Carbon Nitride Composites Research Articles

Defective nano-silica loaded polymeric carbon nitride for visible light driven CO2 reduction and dye degradation

A hybrid composite of polymeric carbon nitride (PCN) and defective nano-silica (n-SiOx) photocatalyst has been synthesized, exhibiting a high surface area, improved light response, and reduced charge recombination. The synergistic formation of PCN-n-SiOx interface facilitated photoinduced charge transfer from PCN to n-SiOx, resulting in suppressed carrier recombination. The resultant hybrid PCN-n-SiOx sample demonstrated a three-fold photocatalytic reduction of CO2 into methanol and formic acid. Furthermore, photoelectrocatalytic CO2 reduction selectively yielded 283.0 μmol L−1 of formic acid, a five-fold increment compared to bare PCN (57.0 μmol L−1). These findings hold promise for the development of PCN-based hybrid composites for solar-powered applications.

Integration between CuMOF and g-C3N4 for effective suppressing charge recombination in photocatalytic peroxymonosulfate activation

In this work, CuMOF and graphite phase carbon nitride (g-C3N4) composite was synthesized, and tetracycline hydrochloride (TC) in water was degraded under simulated solar light irradiation with the assistance of peroxymonosulfate (PMS). The prepared g-C3N4/CuMOF samples were characterized by XRD, FT-IR, SEM, TEM and XPS. It is found that the introduction of CuMOF into g-C3N4 was not only beneficial to the charge separation of g-C3N4, but also greatly accelerated the activation of PMS. Through the initial pH value, PMS concentration, catalyst concentration, catalyst repeated use and other factors, the degradation performance of g-C3N4/CuMOF was studied. The photocatalytic experiment results showed that in the presence of PMS, the degradation rate of TC reached 90 % within 30 min. In addition, the reaction mechanism of the g-C3N4/CuMOF/PMS system was studied by using scavenging experiments and electron spin resonance (ESR) technology. This work provides a promising way for the rational design of high-performance and low-cost photocatalysts for environmental remediation.

Photocatalytic hydrogen under visible light by nitrogen-doped rutile titania graphitic carbon nitride composites: an experimental and theoretical study

Photocatalytic hydrogen under visible light by nitrogen-doped rutile titania graphitic carbon nitride composites: an experimental and theoretical study

PLATINUM – MESOPOROUS CARBON NITRIDE NANOCOMPOSITES: SYNTHESIS, CHARACTERIZATION AND CATALYTIC PERFORMANCE IN PHENYLACETYLENE HYDROGENATION

The platinum nanocomposites were synthesized by chemical reduction of H2PtCl6·6H2O in situ with a methanol—water mixture using mesoporous graphitic carbon nitride as a stabilizing matrix and a catalyst support. The textural, morphological, and optical properties of the obtained platinum – mesoporous carbon nitride composites (Pt/mpg-C3N4) were studied. Pt/mpg-C3N4 has been developed as an effective heterogeneous catalyst for the gas and liquid phase hydrogenation of phenylacetylene. An efficient and versatile approach to the modification of platinum with various organic solvents and ligands for the selective hydrogenation of phenylacetylene to styrene in a flow gas-phase process is pre-sented. The addition of pyridine, piperidine, or morpholine to the starting solution of phenylacetylene in hexane provides 95–100% conversion and 90–92% selectivity to styrene. A sharp increase in the selectivity to styrene without substantial changes in conversion is also observed when THF, ethanol, triethylamine, dioxane, or chloroform are used as diluents. The obtained Pt/mpg-C3N4 composites also demonstrated considerable catalytic activity in the selective hydrogenation of phenylacetylene to styrene at low temperatures in the liquid phase

Mechanical activation-enhanced doping and defect strategy to construct Fe–S co-doped carbon nitride for efficient photocatalytic tetracycline degradation and hydrogen evolution

