Carbon Nitride Nanosheets Research Articles

Stable Cu (I) single copper atoms supported on porous carbon nitride nanosheets for efficient photocatalytic degradation of antibiotics

Stable Cu (I) single copper atoms supported on porous carbon nitride nanosheets for efficient photocatalytic degradation of antibiotics

Decavanadate Supported on Carbon Nitride Nanosheets as Photocatalysts for Selective C–H Bromination of Arenes Using KBr

Decavanadate Supported on Carbon Nitride Nanosheets as Photocatalysts for Selective C–H Bromination of Arenes Using KBr

Boosted photothermal-assisted photocatalytic H2 production by dual heat source-based S-scheme heterojunction

With advances in catalytic research, improvement of catalytic efficiency by using photothermal synergies to strengthen the reaction mechanisms has been focused. In this work, a novel photothermal-assisted photocatalytic H2 production system was constructed by loading Co3O4 nanoparticles on surface of black carbon nitride (BCN) nanosheets, served as the dual thermal source to enhance photothermal effect for synergistically assisting in photocatalytic H2 evolution with optimal H2 production rate reached 3.7 mmol g−1 h−1, significantly higher than that of pure carbon nitride (CN) and BCN. Moreover, the S-scheme heterojunction is also formed between Co3O4 and BCN, leading to the optimization of the charge transfer path, which further promotes the improvement of photothermal-assisted photocatalytic H2 production activity. This study provides the design idea of coupling the multi-heat source effect with the heterojunction electron transport for constructing an efficient photothermal-assisted hydrogen production system.

Enhanced bipolar electrode electrochemiluminescence biosensor for ultrasensitive monitoring of alkaline phosphatase activity during osteoblast differentiation by integrating electrocatalytic and enzymatic strategies

Alkaline phosphatase (ALP) is an important biomarker that reflects osteoblast activity and bone growth. Accurately detecting ALP activity is of pivotal clinical significance for the diagnosis and differentiation of bone system diseases. In this work, an enhanced bipolar electrode electrochemiluminescence (BPE-ECL) biosensor based on enzyme catalysis and electrocatalysis was proposed for ultrasensitive detection of ALP in osteoblasts. Carbon nitride nanosheets (CNNS) were utilized as electrocatalysts to facilitate the electrochemical reaction of bipyridine ruthenium (Ru(bpy)32+) and tripropylamine (TPrA) in the reporting cell. Meanwhile, in the sensing cell, the target ALP catalyzed the conversion of p-aminophenyl phosphate monohydrate into p-aminophenol (p-AP). The p-AP was subsequently oxidized at the anode of the driving electrode, producing electrons and increasing the Faradaic current of BPE. The dual-signal amplification strategy, combining electrocatalysis and enzyme catalysis, resulted in a 10-fold enhancement of the ECL intensity of Ru(bpy)32+/TPrA. The BPE-ECL biosensor achieved ultrasensitive detection of ALP with a detection limit as low as 1.9×10−6 U/L, and was successfully applied to monitor ALP activity in osteoblast cells. Additionally, a portable smartphone imaging was developed for the visual detection of ALP. This research introduces an innovative BPE-ECL biosensor for the monitoring of ALP activity and point-of-care testing (POCT) in osteoblasts in clinical settings.

Enhanced CO2 Reduction via S-Scheme Heterojunction of Amorphous/Crystalline Metal-free Carbon Nitride Photocatalysts

Metal-free carbon nitride nanosheets (CNs) are promising photocatalysts, but face challenges with severe charge recombination and limited visible light absorption. To overcome these challenges, we have developed a 2D/2D amorphous/crystalline carbon nitride (CNs/CCN) S-scheme heterojunction photocatalyst through electrostatic self-assembly. The built-in electric field in the CNs/CCN heterojunction facilitates an S-scheme transfer of photogenerated electrons from CCN to CNs, effectively enhancing electron-hole separation. Our optimized CNs/CCN-1/3 heterojunction exhibits substantially higher production rates of CO and CH4 compared to its individual components. Notably, CNs/CCN-1/3 maintains excellent CO2 reduction efficiency even under irradiation at wavelengths exceeding 700 nm. This study introduces an innovative strategy for the development of CNs-based photocatalysts with improved charge separation and enhanced visible-light absorption.

