Carbon Nitride Research Articles

Enhanced Flexible Piezoelectric Nanogenerators Using Ethanol-Exfoliated g-C3N4/PVDF Composites via 3D Printing for Self-Powered Applications.

This study presents the development of flexible piezoelectric nanogenerators (PENGs) utilizing graphitic carbon nitride (g-C3N4) nanoflakes (CNNFs) and polyvinylidene fluoride (PVDF) composites fabricated via the direct ink writing (DIW) 3D printing method. A novel approach of synthesizing CNNFs using the ethanol exfoliation method was demonstrated, which significantly reduces preparation time and cost compared to traditional acid exfoliation. The CNNFs are incorporated into PVDFs at varying weight percentages (5, 7.5, 10, and 15 wt.%) to optimize the β-phase content and piezoelectric properties. Characterization techniques including XRD, FTIR, and FESEM confirm the successful synthesis and alignment of nanoflakes inside the PVDF matrix. The film with 7.5% CNNF achieves the highest performance, exhibiting a peak output voltage of approximately 6.5 V under a 45 N force. This study also explores the effects of UV light exposure. Under a UV light, the film exhibits an output voltage of 8 V, indicating the device's durability and potential for practical applications. The fabricated device showed significant voltage outputs during various human motions, confirming its suitability for wearable self-powered IoT applications. This work highlights the efficacy of the ethanol exfoliation method and the DIW printing technique in enhancing the performance of flexible PENGs.

Design of ternary GO@AgNPs@g-C3N4 membranes for efficient dye removals in integrated photocatalysis-filtration reactors

Photocatalytic composite membranes (PCMs), which integrate the high degradation efficiency of photocatalysts and the physical separation properties of membranes, have emerged as a promising technology for wastewater treatment. Herein, the ternary GO@AgNPs@g-C3N4 PCM was fabricated through a facile vacuum-filtration assembly of graphene oxide (GO), graphitic phase carbon nitride (g-C3N4), and silver nanoparticles (AgNPs) onto commercial mixed cellulose ester (MCE) substrates. The effects of g-C3N4 synthesized from different precursors and various metal nanoparticles on the performance of PCM were systematically investigated. Interestingly, results show the addition of AgNPs not only significantly improves the photocatalytic performance of PCMs but also enhances the mechanical adhesion between the active layer and the MCE substrate. The resultant PCMs exhibit outstanding photocatalytic performance, maintaining dye removal above 89% even after 25 consecutive cycles. Moreover, dye degradation pathways over the PCMs were investigated through free radical scavenging experiments and electron spin resonance characterizations. This simple assembly method results in a 3–12 times increase in flux compared to the layer-by-layer assembly method. Accordingly, our designed PCMs exhibit significant potential for wastewater treatment and water purification applications.

Research progress on photocatalytic degradation of microplastics by graphitic carbon nitride

Research progress on photocatalytic degradation of microplastics by graphitic carbon nitride

Au-decorated 2D graphitic carbon nitride (g-C3N4)-coated ZnO nanorods for improved UV photodetection application

Au-decorated 2D graphitic carbon nitride (g-C₃N₄)-coated ZnO nanorods for improved UV photodetection application

Two-dimensional tetragonal carbon nitride semiconductors with fascinating electronic/optical properties and low thermal conductivity

Abstract Exploring two-dimensional (2D) tetragonal carbon nitride materials is significant for unlocking new physical properties beyond those offered by traditional hexagonal lattices. In this work, we propose three theoretically stable 2D carbon nitride monolayers with tetragonal lattices, namely T-C3N, P-C3N, and PH-C5N4. Electronic structure calculations indicate that all three monolayers exhibit semiconducting characteristics, with T-C3N showing interesting flat band features. Additionally, these three carbon nitrides exhibit anisotropic and high carrier mobilities and excellent light absorption capabilities in the visible-light and near-infrared regions. Meanwhile, the calculated thermal conductivity (κp) of PH-C5N4 is 63.9 Wm−1K−1 at room temperature, significantly outperforming T-C3N (12.2 Wm−1K−1) and P-C3N (18.9 Wm−1K−1). Phonon scattering rates and Grüneisen parameters confirm the origin for the relatively high κp in PH-C5N4. Our study proposes three tetragonal carbon nitride structures with novel physical properties, which lays a theoretical foundation for the multifunctional applications of 2D carbon nitride materials.