Achieving a simultaneous increase in the redox performance of carbon nitride (CN) remains a challenge owing to the low utilization efficiency of photogenerated carriers. Herein, a novel “mechanical activation (MA)-enhanced doping and defect” strategy was proposed for structural modification of CN to enhance its performance. Specifically, CN, FeCl3, and thiourea were treated by MA to prepare a precursor with uniform dispersion and anchoring of Fe and S components in CN, and then the MA-treated precursor was calcinated to obtain a Fe–S co-doped CN composite (MA-Fe-S-CN) with abundant N vacancies. Under visible light illumination, MA-Fe-S-CN displayed outstanding photocatalytic performance for tetracycline (TC) removal (92.7%) and hydrogen evolution (2965 µmol g−1h−1) within 120 min, which was 3.3 and 4.1 times higher than those of CN, respectively. The superlative redox performance of MA-Fe-S-CN was attributed to that MA-enhanced Fe–S co-doping and N vacancies effectively modified the built-in electric field, electronic structure, and redox potential of CN. Experimental and theoretical analysis revealed that photogenerated electrons were trapped by N vacancies and directed to Fe active sites through efficient charge transfer channels (Fe–N and Fe–S), resulting in rapid charge transfer and effective separation and utilization of carriers. On this basis, possible mechanisms of photocatalytic TC degradation and hydrogen evolution were proposed. This work provides a green and economically feasible way for improving the redox performance of CN.

Visible-light-assisted activation of peroxymonosulfate (PMS) over CoOx @C/g-C3N4 composite for efficient organic pollutant degradation

As a promising advanced oxidation process, photo-assisted peroxymonosulfate (PMS) activation for wastewater treatment has attracted widespread attentions. However, rational design of synergetic and recyclable catalysts for PMS photo-activation remains a big challenge. In this study, a carbon layer-coated amorphous CoOx supported on graphitic carbon nitride (CoOx @C/g-C3N4) composite was fabricated to drive visible-light-assisted activation of PMS for efficient organic pollutant degradation. Amorphous CoOx nanoparticles were in-situ grown on two-dimensional g-C3N4 substrate, among which a carbon layer serves as a high-speed electron transmission channel, facilitating the separation of photogenerated electron-hole pairs and accelerating the Co3+/Co2+ redox cycle. Simultaneously, the carbon layer provides a protective film to suppress Co leaching, thereby improving the catalytic activity and reusability. Owing to the unique heterostructure and synergetic effect, the optimized 6% CoOx @C/g-C3N4 composite exhibits superior catalytic efficiency and excellent cycling stability towards the degradation of various organic pollutants, which displays nearly 100% elimination of tetracycline (TC) within 80 mins. The h+, SO4•- and •OH are determined as the main contributors in the visible light-assisted PMS activation system, and the possible catalytic mechanism is also proposed. This work demonstrates a feasible strategy for constructing synergetic and effective photo-activation PMS catalysts for water remediation.

Building optimistic perovskite-polymer composite solar cells: Feasible involvement of a BLP inclusion to efficiently stable perovskite films

The character of perovskite film sustains the tenable concern frustrating the construction of perovskite solar cells (PSCs) with both competent stability and acceptable photovoltaic performance. In the present study, quaternized poly(aryl ether sulfone)s-reinforced carbon nitride or organic-inorganic blend composite containing quaternized polymer (BLP) materials derived from quaternized poly(aryl ether sulfone)s or polymer of quaternary ammonium chloride (PQACl), and graphitic carbon nitride (sCN), is integrated into perovskite. The PQACl inclusion is a promising material which consists of a cationic quaternary ammonium and an anionic chloride ions. The sufficiently good amount of BLP inclusion in the perovskite system favors the crystal morphology, represses the generation of defects through sequestering the counter ions and reducing ions movements. Well-mannered investigations reveal that BLP inclusion extremely initiates hydrogen bonding interactions with the perovskite, which lowers charge carrier recombination. As a result, the most efficient PSC device processed with PVK-BLP4 film shows a PCE of 19.38% compared with 16.74% in the pure PVK. And the optimized device based on the exploration of a BLP inclusion maintains over 72% of the original efficiency after appropriately continuous 210h thermal handling at 85 °C under 40–50 RH% moisture. The fabrication of BLP-decorated perovskite films is an inspiring engineering for use in solar cells.

