Carbon Nitride Research Articles

Sensitive and fast electrochemical recognition of nitroaromatic explosives in liquid phase using ultrathin graphitic carbon nitride nanotubes

In the present work, a simple, effective method to synthesis high-quality carbon nitride nanotubes with ∼90 nm diameter and 5–9 nm in thickness along with a high-yield (63 %) via template-free hydrothermal synthesis is reported. By using these graphitic carbon nitride nanotubes an advanced electrochemical sensor was demonstrated to selectively sense explosive 2,4-dinitrotoluene. It is demonstrated that bigger linear range towards 2,4-dinitrotoluene, sensing up to 425 μM is reported. Furthermore, the experiments demonstrated that this sensor possesses a high sensitivity not only for 2,4-dinitrotoluene but also for other nitroaromatic explosives.

Sustainable energy generation: High-performance NiCo2S4@S-g-C3N4 bifunctional electrocatalyst advances water splitting efficiency

Efforts to create cost-effective electrocatalysts from abundant materials, for the utilization of water electrolysis reactions, are viewed as promising sources for sustainable clean energy generation. This article describes the synthesis of cobalt sulphide (CoS) nanoparticles using a straightforward and environmentally friendly one-pot hydrothermal process. The series of nickel-doped CoS (NiCo2-x S4) introduced with varying the weight percentage of Ni (1, 2, 4, 8, 6, and 10 wt%), and the composite Ni-dopped CoS on varying the weight percentage (10, 30, 50, 70, and 90 wt %) of sulfur-doped graphitic carbon nitride (NiCo2S4@S-g-C3N4) was created. Utilizing X-ray diffraction analysis (XRD), EDS, FTIR, and scanning electron microscopy (SEM) synthesized electrocatalysts were characterized. Doped with Fluorine After being changed with an electrocatalyst, tin oxide was used as the working electrode to monitor the electrochemical activity of the whole water splitting process using chronopotentiometry, cyclic voltammetry (CV), linear sweep voltammetry (LSV), and EIS. NiCo2S4@S-g-C3N4 exhibited higher electrocatalytic performance with an overpotential 370 mV for OER and 415 mV for HER at the current intensity of 10 mAcm−2. Transition metal sulfide electrocatalysts exhibit good electrolytic performance, due to their high surface areas and intrinsically high catalytic activity. These findings suggest that the NiCo2S4@S-g-C3N4 composite possesses a significant role for use in energy conversion and energy storage applications.

Visible-light-driven photocatalytic degradation of ibuprofen by Cu-doped tubular C3N4: Mechanisms, degradation pathway and DFT calculation

The copper-modified tubular carbon nitride (CTCN) with higher specific surface area and pore volume was prepared by a simple in-situ hydrolysis and self-assembly. Increased ∼4.7-fold and ∼2.3-fold degradation rate for a representative refractory water pollutant (Ibuprofen, IBP) were achieved with low-energy light source (LED, 420 ± 10 nm), as compared to graphitic carbon nitride (GCN) and tubular carbon nitride (TCN), respectively. The high efficiency of IBP removal was supported by narrow band gap (2.15 eV), high photocurrent intensity (1.10 μA/cm2) and the high surface -OH group (14.75 μg/cm3) of CTCN. According to analysis of the various reactive species in the degradation, the superoxide radical (•O2−) played a dominant role, followed by •OH and h+, responsible for IBP degradation. Furthermore, Fukui functions were employed to predict the active sites of IBP, and combined with the HPLC-MS/MS results, possible mechanisms and pathways for photocatalytic degradation were indicated. This study will lay an important scientific foundation and a possible new approach for the treatment of emerging aromatic organic pollutants in visible-light-driven heterogeneous catalytic oxidation environment.

A facile method for boosting the graphitic carbon nitride's photocatalytic activity based on 0D/2D S-scheme heterojunction nanocomposite architecture

Graphitic carbon nitride (g-C3N4) has received significant interest as a metal-free photocatalyst. The S-scheme photocatalytic system has great potential to improve the charge separation in semiconductor photocatalysts. In this study, we have fabricated non-toxic and low-cost photocatalytic nanocomposites of 0D/2D S-scheme heterojunction composed of iron oxide and graphitic carbon nitride by a facile method. The developed facile method provides a sustainable way with a high atom economy to further enhance the photocatalytic performance of exfoliated g-C3N4. The 0D-iron oxide/2D-C3N4 exhibited nearly 10 times better than bulk g-C3N4 and almost 60 % better than exfoliated g-C3N4 under simulated solar light irradiation. The experimental results demonstrated that the effective charge-carrier mechanism led to an improved generation of reactive oxygen species (ROSs), resulting in an impressive photocatalytic performance. A serial photocatalytic test was also conducted to understand photocatalytic reaction mechanisms with various scavengers.

