3N4 Composites Research Articles

Vanadium doped nickel oxide/g-C3N4 composites for multifunctional biosensing of dopamine, ascorbic acid and H2O2

We demonstrated a nonenzymatic electrochemical sensor based upon vanadium-doped nickel oxide composite with graphitic carbon nitride. The g-C3N4 was prepared by annealing Urea at 550 °C for 3 h in a muffle furnace. The nanocomposite was synthesized using a microwave-assisted method, followed by thermal annealing at different temperatures. The successful formation of V–NiO/g-C3N4 was confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. SEM images show the layered sheets with porous structure, which depends on annealing temperature; as we increase the temperature, the porosity increases. Afterwards, the electrochemical sensing properties were verified by CV, LSV, DPV, and amperometric studies in 0.2 M KOH in the presence of Ascorbic acid and Dopamine. The experimental results show that our prepared sample has excellent electrochemical biosensing abilities towards AA and DA with LOD 1.16 μM and 0.16 μM, respectively. It also offers good selectivity, exceptional reproducibility, and long-term stability owing to the combined effect of NiO and g-C3N4. Finally, the electrochemical sensing of H2O2 was detected in the same environment by conducting CV and amperometric studies. Our modified electrode has proven its noble ability to sense H2O2 with excellent repeatability, stability and low LOD 0.2 μM with a wide linear working range (0.5 mM–4 mM). It has the potential to be used for multi-molecule selection biosensing with excellent selectivity and sensitivity.

Comprehensive Study on the Properties of AZ91/x-Si3N4 Composites for Their Prospective Application

Metal alloy matrix composites are generally lightweight structural materials with a high strength-to-weight ratio. They can be extensively used in various fields of modern engineering applications, such as aerospace and automotive components and biomedical engineering. This study focuses on the development and characterization of lightweight metal alloy matrix composites for industrial applications, with a particular emphasis on magnesium (Mg) alloys as a replacement for aluminum-based alloys. Mg alloys offer significant weight advantages, being 33% lighter than aluminum and 75% lighter than steel, making them highly desirable for use in various engineering fields. In the present study, Mg (AZ91) alloy reinforced with x-Si3N4 composites (x = 0, 1, 3, 5, 7, 9 wt.%) were fabricated using a liquid state process. The AZ91/x-Si3N4 composites were evaluated through physical, mechanical, wear, and microstructural characterization. The experimental results, supported by statistical analysis, demonstrated that the incorporation of Si3N4 particles amplified the mechanical properties, wear resistance, and porosity of the composites. However, the presence of the reinforced particles resulted in reduced forgeability and elongation, limiting certain deformation characteristics. The existence of the reinforced particles within the composites was confirmed through SEM analysis, providing visual evidence of their distribution and interaction within the Mg alloy matrix. Finally, it was concluded that the implication of the study could be sought for the light structural parts of aerospace, automotive, biomedical, and prosthetic applications.

Simultaneously Utilizing Excited Holes and Electrons for Piezoelectric-Enhanced Photoproduction of H2O2 from S-Scheme 2D S-Doped VOx/g-C3N4 Nanostructures.

2D/2D step-scheme (S-scheme) piezo-photocatalysts for the production of fine chemicals, such as hydrogen peroxide (H2O2), have attracted significant attention of global scientists owing to the efficiency in utilizing surface piezoelectric effects from 2D materials to overcome rapid charge recombination in photocatalytic processes. In this research, we reported the fabrication of 2D S-doped VOx deposited on 2D g-C3N4 to produce H2O2 via the piezo-photocatalytic process with high production yields at 20.19 mmol g-1 h-1, which was 1.75 and 4.87 times higher than that from solely piezo-catalytic and photocatalytic H2O2 generation. The finding pointed out that adding sulfur (S) to VOx can help to improve the catalytic outcomes by modifying the electronic properties of pristine VOx. In addition, when coupled with g-C3N4, the presence of S limits the formation of graphene in the VOx/g-C3N4 composites, causing shielding effects and pushing the cascade reactions toward water generation in the materials. Besides, the research also sheds light on the charge transport between g-C3N4 and S-VOx under irradiation and how the composites work to trigger the formation of H2O2. The presence of S in the composite systems enhances charge transfer between two semiconductors by strengthening the internal electric fields (IEF) to drive electrons moving in one direction, as demonstrated by density functional theory (DFT) calculations. Moreover, the formation of H2O2 significantly relies on the reduction of oxygen to generate oxygenic radical species at the g-C3N4 sites. Meanwhile, S-VOx provides oxidative sites in the composites to oxidize water molecules to directly or indirectly generate H2O2 or O2, which will further participate in the reactions to produce the final products. This study confirms the validation of S-scheme piezo-photocatalysts, thus encouraging further research on developing heterojunction materials with high catalytic efficiency, which can be used in practical conditions.

