Graphitic Carbon Nitride Sheets Research Articles

A robust floating oxygen-doped graphitic carbon nitride sheet for efficient photocatalytic CO2 conversion

Photocatalytic CO2 reduction offers a promising approach for converting CO2 into valuable chemicals. However, typical conversion systems suffer from inefficient CO2 mass transfer and complex recycling processes. In this study, we developed a floating sheet as a robust photocatalytic CO2 conversion system by integrating graphitic carbon nitride (CN) nanosheets onto polytetrafluoroethylene (PTFE) fiber membrane, followed by oxygen (O) doping into the CN (CN-O) via oxygen-plasma treatment. The floatable CN-O/PTFE sheet exhibits slight wettability in water under 0.25 MPa of CO2 pressure in our reactor system, facilitating the delivery of dissolved CO2 to the CN-O photocatalyst surface. O-doping enhances the visible light absorption and improves the separation and transport efficiency of photogenerated electrons and holes due to O-doping-induced states in CN. Consequently, the floating CN-O/PTFE system achieves an exceptional photocatalytic CO2 conversion rate of 102.3 μmol g-1h−1, approximately 4.8 times higher than a conventional CN-powder dispersion system in water. Moreover, the sheet demonstrates excellent cycling durability, with no significant exfoliation of the catalytic layer or reduction in CO2 photoreduction activity after 20 consecutive cycles. This study presents a novel approach to designing photocatalytic systems for efficient CO2 conversion.

3D/2D-Bismuth Oxybromide Spheres with Selenium-Doped Graphitic Carbon Nitride Sheets: An Efficient Electrocatalyst for the Detection of Arsenic Drug Roxarsone.

Heavy metals are crucial carcinogenic agents threatening the environment and living habituates. Among them, arsenic (As) is an important metalloid that is categorized as a group I toxic carcinogen. Roxarsone (RX) is an organoarsenic antibiotic compound primarily used as a veterinarian drug and growth promoter for poultry animals. The extensive usage of RX increased the accumulation of As in living beings and the ecosystem. Therefore, we have prepared an electrochemical sensor based on 3D bismuth oxybromide with 2D selenium-doped graphitic carbon nitride (BOB/SCN) electrocatalyst for the rapid detection of RX. The elemental and structural details were thoroughly investigated with several spectroscopic techniques. The electrochemical properties were measured by impedance and voltammetric measurements. The electrocatalytic behavior toward the RX was estimated with different voltammetric methods. Therefore, our BOB/SCN-based electrochemical sensor demonstrated a low detection limit (2.3 nM), low quantification value (7.7 nM), optimal sensitivity (0.675 μA μM-1 cm-2), and good linear ranges (0.01-77 and 77-857 μM). Additionally, this sensor showed good electrochemical performance and was applied to monitor the RX in various real samples with remarkable recoveries. Based on these results, our BOB/SCN sensor is a promising electrochemical platform for determining RX.

In-situ Growth of CuO Nanoflakes on Graphitic Carbon Nitride Sheets: An Electro‐active Interface for Electrocatalytic Oxidation and Detection of Riboflavin in Food and Nutritional Supplements

The altered riboflavin (RF) level is considered a biomarker for early diagnosis of human ailments and also serves as an internal marker for tracing food quality and adulteration. This necessitates the need for a sensitive, selective, and affordable method for RF estimation in real samples. RF, a biological chelating ligand, is known to have an affinity for complex formation with Cu(II) by coordinating through the electron-rich nitrogen and oxygen atoms on its structure. Motivated by this, CuO nanoflakes grown over graphitic carbon nitride (gCN) support is presented as an electroactive interface (gCN.CuNF|GCE) for electrochemical RF detection. A systematic analysis of the tailored electroactive interface is presented using HR-SEM, XRD, FT-IR, and XPS. The electrochemical analysis reveals the electro-oxidation of RF at gCN.CuNF|GCE with a 4.6 times higher current and a ∼13 mV potential shift, outlining the electro-catalytic activity of the composite material towards RF. The developed sensor exhibited a discernible peak even for 25 nM RF, showcasing an LOD of 6 nM. Furthermore, excellent selectivity for RF was observed even with potential interfering species, including cyanocobalamin. Besides detectability at the nanomolar range, excellent performance was verified for repeatability and RF analysis in food and pharmaceutical samples.