Chiral Pd(II) Nanofiber Promoting Electron Transfer of g-C3N4 for Efficient Photocatalytic Hydrogen Production.

The rapid transfer and separation of photogenerated electrons is very important for the improvement of photocatalytic efficiency. Here, chiral induced spin selectivity effect (CISS effect) was developed to accelerate electron transfer for efficient photocatalytic hydrogen production. A chiral and achiral racemic supramolecular Pd(II) complex nanofiber was fabricated via supramolecular self-assembly of chiral L-Py or its racemes with Pd(II) and used to modify carbon nitride (g-C3N4). The obtained chiral photocatalyst L-Py-Pd/g-C3N4-4 and achiral photocatalyst Rac-Pd/g-C3N4-4, show enhanced photocatalytic activities with hydrogen evolution rates of 2476 and 1339 μmol g-1 h-1, respectively, while that of pure g-C3N4 is 30.5 μmol g-1 h-1. Chiral photocatalyst has 85% higher activity than achiral one and is 82.5-fold of pure g-C3N4, due to better suppression of the recombination of photogenerated electron-hole pairs in the interface of g-C3N4 contact with chiral molecule. Spectral tests and photoelectrochemical tests proved that the chiral supramolecular Pd(II) complex can act both as an electron spin filter and hydrogen reduction catalytic center to enhance photocatalytic efficiency. This work offers a new route to facilitate electron transfer by the CISS effect for photocatalytic hydrogen evolution.

Catalytic engineering of transition metal (TM: Ni, Pd, Pt)-coordinated Ge-doped graphitic carbon nitride (Ge@g-c3n4) nanostructures for petroleum hydrocarbon separation: An outlook from theoretical calculations

The extraction, processing, and utilization of petroleum often results in the release of diverse hydrocarbon pollutants into the environment, leading to severe ecological and health implications. Herein, the adsorption and separation of ethane (EAN), ethene (EEN), ethyne (EYN), and benzene (BZN) fractions of paraffin, olefin, acetylene, and aromatic petroleum hydrocarbons were investigated via the catalytically engineered nickel group transition metals; nickel (Ni), palladium (Pd), and platinum (Pt). These transition metals were coordinated on Germanium-doped graphitic carbon nitride (Ge@g-C3N4) nanostructures, and the behavior of the systems was studied through Kohn–Sham density functional theory (KS-DFT) with the B3LYP–D3(BJ)/Def2-SVP computational method. The adsorption of petroleum hydrocarbons decreased in the order Ge_Ni@C3N4 > Ge_Pd@C3N4 > Ge_Pt@C3N4>Ge_Pt@C3N4. These results showed that the coordination of Ni, Pd, and Pt within Ge@C3N4 improved the separation of petroleum hydrocarbons.

Atmosphere engineering of metal-free Te/C3N4 p-n heterojunction for nearly 100% photocatalytic converting CO2 to CO

Carbon nitride (CN)-based heterojunction photocatalysts hold promise for efficient carbon dioxide (CO2) reduction. However, suboptimal production yields and limited selectivity in CO2 conversion pose significant barriers to achieving efficient CO2 conversion. Here, we present the construction of a p-n heterojunction between ultrasmall Te NPs and CN nanosheet using a novel tandem hydrothermal-calcination synthesis strategy. Through ammonia-assisted calcination, ultrasmall Te NPs are grown in-situ on the CN nanosheets’ surface, resulting in the generation of a robust p-n heterojunction. The synthesized heterojunction exhibits increased specific surface area, reinforced visible light absorption, intensive CO2 adsorption capacity, and efficient charge transfer. The optimum Te/CN-NH3 demonstrates superior photocatalytic CO2 reduction activity and durability, with nearly 100 ​% selectivity for CO and a yield as high as 92.0 ​μmol ​g−1 ​h−1, a fourfold increase compared to pure CN. Experimental and theoretical calculations unravel that the strong built-in electric field of the Te/CN-NH3 p-n heterojunction accelerates the migration of photogenerated electrons from Te NPs to the N site on CN nanosheets, thereby promoting CO2 reduction. This study provides a promising material design approach for the construction of high-performance p-n heterojunction photocatalysts.

