Graphitic Nanosheets Research Articles

Graphitic carbon nitride nanosheet and ferroelectric PbTiO3 nanoplates S-scheme heterostructure for enhancing hydrogen production and textile dye degradation

Graphitic carbon nitride (g-C3N4) is a reliable photocatalyst that can be activated by visible light. However, its photocatalytic efficiencies are hindered by the rapid recombination of charge carriers on its surface. A hybrid photocatalyst consisting of a ferroelectric PbTiO3 nanoplate/g-C3N4 S-scheme heterojunction was synthesized using an ultrasonic-assisted hydrothermal method, to overcome the aforementioned limitation. The PbTiO3 nanoplates incorporated into the g-C3N4 matrix created a strong electric field, resulting in superior photocatalytic activities. This improvement can be attributed to the efficient separation of the photogenerated charge carriers. The hybrid photocatalyst (10PTCN) exhibits an impressive H2 evolution rate (1587.82 µmol.g−1.h−1) under simulated solar irradiation. The hybrid photocatalysts demonstrated 99.40 % methylene blue (30 mg·L−1) in 90 min under simulated solar irradiation with remarkable reusability. This work contributes to enhancing the understanding of utilizing ferroelectric 2D nanoplates to develop efficient charge transfer schemes for improved photocatalysts.

Construction of Phosphorus‐Doped g‐C3N4 Nanosheets and Activation of Sodium Percarbonate for Degradation of Organic Pollutants in Wastewater

AbstractA novel phosphorus‐doped graphitic carbon nitride nanosheets (PS‐CN) photocatalyst was prepared by thermal polycondensation and thermal stripping method, and its physicochemical properties were characterized. The results show that PS‐CN formed a thin sheet and multi‐cavity structure by thermal delamination that could enhance the surface area, light reception, and adsorption capacity. The prepared PS‐CN activated sodium percarbonate system (PS‐CN/SPC) was developed for the degradation of dyeing wastewater with methylene blue (MB) as the target pollutant and the degradation mechanism was analyzed. At room temperature (20 °C), the degradation rate of MB in PS‐CN/SPC system within 10 min (88.13 %) was three times that of pure g‐C3N4. In addition, the MB was completely degraded under visible light within 60 min. Moreover, PS‐CN exhibited excellent reusability that the degradation rates of MB have remained above 96 % in five consecutive cycles. The free radical quenching experiments showed that hole (h+), hydroxyl radical (•OH) and superoxide radical (•O2−) all participated in MB degradation, and •OH was the main active species. The PS‐CN/SPC system would provide a high‐value solution for the treatment of dye wastewater due to the low cost of raw materials, superior photocatalytic activity, simple synthesis method, and reusability of the catalyst.

Electrochemically prepared ultrathin two-dimensional graphitic nanosheets as cathodes for advanced Zn-based energy storage devices

Abstract Zinc-ion supercapacitors (ZISCs) exhibit great potential to store energy owing to the benefits of high power density and environmentally friendly features. However, solving the drawbacks of low specific energy and poor cyclic performance at high current rates is necessary. Thus, developing better cathode materials is a practical and efficient way to overcome these limitations. This work presents an encouraging design of two-dimensional (2D) graphite ultrathin nanosheets (GUNSs) as a cathode material for ZISCs. The experimental results show that the GUNSs-based cathode material exhibits a wide surface area and rapid charge transformation features. The 2D GUNS as a cathode was tested in three-electrode systems, and it provided an exceptionally high capacitance of 641 F/g at 1 A/g in an aqueous ZnSO4 electrolyte, better than GUNS-N2 (462 F/g at 1 A/g) and pristine graphite (225.8 F/g at 1 A/g). The 2D GUNS has a rate performance of 43.8% at a current density of 20 A/g, better than GUNS-N2 (35.6%) and pristine graphite (8.4%) at the same conditions. Furthermore, a ZISC device was fabricated using GUNSs as cathode and Zn-foil as anode with 1 M ZnSO4 electrolyte (denoted as GUNSs//Zn). The as-fabricated GUNSs//Zn device exhibits an excellent capacitance of 182.5 F/g at 1 A/g with good capacitance retention of 97.2%, which is better than pristine graphite (94.6%), and nitrogen-doped GUNS (GUNS-N2) cathode (95.7%). In addition, the GUNSs//Zn device demonstrated an ultrahigh cyclic life of 10,000 cycles, and 96.76% of capacitance was maintained. Furthermore, the GUNSs//Zn device delivers a specific energy of 64.88 W h/kg at an ultrahigh specific power of 802.67 W/kg and can run a light-emitting diode for practical applications.