Enhanced performance of H-C3N2 monolayer as anode material for Li-ion batteries by phosphorus doping

Graphitic carbon nitride sheets (CxNy), which possess a two-dimensional structure similar to N-doped graphene, have been extensively studied as potential anode materials for ion batteries due to their high nitrogen content and porous defect sites that can serve as atomic storage sites for alkali metals. compared with most carbon nitride sheets, monolayer H-C3N2 has the characteristics of higher pyridinic nitrogen content and porosity, and can provide more Li adsorption sites, resulting in a superior theoretical capacity of 2791 mAh/g. However, the high diffusion barrier of 1.75 eV implies the low charge/discharge rate, which limits its application in lithium-ion batteries. Here, this paper demonstrates that doping P atoms in H-C3N2 (PC18N11) has some advantages for application in batteries. Specifically, monolayer PC18N11 exhibits excellent stability and conductivity, much higher theoretical specific capacity (3542 mAh/g). Moreover, PC18N11 exhibits metallic properties when Li-ion is adsorbed, the conductivity is improved, and the interaction between Li-ions will greatly reduce the diffusion barrier. These favorable properties indicate that P-doped H-C3N2 monolayer is a promising anode material for Li-ion batteries.

Graphitic carbon nitride sheets sandwiched metal oxides: A novel platform for S-Scheme heterojunction generation for efficient photodegradation of volatile organics

This study reports the preparation of new kind of S-Scheme heterojunction (SSHJ) photocatalyst by distributing two semiconducting metal oxides (titanium dioxide and ZnO) onto the surface of graphitic carbon nitride (G-CN) two dimensional (2D) sheets. The composite photocatalysts, designated as T/Z@ GCN SSHJ, were prepared with different mass ratios of T,Z and G-CN.X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy were used to characterize the microstructure, morphology, chemical composition, electronic states, and optical properties of the T/Z@ GCN SSHJ composite. TEM image of the typical T/Z@ GCN SSHJ composite shows the presence of distribution of particles with sizes in the range 40–80 nm on the lamellar surface of G-CN inferring the formation of a heterostructure Z(0 D) /G-CN(2D)/T(0D) SSHJ composite. The comparison of the core level XPS spectrum of Ti 2p, Zn 2p, C1s, O1s and N1s of T/Z@ GCNSSHJ composite with the binary composites (T+G-CN and Z+G-CN) and pristine components clearly suggests that that Z, T and G-CN are kept together through van der Walls interactions. The T/Z@ GCN SSHJ composite photocatalyst with T: Z: G-CN mass ratio of 1.0: 0.80: 0.12 exhibited enhanced photocatalytic degradation (%) over binary and pristine single components for all the tested volatile organic compounds (VOCs), namely, acetaldehyde (ACD), ethyl acetate (EA), toluene (T) and benzaldehyde (BA). On comparing the % removal of VOCs after 20 minute of light irradiation, BA showed the highest removal % (94.3 %) and the others take the following order: ACD (70.9 %) >EA (56.45 %)> TL (40.12 %). The study explains the enhanced performance of T/Z@ G-CN HJ composite towards VOC photodegradation in terms of S-Scheme based charge transfer and internal electric field driven efficient charge separation. The charge transfer process of T/Z@ GCN HJ composite photocatalysts is discussed through S-Scheme HJ formation and supported with electronic states and band energy levels of the constituent components derived through the results of XPS and DRS analysis. This study gives insight into the design for regulating the hetero-interfaces for enhancing the photocatalysis and expected to further understand into charge transfer mechanism at multi-junction-based photocatalysts.

