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Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C3N4 nanosheets
摘要： Exfoliation of bulk graphitic carbon nitride (g-C3N4) into two-dimensional (2D) nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g-C3N4 nanosheets (CN) have larger specific surface areas and more reaction sites. In addition, poly-o-phenylenediamine (PoPD) can improve the electrical conductivity and photocatalytic activity of semiconductor materials. Here, the novel efficient composite PoPD/AgCl/g-C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach. The obtained photocatalysts have larger specific surface areas and could achieve better visible-light response. However, silver chloride (AgCl) is susceptible to agglomeration and photocorrosion. The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density, which is three times that of CN. Obviously enhanced photocatalytic activities of PoPD/AgCl/g-C3N4 are revealed through the photodegradation of tetracycline. The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly. Furthermore, ?O2? and h+ are the main active species, which are confirmed through a trapping experiment and ESR spin-trap technique. Therefore, the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst, in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles. This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.
关键词： AgCl,Visible light irradiation,Poly-o-phenylenediamine,g-C3N4 nanosheets,Photocatalytic
更新于2025-09-09 09:28:46
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Luminescent MOF nanosheets for enzyme assisted detection of H2O2 and glucose and activity assay of glucose oxidase
摘要： 2D metal-organic framework (MOF) nanosheets have emerged as a novel kind of sensing materials due to the large external surface area and accessible active sites on the surface. In this work, we successfully prepared luminescent MOF nanosheets (In-aip) with thickness of 4 nm by the cation-exchange mediated sonication of a 2D connected anionic MOF. Using In-aip as fluorescent sensor, an enzyme assisted system was established for the analysis of H2O2 with the quenching effect of the oxidation product on its emission. The nanosheet morphology of In-aip ensures its high capture efficiency of unstable intermediate, so high sensitivity was achieved (detection limit = 0.87 μM). With high sensitivity and wide quantitative range, this H2O2 sensing system could be used as a universal platform for the analysis of H2O2 related biomolecules and enzymes. By multi-enzyme cascade catalysis, a detection method of glucose and an activity assay of glucose oxidase were developed based on it. This work is the first example of using luminescent MOF nanosheets to bioanalysis and shows their wide application potential.
关键词： Fluorescence,Nanosheets,H2O2,Metal-organic frameworks,Enzyme assisted sensing
更新于2025-09-09 09:28:46
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Quantifying the Exfoliation Ease Level of 2D Materials via Mechanical Anisotropy
摘要： The isolation of 2D materials from mother bulks into nanoscale is of vital importance for fulfilling their applications in many technological fields. Among known methods, mechanical exfoliation is one of the most widely utilized ways due to its simplicity. For a given 2D material, both its inter-layer and intra-layer bonding strengths need to be taken into accounted for understanding the exfoliation process as the former dominates the ease level for cleaving adjacent molecular layers while the later regulates the ability for resisting cracking. In this regard, strong intra-layer but weak inter-layer bonding interactions respectively lead to large and thin nanosheets, hence facile exfoliation (and vice versa). As the bonding forces can be directly reflected through elastic properties of materials, here we propose to use the ratio between the in-plane and out-of-plane elastic modulus (E) as a universal index, AIn/Out (= EIn-plane/EOut-of-plane), to quantify the ease level of a 2D material’s mechanical exfoliation. Such ratios, which can be facilely obtained from routine computational and mechanical experiments, could provide useful information for estimating suitable exfoliation methods of 2D materials.