Enzyme-free intelligent films in electrochemistry of malathion with a binary architecture: Combined Cu2+ complexed carbon nitride nanosheets and poly(N,N-dimethylacrylamide) hydrogels

In the present work, surface and interfacial modifications have been used to successfully prepare a low-cost enzyme-free electrochemical sensor was constructed and assembled a smart binary hydrogel film of Cu@g-C3N4 NSs/PDEA (g-C3N4 NSs: graphitic C3N4 nanosheets; PDEA: poly(N,N- dimethylacrylamide). On account of g-C3N4 NSs have multiple uniform nitrogen coordination sites, making it easy to adsorb metal ions. Complexation of Cu2+ to g-C3N4 NSs enhances the electrical conductivity while increasing the specific surface area of the nanomaterials. They are used for trace monitoring of malathion. It showed good stability when detecting malathion in synthetic urine. A 4-Input/7-Output logic gate system including OR, AND and NOT is constructed using membrane electrode switching behavior for pH, temperature, SO42–, and methanol. And a 2-to-4 decoder was constructed. The complexity of non-traditional computer systems is enriched by this logic gate system about contaminants.

Anti-fouling graphene oxide membranes intercalated with Co-anchored graphitic carbon nitride nanosheet for enhanced water purification

Membrane separation technology has been widely used in wastewater recycling. Graphene oxide (GO) membranes have been widely developed, but membrane fouling is still a serious challenge. Here, GO-based membranes intercalated with Co-anchored graphitic carbon nitride nanosheet (Co@CNN) were prepared by a vacuum-filtrated assembly strategy. The resulting GO/Co@CNN membrane with an appropriate interlayer d-spacing (0.81 nm) and loading yield (0.30 ± 0.03 mg/cm2) can effectively separate methyl blue (MB) with a flux of 66.9 ± 2.7 L m-2h−1 under 1 bar, although the membrane has been fouled due to the adsorption of MB on the sample. Co@CNN can activate potassium peroxymonosulfat (PMS) to generate multiple active free radicals for the oxidation of MB via an advanced oxidation process (AOP). Therefore, the fouled membrane renews and can be employed to deal with wastewater repeatedly.

Hetero-Single-Atom F and P-Doped Layered Graphitic Carbon Nitride Nanosheets for Electrochemical Quantification of Vanillin in Food Samples

Hetero-Single-Atom F and P-Doped Layered Graphitic Carbon Nitride Nanosheets for Electrochemical Quantification of Vanillin in Food Samples

Preparation of a fast and simple electrochemical sensor of bismuth telluride decorated on graphitic carbon nitride nanosheets for determination of epinephrine in biological samples

The current research work synthesized bismuth telluride nanocomposite as a sensor for measuring epinephrine. The synthesized bismuth telluride was characterized using X-ray diffraction, transmission electron microscopy, Raman analysis, energy dispersive X-ray spectroscopy, and field emission scanning electron microscopy. Differential pulse voltammetry was used to measure epinephrine. The linear range for epinephrine was 10 µM - 783.56 µM and the detection limit was calculated to be 0.710 µM. The advantages of the proposed sensor include good stability, excellent reproducibility, excellent selectivity, an easy synthesis method, and a short analysis time. The efficiency of this electrode was checked in biological samples to measure epinephrine. The obtained results indicate the high success of the modified electrode for epinephrine drug measurement.

G-C3N4@CuO electrostatic self-assembly toward Ralstonia solanacearum: Insights from cytomembrane and motility disruption.