Designing Black Phosphorus and Heptazine-Based Crystalline Carbon Nitride Composites for Photocatalytic Water Splitting

Black phosphorus (BP) and heptazine-based crystalline carbon nitride (KPHI) composite photocatalysts were synthesized by molten salt and ultrasound-assisted liquid phase exfoliation methods. The structure, morphology and optical properties of the as-prepared BP/KPHI composites were evaluated by various characterization techniques. In addition, the photocatalytic performance of BP/KPHI composites for hydrogen production was investigated. The photocatalytic activity of BP/KPHI composite catalysts could be modulated by changing the loading mass ratio of BP. The BP/KPHI composite photocatalyst with a mass ratio of 10% exhibited the highest photocatalytic activity with the hydrogen production rate of 4.3 mmol g−1 h−1, about three times higher than that of pristine KPHI. Benefiting from the advantages of simplicity, rapidity, high yield and good controllability, this nanocomposite photocatalyst has the potential to serve as an excellent photocatalytic material for solar energy conversion.

Differently Prepared PbO2/Graphitic Carbon Nitride Composites for Efficient Electrochemical Removal of Reactive Black 5 Dye

In this paper, electrochemical degradation of Reactive Black 5 (RB5) textile azo dye was examined in regard to different synthesis procedures for making PbO2–graphitic carbon nitride (g-C3N4) electrode. The reaction of PbOH3- with ClO− in the presence of different surfactants, i.e., cetyltrimethylammonium bromide (CTAB) and tetrabutylammonium phosphate (TBAP), under conventional conditions, resulted in the formation of PbO2 with varying morphology. The obtained materials were combined with g-C3N4 for the preparation of the final composite materials, which were then characterized morphologically and electrochemically. After optimizing the degradation method, it was shown that an anode comprising a steel electrode coated with the composite of PbO2 synthesized using CTAB as template and g-C3N4, and using 0.15 M Na2SO4 as the supporting electrolyte, gave the best performance for RB5 dye removal from a 35 mg/L solution. The treatment duration was 60 min, applying a current of 0.17 A (electrode surface 4 cm2, current density of 42.5 mA/cm2), while the initial pH of the testing solution was 2. The reusability and longevity of the electrode surface (which showed no significant change in activity throughout the study) may suggest that this approach is a promising candidate for wastewater treatment and pollutant removal.

Facile synthesis of gC3N4/MoS2 composite for rapid sequestration of lead and methylene blue and its potential application in paint industry wastewater remediation

In this study, a composite of graphitic carbon nitride coated Molybdenum Disulphide (gC3N4/MoS2) has been synthesized by thermal polymerization in a very cost-effective facile approach. The study explores the properties of synthesized gC3N4/MoS2 via various characterization techniques. It looks into its applications in the capture of Lead (Pb2+) and Methylene Blue (MB) in single and binary associations in a batch process and finally targets paint industry wastewater treatment. The uniqueness of the work lies in the ease of adsorbent synthesis and rapid sequestration of Pb from aqueous solutions of only Pb, Pb -dye, and Pb from the actual paint industry wastewater. Maximum Pb uptake capacity (qmax) attained was 60.06 mg/g at pH = 4, and Pb2+ concentration = 5–50 mg/L. The adsorption of Pb2+ followed Pseudo second order kinetics (R2 = 0.90–0.97) and Freundlich isotherm model (R2 = 0.90–0.98), where all models were plotted nonlinearly. Similarly, for MB qmax was 32.69 mg/g at pH = 6, and MB concentration = 10–60 mg/L. The adsorption of MB followed PSO and Elovich model with R2 0.96–0.98 and 0.99, respectively, and Freundlich model with R2 = 0.90–0.97. Pb2+ is readily adsorbed on gC3N4/MoS2 in the presence of MB, irrespective of contact time, adsorbent dose, and MB concentration. gC3N4/MoS2 rapidly captures Pb from the actual paint industry wastewater even with multiple competitive cations and anions, both organic and inorganic, with 99 % efficiency. Overall, the adsorbent gC3N4/MoS2 holds promise for treating Pb and dyes containing wastewater in terms of economy in synthesis and adsorption capacity.

