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Exfoliated $$\hbox {WS}_{2}$$WS2 nanosheets: optical, photocatalytic and nitrogen-adsorption/desorption characteristics
摘要： In this work, we report on structural, optical, photocatalytic and nitrogen adsorption–desorption characteristics of WS2 nanosheets developed via a hydrothermal route. X-ray diffraction (XRD) studies have revealed a hexagonal crystal structure, whereas nanodimensional sheets are apparently observed in scanning and transmission electron microscopy (SEM and TEM) micrographs. As compared to the bulk counterpart, the WS2 nanosheets exhibited a clear blue shift. Through Brunauer–Emmett–Teller (BET) surface area analysis, average surface area, pore volume and pore size of the NSs were calculated as 211.5 m2 g?1, 0.433 cc g?1 and 3.8 nm, respectively. The photocatalytic activity of the WS2 nanosheets was also examined with malachite green (MG) as the target dye under both UV and day light (visible) illumination conditions. Accordingly, a degradation ef?ciency as high as 67.4 and 86.6% were witnessed for an irradiation time duration of 60 min. The nano-WS2 systems have immense potential in optoelectronics, solid-lubrication and other next generation elements.
关键词： sorption process,photocatalysis,TMDC,Nanosheets
更新于2025-09-04 15:30:14
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Etching reaction-based photoelectrochemical immunoassay of aflatoxin B1 in foodstuff using cobalt oxyhydroxide nanosheets-coating cadmium sulfide nanoparticles as the signal tags
摘要： A new split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of aflatoxin B1 (AFB1) in foodstuffs, coupling with enzymatic hydrolysate-triggered etching reaction of cobalt oxyhydroxide (CoOOH) on cadmium sulfide (CdS) nanoparticles-functionalized interface. Initially, the photosensitive electrode was prepared by coating CoOOH nanosheets on the surface of CdS nanoparticles to quench the photocurrent. Thereafter, a competitive-type enzyme immunoreaction was carried out on monoclonal anti-AFB1 antibody-conjugated magnetic bead by using alkaline phosphatase (ALP)-labeled bovine serum albumin-AFB1 (AFB1-BSA) conjugate as the competitor. With the formation of immunocomplex, the carried ALP hydrolyzed ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA) and phosphate. The former ascorbic acid produced etched or dissolved CoOOH nanosheets into Co2+ ions, thus resulting in the exposure of CdS nanoparticles on the surface to enhance the photocurrent of the modified electrode. Under optimum conditions, the photocurrent decreased linearly with the increasing AFB1 concentration in the dynamic range of 0.01 – 10 ng mL-1, and the limit of detection was 2.6 pg mL-1. The precision of this method (expressed as RSD) was ± 8.6%. In addition, the accuracy was monitored by analyzing spiked food samples, and gave the well-matched results with the referenced ELISA method.
关键词： cobalt oxyhydroxide nanosheets,cadmium sulfide nanoparticles,aflatoxin B1,photoelectrochemical immunoassay,etching reaction
更新于2025-09-04 15:30:14
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MOFs-derived ultrathin holey Co3O4 nanosheets for enhanced visible light CO2 reduction
摘要： Reducing carbon dioxide (CO2) to various value-added chemical products by photocatalysis could effectively alleviate the serious problems of global warming and energy shortages. Currently, most commonly prepared photocatalysts present poor performance under visible light irradiation. In this study, we adopted a facile, scalable and controllable approach to prepare ultrathin two-dimensional (2D) porous Co3O4 catalysts (Co3O4-NS) by air calcining of the ultrathin metal-organic framework (MOFs) nanosheet templates to validly reduce CO2 with a Ru-based photosensitizer under visible light irradiation. Benefitting from the structural nature of MOFs precursors, the calcined Co3O4-NS inherit the morphology of 2D and well-developed porosity, which support the transport of electrons, enhance the adsorption of CO2 molecules, and render abundant catalytic sites for CO2 activation. As a result, the CO generation rate is approximately 4.52 μmol·h-1 with selectivity of 70.1%, which is superior to the Co3O4 bulk catalysts (Co3O4-BK). Additionally, density functional theory (DFT) calculations reveal that the model of Co3O4 monolayer has stronger CO2 adsorption energy than that of the Co3O4 bulk, which is beneficial for the CO2-to-CO conversion. This MOF-engaged strategy provides new insight into the controlled synthesis of advanced ultrathin holey nanosheets to improve the efficiency of photocatalytic CO2 reduction.