Cationic-Surfactant (CTAB) Assisted Preparation of 2D Graphitic Carbon Nitride (g-C3N4) Sheets Advances Supercapacitive Performance

The distinct physicochemical characteristics of metal-free graphitic carbon nitride (g-C3N4) are gaining interest in various fields, including energy storage and conversion. However, the electrochemical performance of this material is constrained, owing to its minimal surface area. Incorporating a surfactant is one of the ways to resolve the issue of surface area and therefore improve the electrochemical performance of g-C3N4. This research delves into a method aimed at improving the supercapacitive capabilities of 2D g-C3N4 sheets through the implementation of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Electrochemical studies reveal that the CTAB-assisted g-C3N4 sheets exhibit remarkable improvements in specific capacitance, cyclic stability, and comparative rate capability in relation to pristine g-C3N4. The specific capacitance of g-C3N4 with CTAB exceeds about 28%, which gives 162. 8 F g−1. This value is 117.7 F g−1 for electrode material without CTAB at 0.5 mA cm−2. This improved electrochemical performance can be credited to the heightened surface area, improved electronic conductivity, and optimized charge transfer kinetics facilitated by the CTAB surfactant. We aim to emphasize the enhancement of the overall performance of g-C3N4-based supercapacitors for advanced energy storage systems.

Complete photodegradation of tetracycline induced by surface microenvironment of graphitic carbon nitride/silver phosphate

Silver phosphate (Ag3PO4) is a promising photocatalyst, but the photo-corrosion issue limits an effective and comprehensive photocatalysis degradation of tetracycline (TC). In this work, a unique graphitic carbon nitride-Ag3PO4 (KCN-AP(40 %)) core-shell structure was prepared via a simple chemical sedimentation method. The unique graphitic carbon nitride sheet encloses Ag3PO4 to trap excited electrons from the conduction band position of Ag3PO4, suppressing the reduction of Ag+ and Ag metal deposition on the surface of Ag3PO4. Under visible light irradiation, the optimized KCN-AP(40 %) can photodegrade nearby 100 % of TC within 20 min with a first-order kinetic constant of 0.127 min−1, which is 3.34 and 3.97-folds higher than those of Ag3PO4 and graphitic carbon nitride, respectively. A series of factors that may affect photoactivity of KCN-AP (40 %) including pH, inorganic ions, and organic matter are investigated. In final, the photodegradation mechanisms and intermediates were proposed based on ex-situ HPLC-MS. This work explains the deep decomposition of TC and presents a facile approach for designing and manufacturing Ag3PO4 based nanohybrids.

Enhancing the efficiency of magnetically driven carbon nitride-based nanocomposites with magnetic nanoflowers for the removal of methylene blue dye at neutral pH.

The present study focuses on the elaboration of magnetic nanocomposites by the in situ incorporation of magnetite (Fe3O4) nanoparticles (NPs) with spherical and nanoflower-like morphologies in graphitic carbon nitride (g-C3N4) sheets using two different synthetic routes. Nanomaterials are characterized by TEM, SEM, XRD, FTIR, BET, zetametry, vibrating sample magnetometry, and UV-vis absorption spectroscopy. The decoration of the carbon nitride matrix with the magnetic NPs enhanced optical and textural properties. The influence of the morphology of the magnetic NPs on the adsorptive and photocatalytic properties of the nanocomposites under different pH conditions (4.5, 6.9, and 10.6) was assessed from batch tests to remove methylene blue (MB) from aqueous solutions. In extreme pH conditions, the nanocomposites exhibited lower or equivalent MB removal capacity compared to the pure g-C3N4. However, at neutral medium, the nanocomposite with incorporated Fe3O4 nanoflowers showed a significantly higher removal efficiency (80.7%) due to the combination of a high adsorption capacity and a good photocatalytic activity in this pH region. The proposed nanocomposite is a promising alternative to remove cationic dyes from water by magnetic assistance, since no pH adjustment of the polluted effluent is required, reducing costs and environmental impact in the dyeing industry.

