of target pollutants such as methylene blue (MB) dye, rhodamine B (RhB) dye, and tetracycline (TC) antibiotic. Furthermore, the chemical oxygen demand (COD) removal efficiency for real wastewater was determined to explore the practical application of KPCN/GO/ZnFe2O4 photocatalyst. The degradation efficiencies of bare graphitic carbon nitride, KPCN, KPCN/GO, and KPCN/GO/ZnFe2O4 photocatalysts for tetracycline antibiotics were 30%, 42%, 57%, and 87% within 60 min, respectively. Moreover, KPCN/GO/ZnFe2O4 photocatalyst showed 71% COD removal efficiency within 240 min. The •OH and •O2− were the major reactive species in the photocatalytic process. Results showed that the degradation efficiencies of graphitic carbon nitride were greatly enhanced upon doping and further improved with the addition of GO and ZnFe2O4. Doping improved light harvesting, GO enhanced the adsorption ability and heterojunction with ZnFe2O4 enhanced the charge separation as well as the reusability of synthesized KPCN/GO/ZnFe2O4 photocatalyst.

Heterojunction of (P, S) co-doped g-C3N4 and 2D TiO2 for improved carbamazepine and acetaminophen photocatalytic degradation

Novel photocatalysts of phosphorus and sulfur co-doped graphitic carbon nitride incorporated in 2D TiO2 structure were successfully fabricated and applied for solar-driven degradation of emerging pollutants from the group of pharmaceuticals not susceptible to biodegradation. The hybrid photocatalysts with different loadings of (P, S)-doped g-C3N4 were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (DR/UV–vis), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM). The optimum (P, S)-doped g-C3N4/TiO2 (5 %) composite revealed improved photocatalytic activity towards the degradation of carbamazepine and acetaminophen. For CBZ, about 100 % degradation was achieved in less than 30 min of photodegradation, whereas for ACT, the complete removal was observed in 60 min of irradiation under simulated solar light. The multi-anion doped g-C3N4/2D TiO2 composite demonstrated an excellent synergy towards the degradation of CBZ and ACT with a synergy index of 1.35 and 1.62. Moreover, the mineralization efficiency measured as TOC removal was 76 % and 40 % for CBZ and ACT, respectively. The reactive oxygen species responsible for the degradation of selected pharmaceuticals are superoxide (O2–) and hydroxyl radicals (HO), and the kinetics of reactions proved to fit the first-order kinetics with a rate constant of 0.21 min−1 for CBZ degradation and 0.074 min−1 for ACT degradation. Our results suggest that (P, S)-doped g-C3N4/ 2D TiO2 heterostructure is a Z-scheme heterojunction, which can effectively separate photogenerated charge carriers. The emissions and decay times analyzed for single components and the optimal (P, S)-doped g-C3N4/ 2D TiO2 (5 %) composite confirmed interfacial charge transfer between TiO2 nanosheets and (P, S)-g-C3N4 and more effective separation of electron-hole pairs. Identification of carbamazepine and acetaminophen intermediates was performed using LC-MS analysis in combination with additional DFT calculations of the possible by-products formation. Regarding reusability, the photocatalytic activity of (P, S)-doped g-C3N4/ 2D TiO2 (5 %) was stable after subsequent cycles of carbamazepine and acetaminophen degradation.

Design and Architecture of P-O Co-Doped Porous g-C3N4 by Supramolecular Self-Assembly for Enhanced Hydrogen Evolution

A novel phosphorus and oxygen co-doped graphitic carbon nitride (sheetP-O-CNSSA) photocatalyst was successfully synthesized and applied for H2 evolution under visible light. In the synthesis process of sheetP-O-CNSSA, the supramolecular complex was developed by the self-assembly and copolymerization reaction among melamine, cyanuric acid (CA) and trithiocyanuric acid (TCA) to act as g-C3N4 precursors, while (NH4)2HPO4 was applied as P and O precursors for element doping. The chemical structures, morphologies, and optical properties of the sheetP-O-CNSSA were characterized by a series of measurements, i.e., XRD, FT-IR, SEM, TEM, UV-vis DRS, and PL. The results suggested that the introduction of P and O elements could enhance the separation and migration efficiency of photogenerated electrons and holes in the energy band of g-C3N4. The photocatalytic tests over Erythrosin B (EB) sensitized sheetP-O-CNSSA indicated that the hydrogen evolution was greatly enhanced compared with other catalysts and non-sensitized sheetP-O-CNSSA under visible light irradiation. Finally, a possible dye-sensitized photocatalysis mechanism was also proposed on the basis of the as-obtained results.