Synthesis of nanosheet-like α-Ni(OH)2/g-C3N4 hybrid anode material with enhanced lithium storage performance

Nickel hydroxide (Ni(OH)2) has been recognized as a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity, cost-effectiveness, and simple synthesis method. However, the application of Ni(OH)2 is hampered by its volume effect and poor electrical conductivity. To address these challenges, herein, a α-Ni(OH)2/g-C3N4 composite is prepared by a hydrothermal approach. The composite possesses a hierarchical nanosheet-like morphology with fibrous nanostructures on the surface. Due to the unique hybrid nanostructure and the synergistic effect of α-Ni(OH)2 and g-C3N4 components, the α-Ni(OH)2/g-C3N4 composite exhibits significantly enhanced lithium storage performance in terms of electrochemical activity, cyclability, and kinetics than the bare α-Ni(OH)2 counterpart. Specifically, the α-Ni(OH)2/g-C3N4 achieves a remarkable capacity of 696 mA h g−1 after 400 cycles at 0.5 A g−1, far larger than the corresponding value (96 mA h g−1) of pure α-Ni(OH)2. CV and GITT analysis demonstrate the α-Ni(OH)2/g-C3N4 composite has an obvious pseudocapacitance behavior and a much smaller polarization effect than the bare α-Ni(OH)2 during cycling. This work could provide clues for the structural design and performance improvement of nickel hydroxide-based anode materials for LIBs.

Extremely interfacial bonding and photocatalytic environmental remediation on amouphous-TiO2/g-C3N4 heterojunctions by mechanochemical synthesis

TiO2/g-C3N4 composites have emerged as the most potent alternative for green photocatalysis, but are plagued by low photoactivity due to poor interfacial bonding. Herein, we report a straightforward mechanical ball milling method to fabricate an amorphous TiO2/g-C3N4 heterojunction. EPR, XPS and XAFS are used to prove that the N atoms of g-C3N4 was successfully doped into the crystal lattice of Am-TiO2 and formed typical Ti···N structure. The obtained 30-AT/CN (30 wt% g-C3N4) composites can form more heterojunction interfacial bonds and extremely improve the separation of charge carriers, showing superior photocatalytic reduction performance of perrhenate (non-radioactive chemical substitute for pertechnetate) and higher photochemical degradation rate of rhodamine B than the bulk counterpart. The material has a progressive Z-scheme heterojunction (S-scheme heterojunction), which increases the transfer ability and prolongs the lifetime of the photogenerated charge carriers. These results suggest a wide range of applications in the preparation method of heterojunction photocatalysts that are potential candidates for environmental remediation.

Development of 2D/2D h-MoO3/Ag/g-C3N4 heterojunction photocatalyst with enhanced photocatalytic performance for the detoxification of methylene blue and tetracycline under solar light illumination