Multifunctional graphitic carbon nitride/manganese dioxide/epoxy nanocomposite coating on steel for enhanced anticorrosion, flame retardant, mechanical, and hydrophobic properties

Benzidine (Bz) was used to modify the nanofiller, manganese dioxide (MnO2), and the resulting Bz/MnO2 was then encased in pure epoxy resin (EP) with graphitic carbon nitride (GCN). The effectiveness of epoxy-coated mild steel in protecting against varying concentrations of GCN/Bz-MnO2 was assessed through the use of electrochemical techniques in natural seawater. The flame retardancy capabilities of the epoxy coating were significantly improved by the incorporation of GCN/Bz-MnO2. The EP-GCN-Bz/MnO2 nanocomposites display peak heat release rate (PHRR) and total heat release (THR) values which are 79 % and 62 % lesser than that of pure EP, respectively. When compared to a pure epoxy coating, the results of salt spray tests indicated that the addition of GCN/Bz-MnO2 improved corrosion protection and decreased water absorption. Electrochemical impedance spectroscopy (EIS) studies showed that the epoxy-GCN/Bz-MnO2 coating still had an improved resistance of 6.40E10 Ω.cm2 even after 30 days of exposure to seawater. Scanning electrochemical microscopy (SECM) displayed lowest ferrous ion dissipation (1.0 I/nA) in the EP-GCN/Bz-MnO2 nanocomposite coated steel. Potentiodynamic polarization testing showed that EP-GCN-Bz/MnO2 had a lower current density (icorr: 0.03 µA/cm2) in comparison with other coatings. This is mainly because the Bz alteration of the MnO2 nanoparticles and their successful coordination with GCN sheets result in a noticeably more compact nanostructure that lowers aggregation and increases binding capacity. Surface-modified GCN was found to be improved in its breakdown products, leading to the production of a strong, inert nanolayered covering, according to Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) analysis. Water contact angle (WCA) of 160° demonstrates the exceptional water resistance of the recently developed EP-GCN/Bz-MnO2 coating. In terms of hardness and adhesion strength, Bz/MnO2 wrapped in GCN had good mechanical characteristics on the epoxy substrate. The improved adhesive strength (18.3 MPa) for mild steel coated with EP-GCN/Bz-MnO2 was attained prior to being immersed in seawater. The EP-GCN/Bz-MnO2 crystallizes form a robust, inert coating that prevents ions from accessing the specimen. The coating has increased adhesive strength as a result, and it can withstand deep immersions without losing its integrity. Hence, the EP-GCN/Bz-MnO2 nanocomposite might work as a useful coating component in the automotive industry.

Enhancement of Pb(ii) adsorptive removal by incorporation of UiO-66-COOH into the magnetic graphitic carbon nitride nanosheets.

Efficient elimination of Lead (Pb(ii)) from aqueous solutions has become a crucial area of focus in the wastewater treatment industry. In this study, novel mesoporous magnetic g-C3N4/Fe3O4/UiO-66-COOH was synthesized by combining the acid-functionalized metal-organic framework (MOF) of UiO-66-COOH via a facile novel solvothermal method with magnetic graphitic carbon nitride (g-C3N4/Fe3O4) sheets to enhance Pb(ii) adsorption in water. The study investigated various influential adsorption parameters, including pH, dosage, contact time, ion concentration, and temperature. The Langmuir model, which depicts monolayer adsorption on a uniform surface, was a more suitable fit for the adsorption isotherms. The kinetics conformed to the pseudo-second-order model, indicating a chemical adsorption mechanism. According to the Langmuir model, the adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is expected to reach a maximum of 285.8 mg L-1. This value is 2.6 times higher than g-C3N4/Fe3O4 and 1.6 times higher than UiO-66-COOH. The enhanced adsorption capacity of g-C3N4/Fe3O4/UiO-66-COOH is attributed to its superior characteristics, such as abundant functional groups and high surface area which is 2.16 times higher than g-C3N4/Fe3O4. The adsorption thermodynamics indicated that the adsorption occurred spontaneously and was characterized as exothermic. g-C3N4/Fe3O4/UiO-66-COOH material exhibited good recyclability for up to five runs.