关键词： nanosheets,elastic modulus,2D materials,mechanical exfoliation,mechanical anisotropy
更新于2025-09-09 09:28:46
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Green and Efficient Production of Boron Nitride Nanosheets via Oxygen Doping-Facilitated Liquid Exfoliation
摘要： As the structural analogue of graphene, boron nitride nanosheets (BNNSs) are anticipated to have a wide range of potential applications. BNNSs exhibit good mechanical properties, outstanding thermal conductivity, oxidation and chemical stability and are excellent electrical insulators. While BNNSs have gained recognition as one of the most versatile 2D materials in recent years, their application in research and industry is still hampered by the lack of methods to produce BNNSs in large quantity and a cost-effective way. In this study, we report highly efficient h-BN exfoliation via the oxygen doping-facilitated liquid exfoliation. Oxygen atoms are introduced into the hexagonal boron nitride (h-BN) structure via a facile thermal treatment. The relationship of thermal treatment, structural changes and h-BN exfoliation are studied to elucidate the key factor for advancing the BNNS production. The optimum concentration of hydroxyl groups and weakening of interlayer interactions have synergistically facilitated the delamination of h-BN in water under mild exfoliation conditions, resulting in up to 1255% yield increment and without noticeable new defects in the BNNS structure as compared with the untreated control. An efficient and environmentally friendly exfoliation process of h-BN is a crucial starting point towards the cost-effective and mass production of BNNSs which is needed for the currently identified and myriad future applications of BNNSs.
关键词： oxygen-doping,nanoplatelets,boron nitride nanosheets,2D nanomaterials
更新于2025-09-09 09:28:46
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Design of graphitic carbon nitride supported Ag–Cu2O composites with hierarchical structures for enhanced photocatalytic properties
摘要： A novel ternary photocatalytic nanocomposite, Ag–Cu2O/C3N4, has been successfully synthesized via a facile two-step reduction procedure at room temperature, wherein Ag nanoparticles are directly growing on the surface of Cu2O supported by C3N4 nanosheets. The resulting ternary Ag–Cu2O/C3N4 photocatalyst exhibits enhanced photocatalytic activity towards methyl orange (MO) degradation compared with its conterparts (Cu2O, spherical Ag–Cu2O and Cu2O/C3N4), demonstrating a removal rate of MO up to 95.7% within 30 min. The enhanced photocatalytic activity can be ascribed to the following factors: 1) the surface plasmon resonance effect of Ag nanoparticles broadening the visible light response of Cu2O; 2) the introduction of C3N4 functioning not only as a fast electron delivery but also a fine stabilizer to prevent the Ag–Cu2O composite from agglomeration. Mechanism studies reveal that MO is cracked into smaller fragments and the h+ is the main reactive species participating in the photocatalytic process. Moreover, the Ag–Cu2O/C3N4 photocatalyst also shows high photodegradation ability for another two representative azo dyes, acid orange II and congo red. This study demonstrates the potential of Ag–Cu2O/C3N4 in the degradation of azo dyes and also provides a guide to design of Cu2O-based ternary photocatalysts for further wastewater remediation.
关键词： Wastewater remediation,Cuprous oxide,Photocatalysis,C3N4 nanosheets,Fragments,Mechanism
更新于2025-09-09 09:28:46
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Oxygen Vacancy-Rich Ultrathin Sulfur-Doped Bismuth Oxybromide Nanosheet as a Highly Efficient Visible-Light Responsive Photocatalyst for Environmental Remediation
摘要： Designing ultrathin two-dimensional (2D) defective materials and metal-free doped materials as photocatalysts both have received enormous attentions in the field of environmental remediation due to their great potential for removing colorless contaminants. However, whether the synergism of defects and metal-free doping exists and the corresponding oxidative mechanism is unclear, which retard further developments of high performance catalysts. Here, a novel oxygen vacancy (OV)-rich ultrathin sulfur-doped BiOBr nanosheet (BB-xS) was synthesized through a facile one-step solvothermal method. Under visible light irradiation, the optimal BB-5S sample exhibited 98% degradation efficiency of 4-chlorophenol (4-CP) within 120min, which was 4.9 and 18.0 times greater than that of pristine ultrathin BiOBr and oxygen vacancy-poor sulfur-doped BiOBr, respectively. Also, this excellent photoactivity could extend to other colorless organic contaminants, such as bisphenol analogues and sulfonamides, verifying the universal applicability of BB-xS. Based on experimental results and density functional theory (DFT) calculations, it was manifested that a sub-band was generated via the synergistic effect of oxygen vacancies and sulfur doping, and it greatly enhanced the visible-light absorption capability and suppressed the photoinduced charge recombination, which would be beneficial to improve the photocatalytic activity. Additionally, the corresponding photocatalytic degradation pathway of 4-CP was also proposed. This work can provide a new protocol for the design and construction of highly active photocatalysts toward environmental remediation.