Photocatalytic oxidation for efficient 4-chloro-guaiacol degradation over Co-doped graphitic carbon nitride and the effect of Co-doping concentration on optical properties of carbon nitride

This paper investigates the fabrication of Co-doped carbon nitride (C3N4-Co) and its application in degrade 4-chloro-guaiacol. Co-doped carbon nitride significantly enhanced the photocatalytic activity for 4-chloro-guaiacol degradation compared to unmodified carbon nitride. Under the same conditions, the degradation rate of 4-chloro-guaiacol by unmodified C3N4 was only 30.7 %, however it increased to 73.7 % by Co-doped carbon nitride (0.25 wt%). Co-doping can extend the wavelength range, improve oxygen adsorption, and reduce electron-hole recombination. However, the greater the amount of Co-doping. But, when the doping level is too high, excessive oxygen adsorption may occur on the surface of the active site, obstructing 4-chloro-guaiacol adsorption and reducing the catalytic efficiency. This work could provide useful information regarding AOX degradation for future research.

Design of copper oxide and oxygen codoped graphitic carbon nitride activator for efficient radical and nonradical activation of peroxymonosulfate

Rational regulation of stable graphitic carbon nitride (CN) for superior peroxymonosulfate (PMS) activation is important in the catalytic degradation of water contaminants. In this work, the copper oxide and oxygen co-doped graphitic carbon nitride (CuO/O-CN) was prepared via one-step synthesis and applied in activating PMS for oxytetracycline (OTC) degradation, displaying superior catalytic performance. Systematic characterization and theoretical calculations indicated that the synergistic effect between the oxygen site of CN and CuO can modulate the electronic structure of the whole composite further facilitating the formation of non-radical 1O2 and various reactive radicals. Results of the influencing factor experiments revealed that CuO/O-CN has a strong resistance to the environmental impact. The degradation efficiency of OTC in the real water environment even exceeded that in the deionized water. After four successive runs of the optimal catalyst, the OTC removal rate was still as high as 91.3%. This work developed a high-efficiency PMS activator to remove refractory pollutants via both radical pathway and non-radical pathway, which showed a promising potential in the treatment of wastewaters.

Boron and Phosphorus Co-Doped Graphitic Carbon Nitride Cooperate with Bu4NBr as Binary Heterogeneous Catalysts for the Cycloaddition of CO2 to Epoxides

The development of a cost-effective heterogeneous catalytic system for the cycloaddition reaction of CO2 and epoxides is of great importance. In this manuscript, three kinds of boron and phosphorus co-doping graphitic carbon nitride (BP-CN) were prepared and characterized. Among them, BP-CN-1 displayed the optimal catalytic performance in the presence of Bu4NBr (tetrabutylammonium bromide) for the CO2 cycloaddition with propylene oxide, and 95% propylene carbonate yield was obtained under a 120 °C, 2 MPa, 6 h condition. Moreover, the BP-CN-1/Bu4NBr catalytic system is compatible with various epoxides and also exhibits excellent recycling performance under metal- and solvent-free conditions. Hence, BP-CN-1 exhibited an attractive application for the efficient fixation of CO2 due to the simple, eco-friendly synthesis route and effective catalytic activity.

Corrigendum to “Visible light-assisted photodegradation of 2,4-dinitrophenol using Ag2CO3 loaded phosphorus and sulphur co-doped graphitic carbon nitride nanosheets in simulated wastewater” [Arab. J. Chem. 13(1) (2020) 3196–320

Corrigendum to “Visible light-assisted photodegradation of 2,4-dinitrophenol using Ag2CO3 loaded phosphorus and sulphur co-doped graphitic carbon nitride nanosheets in simulated wastewater” [Arab. J. Chem. 13(1) (2020) 3196–320

A novel P/Ni-doped g-C3N4 nanosheets for improving mechanical, thermal and flame-retardant properties of acrylonitrile–butadienestyrene resin