Graphitic carbon nitride/titania nanotube arrays for photoelectrochemical oxidation of methanol under visible light

In this study, the fabrication of ordered and vertically oriented titanium dioxide nanotubes (TiO2 NT) array sensitized with graphitic carbon nitride (g-C3N4) nanosheets (g-C3N4 NS/TiO2 NT) was demonstrated as an attractive class of photocatalysts for the visible-light-driven photoelectrochemical oxidation of methanol. The phase and composition of the fabricated g-C3N4 NS/TiO2 NT structures and their precursors were investigated using X-ray powder diffraction (XRD). The morphological and topological characteristics of the prepared materials were studied using scanning electron microscopy (SEM). Raman spectroscopy was employed to study the electronic properties of composite material. Upon the fabrication, characterization, and use of the prepared structures for photoelectrochemical oxidation of methanol under visible-light illumination (50 W halogen lamp, 0.1 M KOH), the g-C3N4 NS/TiO2 NT array showed a significant increase in the photocurrent (96.2 μA cm−2) compared to the TiO2 NT electrode (79 μA cm−2) with 1.2 times enhancement factor. Moreover, decorating the TiO2 NT array resulted in enhanced dark light density that is 8.7 times more than that of the TiO2 NT electrode. The improved photo- and electrochemical properties of the prepared g-C3N4 NS/TiO2 NT could arise from the synergistic effects of g-C3N4 NS decoration and the unique structural properties of the fabricated vertically aligned TiO2 nanotube arrays. The TiO2 NT/g-C3N4 NS composite modified photo-electrode offers 22.55 times the ambient condition “light off” of the TiO2 NT electrode and 2.3 times the irradiated ones. The present study suggests a simple, stable, reusable, and cost-effective approach for the preparation of g-C3N4 NS/TiO2 NT photocatalyst for designing a DMFC.

Vertically growth of MoS2 nanosheets on g-C3N4 towards enhanced electrocatalytic performance

MoS2 nanosheets were vertically grown in S-doped graphitic carbon nitride (g-C3N4) nanosheets to enhance electrochemical performance. Dicyandiamide was used as a precursor while sodium molybdate and thioacetamide were as additives, and sulfur was introduced into the carbon lattice of thin-layered g-C3N4 by a two-step thermal polymerization. S-g-C3N4/MoS2 (SCN/MoS2) heterojunctions were then created by a solvothermal synthesis. Subsequently, the electrochemical performance of the heterojunctions was explored. The result suggested that the surface of S-g-C3N4 nanosheets load on uniformly arranged layered MoS2 possession revealed the smallest Tafel slope of 77.2 mV dec−1. After 1000 cycles, no significant change was observed for the linear sweep voltammetry curves. The SCN/MoS2 heterojunction revealed a specific capacity of 588 F g−1 after being assembled into an asymmetric supercapacitor. Superior thin g-C3N4 nanosheets and constituting a composite with strong interfacial electronic coupling with MoS2, doping with heteroatomic elements, and changing the surface structure of g-C3N4 enhanced the charge transfer kinetics and improved the electrochemical performance.

Incrimination and impact on recovery times and effects of BN nanostructures on antineoplastic drug-electronic density study.

By delivering the drug to the intended cell location, the use of nanomaterials in the drug delivery system may influence how the patient receives the medication and may assist in mitigating severe side effects. Density functional theory was used to assess the use of boron carbon nitride nanocages (BNCNCs), boron nitride (BNNSs), and boron carbon nitride nanosheets (BNCNSs) as melphalan (Mln) drug carriers in both the gaseous and fluid phases. We systematically examined the dipole moment, density of states, frontier molecular orbital, and optimal adsorption energy to understand the targeted drug delivery potential of these nanostructures. Adsorption energy analysis revealed that in both gas and water media, Mln drug adsorption takes place spontaneously on all the conjugated structures. The occurrence of adsorption energy as physisorbed energy suggests that the process is reversible, and desorption can take place with a much lower energy input. This physical contact is appropriate for the unquestionable unloading of Mln medications to the intended location. The reactivity is higher in BNNSs and BNCNSs, while the stability is higher in BNCNCs. The recovery time shows a shorter time for BNNSs and BNCNSs, while BNCNC shows a potential desorption time in higher temperature. These conclusions are corroborated by the results of the quantum theory of atoms in molecules (QTAIM). After the interaction analysis, it was observed that the BNCNCs can act as potential carriers for the melphalan. From dipole moment analysis, all three nanostructures show a high hydrophilic nature but quite higher in BNCNCs after doping in both media. Overall, all the structures show the potential carrier for melphalan drug. The quantum mechanical approach, or DFT, has been used to study the fundamental structural, electrical, thermodynamic, and other aspects of proposed structures to develop an acceptable Mln drug detector. The adsorbate and all adsorbents were optimized via the hybrid B3LYP functional and the 6-311G + + (2d, p) basis set approach prior to the adsorption process. The Gaussian 09 package was used at 298K as the constant temperature and 1 atm as the constant pressure. The structures are examined using the same functional models for solvation analysis-6-311 G + + (2d, p) and B3LYP-as well as the polarized continuum model (PCM) model as the foundation set. Density of states was studied using GaussSum 3.0 software. The interaction studies QTAIM and RDG were studied using VMD and Multiwfn software.