In this study, direct thermal polycondensation, hydrothermal, and ultrasonic techniques were used to fabricate photocatalysts consisting of bare g-C3N4 (GCN), h-MoO3 (MoO3), MoO3/g-C3N4 (MGCN), and MoO3/Ag/g-C3N4 (MAGCN) composites. These methods were used to improve the photocatalytic effect, especially for environmental applications. The surface and chemical properties of the fabricated samples were investigated by XRD, FT-IR, FE-SEM, HR-TEM, UV-DRS, XPS, and PL analysis. Bare and composite photocatalysts were tested for photodegradation of the methylene blue (MB) dye and tetracycline (TC) antibiotic under solar irradiation. The MAGCN composite material exhibits remarkable efficiency in degrading 99% of MB dye and 90% of TC antibiotic within a time frame of 60 min when exposed to sunlight irradiation. The degradation rate constants (k) of MB and TC in the most active MAGCN photocatalyst were 11.02 and 7.03 times higher than those of pristine GCN, respectively. The scavenger reaction shows that the most important reactive species in the photocatalytic process are superoxide and photogenerated holes. The outstanding photocatalytic efficiency of the MAGCN catalyst was demonstrated by the fact that Ag nanoparticles act as mediators of fast charge transfer, resulting in higher absorption of sunlight, enhanced charge separation/transfer, and regeneration by MoO3 and GCN. The MAGCN photocatalyst exhibits remarkable activity, maintains its performance over six consecutive reaction cycles, and exhibits excellent stability and reusability. Intermediates were analyzed by GC-MS, and suitable degradation pathways were proposed. These results enable the development of an effective Z-scheme heterojunction photocatalyst and facilitate its wide application in the degradation of organic pollutants in wastewater.

Constructing adaptive silicon–carbon interconnected network for high-energy lithium-ion batteries

Nano-silicon (n-Si)/graphite anodes are highly desirable for high-energy lithium-ion batteries. Nevertheless, the high surface energy of n-Si grains is prone to causing serious agglomeration. In this work, the modified n-Si is evenly dispersed on the g-C3N4 carbon mesh that acquired through melamine heat treatment constructing an adaptive Si-carbon interconnection network structure (mSi50/g-C3N4). Ideally, the mSi50/g-C3N4 composite can be well dispersed and fill the gaps in graphite through traditional ball milling processes. The obtained mSi50/g-C3N4/Gr composite prevents the accumulation of Si grains which is beneficial for expediting ion transport, improving conductivity and structural stability. As a result, this anode provides a reversible capacity of 621 mAh⋅g−1 at 0.2 C, with high-capacity retention of 93.3 % after 300 cycles at 1 C and low volume expansion of only 28.6 %. Furthermore, it also maintains excellent cycling stability in full batteries with LiFePO4 cathode. Therefore, constructing the mSi50/g-C3N4 network is an effective strategy to achieve uniform dispersion of Si in graphite and promote larger scale industrialization of n-Si/graphite anode.

Ultrasensitive dual-mode detection of amyloid β oligomer via Au NRs modulated photoelectrochemical/electrochemiluminescent response from HOFs/g-C3N4

In this work, a heterojunction composite of HOFs/g-C3N4 was synthesized using solution-plasticized self-assembly of g-C3N4 nanosheet on hydrogen-bonded organic frameworks (HOFs). HOFs/g-C3N4 was then used as a substrate material to construct a novel photoelectrochemical/electrochemiluminescent (PEC/ECL) biosensor for the detection of amyloid β oligomer (Aβo). HOFs/g-C3N4 composites were first drop-coated on the electrode surface. Subsequently, the Aβ aptamer was modified on the electrode surface via amide bonding. The target Aβo and the gold nanorods (Au NRs)-labeled Aβ recognition peptide (Au NRs-KLVFF) were simultaneously dropped onto the electrode surface, thus a “sandwich” dual-mode biosensor was constructed. In the PEC detection of the Aβo, the surface plasmon resonance effect of Au NRs enhanced the visible absorption of HOF/g-C3N4, and the sensor exhibited a "signal-on" photocurrent signal. Meanwhile, the ECL emission spectrum of HOF/g-C3N4 in ECL mode overlaps with the ultraviolet-visible (UV) absorption of Au NRs, and the sensor signal showed a “signal-off” ECL response. Under the optimal conditions experiments, the constructed dual-mode biosensor showed a wide detection range and low detection limit for Aβo. The proposed dual-mode detection method has a detection range of 10 fM to 10 nM with a detection limit of 5.97 fM for PEC detection and a detection range of 0.1 pM to 1.0 μM with a detection limit of 0.051 pM for ECL detection respectively. Additionally, the detection method achieved satisfactory results in the analysis of real samples. Dual-mode sensing platform provides a new strategy for HOFs application in PEC/ECL assay and sensitive detection of AβO.

Construction of flake ball-shaped Bi2WO6 embedded on phenyl functionalized g-C3N4 nanosheet for efficient degradation insight of colorless pollutants and its biological application.