Modulating Schottky barriers and active sites of Ag-Ni bi-metallic cluster on mesoporous carbon nitride for enhanced photocatalytic hydrogen evolution

The advancement of photocatalysis relies on the development of novel hetero-structured materials with unique architectures. In this study, we successfully synthesized a hetero-structured g-C3N4 (GCN) material with a distinctive surface-interface modification. To further enhance its photocatalytic performance, we optimized the Ag and Ni concentration to maximize the visible light absorption and catalytic active sites for hydrogen evolution reactions. By using systematic physicochemical characterizations and density functional theory (DFT) calculations, we elucidated the pivotal role of graphitic carbon nitride (g-C3N4) in facilitating the formation of an efficient charge transfer channel and promoting the effective generation and separation of photo-generated carriers. From the DFT calculations, we also demonstrated that the Ag and Ni nanoparticles provide more efficient visible light absorption and active sites than Ni nanoparticles for water splitting and hydrogen evolution and In-situ TEM exploration. Furthermore, the hetero microstructure consisting of thin g-C3N4 nano scrolls has a crucial role in shortening the migration distance of the carriers, effectively suppressing carrier recombination. Consequently, these extraordinary characteristics resulted in a superior solar light-driven photocatalytic H2 evolution rate of 2507 μmol.h-1.g−1, surpassing the rate achieved by g-C3N4 heterostructures by a remarkable 18.6-folds. Moreover, the apparent quantum efficiency of this hetero-structured material reached an exceptional value of 1.6 % under a 1.5 G air mass filter.

Construction of a novel Mott-Schottky heterostructure gas sensor g-C3N4/SnO2 with layered nanorods array for high-sensitivity acetone detection

Developing exhaled acetone sensors with high performance can be effectively applied to the medical diagnosis and the health monitoring. Herein, a two-dimensional (2D) layered graphitic carbon nitride (g-C3N4) with tunable electronic structure, abundant edge sites, and high stability is proposed, and it is further coupled with stannic oxide (SnO2) by one-step hydrothermal approach to construct a Mott-Schottky heterostructure with layered nanorods array. The exceptional response of the as-fabricated g-C3N4/SnO2 gas sensor to 50 ppm acetone at 100 °C is four times higher than that of the pristine SnO2 sensor. Additionally, the g-C3N4/SnO2 sensor’s remarkable selectivity, long-term stability against acetone gas, and detection limit of 250 ppb are exhibited. The unique hierarchical design and the Mott-Schottky heterostructure creation which validated by electrochemical study, may be in charge of the enhanced acetone sensing capabilities of g-C3N4/SnO2 gas sensor. This work will provide a concise and effective avenue to construct hierarchical composite with Mott-Schottky heterostructure for high-performance acetone gas sensor.

Innovations in photocatalytic trifluoromethylation: Role of heterogeneous Bi4NbO8Cl in radical generation

Photocatalytic selective trifluoromethylation reactions have garnered significant attention, particularly for their applications in pharmaceuticals, agrochemicals, and materials science. However, existing heterogeneous catalysts such as graphitic carbon nitride, CdS nanorods, and Au@ZnO core–shell nanoparticles exhibit certain limitations, including low catalytic efficiency, inadequate selectivity, and demanding reaction conditions. To address these challenges, we have developed a novel heterogeneous photocatalyst, i.e., Bi4NbO8Cl, and systematically investigated its performance in visible-light-induced hydroxytrifluoromethylation of alkenes and trifluoromethylation of (hetero)aromatics. Notably, the Bi4NbO8Cl photocatalyst exhibits remarkable stability and reusability, maintaining its performance and structural integrity over five cycles. These findings highlight the economic and practical potential of Bi4NbO8Cl, positioning it as a promising candidate for industrial applications in photocatalysis.