RuO2 nanoparticles anchored on g-C3N4 as an efficient bifunctional electrocatalyst for water splitting in acidic media.

The electrolysis of water, particularly proton exchange membrane (PEM) water electrolysis, holds great promise for hydrogen production in industry. However, the catalyst used in this process is prone to dissolution in acidic environments, making it imperative to develop cost-effective, highly efficient, and acid-stable electrocatalytic materials to overcome this challenge and enable large-scale application of PEM water electrolysis technology. Herein, we prepared ruthenium oxide (RuO2)/graphitic carbon nitride (g-C3N4) composites (RuO2/C3N4) via a combination of sol-gel and annealing methods. The g-C3N4 provides a large surface area, while RuO2 is uniformly deposited on the g-C3N4 surface. The interaction between g-C3N4 and RuO2 stabilizes the RuO2 nanoparticles and enhances long-term water oxidation stability. This unique structure and the combined advantages of RuO2 and g-C3N4 yield exceptional electrocatalytic activity toward both the oxygen evolution reaction (OER, 240 mV@10 mA cm-2) and the hydrogen evolution reaction (HER, 109 mV@10 mA cm-2), with excellent durability (over 28 h), and a cell voltage of 1.607 V at 10 mA cm-2 when used in an RuO2/C3N4||RuO2/C3N4 electrolyzer. This study highlights the efficacy of the g-C3N4 support method in designing highly stable Ru-based OER electrocatalysts for efficient acidic water splitting.

The environmentally friendly approaches based on the heterojunction interface of the LaFeO3/Fe2O3@g-C3N4 composite for the disposable and laboratory sensing of triclosan.

Triclosan (TCS) is a polychlorinated phenoxy phenol (PCPPs) used as a disinfectant and a broad-spectrum antibacterial and antifungal agent in personal hygiene products. TCS easily forms diphenyl ethers and dioxins, which are persistent organic pollutants. This work used a double approach for the TSC sensing: a) screen-printed (SPE) electrochemical platform for on-site application, modified with lanthanum iron oxide and graphitic carbon nitride composite (LaFeO3/Fe2O3@g-C3N4/SPE); and b) carbon paste electrode (CPE), modified with the same material and used in laboratory conditions. Linear range from 0.1 μM to 10 μM, the limit of detection (LOD) of 29 nM and the limit of quantification (LOQ) of 91 nM were obtained for CP electrode in BRBS pH 8. SPE showed the best analytical parameters in BRBS at pH 3, with a linear range from 0.3 μM to 7 μM, LOD of 0.09 μM and LOQ of 0.28 μM. Furthermore, the influence of potential interferents was investigated and proven to be negligible. Determination of TSC was performed to estimate the environmental impact of this compound as well as the practical usefulness of the proposed sensor in the real sample analysis, confirmed with a HPLC analysis.

Acid protonation promoted different crystal phase structure silicon carbide-based carbon nitride composites to enhance the photocatalytic degradation of dye wastewater

Acid-protonated crystalline silicon carbide-supported carbon nitride photocatalytic composites were successfully prepared by the impregnation-heat treatment method (P-g-C3N4/β-SiC and P-g-C3N4/α-SiC).

Solvothermal Synthesis of g-C3N4/TiO2 Hybrid Photocatalyst with a Broaden Activation Spectrum

A solvothermal self-made composite of graphitic carbon nitride (g-C3N4) and commercially available titanium dioxide (TiO2) demonstrated the removal of commercial acid green-25 (AG-25) textile dye in a saline water matrix when activated by ultraviolet (UV) and visible light. The g-C3N4-TiO2 composite was characterized by X-ray diffraction (XRD), Nitrogen sorption–desorption recording and modeling by the Brunauer–Emmett–Teller (BET) theory, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electron spin resonance (ESR). The solvothermal process did not modify the crystalline structure of the g-C3N4 and TiO2 but enhanced the surface area by interlayer delamination of g-C3N4. Under a simulated solar spectrum (including UVA/B and vis wavelengths), the degradation rate of AG-25 by the composite was two and four times higher than that of TiO2 and pure g-C3N4, respectively (0.04, 0.02, and 0.01 min−1). Unlike TiO2, the g-C3N4-TiO2 composite was activated with visible light (the UV portion of the solar spectrum was filtered out). This work provides insight into the contribution of various reactive oxidative species (ROS) to the degradation of AG-25 by the composite.