A DFT study the role of pristine and metal doped of g-CN nanosheet for drug delivery system

This research focuses on investigating how a targeted drug delivery system (DDS) can improve distribution and bioavailability of a drug on tumor cells. Specifically, study examines the use of pristine and Al-doped graphitic carbon nitride (C3N) sheets as the delivery system. By employing density functional theory (DFT), researchers analyze interaction between anticancer drug cisplatin (Cis) and sheets. Results demonstrate that doping process modifies characteristics of pristine sheets, leading to improved adsorption of anticancer drugs. Al-doped sheet exhibits a cohesive energy within range of 4.96 eV, indicating its high stability. Present work has uncovered that adsorption of Cis drug over pristine C3N sheet is weak, with low adsorption energy (Eads) values of approximately −3.26 eV and −2.19 eV in a gaseous (aqueous) phase, respectively. However, Eads is significantly enhanced by approximately 85.92 % through introduction of Al doping in pristine C3N sheet. Primary interactions within the complexes are examined employing non-covalent interaction (NCI) analysis, utilizing a reduced density gradient (RDG) map. Cis@Al-C3N complex reveals that non-covalent interactions have a significant role in drug adsorption. Moreover, NCI indicates van der Waals interactions exert a substantial impact on interaction between carrier sheets and anticancer drug. Present investigation sets foundation for future research focusing on utilization of doped C3N sheets as effective drug carriers in targeted DDSs, potentially benefiting a wide range of drugs.

Comparative investigation of the characterization and photoactivity of gold-decorated graphitic carbon nitride: A study aspect of various synthesis approaches

In recent decades, photocatalysis has been broadly considered one of the potential approaches for different environmental and medicinal applications. Different synthesis methods possess different benefits and drawbacks, requiring thorough comparison to optimize the usage of precursors, equipment, and photocatalysis activity of the materials. In this study, the gold-decorated graphitic carbon nitride nanocomposites (AuCN) were successfully fabricated via different methods, including hydrothermal (HT), radiation under visible light (Ir), and chemical reduction (VC). The characterization of the prepared materials was investigated, which showed an efficient exfoliation of graphitic carbon nitride (g-C3N4 − CN) sheets and uniform embedment of gold nanoparticles (AuNPs). The AuCN sample synthesized from the chemical approach (AuCN-VC) showed the strongest signals of the AuNPs content, while the material prepared from the hydrothermal method (AuCN-HT) indicated a better CN crystalline structure. Furthermore, the photoactivity of the fabricated materials was also compared with pristine CN via the analysis of band structure, elucidating an improvement in the band gap energy to 2.25, 2.59, and 2.68 eV for the hydrothermal, irradiation, and chemical approaches, respectively. According to the photocatalysis results, AuCN-VC possessed the highest photo behavior under visible illumination with the hydrogen peroxide yield production at 271.5 mM/g.h. Meanwhile, the observation in the antibacterial activity exhibited the greatest performance regarding AuCN-HT with the recorded inhibition zone diameters of 9.3 and 8.6 mm against P. aeruginosa and S. aureus, respectively, under photo-excitation. According to the aforementioned results, the synthesized AuCN composites suggest great potential in a wide range of applications in environmental remediation and renewable production.

Novel and facile strategy for immobilization of Ag3PW12 crystals on graphitic carbon nitride (g-C3-N4) sheets, a superior photocatalyst for decomposition of organic waste