A facile solvent-free solid-state method was adapted to synthesize the spherical-shaped Bi2WO6 engraved on phenyl-doped g-C3N4 nanosheet, i.e., Bi2WO6/Ph-gC3N4 (or BPCN) composites with varying weights of Bi2WO6. Several spectral analyses were used to characterize all the synthesized nanomaterials. The synthesized photocatalyst showed good absorption under visible light as confirmed by UV-visible DRS analysis. Morphological analyses like SEM and TEM determine the successful fabrication of binary heterocomposite. Further, the elements available in the fabricated binary nanocomposite were confirmed by XPS. The photocatalyst was used for the aerobic photocatalytic degradation of a few colorless pollutants like bisphenol A (BPA, 30mgL-1), a microplastic constituent, and tetracycline (TC, 40mgL-1), an antibiotic derivative to achieve the impressive results. The less intense PL signal obtained for the 20BPCN heterocomposite reveals the remarkable enhancement in e--h+ pair separation and recombination rate. The quenching study, alkaline terephthalic acid photoluminescence test (TA-PL), and NBT phototransformation study explain the formation of reactive species involved in the decomposition process. An oral cancer cell line (A-254) was tested for the anticancer activity analysis of the 20BPCN photocatalyst. Based on the obtained results, a Z-scheme electron transfer mechanism has been proposed for the photodegradation of model compounds.

Enhanced photoreduction of U(VI) in solution by Ti3C2Tx/g-C3N4 composites

The enhanced transfer efficiency of electron from photocatalyst to U(VI) is crucial for U(VI) photoreduction. Herein, we developed porous 2D/2D Ti3C2Tx/g-C3N4 heterojunction structure through the pyrolysis gasification of urea during direct calculation of Ti3C2 nanosheet and urea. Ti3C2Tx/g-C3N4 hybrid displayed the exceptional photocatalytic performance, high reaction rate constant (k1 = 0.0228 min−1) and rapid removal kinetics due to high photocatalytic activity, good chemical stability and highly efficient separation of photo-generated electron-hole pairs. According to quenching experiments and ESR analysis, the superoxide (.O2-) radicals played an important role in U(VI) photoreduction by Ti3C2Tx/g-C3N4. The higher efficient migration of photo-generated electrons from g-C3N4 to Ti3C2 co-catalyst was attributed to the tight interfacial interaction of –NHx of g-C3N4 with Ti3C2 via NHx-Ti chemical bonding, which increased the photoreduction of U(VI) into U(IV) by XPS analysis. The findings are crucial for designing g-C3N4-based catalysts by manipulating electronic structure for enhanced U(VI) photoreduction.

Locally released H2 and O2 from an artificial periosteum modulate the survival and reparative activities of stem cells derived from the aged human nasal mucosa after transplantation

Stem cell therapies are limited by poor cell survival and engraftment. Elderly diabetic patients (EDPs) have a greater risk of bone graft failure. Herein, a g-C3N4/polydopamine (PDA@g-C3N4) composite nanosheet was successfully fabricated via in situ polymerization of PDA on a g-C3N4 surface. Then, the PDA/g-C3N4 composite was crosslinked with a fibrin hydrogel to prepare an artificial periosteum for EDPs. With the help of NIR, we showed that the synthetic artificial periosteum released H2 and O2 and enhanced the survival and osteogenic differentiation of aged human nasal mucosa-derived ectodermal stem cells (hEMSCs) in microenvironments characterized by oxidative stress and hypoxia. The artificial periosteum had pleiotropic effects on aged hEMSC reparative activities, modulating cytokine secretion and the protein expression of effectors associated with vascularization, and bone formation in vivo. Our findings imply that the developed artificial periosteum loaded with hEMSCs has great promise for the repair of bone defects in EDPs.