A novel strategy for efficient capture of intact harmful algal cells using Zinc oxide modified carbon nitride composites

The development of safe and efficient materials to remove harmful algae is continuing to be a major challenge in controlling cyanobacterial blooms in eutrophication waters. Herein, we present a novel strategy that combines Zinc oxide (ZnO) with carbon nitride composites to efficiently collect the intact Microcystis aeruginosa cells. The influence of different dosages of g-C3N4 precursors were assessed and the synthesized catalysts were characterized. The results revealed that 93.0 % of algae cells were removed by the ZnO/CN (2:1) system within 10 min at a dose of 4.0 g L−1. Regardless of the variation in initial cell density, the final removal efficiency reached >90.0 %. The integrity of the algal cell membrane was observed by K+ release and intracellular organic matter such as MC-LR during the removal process, which were further verified by SEM images. The Zeta potential values indicated that the improved effectiveness may be attributed to the electrostatic attraction and coagulation by ZnO/CN. The removal mechanism of ZnO/CN was revealed through charge neutralizing flocculation and the different types of flocculants were compared. The present work provides a new insight in using ZnO nanoparticles modified carbon-based composites in treating cyanobacterial blooms.

Fabrication of highly efficient Au and layered double hydroxide modified g-C3N4 ternary composites for degradation of pharmaceutical drug: Pathways and mechanism

Graphitic carbon nitride (CN), a conjugated polymer widely recognized as a chemically stable and low toxic catalyst for the degradation of organic molecules. But it acquires certain limitations like a limited visible light response, high recombination rate of charge carriers, and lower charge density. To overcome such drawbacks, we synthesized a series of Ni-Al layer double hydroxide (LDH)/CN composites by loading 5–15 wt% of Ni-Al LDH onto CN by electrostatic self-assembly method. Further, Au nanoparticles were deposited photochemically on LDH/CN nanocomposites. The Au/LDH/CN nanocomposites exhibited enhanced photocatalytic degradation of tetracycline (TCH) under visible light. Particularly, the Au/LDH/CN nanocomposite with LDH and Au contents of 10 and 1 wt%, sequentially, displayed the highest degradation, which was much better than that for pure CN. The face-to-face interface between LDH and CN and the electron-accepting capability of Au nanoparticles in Au@LDH/CN boosts the separation and transfer efficiencies of photogenerated charge carriers. The intermediate products formed after the degradation of TCH were detected by LCMS and possible degradation pathways were shown. Based on photoluminescence, scavenging experiments, and LC-MS analysis, a possible mechanism for degradation of TCH on Au@LDH/CN nanocomposite was proposed.

Performance study of erbium-doped modified graphite-phase carbon nitride catalyzed degradation of RhB

In order to improve the photocatalytic ability of graphite-phase carbon nitride, Er was selected as a precursor to modify graphite-phase carbon nitride, and the graphite-phase carbon nitride composite (Er/g-C3N4) doped with rare earth (Er) was prepared by thermal polymerization. The results showed that the 0.5% Er/ g-C3N4 composite had strong visible light absorption. The results showed that the 0.5% Er/ g-C3N4 catalyst had a good visible light absorption and the 0.5% Er/ g-C3N4 catalyst had a better degradation effect on RhB.

Enhanced Room-Temperature Ethanol Detection by Quasi 2D Nanosheets of an Exfoliated Polymeric Graphitized Carbon Nitride Composite-Based Patterned Sensor.