Understanding the role of transition metal implantation on 2D graphitic carbon nitride for solid-state hydrogen storage: A first principles study

Modifying 2D materials with transition metals (TMs) proves to be an effective approach for enhancing their properties in hydrogen storage. In this article, the hydrogen interaction and adsorption over transition metal (TM) atoms (V, Mn, Fe, and Cu) implanted graphitic carbon nitride (gC3N4) is investigated using density functional theory (DFT). The stability of the TM atom on the gC3N4 surface is studied using binding energy and charge density calculations. The adsorption of H2 on the gC3N4 and TM-implanted gC3N4 surfaces is studied using adsorption energy, density of states (DOS), projected density of states (PDOS), charge density difference, and Lowdin occupancy analysis. The obtained results show that the Fe-gC3N4 system exhibits the highest adsorption energy of −1.025 eV for one H2. It is found that each Fe atom implanted on gC3N4 can stably adsorb up to 8H2 molecules, and the average adsorption energy of the 8H2 molecules is −0.201 eV/H2. In the context of practical applications for these materials, desorption is investigated employing the van't Hoff equation. Our findings affirm that the Fe-gC3N4 system can serve as an efficient material for solid-state hydrogen storage.

Preparation of S-C3N4/AgCdS Z-Scheme Heterojunction Photocatalyst and Its Effectively Improved Photocatalytic Performance.

In this study, S-doped graphitic carbon nitride (S-C3N4) was prepared using the high-temperature polymerization method, and then S-C3N4/AgCdS heterojunction photocatalyst was obtained using the chemical deposition method through loading Ag-doped CdS nanoparticles (AgCdS NPs) on the surface of S-C3N4. Experimental results show that the AgCdS NPs were evenly dispersed on the surface of S-C3N4, indicating that a good heterojunction structure was formed. Compared to S-C3N4, CdS, AgCdS and S-C3N4/CdS, the photocatalytic performance of S-C3N4/AgCdS has been significantly improved, and exhibits excellent photocatalytic degradation performance of Rhodamine B and methyl orange. The doping of Ag in collaboration with the construction of a Z-scheme heterojunction system promoted the effective separation and transport of the photogenerated carriers in S-C3N4/AgCdS, significantly accelerated its photocatalytic reaction process, and thus improved its photocatalytic performance.

Electrochemically assisted preparation of graphitic carbon nitride nanosheet membranes for efficient water purification

The development of a highly effective nanofiltration membrane for water purification is crucial for wastewater recovery. The graphitic carbon nitride (g-C3N4) membrane can be an ideal candidate for advanced water treatment due to its intrinsic porous structure and superior physicochemical stability. However, the developments of the g-C3N4 membranes are limited by their traditional preparation methods involving complicated processes, long reaction time and high-temperature conditions. A simple electrochemical-assisted strategy for the rapid preparation of the g-C3N4 nanosheet membranes at room temperature has been developed in this study. The ultra-thin g-C3N4 membrane with a uniform structure can be synthesized within 40 min, which is at least 7 times quicker compared to the traditional methods. The as-prepared g-C3N4 membrane shows a high water flux rate of ∼ 90 L m−2 h−1 bar−1. Simultaneously, an excellent rejection rate of 99.1% toward Evans blue is achieved based on the synergistic effect of size sieving and electrostatic repulsion. The breakthrough in the preparation method of g-C3N4 nanosheet membranes in this work is of great significance to the development of g-C3N4 membranes in the field of water purification.

G-C3N4/TiO2 nanotube array for enhanced photoelectrochemical water splitting

Graphitic carbon nitride (g-C3N4) and TiO2 nanotubes (TNT) have made significant breakthroughs in the field of photocatalysis because of their unique features, such as environmental friendliness, low cost and good stability. Herein, we present the improved photo-electrochemical performance under AM 1.5G irradiation of three different photoanodes based on TNT coated with g-C3N4 via the effortless thermal treatment of anodized TNT sheets over melamine (TNT-M), urea (TNT-U) and dicyanamide (TNT -D). A maximum photocurrent of up to 0.14 mA cm−2 at 1.23 V (vs. RHE) is obtained under illumination using AM 1.5 G light source for TNT-D, which is ten times greater than pristine TNT (0.014 mA cm−2). A good photoelectrochemical stability with efficient charge transfer is observed, and electrochemical impedance spectra reveal that better photoelectrochemical performance is due to the reduced electron-hole pair recombination via the development of heterojunction between TNT and g-C3N4 compared to the bare-TNT electrode.