Ralstonia solanacearum, a notorious and refractory bacterial plant pathogen, threatens multiple vegetable crops and causes significant economic loss in agriculture. Long-term use of traditional medicines not only increases the problem of drug resistance, but also causes great environmental pollution. Therefore, there is an urgent need to develop new agents with high efficacy and low toxicity. In this study, we have synthesized and characterized graphitic carbon nitride incorporated copper oxide composite (g-C3N4@CuO), which showed higher antimicrobial effect than graphitic carbon nitride nanosheets (g-C3N4 nanosheets) and copper oxide nanoparticles (CuONPs). Ralstonia solanacearum exposed to g-C3N4@CuO exhibited higher levels of oxygen toxicity, cell membrane damage, DNA damage, motility disruption and even cell death compared to g-C3N4 nanosheets and CuONPs. In addition, g-C3N4@CuO was more effective in the control of tobacco bacterial wilt than g-C3N4 nanosheets and CuONPs. Thus, this study provides a new perspective on g-C3N4@CuO control of bacterial diseases in crops, and the mechanism is related to the destruction of cell membrane damage and motility disruption. © 2024 Society of Chemical Industry.

The first-principles study of pure and doped g-CN nanosheet as a drug delivery system

Nanomaterials are increasingly being studied for their potential to serve as drug delivery systems that can transport anticancer drugs directly to tumor cells, thereby minimizing side effects and enhancing treatment effectiveness. This innovative application of nanotechnology holds significant promise in the field of biomedicine. Within the current piece of research, pure graphitic carbon nitride nanosheet (PC3NNS) and Si-doped C3NNS (C3NNS) were selected as a drug delivery system (DDS) for examining the distribution and bioavailability of 6-Mercaptopurine (6-MP) on cancerous cells through the DFT. After doping the Si atom, the attributes of PC3NNS changed, thereby increasing the adhesion process of 6-MP. The adhesion energy of the Si@C3NNS was in the range of 5.5 eV, which demonstrated that it was highly stable. The current work demonstrated the poor adhesion of 6-MP on the PC3NNS with the adhesion energy of approximately −1.72 eV and −2.83 eV in water and gaseous phases respectively. The adhesion energy increased by around 96.21 % after the Si atom was doped on the PC3NNS. The non-covalent interaction (NCI) analysis and the reduced density gradient (RDG) map analysis were performed to examination the main interactions between nanosheet and drug. It was demonstrated that NCIs played a key role in the adhesion of 6-MP in the complex of 6-MP@Si-C3N. Moreover, the NCI analysis demonstrated the significant impact of van der Waals interactions upon the interactions between 6-MP and the nanosheets. The current work can provide insights into the application of C3NNSs as promising drug carriers for many drugs in targeted DDSs.

Porous and graphitic carbon nanosheets with controllable structure for zinc-ion hybrid capacitor

The imbalances of storage capacity and reaction kinetics between carbonaceous cathodes and zinc (Zn) anodes restrict the widespread application of Zn-ion hybrid capacitor (ZIHC). Structure optimization is a promising strategy for carbon materials to achieve sufficient Zn2+ storage sites and satisfied ion–electron kinetics. Herein, porous graphitic carbon nanosheets (PGCN) were simply synthesized using a K3[Fe(C2O4)3]- and urea-assisted foaming strategy with polyvinylpyrrolidone as carbon precursor, followed by activation and graphitization. Sufficient pores with well-matched pore sizes (0.80–1.94 nm) distributed across the carbon nanosheets can effectively shorten mass-transfer distance, promoting accessibility to active sites. A partially graphitic carbon structure with high graphitization degree can accelerate electron transfer. Furthermore, high nitrogen doping (7.2 at.%) provides additional Zn2+ storage sites to increase storage capacity. Consequently, a PGCN-based ZIHC has an exceptional specific capacity of 181 mAh g−1 at 0.5 A g−1, superb energy density of 145 Wh kg−1, and excellent cycling ability without capacity decay over 10,000 cycles. In addition, the flexible solid-state device assembled with PGCN exhibits excellent electrochemical performances even when bent at various angles. This study proposes a straightforward and economical strategy to construct porous graphitic carbon nanosheets with enhanced storage capacity and fast reaction kinetics for the high performance of ZIHC.