Building Asymmetric Zn-N3 Bridge between 2D Photocatalyst and Co-catalyst for Directed Charge Transfer toward Efficient H2O2 Synthesis.

Two-dimensional (2D) polymeric semiconductors are a class of promising photocatalysts; however, it remains challenging to facilitate their interlayer charge transfer for suppressed in-plane charge recombination and thus improved quantum efficiency. Although some strategies, such as π-π stacking and van der Waals interaction, have been developed so far, directed interlayer charge transfer still cannot be achieved. Herein, we report a strategy of forming asymmetric Zn-N3 units that can bridge nitrogen (N)-doped carbon layers with polymeric carbon nitride nanosheets (C3N4-Zn-N(C)) to address this challenge. The symmetry-breaking Zn-N3 moiety, which has an asymmetric local charge distribution, enables directed interfacial charge transfer between the C3N4 photocatalyst and the N-doped carbon co-catalyst. As evidenced by femtosecond transient absorption spectroscopy, charge separation can be significantly enhanced by the interfacial asymmetric Zn-N3 bonding bridges. As a result, the designed C3N4-Zn-N(C) catalyst exhibits dramatically enhanced H2O2 photosynthesis activity, outperforming most of the reported C3N4-based catalysts. This work highlights the importance of tailoring interfacial chemical bonding channels in polymeric photocatalysts at the molecular level to achieve effective spatial charge separation.

Building Asymmetric Zn–N3 Bridge between 2D Photocatalyst and Co‐catalyst for Directed Charge Transfer toward Efficient H2O2 Synthesis

Two‐dimensional (2D) polymeric semiconductors are a class of promising photocatalysts; however, it remains challenging to facilitate their interlayer charge transfer for suppressed in‐plane charge recombination and thus improved quantum efficiency. Although some strategies, such as π‐π stacking and van der Waals interaction, have been developed so far, directed interlayer charge transfer still cannot be achieved. Herein, we report a strategy of forming asymmetric Zn–N3 units that can bridge nitrogen (N)‐doped carbon layers with polymeric carbon nitride nanosheets (C3N4‐Zn‐N(C)) to address this challenge. The symmetry‐breaking Zn–N3 moiety, which has an asymmetric local charge distribution, enables directed interfacial charge transfer between the C3N4 photocatalyst and the N‐doped carbon co‐catalyst. As evidenced by femtosecond transient absorption spectroscopy, charge separation can be significantly enhanced by the interfacial asymmetric Zn–N3 bonding bridges. As a result, the designed C3N4‐Zn‐N(C) catalyst exhibits dramatically enhanced H2O2 photosynthesis activity, outperforming most of the reported C3N4‐based catalysts. This work highlights the importance of tailoring interfacial chemical bonding channels in polymeric photocatalysts at the molecular level to achieve effective spatial charge separation.

Oxygen-doped Porous Ultrathin Graphitic Carbon Nitride Nanosheets for Photocatalytic Hydrogen Evolution and Rhodamine B Degradation.

Graphite phase carbon nitride (g-C3N4) is a highly promising metal-free photocatalyst. However, its applicability is restricted by low activity, due to weak quantum efficiency and small specific surface area. Exfoliating bulk crystals into porous thin-layer nanosheets and introducing element doping have been shown to improve photocatalytic efficiency, but these methods are often complex, time-consuming, and costly processes. In this study, we successfully synthesized porous oxygen-doped g-C3N4 (OCN) nanosheets utilizing a straightforward method. Our findings show that OCN have much higher light absorption and visible-light photocatalytic activity than bulk g-C3N4 (BCN) and nonporous g-C3N4 (CN). The OCN photocatalyst has a remarkable hydrogen evolution reaction (HER) rate of 8.02 mmol·g-1 h-1, which is 8 times greater than BCN. Additionally, the OCN shows a high degradation rate of 97.3% for Rhodamine B (RhB). This enhanced photocatalytic activity is ascribed to the narrow band gap and superior electron transfer capacity. Our findings suggest a potential technique for generating efficient g-C3N4 photocatalysts.