Development of a labeled-free and labeled electrochemical aptasensor for the detection of cancer antigen 125 by using magnetic g-C3N4/MoS2 nanocomposite

Efficient and timely detection of cancer biomarkers is pivotal for enhancing treatment outcomes and mitigating patient mortality. This study addresses the pressing need for a swift, accurate, and non-invasive method to identify cancer antigen 125 (CA125), a vital biomarker in ovarian cancer. Leveraging the growing prominence of nano-biosensors for their high selectivity and sensitivity, we present the development and characterization of an innovative electrochemical nano-biosensor. The sensor, featuring aptamer strands immobilized on a glassy carbon electrode modified with graphitic carbon nitrides, molybdenum disulfide, and magnetic nanoparticles (g-C3N4/MoS2/Fe3O4), demonstrates superior sensitivity and accuracy in CA125 detection. Utilizing methylene blue for electrochemical detection of labeled CA125 and ferrocyanide for label-free detection, our aptasensor achieves a low limit of detection (LOD) at 0.202 U.mL−1 and 0.215 U.mL−1, respectively, with a broad detection range from 2 to 10 U.mL−1. The modified electrode exhibits a pronounced affinity for CA125, demonstrating enhanced stability compared to other biomolecules. Crucially, the evaluation of both patient and normal serum samples underscores the aptasensor's remarkable performance. These findings not only establish a robust foundation for future research in ovarian cancer diagnosis but also highlight the potential clinical impact of our electrochemical nano-biosensor in advancing early cancer detection methodologies.

Premise setting for sustainable developing adsorption in environmental remediation using graphitic carbon nitride@agar-derived porous carbon composite

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 – equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.

Puffed millet derived bi-functional carbon nitride nano-sheets as efficient photocatalyst and high performance supercapacitor electrode material

The graphitic carbon nitride has been synthesized by eco-friendly method using millet seeds. The thermal puffing effect had turned millet into puffed millet and formed adjacent nanosheets nanostructure. High surface area of g-CN was achieved by using KOH through activation process and nanosheets are in the range of 150–250 nm. CV measurement demonstrated that it has capacitance of 250F/g with high stability and cyclic retention (92.2 %) which are crucial for supercapacitors. The degradation of methyl orange exhibited good photocatalytic performance (efficiency >90 %). This depicts that both “puffing effect” and chemical activation process could change biomaterials into functional materials for practical application.

Understanding the Effect of Saturated Gases on Catalytic Performance of Graphitic Carbon Nitride (g‐C3N4) for H2O2 Generation and Dye Degradation in the Presence of Ultrasound

In this article, the effect of saturated gases on H2O2 generation and dye degradation is examined using graphitic carbon nitride (g‐C3N4) as a piezoelectric catalyst. A detailed catalytic evaluation is carried out using a double‐bath sono‐reactor, where the performance of g‐C3N4 for H2O2 production and degradation of rhodamine B and indigo carmine dyes is evaluated for a range of catalyst dosage levels and saturated gases. Specific gases are selected to understand their role in the sonochemical production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and to elucidate the catalytic mechanism. The use of an Ar–O2 gas mixture leads to the highest yield for H2O2 production and dye degradation due to the positive effect of argon and oxygen in the generation of H2O2 and ROS, respectively. The presence of nitrogen in both air and in an Ar–air mixture increases H2O2 generation since RNS improves the conversion of •OH into H2O2. In contrast, air and Ar–air negatively influences the generation of ROS, which results in a low rate of dye degradation. In this work, new insights of the mechanisms of sonochemical and piezocatalytic processes in the use of graphitic carbon nitride in catalytic applications are provided.