Solar photocatalytic CeO2/g-C3N4 removal of micropollutants in the water environment through the generation of singlet oxygen

The synthesis of photocatalysts with good photocatalytic performance to selectively oxidize micropollutants in complex water environments has received widespread attention. This study successfully synthesized a CeO2/g-C3N4 composite, which could degrade sulfamethoxazole (SMX) up to 95 % under simulated sunlight (SSL) in 60 min. Additionally, it exhibited favorable selective oxidation characteristics in complex water environments. EPR and radical scavenging experiments proved the main oxidation contributions of singlet oxygen (1O2) in the system. Photoluminescence spectroscopy demonstrated that the composite material could generate more triplet excitons to generate 1O2 with ground-state oxygen (3O2) through an energy transfer pathway. The product analysis of the two models of micropollutants, SMX and carbamazepine, indicated an overall rise in the biodegradability of the majority of intermediates, accompanied by a decrease in acute toxicity. The composite showed high stability even after 5 cycles. Various micropollutants have degradation of varying degrees in different natural water matrices. In summary, this study introduced a novel photocatalytic oxidation strategy with selective oxidation capability, providing possibilities for practical applications and environmentally friendly photocatalytic processes.

Template-free synthesis of hierarchical graphitic carbon nitride (H-gC3N4) embedded with NiO for water splitting and CO2 reduction with the role of hole scavenger: A comparative investigation

Hierarchical graphitic carbon nitride (H-gC3N4) embedded with nickel oxide (NiO) were synthesized using a template-free hydrothermal approach. The performance of NiO/H-gC3N4 composite was investigated for photocatalytic water splitting in a slurry system to produce H2. Similarly, photocatalytic CO2 reduction to generate CO under visible light was conducted in a gas-phase photoreactor system. Optimized 2% NiO/H-gC3N4 composite enables H2 production of 1010 μmol g−1 h−1, which was 13.93 folds higher than using pure H-gC3N4. Similarly, the highest CO evolution rate of 96.7 μmol g−1 h−1 was obtained, 3.85 folds higher than using H-gC3N4. The enhanced photoactivity resulted mainly from the distinctive interlayer structure, improved light penetration, reduced charge carrier recombination and increased surface-reactive active sites. The methanol sacrificial reagent, owing to its capacity to generate extra protons, proved pathways in augmenting the yields of both H2 and CO. While the efficiency of water splitting for H2 production surpassed that of CO2 reduction, it exhibited lower stability. The recently developed composite demonstrated consistent and sustained photocatalytic efficiency for CO production throughout five consecutive cycles.

Construction of a direct Z-scheme Cs3Bi2Cl9/g-C3N4 heterojunction composite for efficient photocatalytic degradation of various pollutants in water: Performance, kinetics and degradation mechanism

The use of emerging composite materials has been booming to remove environmental pollutants. The aim of this research is to develop a new composite based on Cs3Bi2Cl9 perovskite and graphitic carbon nitride (g-C3N4) to investigate the photocatalytic performance under visible light irradiation. To achieve this, we produce the Cs3Bi2Cl9/g-C3N4 heterojunctions through a simple self-assembly synthesis. The as-synthesized composites are characterized using XRD, FTIR, FESEM, TEM, BET and EDX techniques. The photocatalytic performance of Cs3Bi2Cl9/g-C3N4 is examined in the degradation of various water contaminants, including 4-nitrophenol (4-NP), tetracycline antibiotic (TC), methylene blue (MB) and methyl orange (MO). The experimental results indicate the superior photocatalytic performance of the composites in the degradation of pollutants compared to pure Cs3Bi2Cl9 and g-C3N4. The 10% Cs3Bi2Cl9/g-C3N4 composite achieves the optimal degradation efficiency of 100, 92, 98.7, and 85.1% of 4-NP, TC, MB, and MO, respectively. This superior photocatalytic activity attributes to improved optical and electrochemical properties, including enhanced absorption ability, narrowing band gap, promoted separation efficiency of photogenerated carriers, and a high redox potential, which is confirmed by UV–vis DRS, PL, EIS, and CV analyses. The 10% Cs3Bi2Cl9/g-C3N4 composite also demonstrates high photocatalytic stability after four consecutive cycles. Radical trapping tests show that superoxide radicals (•O2−), holes (h+), and hydroxyl radicals (•OH) contribute to the photocatalytic process. Based on the obtained data, a direct Z-scheme heterojunction mechanism is proposed. Overall, this research offers a new stable photocatalyst with excellent prospect for photocatalytic applications.