Ultra-sensitive zinc cobaltate assembled on N-rich carbon nitride electrochemical sensor for the detection of paraquat in food samples

BackgroundParaquat (PQ) from agricultural waste cause contamination in water bodies, groundwater, soil, and foods has received increasing attention regarding health safety. On-site-based detection is much needed along with rapid results, selectivity and sensitivity, which can be achieved through an electrochemical-based sensor. MethodsThis work provides, an electrochemical sensor based on zinc cobaltite (ZnCo2O4) nanostructure strongly attracted through electrostatic interaction with the carbon nitride (C3N5; CN) nanosheets modified on a glassy carbon electrode (GCE) for the determination of paraquat (PQ). The strong immobilization of ZnCo2O4 over CN2 on GCE synergistically shows excellent sensing of PQ due to high interfacial charge transfer effect. Significant findingsIn addition, the electrochemical studies were performed using CV and DPV analysis which exhibits a good limit of detection (7.6 nM) and sensitivity (0.201 µA cm-2) towards PQ detection. Furthermore, the modified electrode was applied practically in real food samples for PQ detection with excellent recoveries.

Porous activated carbon integrated carbon nitride nanosheets as functionalized separators for the efficient polysulfide entrapment in Li[sbnd]S batteries

Electrification of vehicles, hybrid aircraft and the advancement of portable electronics are exacting the deployment of high energy-dense batteries. The high theoretical capacity of sulfur (1675 mAh g−1), cost-effectiveness and environmental benignity of the lithium‑sulfur batteries (LSBs) are propitious for electrochemical energy storage beyond Li-ion battery technology. In this work, we described a simple, scalable preparation and electrochemical performance of porous activated carbon (PC)-infused graphitic carbon nitride (GCN) nanosheets with various ratios (PC@GCN 11, PC@GCN 12 and PC@GCN 21) as a polysulfide anchoring functionalized separator for LSBs. The high specific area (822 m2/g), hetero porosity, conductive carbon framework, surface functionalities and enriched N-doping of the PC@GCN synergistically induce mitigation of polysulfides via chemical and physical adsorption pathways in LSBs. The PC@GCN 21 modified separator demonstrates a high initial discharge capacity of 1389 mAh g−1 at a 0.1C rate and exhibits better capacity retention over 500 cycles at a 1C rate (655 mAh g−1) with sulfur loading of 3.8 mg/cm2 accompanied by high coulombic efficiency (94 %). The assembled cell with high S-loading (5.12 mg/cm2) shows a high initial discharge capacity of 712 mAh g−1 at 0.1C rate conditions. High Li-ion transference number (0.714), stable shuttle current, minimal coulombic efficiency loss (0.84 %), low shuttle factor and negligible self-discharge behaviour support the superior performance of the PC@GCN 21 coated cells. This report demonstrates that combining the high surface area, non-polar porous carbon with polar graphitic carbon nitride is a practical approach for designing metal-free functionalized separators for energy-dense LSBs.

Ternary Boron Carbon Nitride nanosheets with improved and controllable linear and nonlinear optical response for efficient photocatalytic performance

This work reports the systematic variation of linear and nonlinear optical (NLO) properties of ternary boron carbon nitride (BCN) nanosheets with varying carbon concentrations. These nanosheets are synthesized by the thermal substitutional method to modulate the band-gap of BCN nanosheets by varying the hBN and graphene domain ratios which is confirmed through UV-Vis absorption spectroscopy. The third-order optical nonlinearity of nanosheets was explored through the Z-scan technique. With increases in both carbon content and laser power, samples' NLO properties have shifted from saturable absorption to reverse saturable absorption. The enhanced nonlinearity with carbon concentration in BCN samples was responsible for higher photoinduced charge separation time. In UV-Vis driven photoreduction of organic pollutants, BCN nanosheets with a decreased bandgap and an increased charge separation time show higher catalytic efficiency. Therefore, based on the combined effect of many processes, the results revealed that the BCN nanosheets displayed greater potential for photoinduced reduction.

Palladium–Copper Alloy Nanoparticles Supported on Carbon Nitride Nanosheets as a Photocatalyst for Degradation of Ciprofloxacin

Palladium–Copper Alloy Nanoparticles Supported on Carbon Nitride Nanosheets as a Photocatalyst for Degradation of Ciprofloxacin

All-electrochemical-prepared, efficient and robust superhydrophilic/underwater superoleophobic meshes for synchronously achieving oil-water separation and water-soluble pollutant photodegradation