Enhanced paracetamol photodegradation over synthesized TiO2/g-C3N4 nanocomposites: Effect of g-C3N4 loading on the properties and performance

Water pollution has been a consistent issue faced by mankind worldwide. With the increase in world population and rapid urbanization, it has become even more concerning, especially with the detection of new pollutants such as pharmaceutical and personal care products. These compounds must be removed to minimize the adverse effects on all living beings, and one effective method for their elimination is through photocatalytic degradation. In this study, titanium dioxide nanoparticles (TiO2 NPs) was synthesized and nanocomposites were formed with addition of graphitic carbon nitride (GCN) where its loading was varied. These materials were then characterized and used as catalysts to degrade paracetamol, a pharmaceutical product. Structural analysis showed that GCN is present in the nanocomposites indicating the successful modification. Nanocomposites exhibited excellent photocatalytic activity with the highest degradation rate of 0.0364 min−1 was obtained using 2 wt% GCN loading with experimental conditions of an initial paracetamol concentration of 10 ppm, a catalyst dosage of 0.2 g and a pH 5. The synergistic effect that occurred between the two components in the nanocomposites contributed to the high photocatalytic activity, compared to its singular component which is lacking this factor. Overall, nanocomposites have good potential to be used to remove pharmaceutical products from wastewater.

Two new members of the covalent organic frameworks family: Crystalline 2D-oxocarbon and 3D-borocarbon structures

Oxocarbons, known for over two centuries, have recently revealed a long-awaited facet: two-dimensional crystalline structures. Employing an intelligent global optimization algorithm (IGOA) alongside density-functional calculations, we unearthed a quasi-flat oxocarbon (C6O6), featuring an oxygen-decorated hole, and a novel 3D-borocarbon. Comparative analyses with recently synthesized isostructures, such as 2D-porous carbon nitride (C6N6) and 2D-porous boroxine (B6O6), highlight the unique attributes of these compounds. All structures share a common stoichiometry of X6Y6 (which we call COF-66), where X = B, C, and Y = B, N, O (with X ≠ Y), exhibiting a 2D-crystalline structure, except for borocarbon C6B6, which forms a 3D crystal. In our comprehensive study, we conducted a detailed exploration of the electronic structure of X6Y6 compounds, scrutinizing their thermodynamic properties and systematically evaluating phonon stability criteria. With expansive surface areas, diverse pore sizes, biocompatibility, π-conjugation, and distinctive photoelectric properties, these structures, belonging to the covalent organic framework (COF) family, present enticing prospects for fundamental research and hold potential for biosensing applications.

Fabricated layered g-C3N4 nanosheets for high efficiency photocatalytic degradation of atrazine：Insight into terminal-NHx in-situ activation of H2O2

It is well known that graphite-like carbon nitride (g-C3N4) is a good photocatalyst for in-situ the production of H2O2. However, how to activate H2O2 generating the strong oxidizing ·OH is the key factor to affect the degradation of pollutants. In this paper, the layered g-C3N4 nanosheets were prepared by using urea and H2O with different mass ratios and calcined in Muffle furnace by one-step synthesis method. The morphology, composition and structure of photocatalysts were analyzed, indicating that the as-prepared L-g-C3N4-7 had abundant edge regions in comparison with L-g-C3N4 made by solid urea. The photocatalytic performance of g-C3N4 nanosheets was investigated with atrazine (ATZ) as the target pollutant in water. The results revealed that the prepared L-g-C3N4-7 exhibited the best photocatalytic activity in visible light (λ ≥ 420 nm). The degradation of 1.0 mg/L ATZ reached over 96% after 3 hours and the photocatalytic degradation rate constant (k) was 6.8 times than that of L-g-C3N4 photocatalyst. In addition, under the same conditions, the H2O2 production of L-g-C3N4-7 was 4.5 times than that of L-g-C3N4 photocatalyst. Based on the capture experiments of free radicals, it was found that the contribution rate of ·OH in L-g-C3N4-7 photocatalytic increased to 17 % compared to 4 % of L-g-C3N4 photocatalyst during the degradation of ATZ. The ·OH quantitative experiment indicated that the L-g-C3N4-7 photocatalyst could obviously activate H2O2 to generate ·OH and the amount of ·OH was 2.5 times than that of the L-g-C3N4 photocatalyst. More importantly, a large amount of terminal-NHx (14.6 %) in L-g-C3N4-7 was measured by the XPS, FT-IR and zeta potential. The additive H2O2 adsorption experiment in the dark was used to confirm terminal-NHx sites of L-g-C3N4-7 photocatalyst, which was beneficial to adsorb and activate H2O2. The results illustrated that the L-g-C3N4-7 photocatalyst with rich edge regions and terminal-NHx had the characteristics of in-situ the activation of H2O2 to generate ·OH. The findings suggest that designing and developing efficient g-C3N4 photocatalysts pave a new avenue for activating in situ self-synthesizing H2O2 and the removal of atrazine in water.