Facile production of highly porous graphitic nanosheets for enhanced hydrogen storage

Graphitic nanosheets as a two-dimensional material are renowned an ideal candidate for efficient adsorbents due to their rapid adsorption kinetics and superior capacity. This study presents a facile method to develop highly porous graphitic nanosheets (PGNs) from converted carbon blacks (CBs) for hydrogen (H2) storage. The CBs, containing interconnected amorphous and graphitic domains, allows the introduction of numerous H2-friendly adsorption sites during PGNs production. The resulting PGNs show large sheets of 3–5 μm and thicknesses of ∼ 2.5 nm, boasting a remarkable specific surface area of 2,644 m2/g with significant total H2 storage capacities of 11.5 wt% (3.8 kWh kg−1 @ 77 K) and 2.6 wt% (0.87 kWh kg−1, @ 298 K) at 60 bar. This research introduces a promising strategy to enhance PGNs's H2 storage capabilities, paving the way for diverse energy-related fields.

Electrochemical Nanoaptasensor Based on Graphitic Carbon Nitride/Zirconium Dioxide/Multiwalled Carbon Nanotubes for Matrix Metalloproteinase-9 in Human Serum and Saliva.

In this study, a nanocomposite was synthesized by incorporating graphitic carbon nanosheets, carboxyl-functionalized multiwalled carbon nanotubes, and zirconium oxide nanoparticles. The resulting nanocomposite was utilized for the modification of a glassy carbon electrode. Subsequently, matrix metalloproteinase aptamer (AptMMP-9) was immobilized onto the electrode surface through the application of ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride-N-hydroxysuccinimide (EDC-NHS) chemistry. Morphological characterization of the nanomaterials and the nanocomposite was performed using field-emission scanning electron microscopy (FESEM). The nanocomposite substantially increased the electroactive surface area by 205%, facilitating enhanced immobilization of AptMMP-9. The efficacy of the biosensor was evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under optimal conditions, the fabricated sensor demonstrated a broad range of detection from 50 to 1250 pg/mL with an impressive lower limit of detection of 10.51 pg/mL. In addition, the aptasensor exhibited remarkable sensitivity, stability, excellent selectivity, reproducibility, and real-world applicability when tested with human serum and saliva samples. In summary, our developed aptasensor exhibits significant potential as an advanced biosensing tool for the point-of-care quantification of MMP-9, promising advancements in biomarker detection for practical applications.

Efficient removal of U(VI) from aqueous solution by CNN/UiO-66 under simulated sunlight irradiation: the synergy of adsorption and photocatalysis.

The reduction of soluble U(VI) to insoluble and less toxic U(IV) by photocatalysis is an effective method to control uranium contamination. The graphitic carbon nitride nanosheet (CNN)/UiO-66 composites (CNNU) were prepared by thermal polymerization and solvothermal methods for the removal of U(VI). The morphology, crystal structure and optical properties of composites were analyzed by SEM, XRD, BET, UV-DRS, PL and EIS. The results showed the introduction of UiO-66 increased the specific surface of CNN from 9.07 m2/g to 46.24 m2/g, and effectively suppressed the recombination of photogenerated electrons and holes and improved the photocatalytic activity. The U(VI) removal capacity by adsorption and photocatalysis of CNNU was reached 779.47mg/g, which significantly higher than that of adsorption (478.38mg/g). The adsorption process was found to conform to the pseudo-second-order kinetic model and the Langmuir isothermal model. Meanwhile, U(VI) adsorbed on the CNNU was reduced to U(IV) via e- and ·O2- generated in the photocatalytic process. Therefore, this outstanding performance of CNNU in U(VI) removal is attributed to the synergistic effect of adsorption and photocatalytic reduction.