Unveiling the synthesis of highly efficient cerium-doped zinc nanoferrites anchored over graphitic carbon nitride for enhanced photocatalytic water purification implications

Over the past several years, the manufacturing and dispersal of naturally occurring dyes from various paint and textile companies have placed aquatic environments at an elevated risk of devastation. To address this pollution of the environment, it is imperative to focus on removing these dyes in order to address environmental pollution. Herein, we used hydrothermal technique to synthesize cerium-doped zinc nanoferrites anchored over graphitic carbon nitride (Ce0.15Zn0.85Fe2O4/g-CN), a photocatalyst that is both extremely adaptable and exceedingly efficient. The association between the catalytic efficiency and the material properties of the manufactured catalysts was examined with a diverse array of methods of characterization. The photodegradation efficacy of the Ce0.15Zn0.85Fe2O4/g-CN photocatalyst was examined using the methyl violet (MV) dye. The Ce0.15Zn0.85Fe2O4/g-CN photocatalyst exhibited an exceptional photodegradation of 97.19 % under solar light in comparison to pure ZnFe2O4 (73.81 %) and Ce0.15Zn0.85Fe2O4 (84.52 %), respectively, under constant conditions of reaction. The Ce0.15Zn0.85Fe2O4/g-CN photocatalyst’s improvement in photodegradation of the MV dye was attributed to a rise in active sites and an elevation in surface area to 128.67 m2/g as a result of g-CN incorporation in the material and was much greater than ZnFe2O4 (76.87 m2/g) and Ce0.15Zn0.85Fe2O4 (92.08 m2/g). The reaction circumstances were also adjusted to ascertain the impact of multiple variables. Radical trapping agents’ studies were employed to validate reactive oxygen species. The Ce0.15Zn0.85Fe2O4/g-CN photostability and recycling were assessed by executing four consecutive investigations under predetermined conditions for the reaction. Eventually, this research will yield an environmentally benign and economically viable photocatalyst for efficiently degrading MV dye in water reservoirs.

Efficient photocatalytic CO2 and Cr(VI) reduction on carbon quantum dots/carbon nitride heterojunctions

Carbon quantum dots (CQDs), known for their exceptional optical properties, hold the potential to enhance light absorption, charges separation and transfer in semiconductor materials. However, using cheap medicinal materials as precursors in the field of photocatalysis to obtain CQDs has seldom concerned. In this study, we utilized biomass-derived CQDs from carbon-rich licorice powder to improve photocatalytic CO2 and Cr(VI) reduction in polymer carbon nitride (PCN). The CQDs/g-C3N4 heterojunctions were synthesized via a hydrothermal method, and the successful fabrication and integration of CQDs on g-C3N4 surfaces were confirmed through detailed characterization. The optimal sample with a licorice powder to PCN mass ratio of 0.05:1 ((50CQDs/CN) demonstrates a tripling in CO2 conversion efficiency under simulated sunlight compared to the reference PCN. Under visible light irradiation, the 50CQDs/CN also performs superior photocatalytic Cr (VI) removal efficiency, which is 2.48 times of that of the reference PCN. This significant boost is attributable to the successful construction of the CQDs/CN heterojunction and the abundance of functional groups on the CQDs surface, which provide more active sites, improve light absorption and increase charges migration rates. The stability of these new photocatalysts was confirmed through repeated photocatalytic cycles, indicating their potential for practical applications. Mechanistic studies reveal insights into the enhanced photocatalytic pathways and intermediate conversion processes. Our findings present a novel, efficient and sustainable route to fabricate g-C3N4-based photocatalysts, offering a promising strategy for further mitigate the greenhouse gas crisis and environmental pollution.

Enhancing formate yield through electrochemical CO2 reduction using BiOCl and g-C3N4 hybrid catalyst

Electrochemical carbon dioxide (CO2) reduction with bismuth-based catalysts has been widely investigated in the recent few years. This is due to bismuth’s ability to perform selective electrochemical CO2 reduction reaction (eCO2RR) to an important C1 product, the formate (HCOO–). However, boosting the performance of such catalysts is a continuous investigation. In this work, enhancing the active sites for eCO2RR is investigated by forming nanocomposites with graphitic carbon nitride (g-C3N4). BiOCl is synthesized by a simple wet-chemical approach in the presence of glycine as size-controlling agent and formed into nanocomposites, which were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Infrared (IR) Spectroscopy and N2 physisorption. Linear Sweep Voltammetry (LSV) in argon and CO2-saturated atmosphere showed higher current values in the case of CO2. Chronoamperometries (CA) were recorded at −1.06 V vs Reversible Hydrogen Electrode (RHE) for 5400 s obtaining Faradic Efficiencies (FE) varying in the range of 70–77 % depending on the nanocomposites’ composition. In fact, 52.1 wt% BiOCl/g-C3N4 formed the highest yields for formate (with also the highest rate of formation of formate) together with a minimal production of H2 and CO. The effect of nano-structuration induced by glycine, used as a size-controlling agent, to form nanoplates was crucial: microplates of BiOCl produced without glycine showed an FE of 4 %, reaching 85 % in the case of the nanoplates. Post-electrocatalysis characterization revealed the possible role of Bi2O2CO3 as the active phase for eCO2RR.