The high electron-holes recombination rate in pure graphitic carbon nitride (C3–N4) restrict their photocatalytic efficiency. In this research work, we successfully immobilized Ag3PW12O40 a polyoxometalate-base crystal on graphitic carbon nitride 2D sheet through physical grinding method to prevent charges recombination on the surface. Both the materials were prepared separately and then grinded after mixing, to get C3–N4@Ag3PW12 heterojunction. The prepared C3–N4@Ag3PW12 composites were tested with different characterization techniques to confirm its structural integrity and successful fabrication of heterojunction. The composite catalyst showed expansion in UV light absorbance where it promotes from 406 nm to 454 nm for pure C3–N4 and composite C3–N4@Ag3PW12-30 % respectively. The composite showed better electron-holes separation, confirmed from its electrochemical performance such as TPC (total photocurrent) and PL data. The prepared catalysts were tested for the degradation of two types of organic dyes such as methylene blue and Rhodamine B under photoirradiation. The C3–N4@Ag3PW12-30 % composite photocatalyst showed efficient photocatalytic activity and removed 99 % methylene blue in 75 min while removed 99.4 % Rhodamine B in 60 min while the pure Ag3PW12 and C3–N4 could only remove 26.3 % and 37.7 % methylen blue and 43.54 % and 53.38 % rhodamin B respectively, in the same conditions. The results show that, the Ag3PW12 crystals deposition on C3–N4 2D sheets is a preferred approach to enhance the catalytic performance of C3–N4 2D sheet.

Wet-chemical engineering of Ag-BiVO4/Bi2S3 heterostructured nanocomposite on graphitic carbon nitride (g-C3N4) sheets for high performance supercapacitor application

Graphitic carbon nitride (g-C3N4), a structural analogue of graphite has opened a new arena in energy storage. The N-rich g-C3N4 sheets similar to N-doped carbon materials provide large number of defect sites for increased diffusion and adsorption of electrolyte ions. High N-content in g-C3N4 is most suitable to escalate metal‑carbon binding energy which stabilizes the pseudo-active transition metal oxides/chalcogenides over carbon support to realize high capacitive performance. In this study, we have impregnated binary Ag-BiVO4/Bi2S3 heterostructures on g-C3N4 sheets through wet-chemical approach, as novel electrode material for supercapacitor application. As prepared Ag-BiVO4/Bi2S3@g-C3N4 composite (ABVBS@g-C3N4) along with Ag-BiVO4/Bi2S3 (ABVBS), Ag-BiVO4 (ABV), and Bi2S3 (BS) were systematically characterized by different techniques i.e., XRD, FTIR, FESEM, EDS, and BET analysis. When applied for electrochemical tests, among all the analyzed electrodes ternary composite ABVBS@g-C3N4 exhibited highest electrochemical activity with a specific capacitance value of 872 F/g (@5 mV/s) and 815.4 F/g (@1 A/g), and 91.5 % capacitance retention up to 5000 GCD cycles. The initial coulombic efficiency of ABVBS@g-C3N4 was noteworthy (99.42 %) due to very low internal resistance. Moreover, it was analyzed that ternary composite ABVBS@g-C3N4 has lower equivalent series resistance (RES) as 6.73 Ω and charge transfer resistance value as 7.73 Ω, in comparison to other electrodes. This excellent electrochemical performance of ABVBS@g-C3N4 is attributed to combined contributions from ABVBS and g-C3N4 in terms of multiple redox states, increased wettability of electrode, and high structural and chemical stability. Considering the results, our study proposes feasible strategy to generate hybrid electrode materials with optimized properties to serve as energy storage material for next generation supercapacitors.

Cobalt molybdate hollow spheres decorated graphitic carbon nitride sheets for electrochemical sensing of dimetridazole

In the present work, a cobalt molybdate (CoMoO4) hollow spheres-incorporated graphitic carbon nitride (g-CN) composite is prepared for the electrochemical detection of dimetridazole (DZ). The synergistic effect between the hollow-structured CoMoO4 and g-CN nanosheets facilitates the transportation of electrons through kinetic barriers, thereby providing a high electrical conductivity with increased electroactive sites. The proposed CoMoO4@g-CN-modified electrode displayed a wide linear range (0.001–492.77 μM) and a lower detection limit (LOD: 0.4 nM) for the determination of DZ through the amperometry (i–t) method. In addition, the CoMoO4@g-CN-modified electrode achieved good operational stability, anti-interfering ability (five-fold excess amount of co-interfering compounds) and reproducibility. These results demonstrate the increased electrocatalytic activity of CoMoO4@g-CN modified glassy carbon electrode (GCE) towards the detection of DZ in food samples with satisfactory recovery ranges.