关键词： ultrathin nanosheets,Co3O4,photocatalysis,MOFs derived,CO2 reduction
更新于2025-09-04 15:30:14
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Surface defect and rational design of TiO2?x nanobelts/ g-C3N4 nanosheets/ CdS quantum dots?hierarchical structure for enhanced visible-light-driven photocatalysis
摘要： TiO2-x/g-C3N4/CdS ternary heterojunctions are fabricated through thermal polymerization-chemical bath deposition combined with in-situ solid-state chemical reduction approach. The prepared materials are characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy. The results show that the ternary heterojunctions are formed successfully and CdS quantum dots (QDs) and TiO2 are anchored on surface of g-C3N4 nanosheets simultaneously. The visible-light-driven photocatalytic degradation ratio of Bisphenol A and hydrogen production rate are up to 95% and ~254.8 mmol h-1, respectively, which are several times higher than that of pristine TiO2. The excellent visible-light-driven photocatalytic activity can be ascribed to the synergistic effect of TiO2-x, g-C3N4 and CdS QDs which extend the photoresponse to visible light region and favor the spatial separation of photogenerated charge carriers.
关键词： Photocatalysis,Ti3+ self-doping,g-C3N4 nanosheets,CdS quantum dots,TiO2 nanobelts
更新于2025-09-04 15:30:14
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3D heterostructured Ti-based Bi2MoO6/Pd/TiO2 Photocatalysts for High-Efficiency Solar Light Driven Photoelectrocatalytic Hydrogen Generation
摘要： Hydrogen fuel generation using solar light via photoelectrochemical (PEC) methods can help meet growing global energy demands and decrease environmental pollution. The key to efficient PEC hydrogen production is the synthesis of solar light driven photoelectrodes with efficient charge carrier separation. Here, we designed and prepared a ternary Bi2MoO6/Pd/TiO2 photoelectrode composed of Bi2MoO6 nanosheets, Pd nanoparticles (NPs) and TiO2 nanotube arrays (NTAs) on a Ti substrate using electrochemical methods. This novel photoelectrode had good visible light absorbance and significantly improved PEC hydrogen production rates (~5 and > 15 times higher under UV-vis and visible light irradiation, respectively, compared with TiO2 NTAs). The interfacial charge transfer mechanism of Bi2MoO6/Pd/TiO2 NTAs was comprehensively studied by comparing its PEC and photoelectrocatalytic performance with other TiO2 NTAs (i.e. Pd/TiO2 NTAs, Bi2MoO6/TiO2 NTAs and Pd/Bi2MoO6/TiO2 NTAs). For Bi2MoO6/Pd/TiO2 NTAs, Pd NPs homogeneously dispersed across the inside and outside of TiO2 nanotube walls helped to tightly anchor Bi2MoO6 nanosheets onto the TiO2 surface, forming a ternary 3D heterostructure. This structure facilitated interfacial electron injection from Bi2MoO6 to TiO2, accelerating the separation of the photogenerated electron-hole pairs. And significantly enhanced the photocurrent response and hydrogen production rate were achieved compared with other TiO2 NTAs. This 3D ternary semiconductor/metal/semiconductor heterojunction provides a viable approach for designing and synthesizing highly efficient novel photocatalysts that can effectively utilize solar energy.