The ubiquitous application of highly flammable acrylonitrile–butadienestyrene (ABS) resin has brought great fire threat to human and environment. Unfortunately, current flame retardants often improve flame retardancy but reduce mechanical and thermal properties, seriously affecting their practical application. We herein reported novel multifunctional, high-efficiency, phosphorus and nickel co-doped graphitic carbon nitride (Ni-P-C3N4) nanoflakes to address the trade-off between flame retardancy and mechanical/thermal properties. The addition of 2.0wt% of Ni-P-C3N4 increased the initial degradation temperature and tensile strength of ABS composite (ABS/Ni-P-CN2) by 15 °C and 24.3% relative to virgin ABS, indicating its positive effect on thermal and mechanical properties. Compared with ABS, ABS/Ni-P-CN2 exhibited a notable increase in time to ignition, along with 32.4% and 33.8% reductions in peak heat release rate (PHRR) and peak smoke production rate (PSPR), demonstrating excellent anti-ignition, flame-retardant and smoke-suppressive performances. The increased fire safety was mainly due to the physical barrier effect of g-C3N4 nanosheets and the catalytic charring effect of P and Ni. This work offers a novel design strategy to create multifunctional flame retardants for fabricating fire-safe polymer composites with superior thermal and mechanical properties, holding great potential in industries.

O, S-g-C3N4 nanotubes as photovoltaic boosters in quantum dot-sensitized all-weather solar cells: a synergistic approach for enhanced power conversion efficiency in dark-light conditions

All up-to-the-minute solar cells generate highly efficient electricity under sunlight. However, the power outputs are ∼ zero under dark conditions due to the relatively low visible light intensity. We report high-performance quantum dots-sanitized all-weather solar cells (QDSSCs). The devices were based on rationally designed carbon quantum dots (CQDs) decorated oxygen and sulfur co-doped graphitic carbon nitride nanotubes (O, S-g-C3N4 NTs)-sensitized TiO2/long-persistence phosphor (LPP) photoanodes and Pt counter electrodes (CE). O, S-doped-g-C3N4 NTs can act as photo-boosters as well as the blocking layer to prevent the backflow of photoexcited electrons and prevent their recombination with the electrolyte. LPPs can store unabsorbed light ranging from visible to infrared light across the photoanode and convert it into green fluorescence, ultimately persistent CQDs/O, S-g-C3N4 NTs irradiation, and electricity generation under sunlight illumination in all light-dark environments. The maximum PCE was 18.5% for the device 7-CC/L prepared with a composite of CQDs and O, S-g-C3N4 NTs with an optimized weight of 7 mg and 0.2 g, respectively.

Facile synthesis of sulfur and oxygen co-doped graphitic carbon nitride quantum dots for on-off detection of Cu2+ in real samples and living cells

A fluorescent sulfur and oxygen co-doped graphitic carbon nitride quantum dots (S,O-CNQDs) were prepared from ethylenediaminetetraacetic acid disodium salt dihydrate and thiourea as the carbon and sulfur sources. The morphology and surface functional groups of S,O-CNQDs were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The fluorescence of S,O-CNQDs could be quenched efficiently by Cu2+ under the optimum conditions. The S,O-CNQDs could function as an excellent fluorescent probe for Cu2+ detection with a wide linear range of 0.50–15 μM and a low detection limit of 0.58 nM. In addition, this fluorescent probe was employed for monitoring Cu2+ in samples of tap water, lake water, human serum and urine with good recoveries from 99.0% to 110.0%. Moreover, the S,O-CNQDs with high cell penetration and low cytotoxicity were utilized for Cu2+ detection in living cells. Owing to the excellent properties of S,O-CNQDs, the as-prepared S,O-CNQDs can be a potential candidate for biological applications.

Preparation of Co-Doped Graphitic Carbon Nitride and Degradation of MB by Heterogeneous Photo-Fenton-like Reaction System

In this study, Co-porous-g-C3N4(porous Co-Doped graphitic carbon nitride) was synthesized by a one-step calcination method successfully. Co-porous-g-C3N4 was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance, and specific surface area determination. The Photo- Fenton-like system was successfully constructed under the condition of coexistence of Co-porous-g-C3N4 and H2O2. The synergistic effect of Fenton-like system and photo-catalysis was realized. Through the optimization of experimental conditions, the best photocatalytic performance of this heterogeneous reaction system was achieved. The degradation rate of MB (methylene blue, 40 mg/L) could reach 98.3% at 90 min. Co-porous-g-C3N4 had photocatalytic degradation activity for different organic pollutants and had wonderful recyclability and stability. The main degradation effect was attributed to �O2- which could be generated through two channels in the Photo- Fenton-like system. Moreover, the rate of photogenerated electron-hole complexation could be decreased due to the reaction of low-valent cobalt and photoelectrons in this heterogeneous reaction system.