Sulfur and chloride co-doped g-C3N4 in photocatalytic peroxymonosulfate activation for enhanced acetaminophen removal: Combination of experiments and DFT calculations

As a green photocatalyst with simple synthesis method, excellent electronic structure, and metal-free properties, the deficiencies of pristine graphitic carbon nitride, such as high electron transfer resistance and narrow energy band gap, inhibit its photocatalytic activity to some extent. In this paper, we synthesized a sulfur and chlorine co-doped g-C3N4 (SCl-CN) capable of efficient photocatalytic activation of peroxymonosulfate (PMS) by calcining a mixture of ammonium chloride and thiourea. By means of DFT calculation, the contribution of sulfur and chlorine to photogenic electron hole separation was discussed. The electrostatic potential of SCl-CN and the adsorption model between SCl-CN and PMS were deduced, and the activation mechanism of PMS was further analyzed. According to the calculated results, the incorporation of sulfur and chlorine tuned the electronic configuration of the material and intensified the interactions between SCl-CN and PMS. It is shown that free and non-free radicals act simultaneously in the SCl-CN/PMS/Vis system. This study provides a new idea for the study of photocatalytic activation of PMS by non-metallic co-doped carbon nitride.

Carbon nitride interlayer-enhanced TiO2/WO3 nanorods with surface oxygen vacancies for durable photocathodic performance on 304 stainless steel in simulated seawater

To achieve a long-term photocathodic protective effect on metals in the marine environment, efficient charge mobility and electron storage are essential. Herein, we develop an oxygen vacancy (VO)-involved TiO2-wrapped WO3 nanorod composite by PPy-derived carbon nitride interlayer (TiO2/CNx/WO3) for the photoelectrochemical cathodic protection of 304SS in 3.5 % NaCl solution. The introduced CNx can serve not only as an electron channel to accelerate carrier migration but also as an efficient reductant to generate VO at the interfaces of TiO2 and WO3 during crystallization. The incorporated VO tunes the electronic structure and produces the mid-gap states, which lower the energy barrier for electron-hole separation. Meanwhile, WO3 nanorods as an electron self-storage pool make the photocathodic protection functional in darkness. Consequently, the as-prepared TiO2/CNx/WO3 photoanode yields a photocurrent density of 18.23 μA·cm−2 and a photoinduced cathodic polarization potential of −306 mV in simulated seawater. Even in the absence of light illustration, it can polarize 304SS to approximately −200 mV and continuously to 300 mV after 12h. This work will offer a universal strategy for the rational design and fabrication of highly efficient semiconductor composite materials in the field of photocathodic anticorrosion.

Synergistic Incorporation of 2D Graphitic Carbon Nitride into Bimetal Oxide Photoanodes Towards Higher-Performance DSSCs

Synergistic Incorporation of 2D Graphitic Carbon Nitride into Bimetal Oxide Photoanodes Towards Higher-Performance DSSCs

Integrating Machine Learning Potential and X-ray Absorption Spectroscopy for Predicting the Chemical Speciation of Disordered Carbon Nitrides

Integrating Machine Learning Potential and X-ray Absorption Spectroscopy for Predicting the Chemical Speciation of Disordered Carbon Nitrides

Carbon Dots Anchoring Single-Atom Pt on C3N4 Boosting Photocatalytic Hydrogen Evolution.

Carbon nitride (C3N4) has gained considerable attention and has been regarded as an ideal candidate for photocatalytic hydrogen evolution. However, its photocatalytic efficiency is still unsatisfactory due to the rapid recombination rate of photo-generated carriers and restricted surface area with few active sites. Herein, we successfully synthesized a single-atom Pt cocatalyst-loaded photocatalyst by utilizing the anchoring effect of carbon dots (CDs) on C3N4. The introduction of CDs onto the porous C3N4 matrix can greatly enhance the specific surface area of C3N4 to provide more surface-active sites, increase light absorption capabilities, as well as improve the charge separation efficiency. Notably, the functional groups of CDs can efficiently anchor the single-atom Pt, thus improving the atomic utilization efficiency of Pt cocatalysts. A strong interaction is formed via the connection of Pt-N bonds, which enhances the efficiency of photogenerated electron separation. This unique structure remarkably improves its H2 evolution performance under visible light irradiation with a rate of 15.09 mmol h-1 g-1. This work provides a new approach to constructing efficient photocatalysts by using CDs for sustainable hydrogen generation, offering a practical approach to utilizing solar energy for clean fuel production.