Spontaneous adsorption effect of graphitic carbon nitride nanosheets to improve sintering behavior of yttria-stabilized zirconia microbeads

Yttria-stabilized zirconia (YSZ) is a ceramic material in which the zirconium dioxide structure is stabilized at room temperature by adding yttrium oxide. However, the YSZ formed by the thick film process on a pre-sintered dense substrate suffers from sintering problems such as different sintering shrinkage rates due to phase transitions and thermal conductivity. This in turn can lead to de-bonding, cracking, delamination, and abnormal growth. We prepared a spherical YSZ green body of approximately 38 μm diameter formed by an organic binder based on a sintered YSZ seed with 15 to 20 μm diameter. In addition, the application of two-dimensional g-C3N4 nanosheets that can be adsorbed on the surface and pores of the green body before the sintering process was evaluated. The YSZ green body with adsorbed surface-modified g-C3N4 nanosheets could be synthesized by stable spontaneous adsorption due to zeta-potential attraction onto the surface of zirconia particles in an aqueous solution. Consequentially, the formation of large grains due to abnormal grain growth was reduced as g-C3N4 was adsorbed. The spontaneous adsorption of nanosheets controls the surface diffusion mechanism by sequentially lowering the energy from a high surface energy in the initial stage of sintering. Uniform grain growth thus can be induced according to the activation energy level of the controlled surface diffusion.

In situ synthesis of graphitic carbon nitride nanosheet/Ti3C2Tx MXene/TiO2 Z-scheme heterojunctions boosting charge transfer for full-spectrum driven photocatalytic sterilization

The development of a full-spectrum responsive photocatalytic germicide with excellent charge separation efficiency to harvest high antimicrobial efficacy is a key goal yet a challenging conundrum. Herein, graphitic carbon nitride nanosheet (PCNS)/Ti3C2Tx MXene/TiO2 (PMT) Z-scheme heterojunctions with robust interface contact were crafted by in situ interfacial engineering. The strong internal electrical field (IEF) from PCNS to TiO2, evinced by the Kelvin Probe Force Microscopy (KPFM) characterization, can obtain high charge separation efficiency with 73.99%, compared to Schottky junction PCNS/Ti3C2Tx (PM, 32.88%) and PCNS (17.70%). The Ti3C2Tx component can not only serve as a transfer pathway to accelerate the recombination of photoexcited electrons of TiO2 and holes of PCNS under the Ultraviolet–visible (UV–vis) light irradiation, but also replenish the photogenic electron concentrations to semiconductors in the near-infrared (NIR) light illumination. Meanwhile, the increased temperature due to the localized surface plasmon resonance (LSPR) can further boost the electronic activity to the generation of reactive oxygen species (ROS). Taken together, the PMT performs a high disinfection efficiency up to 99.40% under full solar spectrum illumination, 3.88 and 9.75 times higher than PCNS and TiO2, respectively, surpassing many reported Z-scheme heterojunctions. This work offers guidance for the design of Z-scheme heterojunction with the implanting of plasmons to secure excellent full-spectrum responsive photocatalytic sterilization performance.

Nano carbon-modified air purification filters for removal and detection of particulate matters from ambient air

Particulate matters (PMs) pose significant risks to human health and the environment, necessitating research to enhance air purification filters and reduce harmful emissions. This study focuses on the preparation of carbon nanomaterials, including graphitic carbon nitride nanosheets (g-C3N4 NSs), reduced graphene oxide (r-GO), and carbon nanotubes (CNT), for modifying filters in air particle monitoring devices. The objective is to investigate the impact of these nanomaterials on enhancing PM adsorption efficiency. Quantitative and qualitative analyses of the modified filters’ adsorption efficiency towards PMs are performed using spectroscopic techniques such as Energy-Dispersive X-ray Spectroscopy (EDX), Inductively Coupled Plasma (ICP), and Laser-Induced Breakdown Spectroscopy (LIBS). The results reveal that CNT-modified filters exhibit superior adsorption efficiency compared to the control, g-C3N4, and r-GO-modified filters. The exceptional performance of CNTs is attributed to their large specific surface area and pore volume. Additionally, LIBS demonstrates its capability to detect heavy metals like Cd, which remain undetected by EDX and ICP. The technique proves sensitive for heavy metal monitoring. This novel approach is expected to garner significant attention and contribute to the development of improved air purification technologies.