Hybrid HMX multi-level assembled under the constraint of 2D materials with efficiently reduced sensitivity and optimized thermal stability

The interfacial interaction between HMX molecules and coating materials is the key to the safety performance of explosives and has received extensive attention. However, screening suitable coating agents to enhance the interfacial effect to obtain high-energy and low-sensitivity explosives has long been a major challenge. In this work, HMX-PEI/rGO/g-C3N4 (HPrGC) composites were innovatively prepared by a multi-level coating strategy of two-dimensional graphite rGO and g-C3N4. The g-C3N4 used for desensitization has a rich π-conjugated system and shows outstanding ability in reducing friction sensitivity. The hierarchical structure of HPrGC formed by electrostatic self-assembly and π-π stacking can effectively dissipate energy accumulation under heat and mechanical stimulation through structural evolution, thus exhibiting a prominent synergistic desensitization effect on HMX. The results show that rGO/g-C3N4 coating has no effect on the crystal structure and chemical structure of HMX. More importantly, the perfect combination of g-C3N4 and rGO endows HPrGC with enhanced thermal stability and ideal mechanical sensitivity (IS: 21 J, FS: 216 N). Obviously, the new fabrication of HPrGC enriches the variety of desensitizer materials and helps to deepen the understanding of the interaction between explosives and coatings.

Study structure characteristics and the photocatalytic degradation of Rhodamine B on C/g-C<sub>3</sub>N<sub>4</sub> composites

C/g-C3N4 composites were successfully synthesized by calcination method from precursors g-C3N4 (CN) with carbon from orange peel (OC). The products were characterized by physicochemical methods such as XRD, IR, SEM, BET, UV-Vis. The photocatalytic activity of the material was evaluated through the degradation of RhB in the visible light. Experimental results show that the OC/CN-150 composite exhibits the optimal catalytic activity of 90% after 1 hour of illumination. This study highlights the role of carbon synthesized from biomass sources. Besides, it can be combined with other materials to create composites to apply for photocatalysis to solve environmental problems.

Flexible Triboelectric Nanogenerators based on Hydrogel/g-C3N4 Composites for Biomechanical Energy Harvesting and Self-Powered Sensing.

Flexible and stretchable triboelectric nanogenerators (TENGs) have been rapidly advanced owing to the demand for portable and wearable electronic devices that can work under universal or motional circumstances. While versatile materials can be applied in a TENG as dielectric materials, flexible and cost-effective electrodes are crucially important for the output performance of TENGs. Herein, we developed a poly(vinyl alcohol) (PVA) hydrogel TENG doped with a novel two-dimensional material, graphitic carbon nitride (g-C3N4), which could act as both a cost-effective flexible electrode and a positive dielectric for TENG with different morphologies. The measured peak-to-peak open-circuit voltage of the TENG reached 80 V at a dopant concentration of 2.7 wt % in single-electrode mode, which is far higher than that of the pristine PVA hydrogel TENG. As a demonstration of the application, the g-C3N4/PVA hydrogel TENG can be adopted as electronic skin to monitor the movement of the human body. Low-frequency mechanical energy-harvesting devices in different morphologies including discoid flake shape, tube shape, and spiral shape in the single-electrode mode or contact-separation mode have been designed, fabricated, and evaluated. All of these merits of the proposed hydrogel TENG after doping two-dimensional (2D) material g-C3N4 have demonstrated their promising potential for versatile applications in biomechanical energy harvesting and self-powered sensing.

Enhancing supercapacitor performance with biomass-derived activated carbon interlinked CoS2 embedded graphitic carbon nitride