关键词： photocatalytic degradation,Ultrathin two-dimensional nanosheets,sulfur-doped,oxygen vacancy,colorless organic contaminants
更新于2025-09-09 09:28:46
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Photoelectrochemical biosensor for hydroxymethylated DNA detection and T4-β-glucosyltransferase activity assay based on WS2 nanosheets and carbon dots
摘要： 5-Hydroxymethylcytosine (5hmC) plays an important role in switching genes on and off in mammals, and it is implicated in both embryonic development and cancer progression. Herein, a novel photoelectrochemical (PEC) biosensor was developed for 5hmC detection based on WS2 nanosheets as the photoactive material and boronic acid functionalized carbon dots (B-CDs) for signal amplification unit. This biosensor can also be used for T4-β-glucosyltransferase (β-GT) activity assessment. Firstly, WS2 nanosheets and gold nanoparticles (AuNPs) were immobilized on an ITO electrode surface. Then probe DNA was immobilized on this electrode surface via Au-S bond. Afterwards, the complementary DNA containing 5hmC was then captured on the modified electrode surface by hybridization. Subsequently, β-GT transferred glucose from uridine diphosphoglucose to the hydroxyl groups of the 5hmC residues. After glycosylation, B-CDs could further be immobilized on the modified electrode surface resulting in a strong photocurrent. The PEC biosensor afforded high selectivity, excellent sensitivity and good reproducibility, with detection limits of 0.0034 nM and 0.028 unit/mL for 5hmC and β-GT, respectively. Results demonstrate that the photoelectrochemical strategy introduced here based on WS2 nanosheets and B-CDs offers a versatile platform for hydroxymethylated DNA detection, β-GT activity assessment and β-GT inhibitor screening.
关键词： Photoelectrochemical biosensor,DNA hydroxymethylation,β-Glucosyltransferase,WS2 nanosheets,carbon dots
更新于2025-09-09 09:28:46
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A Highly Efficient Au-MoS2 Nanocatalyst for Tunable Piezocatalytic and Photocatalytic Water Disinfection
摘要： Clean water is essential in our daily life. However, nearly one billion people are forced to drink water contaminated with bacteria, leading to diarrhea, dehydration, and even death. Previously, various photocatalysts have been applied to replace high-cost and highly toxic methods for sewage treatment. Nevertheless, the requirement of external light sources limits their application. Herein, we develop a new type of nanocatalyst based on single- and few-layered molybdenum disulfide (MoS2) nanosheets (NSs) that can catalyze the generation of reactive oxygen species (ROS) to inactivate bacteria either through a piezoelectric effect (mechanical vibration) or photocatalytic effect (light irradiation). After 60 minutes of mechanical vibration or visible-light irradiation, the MoS2 NSs can reduce Escherichia coli (E. Coli) by 99.999%. In addition, the ROS generation efficiency and bacterial disinfection performance of the catalyst can be enhanced by depositing Au nanoparticles (NPs) on MoS2 NSs. The period of mechanical vibration or visible-light irradiation that achieves the same 99.999% reduction in E. coli is shortened to 45 minutes. Moreover, a hybridization of the piezoelectric and photocatalytic effects results in a performance superior to that obtained with the individual effects. A 99.999% reduction in E. coli is also accomplished within 15 minutes through a combination of mechanical vibration and near-infrared (NIR)-light irradiation. This MoS2 nanocatalyst is a promising candidate for nextgeneration water purification systems because of its ability to be triggered by diverse environmental stimuli.