Facile synthesis of mesoporous Co3O4 anchoring on the g-C3N4 nanosheets for high performance supercapacitor

The rational design of the hybrid supercapacitor is the proficient way to confront the problem addressed in the supercapacitor through the collective advantage of each material and even shows laudable electrochemical properties from intertwined effects. A hydrothermal technique was used to effectively incorporate cobalt oxide into layered g-C3N4 nanosheets for a high-performance-based hybrid supercapacitor. The nanocomposite of Co3O4/g-C3N4 (with 0.01 M Co3O4) achieved a maximum specific capacitance of approximately 455 F/g at a current density of 1 A/g. It exhibited 95 % cyclic stability over 10,000 cycles, without sacrificing its coulombic efficiency in a three-electrode configuration. The enhanced charge storage contribution arises from the effective incorporation of cobalt oxide into the layered carbon nitride, increasing the number of electrochemically active sites for electrolytic ions. A symmetric device was fabricated using a KOH gel-based electrolyte, delivering high energy and power density of 28.13 Wh/kg and 1.68 kW/kg, respectively, with a maximum cell operating voltage of 1.2 V. Furthermore, the device demonstrated excellent cyclic stability of 95 % with constant coulombic efficiency.

From aromatic rings to aliphatic compounds - degradation of duloxetine with the use of visible light driven Z-scheme photocatalyst

The growing consumption of antidepressants, associated with their high chemical stability and low biodegradability, become a serious problem for aquatic environment. Many of their components are resistant to conventional water treatment technologies. The photocatalytic processes with the use of semiconductors becoming attractive methods of drugs degradation because the highly reactive species: electrons, holes, hydroxyl radicals (⦁OH) and superoxide anion radicals (O2⦁−) generated under illumination may be involved directly or indirectly in decomposition of complicated organic molecules.In this work we have shown for the first time that Z-scheme photocatalyst, consisted of bismuth vanadate (BiVO4), graphitic-like carbon nitride (g-C3N4) and Au nanoparticles (Au NPs) as a charge transfer mediator, is very efficient in degradation of duloxetine (DLX). We performed the comprehensive evaluation focused not only on degradation rate, mechanism of photocatalytic process, but also identification of decomposition products and the pathways of DLX degradation. Due to application of the elaborated Z-scheme photocatalyst, the degradation rate constant was more than 2-3 times higher than that obtained for photolysis, but more important, the final compounds were mainly aliphatic products, formed by opening of aromatic rings. The chemical structure of the degradation products were determined with the use of HPLC and LC-MS. The toxicity of photoproducts with respect to water organisms was tested by means of Spirotox and Microtox assays. The Microtox test indicated that toxicity of the products after 6h of the solution irradiation in the presence of Z-scheme photocatalyst is about 4 times lower than that after photolysis.

Synergistic enhancement of the photocatalytic activity of g-C3N4 via in-situ surface alkalization and CQDs loading strategies

The CQDs/alkaline carbon nitride heterojunction photocatalysts were synthesized employing dicyandiamide as the nitrogen material, Citric acid was used as the carbon source, while KCl and NH4Cl were as alkaline reagents. The study investigated the influence of CQDs on the adsorption performance, photocatalytic activity, and band structure of alkalized carbon nitride. The dark adsorption results revealed that CNK/CQDs1: 12 exhibited outstanding adsorption performance, capable of degrading adsorbed pollutants in a relatively short period. The photocatalytic degradation study demonstrates that CNK/CQDs1:12 exhibits significantly higher degradation efficiencies compared to the pristine CN and alkalinized CNK samples, with degradation efficiencies of 94.4 % for Methylene Blue (MB) and 71.68 % for tetracycline hydrochloride (TC-HCl) within 60 min. This is due to the synergistic effects of alkalization of the g-C3N4 surface and CQDs loading, which modified the heterojunction interfacial charge transfer efficiency, suppressing the recombination of photoelectron-hole pair, extending the life span of transient photogenerated carriers, thereby improving photocatalytic activity. Free radical trapping experiment indicated that h+ and ·O2− are the primary active species during the photocatalytic degradation process of CNK/CQDs1:12.