Superhydrophilic/underwater superoleophobic “water-removing” type membranes can overcome the issue of surface themselves easily fouled or even blocked by oils that seriously affects the oil-water separation capacity and limits the recycle use, and thus attract a great deal of research attention. In this work, we employed the electrochemical deposition method to fabricate Cu3(PO4)2 nanosheets (NSs) vertically grown on a copper mesh (COM) to achieve efficient oil-water separation, followed by the deposition of titanium dioxide (TiO2) nanoparticles and graphitic carbon nitride (g-C3N4) nanosheets on the surface of Cu3(PO4)2 nanosheets-wrapped mesh (Cu3(PO4)2@COM), respectively. The composited meshes of TiO2@Cu3(PO4)2@COM and g-C3N4@Cu3(PO4)2@COM not only showed the considerable superhydrophilic/underwater superoleophobic property in the application of oil-water separation, but also simultaneously exhibited the desirable photocatalytic activity for the degradation of water-soluble pollutants as the water passed through the meshes. The oil-water separation efficiency of TiO2@Cu3(PO4)2@COM and g-C3N4@Cu3(PO4)2@COM can reach as high as 97 % and 96 % that both of meshes have the water flux of various water-oil mixtures above 3250 L/m2h, along with their degradation efficiency of 79 % and 90 % for RhB pollutant under full spectrum light irradiation, respectively. In addition, the as-prepared meshes have the robust, sustainable and stable properties through ten-cycles test of oil-water separation and photocatalytic degradation without significant performance decay. Our primary results provide a potential and simple route to construct multifunctional membrane materials for synchronously achieving water purification in oily wastewater.

Dual-Mechanism Quenching Electrochemiluminescence System by Coupling Energy Transfer with Electron Transfer for Sensitive Competitive Aptamer-Based Detection of Furanyl Fentanyl in Food.

Resonance energy transfer (RET) quenching is significantly important for developing electrochemiluminescence (ECL) sensors, but RET platforms face challenges like interference from other fluorescent substances and reliance on energy transfer efficiency. This study used Zn-PTC, formed by zinc ions coordinated with perylene-3,4,9,10-tetracarboxylate, as a dual-mechanism quencher to reduce the ECL intensity of carbon nitride nanosheets (Tg-CNNSs). Co3O4/NiCo2O4 acts as a coreaction promoter, enhancing and stabilizing the luminescence of Tg-CNNSs. Zn-PTC absorbs energy from Tg-CNNSs, altering the fluorescence lifetime to confirm energy transfer, while energy-level matching demonstrates electron transfer. By leveraging both RET and electron transfer mechanisms, the designed ECL aptasensor significantly reduces signal fluctuations that may arise from a single mechanism, resulting in more stable and reliable detection outcomes. The ECL aptasensor designed for furanyl fentanyl (FUF) detection shows excellent performance with a detection limit of 5.7 × 10-15 g/L, offering new pathways for detecting FUF and other small molecules.

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

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

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

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

Understanding oxidation potential and degradation mechanism of acid-treated TiO2 coupled g-C3N4 S-scheme heterojunction photocatalyst for the removal of gaseous formaldehyde

In this work, a step (S)-scheme heterojunction catalyst is synthesized by coupling acid-treated TiO2 (ATT) with graphitic carbon nitride nanosheet (g-C3N4: GCN) and used for adsorption-photocatalytic removal of gaseous formaldehyde (FA: 100 - 500 ppm). The acid treatment of TiO2 proves to be an effective approach for improving the surface porosity of ATT with more abundant active sites for efficient catalytic reactions. Similarly, the S-scheme heterojunction displays superior redox potential (i.e., availability of free e- at conduction band of GCN (reduction potential of −0.485 eV/NHE) and free h+ at valance band of ATT (oxidation potential 2.79 eV/NHE)). As such, in a dynamic packed-bed flow reactor, the improved textural and optical properties of ATT-GCN (bed mass = 10 mg) offer outstanding adsorption and photocatalytic oxidation potential, effectively removing 86% of 200 ppm FA vapor at a reaction rate of 70.2 nmole mg−1 min−1 under slightly humidified conditions (e.g., 20% relative humidity (RH) and 21% O2) when exposed to 32-W UV-A light source. Under these operational conditions, the ATT-GCN achieves the superior performance metrics (e.g., quantum yield of 5.1E-02 molec. photon-1, space–time yield of 5.1E-03 molec. photon-1 mg−1, and specific clean air delivery rate of 515.4 L g-1 h−1). In-situ Kelvin probe microscope analysis of ATT-GCN postulates the formation of a strong built-in electric field to improve the separation of charge carriers. Considerations on the degradation pathway and intermediate dynamics with the aid of in-situ DRIFTS analysis suggest that the presence of water molecules (e.g., 20% RH) is beneficial for accelerating the oxidation and mineralization of FA molecules relative to a dry gas stream. The overall outcomes of this work are expected to help deliver new paths for the construction of advanced photocatalytic systems for upscaled applications toward air quality management.