Electron-enriched single-Pd-sites on g-C3N4 nanosheets achieved by in-situ anchoring twinned Pd nanoparticles for efficient CO2 photoreduction

Modulating electronic structures of single-atom metal cocatalysts is vital for highly active photoreduction of CO2, and it's especially challenging to develop a facile method to modify the dispersion of atomical photocatalytic sites. We herein report an ion-loading pyrolysis route to in-situ anchor Pd single atoms as well as twinned Pd nanoparticles on ultra-thin graphitic carbon nitride nanosheets (PdTP/PdSA-CN) for high-efficiency photoreduction of CO2. The anchored Pd twinned nanoparticles donate electrons to adjacent single Pd–N4 sites through the carbon nitride networks, and the optimized PdTP/PdSA-CN photocatalyst exhibits a CO evolution rate up to 46.5 ​μmol ​g−1 ​h−1 with nearly 100% selectivity. As revealed by spectroscopic and theoretical analyses, the superior photocatalytic activity is attributed to the lowered desorption barrier of carbonyl species at electron-enriched Pd single atoms, together with the improved efficiencies of light-harvesting and charge separation/transport. This work has demonstrated the engineering of the electron density of single active sites with twinned metal nanoparticles assisted by strong electronic interaction with the support of the atomic metal, and unveiled the underlying mechanism for expedited photocatalytic efficiency.

Copper sulfide-incorporated layered porous sulfur-doped graphitic carbon nitride nanosheets for an efficient catalytic reduction of 4-nitrophenol

A straightforward one-pot synthesis of CuS nanoparticles directly grown on layered porous sulfur-doped graphitic carbon nitride nanosheets (CuS/S-g-C3N4) acts as a catalyst for the reduction of 4-nitrophenol.

A graphitic C3N4 nanocomposite-based fluorescence platform for label-free analysis of trace mercury ions.

In this study, a nanocomposite consisting of graphitic carbon nitride nanosheets loaded with graphitic carbon nitride quantum dots (CNQDs/CNNNs) was synthesized via a one-step pyrolysis method. This nanocomposite exhibited excellent thermal stability, photobleaching and salt resistance. Then a new fluorescence sensing platform based on CNQDs/CNNNs was constructed, which showed high sensitivity and selectivity towards trace mercury ions (Hg2+). By using X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra and density functional theory, the fluorescence response mechanism was elucidated where Hg2+ could interact with CNQDs/CNNNs, causing a structural change in the nanocomposite, further affecting its bandgap structure, and finally leading to fluorescence quenching. The linear range for detecting Hg2+ was found to be 0.025-4.0 μmol L-1, with a detection limit of 7.82 nmol L-1. This strategy provided the advantages of a rapid response and a broad detection range, making it suitable for quantitative detection of Hg2+ in environmental water.

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets.

Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst used for visible-driven hydrogen production, CO2 reduction, and organic pollutant degradation. In addition to the most attractive feature of visible photoactivity, its other benefits include thermal and photochemical stability, cost-effectiveness, and simple and easy-scale-up synthesis. However, its performance is still limited due to its low absorption at longer wavelengths in the visible range, and high charge recombination. In addition, the exfoliated nanosheets easily aggregate, causing the reduction in specific surface area, and thus its photoactivity. Herein, we propose the use of ultra-thin porous g-C3N4 nanosheets to overcome these limitations and improve its photocatalytic performance. Through the optimization of a novel multi-step synthetic protocol, based on an initial thermal treatment, the use of nitric acid (HNO3), and an ultrasonication step, we were able to obtain very thin and well-tuned material that yielded exceptional photodegradation performance of methyl orange (MO) under visible light irradiation, without the need for any co-catalyst. About 96% of MO was degraded in as short as 30 min, achieving a normalized apparent reaction rate constant (k) of 1.1 × 10-2 min-1mg-1. This represents the highest k value ever reported using C3N4-based photocatalysts for MO degradation, based on our thorough literature search. Ultrasonication in acid not only prevents agglomeration of g-C3N4 nanosheets but also tunes pore size distribution and plays a key role in this achievement. We also studied their performance in a photocatalytic hydrogen evolution reaction (HER), achieving a production of 1842 µmol h-1 g-1. Through a profound analysis of all the samples' structure, morphology, and optical properties, we provide physical insight into the improved performance of our optimized porous g-C3N4 sample for both photocatalytic reactions. This research may serve as a guide for improving the photocatalytic activity of porous two-dimensional (2D) semiconductors under visible light irradiation.