A novel room-temperature gas sensor composed of polymeric graphitic carbon nitride composite was fabricated and used for the detection of ethanol vapor under ambient conditions. Polymeric carbon nitride (PCN) microstructures composed of fluffy nanosheets were synthesized via a thermal polycondensation mechanism using melamine as the precursor, followed by vigorous chemical exfoliation. These sheet-like microstructures were employed as active materials in the form of composites, along with carbon paste consisting of graphite nanoplatelets and carbon black. The active sensing layer was fabricated on a PET sheet and assembled on an interdigitated gold electrode. The as-fabricated sensor exhibited excellent sensing efficiency (>100% response at 10 ppm) along with high selectivity and stability. In particular, for ultralow concentrations such as 1 ppm (>10% response), this resistive-based sensor exhibited a swift response time provided under ambient conditions. The exfoliated PCN composite sensor was found to be working with appreciable efficiency at moderate relative humidity (%) with the least fluctuation in response signals also demonstrating long-term stability for 30 days with consistent response signals.

Polymeric Carbon Nitride/Iron Oxide Composites: A Novel Class of Catalysts with Reduced Metal Content for Ammonium Perchlorate Thermal Decomposition.

The ever-growing number of space launches triggering an enormous release of metallic dead weight into the atmosphere has become a global concern. Despite technological advancements, the inclusion of environmental concerns in space research has become the need of the hour. Here, we report the impact of iron oxide (Fe2O3)-doped polymeric carbon nitride (gCN) composites with varying metal contents (namely, GF1, GF2, and GF3 with iron contents of 0.1, 0.25, and 2 mmol, respectively) as a new class of catalysts for ammonium perchlorate (AP) thermolysis. Morphology studies revealed the dendritic morphology of the synthesized Fe2O3, and X-ray photoelectron spectroscopy (XPS) analysis confirmed the effective interaction between Fe2O3 and gCN in the composites. Among all of the synthesized composites, GF2 shows superior catalytic competence toward AP decomposition by amalgamating the double-stage decomposition process into a single stage followed by a considerable decrease in the decomposition temperature. The kinetic parameters calculated for the thermal decomposition of AP with and without catalysts using the KAS method substantiated the above results by significantly reducing the activation energy from 173.2 to 151.7 kJ/mol. Later, thermogravimetric and mass-spectrometric (TG-MS) analysis gives a clear idea about the catalytic efficiency of the synthesized catalyst GF2 toward AP decomposition from the accelerated emission of decomposition products NO, NO2, Cl, HCl, Cl2, and N2O in the presence of GF2. In a nutshell, gCN/Fe2O3 will open up new horizons in the field of synthesis of new catalytic systems with minimal metal content for composite solid propellants.

Cu nanocrystals enhanced charge separation and transfer in superior thin g-C3N4 nanosheets

A two-step thermal condensation approach was developed to fabricate Cu and graphic carbon nitride (g-C3N4) composites. Cu nanocrystals (NCs) with a size range of 2 – 5 nm were embedded in superior thin g-C3N4 nanosheets. Although little amount of Cu NCs was incorporated in g-C3N4 nanosheets, Cu/g-C3N4 composites revealed promoting influence towards photocatalytic H2 generation and photodegradation of pollutions. Namely, the sample 680-Cu0.05% (with Cu of 0.05 wt%) revealed the best photocatalytic performance. Electrochemical test indicates that Cu NCs improve the productivity of the samples. Narrowed band gap in Cu/g-C3N4 composite samples resulted in an expanded photo adsorption in visible light range. The composites also revealed enhanced optical current response and small interfacial charge transport resistances compared with pure g-C3N4 nanosheets (sample Pure-680). The photocatalytic H2 generation rate of the composite was ~ 2790 μmol g−1 h−1, which is 2.3 times of that of Pure-680. The degradation efficiency of rhodamine B using the composite sample reached 95.5 % with a photodegradation rate of 0.0774 min−1 and was described a zero-order kinetics model (C0-C=kt) with a process completing within 35 min. The test of photocatalytic hydrogen evolution stability indicated that it was almost no degradation when using the composite sample after 8 cycles. This work proposes an efficient method to improve the separation and transfer efficiencies of photogenerated carriers in g-C3N4 and could be applied in another two-dimensional composite photocatalysts.