Engineering nitrogen vacancies and cyano groups into C3N4 nanosheets for highly efficient photocatalytic H2O2 production

Thermal oxidation of bulky carbon nitride (C3N4, CN) to expose more active sites is an important method to improve the activity of the as-prepared CN nanosheets. Unfortunately, the yield of thermal oxidation is low. Herein, we report dual-deficient CN (DDCN) ultrathin nanosheets engineered with nitrogen vacancies and cyano groups by two-step bottom-up thermal polymerization of belt-like melamine with a high yield of 65%. Featured with abundant exposed active sites, short charge migration distance, wide visible-light absorption, quick charge separation/transfer, enhanced oxygen adsorption ability and 2e oxygen reduction reaction selectivity, the DDCN exhibits a high H2O2 production rate of ∼1031 μmol g1 h1, which is 19.5 times that of CN (53 μmol g1 h1) under visible light irradiation (λ ≥ 420nm). Specifically, the apparent quantum yield (AQY) of DDCN reached 10.7% at 420nm. This study provides a facile dual-defect engineering method to develop highly efficient ultrathin CN-based photocatalysts.

Polyaniline/graphitic carbon nitride/reduced graphene oxide ternary nanocomposite film for flexible thermoelectric application

The present study outlines the preparation of a ternary nanocomposite film comprising of polyaniline doped with camphor sulfonic acid (PANI), reduced graphene oxide (rGO), and graphitic carbon nitride (g-C3N4), and delves into its thermoelectric performance. PANI is known to possess high electrical conductivity (σ) and poor thermal conductivity (κ). However, its potential for thermoelectric applications is constrained by the low value of the Seebeck coefficient (S). The incorporation of g-C3N4in PANI has been demonstrated to result in an improvement of the Seebeck coefficient. Furthermore, the addition of rGO to the PANI/g-C3N4sample counteracts the decrease in electrical conductivity. The PANI/g-C3N4/rGO ternary nanocomposite film exhibits an enhanced Seebeck coefficient of ∼2.2 times when compared to the PANI sample. The Seebeck coefficient of the PANI/g-C3N4/rGO nanocomposite is enhanced by the energy filtering effect that occurs at the interfaces between g-C3N4/PANI and PANI/rGO. Theπ-πinteraction between the PANI chains and rGO is responsible for the increased electrical conductivity resulting from the well-ordered polymer chain arrangement on the g-C3N4and rGO surfaces. The ternary nanocomposite sample demonstrated a synergistic improvement in both electrical conductivity and Seebeck coefficient, resulting in a remarkable ∼4.6-fold increment in power factor and an ∼4.3-fold enhancement in the figure of merit (zT), as compared to the pristine PANI film.

A Well-Coupled Supramolecular System Accelerates Photophosphorylation.

Supramolecular assembly allows multiple chemical/bio-components integrated as one system for cascade biochemical reactions. Herein the graphitic carbon nitrides (g-C3N4) as photocatalyst trapped in a dipeptide hydrogel covering adenosine triphosphate (ATP) synthase accelerates the photophosphorylation through ATP synthesis. Self-assembled N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF) as nanofibrils to allow g-C3N4 nanosheets are embedded as a complex Fmoc-FF/g-C3N4 hydrogel. Fmoc-FF gel exhibits good electronic coupling with g-C3N4, which enables a photo-induced proton generation. The transmembrane proton gradient can be established by ATP synthase-lipid reconstituted on the surface of the Fmoc-FF/g-C3N4 hydrogel to enhance the ATP synthesis. It indicates that the Fmoc-FF/g-C3N4/ATP synthase-lipid film can possess a longer-term ATP production capability and allow repeated immersion for sustained ATP production. Such a hydrogel-supported ATP synthesis platform is achieved by a procedure at a larger scale.