关键词： photocatalytic effect,nanosheets,Molybdenum disulfide,piezocatalytic effect,reactive oxygen species,bacterial disinfection
更新于2025-09-09 09:28:46
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Ferroelectric Polarization Promoted Bulk Charge Separation for Highly Efficient CO2 Photoreduction of SrBi4Ti4O15
摘要： Fast recombination of photogenerated charge carriers in bulk remains the major obstacle for photocatalysis nowadays. Developing ferroelectrics directly as photoactive semiconducting catalysts may be promising in view of the strong ferroelectric polarization that induces the anisotropic charge separation. Here, we report a ferroelectric layered perovskite SrBi4Ti4O15 as a robust photocatalyst for efficient CO2 reduction. In the absence of co-catalysts and sacrificial agents, the annealed SrBi4Ti4O15 nanosheets with the strongest ferroelectricity cast a prominent photocatalytic CO2 reduction activity for CH4 evolution with a rate of 19.8 μmol·h-1·g-1 in the gas-solid reaction system, achieving an apparent quantum yield (AQY) of 1.33% at 365 nm, outperforming most of the reported photocatalysts. The ferroelectric hysteresis loop, piezoresponse force microscopy (PFM) and ns-level time-resolved fluorescence spectra uncover that the outstanding CO2 photoreduction activity of SrBi4Ti4O15 mainly stems from the strong ferroelectric spontaneous polarization along [100] direction, which allows efficient bulk charge separation along opposite direction. DFT calculations also disclose that both electrons and holes show the smallest effective masses along a axis, verifying the high mobility of charge carriers facilitated by ferroelectric polarization. This study suggests that the traditionally semiconducting ferroelectric materials that have long been studied as ferro/piezoelectric ceramics now may be powerfully applied in the photocatalytic field to deal with the growing energy crisis.
关键词： CO2 photoreduction,ferroelectric perovskite,spontaneous polarization,SrBi4Ti4O15 nanosheets,piezoelectric-catalysis
更新于2025-09-09 09:28:46
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Game Theory in Molecular Nanosensing System for Rapid Detection of Hg2+ in Aqueous Solutions
摘要： Game theory—the scientific study of interactive, rational decision making—describes the interaction of two or more players from macroscopic organisms to microscopic cellular and subcellular levels. Life based on molecules is the highest and most complex expression of molecular interactions. However, using simple molecules to expand game theory for molecular decision-making remains challenging. Herein, we demonstrate a proof-of-concept molecular game-theoretical system (molecular prisoner’s dilemma) that relies on formation of the thymine–Hg2+–thymine hairpin structure specifically induced by Hg2+ and fluorescence quenching and molecular adsorption capacities of cobalt oxyhydroxide (CoOOH) nanosheets, resulting in fluorescence intensity and distribution change of polythymine oligonucleotide 33-repeat thymines (T33). The “bait” molecule, T33, interacted with two molecular players, CoOOH and Hg2+, in different states (absence = silence and presence = betrayal), regarded as strategies. We created conflicts (sharing or self-interest) of fluorescence distribution of T33, quantifiable in a 2 × 2 payoff matrix. In addition, the molecular game-theoretical-system based on T33 and CoOOH was used for sensing Hg2+ over the range of 20 to 600 nM with the detection limit of 7.94 nM (3σ) and for determination of Hg2+ in pond water. Inspired by the proof-of-concept for molecular game theory, various molecular decision-making systems could be developed, which would help promote molecular information processing and generating novel molecular intelligent decision systems for environmental monitoring and molecular diagnosis and therapy.
关键词： fluorescent sensing,thymine–Hg2+–thymine,game theory,Hg2+,cobalt oxyhydroxide nanosheets
更新于2025-09-04 15:30:14