A detailed experimental comparison on the hydrogen storage ability of different forms of graphitic carbon nitride (bulk, nanotubes and sheets) with multiwalled carbon nanotubes

The reversible hydrogen storage of graphitic carbon nitride (g-C3N4) nanotubes at room temperature was first studied through experimental methods in this work and was compared to multiwalled carbon nanotubes (MWCNT), bulk g-C3N4, and g-C3N4 nanosheets. Compared with MWCNT which had a similar specific surface area around 60 m2/g, g-C3N4 nanotubes had a higher room temperature hydrogen storage capacity up from 0.46 wt% for MWCNT to 0.78 wt%. This value for the g-C3N4 nanotubes was also higher than the hydrogen storage capacity of bulk g-C3N4 (0.51 wt%) and g-C3N4 nanosheets (0.73 wt%), even though g-C3N4 nanosheets had the highest specific surface area of 161 m2/g. Temperature programming desorption (TPD) was applied to study the desorption behaviours and it was found that chemisorption contributed to the relative high storage capacity of g-C3N4 nanotubes.

Photocatalytic CO2 Reduction to CH4 and Dye Degradation Using Bismuth Oxychloride/Bismuth Oxyiodide/Graphitic Carbon Nitride (BiOmCln/BiOpIq/g-C3N4) Nanocomposite with Enhanced Visible-Light Photocatalytic Activity

The use of visible-light-driven photocatalysts in wastewater treatment, photoreduction of CO2, green solar fuels, and solar cells has elicited substantial research attention. Bismuth oxyhalide and its derivatives are a group of visible-light photocatalysts that can diminish electron–hole recombination in layered structures and boost photocatalytic activity. The energy bandgap of these photocatalysts lies in the range of visible light. A simple hydrothermal method was applied to fabricate a series of bismuth oxychloride/bismuth oxyiodide/grafted graphitic carbon nitride (BiOmCln/BiOpIq/g-C3N4) sheets with different contents of g-C3N4. The fabricated sheets were characterized through XRD, TEM, SEM-EDS, XPS, UV-vis DRS, PL, and BET. The conversion efficiency of CO2 reduction to CH4 of BiOmCln/BiOpIq of 4.09 μmol g−1 can be increased to 39.43 μmol g−1 by compositing with g-C3N4. It had an approximately 9.64 times improvement. The photodegradation rate constant for crystal violet (CV) dye of BiOmCln/BiOpIq of k = 0.0684 can be increased to 0.2456 by compositing with g-C3N4. It had an approximately 3.6 times improvement. The electron paramagnetic resonance results and the quenching effects indicated that 1O2, •OH, h+, and •O2− were active species in the aforementioned photocatalytic degradation. Because of their heterojunction, the prepared ternary nanocomposites possessed the characteristics of a heterojunction of type II band alignment.

Iron/vanadium co-doped tungsten oxide nanostructures anchored on graphitic carbon nitride sheets (FeV-WO3@g-C3N4) as a cost-effective novel electrode material for advanced supercapacitor applications.