This work investigates the improved electrochemical performance of CoS2 on composites CoS2/AC and CoS2/AC/g-C3N4 that are prepared via hydrothermal method and the production of activated carbon is of bio-derived configuration. The structural, vibrational modes, and functional groups of the as synthesized nanostructures are confirmed through X-ray Diffraction (XRD), Raman, and FTIR analyses. The specific surface area of CoS2/AC and CoS2/AC/g-C3N4 is 54.3 m2g−1, and 41.3 m2g−1, respectively. X-ray Photoelectron Spectroscopy (XPS) reveals the charge state of Co2+ and high charge transfer between Co and C in CoS2/AC/g-C3N4 compared to CoS2/AC. Nanoprobe Projection X-ray microscopy (PXM) discloses distorted octahedral coordination of Co2+ and site-dependent charge transfer by Co in CoS2/AC in comparison with CoS2/AC/g-C3N4. Further, the CoS2/AC electrode demonstrates a high specific capacity of 984 Fg−1 in the three-electrode system. The high-performance CoS2/AC electrode produced a high-power density of 2042.21 W Kg−1 and an energy density of 28.36 Whkg−1 in an aqueous electrolyte. The integration of CoS2 nanoparticles into the CoS2/AC and CoS2/AC/g-C3N4 composite framework significantly contributes to the improvement of specific capacity and excellent cycle stability up to 5000 cycles. This improvement could be influenced by several factors, such as reduced ion transport distances, strengthened interfacial interactions, high surface area, distortion of octahedral coordination of Co2+, and spatial-dependent charge transfer by Co in CoS2/AC. The distinct characteristics in specific capacity and cycling stability is attributed to the incorporation of CoS2 nanoparticles within the CoS2/AC and CoS2/AC/g-C3N4 composites that cause the short transport distance of the ions, enhanced interfacial interaction, and further provide better structural stability of the CoS2/AC and CoS2/AC/g-C3N4 composite network.

Three-dimensional porous La(OH)3/g-C3N4 adsorption-photocatalytic synergistic removal of tetracycline.

La(OH)3/g-C3N4 composites were successfully synthesized via one-step calcination using urea, melamine, and La(NO3)3·nH2O as raw materials, and applied to UV-induced photocatalytic tetracycline (TC) removal. Comprehensive characterization by an X-ray diffraction (XRD), Fourier transform infrared reflection (FT-IR), high-resolution transmission electron microscope (HRTEM), and other techniques analyzed effects of La3+ doping, especially N vacancies and cyano groups as active sites. Compared to pure g-C3N4 and La(OH)3, synthesized La(OH)3/g-C3N4 composites exhibited a three-dimensional porous nanosheet structure with specific surface area of 83.62 m2/g and equilibrium TC adsorption capacity up to 285.59 mg/g; La(OH)3 doping significantly improved composite structure. After dispersing 10 mg La-CN-0.5 photocatalyst in 60 mL 40 mg/L TC solution, TC removal reached 91.08% in 30 min under UV irradiation, exhibiting excellent performance. Additionally, La-CN-0.5 showed significant adsorption-photocatalytic synergism, with the quasi-primary kinetic constant increased by 1.83-fold. The efficiency of high tetracycline (TC) concentration treatment through adsorption photocatalytic degradation by La-CN-0.5 was confirmed by the utilization of free radical trapping and electron spin resonance (ESR) tests. The significant involvement of ∙O2-, ∙OH, and h+ in this process was observed. These findings propose that the prepared La-CN-0.5 material exhibits a unique capability for adsorption photocatalysis, providing a promising approach for the efficient removal of high TC concentrations.

Ag/α-Fe2O3/g-C3N4 nanocomposites as Z-scheme heterojunction photocatalysts for degradation of RhB

In this study, Ag/α-Fe2O3/g-C3N4 composites with varying α-Fe2O3 and Ag contents were synthesized by loading α-Fe2O3 and Ag nanoparticles onto the g-C3N4 with a high specific surface area via acid annealing. These composites were then utilized for the photocatalytic degradation of RhB under the irradiation of visible light. For α-Fe2O3/g-C3N4 composites with 5 wt% content of α-Fe2O3, the degradation efficiency reached a peak of 97.57% within 55 min, which was much higher than that of α-Fe2O3 and acid-annealed g-C3N4 with 45.92% and 83.61%, respectively. Furthermore, the photocatalytic degradation efficiency of Ag/α-Fe2O3/g-C3N4 composites reached its maximum of 99.61% with 1% content of Ag. It was demonstrated that the ternary Z-scheme heterojunction construction leaded to a significant enhancement of carrier separation and transfer effects, while the incorporation of Ag serves as electron reservoirs and photoinduced electrons capturers, thereby significantly enhancing the Fenton reaction and photocatalytic performance. This work is significant to drive the widespread application of g-C3N4 based heterojunctions in photocatalytic water purification.