In this work, we studied the effect of iron (Fe) and vanadium (V) co-doping (Fe/V), and graphitic carbon nitride (g-C3N4) on the performance of tungsten oxide (WO3) based electrodes for supercapacitor applications. The lone pair of electrons on nitrogen can improve the surface polarity of the g-C3N4 electrode material, which may results in multiple binding sites on the surface of electrode for interaction with electrolyte ions. As electrolyte ions interact with g-C3N4, they quickly become entangled with FeV-WO3 nanostructures, and the contact between the electrolyte and the working electrode is strengthened. Herein, FeV-WO3@g-C3N4 is fabricated by a wet chemical approach along with pure WO3 and FeV-WO3. All of the prepared samples i.e., WO3, FeV-WO3, and FeV-WO3@g-C3N4 were characterized by XRD, FTIR, EDS, FESEM, XPS, Raman, and BET techniques. Electrochemical performance is evaluated by cyclic voltammetry (CV), galvanic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). It is concluded from electrochemical studies that FeV-WO3@g-C3N4 exhibits the highest electrochemical performance with specific capacitance of 1033.68 F g-1 at scan rate 5 mV s-1 in the potential window range from -0.8 to 0.25 V, that is greater than that for WO3 (422.76 F g-1) and FeV-WO3 (669.76 F g-1). FeV-WO3@g-C3N4 has the highest discharge time (867 s) that shows it has greater storage capacity, and its coulombic efficiency is 96.7%, which is greater than that for WO3 (80.1%) and FeV-WO3 (92.1%), respectively. Furthermore, excellent stability up to 2000 cycles is observed in FeV-WO3@g-C3N4. It is revealed from EIS measurements that equivalent series resistance and charge transfer values calculated for FeV-WO3@g-C3N4 are 1.82 Ω and 0.65 Ω, respectively.

Ag-decorated BiOCl anchored onto the g-C3N4 sheets for boosted photocatalytic and antimicrobial activities

The most promising strategy for environmental preservation and wastewater treatment is to create semiconductor-based photocatalysts. Semiconducting photocatalysts have gained considerable attention for water treatment applications due to their excellent and notable efficiency. The present work is based on the fabrication of bismuth oxychloride (BiOCl), and silver-decorated bismuth oxychloride (Ag@BiOCl) by the facile co-precipitation method. The composite of silver-decorated bismuth oxychloride with graphitic carbon nitride sheets (Ag@BiOCl/g-C3N4) was synthesized using an ultra-sonication approach. The as-fabricated samples were then characterized using different techniques like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), and UV–Visible spectroscopy. XRD confirmed the formation of as prepared samples while FESEM confirmed their flower-like morphology. FTIR and EDX were used respectively to confirm the functional groups and elemental composition of prepared photocatalysts. Furthermore, electrochemical impedance spectroscopy (EIS), and the Mott-Schottky experiment were performed to analyze the charge separation efficiency and recombination rate of photoreactive species. The optical band gap (Eg) was measured using a UV–Visible spectrophotometer. The Eg value of BiOCl and Ag@BiOCl are 3.38 eV and 2.93 eV respectively. Also, the fabricated photocatalysts were used for the photo-degradation of Rhodamine B (RhB), Crystal violet (CV), and phenol. The degradation efficiency of Ag@BiOCl/g-CN is high as compared to pristine BiOCl and Ag@BiOCl. The % degradation of RhB, CV, and phenol by Ag@BiOCl/g-CN are 92 %, 95.29 %, and 40.24 % respectively. The samples were also used as antimicrobial agents against K.Pneumoniae and S.aureus. Ag@BiOCl/g-CN composite demonstrated outstanding antibacterial efficacy against both positive and negative strains.

Silver doped NiAl2O4 nanoplates anchored onto the 2D graphitic carbon nitride sheets for high-performance supercapacitor applications

In the current study, NiAl2O4, and silver doped NiAl2O4 were synthesized via a sol-gel approach and their composite with g-C3N4 was successfully prepared via an ultrasonication approach. The characterization of as fabricated materials was carried out via various conventional techniques. Furthermore, the electrochemical behavior of the as-fabricated electrode materials was investigated via various electrochemical techniques. The results of electrochemical measurements were analyzed for all three prepared electrodes and Ag-NiAl2O4@g-C3N4 nanocomposite was found to be a more active electrode material than other prepared electrodes. Ag-NiAl2O4 @g-C3N4 showed specific capacitance of 768 Fg−1, 94.01% capacitance retention after 6000 CV cycles, 519 s discharge time, 0.51 Ω charge transfer resistance, 27 WhKg−1, and 187.28 WKg−1 energy and power densities respectively. Ag-NiAl2O4@g-C3N4 can be considered a potential and propitious electrode material for high-performance supercapacitors.