关键词： TiO2 nanotube arrays,Pd nanoparticles,Bi2MoO6 nanosheets,Photoelectrocatalytic hydrogen production,Ternary photocatalyst
更新于2025-09-04 15:30:14
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Azide Passivation of Black Phosphorus Nanosheets: Covalent Functionalization Affords Ambient Stability Enhancement
摘要： Two-dimensional (2D) black phosphorus (BP) has been attracting ever-growing interest due to its unique band structure, but suffers from low ambient stability owing to its high reactivity to oxygen. Covalent functionalization has been demonstrated to passivate the reactive BP effectively, however the reported covalent functionalization methods are quite limited to aryl diazonium and nucleophilic additions affording P-C and P-O-C single bonds, for which the retaining of one unpaired electron in the Group-VA phosphorus atom hampers the passivation effect. Herein, we report for the first time covalent azide functionalization of BP nanosheets (BPNSs), leading to significant enhancement of the ambient stability of BP as confirmed by UV-vis spectroscopic studies. The most stable configuration of the azide functionalized BPNSs is predicted by theoretical calculations, featuring the grafting of benzoic acid moiety onto BPNSs (f-BPNSs) via the unprecedented P=N double bonds formed through in-situ nitrene as a reactive intermediate.
关键词： covalent functionalization,2D nanosheets,nitrene,black phosphorus,azide
更新于2025-09-04 15:30:14
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Enzyme-free multicolor biosensor based on Cu2+-modified carbon nitride nanosheets and gold nanobipyramids for sensitive detection of neuron specific enolase
摘要： In this work, we have synthesized Cu2+-modified carbon nitride nanosheets (Cu2+-C3N4) as peroxidase mimic catalytic substance, which is more active than the horseradish peroxidase enzyme in extreme environments. Gold nanobipyramid (Au NBP) is a good chromogenic substrate for multicolor display because the longitudinal plasmon bands of AuNRs can be easily tuned by adjusting their aspect ratios and used as an excellent indicator for colorimetric detection of immunoassays. The generation of TMB2+ from sandwich complex (peroxidase-like catalysis) efficiently etches Au NPBs to produce multicolor variations from brown to olive, green, blue, purple, purple, red, pink, and colorless in presence of varied concentrations of neuron specific enolase (NSE). The experimental results show that the colorimetric detection ranging from 312.5 to 20,000 pM with a detection limit of 92.8 pM, which is higher than other multicolor based sensors. The Cu2+-C3N4 nanosheets and Au NBPs based colorimetric visual (naked eye) semi-quantitative method as a potential platform towards the detection of important biomolecules in clinical and therapeutic applications. The proposed method is simple, low-cost and enzyme-free to detect NSE for the first time.
关键词： Gold nanobipyramids,Cu2+-C3N4 nanosheets,Mimic enzyme activity,Neuron specific enolase,Biosensor
更新于2025-09-04 15:30:14
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Restriction of Molecular Rotors in Ultrathin Two-Dimensional Covalent Organic Framework Nanosheets for Sensing Signal Amplification
摘要： Covalent organic frameworks (COFs) have emerged as promising crystalline porous materials with well-defined structures, high porosity, tunable topology and functionalities suitable for various applications. However, studies of few-layered ultrathin two-dimensional (2D) COF nanosheets, which may lead to unprecedented properties and applications, are still limited. Herein we report the targeted synthesis of three azine-linked and imine-linked 2D COFs named NUS 30-32 using monomers containing aggregation-induced emission (AIE) rotor-active tetraphenylethylene (TPE) moieties, affording micro- and meso- dual pores in NUS-30 and NUS-32, and triple pores in NUS-31. For the first time, we demonstrate that these isostructural bulk COF powders can be exfoliated into ultrathin 2D nanosheets (2 – 4 nm thickness) by temperature-swing gas exfoliation approach. Compared with TPE monomers and COF model compounds, the AIE characteristic of NUS 30-32 nanosheets is distinctly suppressed due to the covalent restriction of the AIE molecular rotors in the confined 2D frameworks. As a result, the enhancement of conjugated conformations of NUS 30-32 nanosheets with unusual structure relaxation show signal amplification effect in biomolecular recognition of amino acids and small pharmaceutical molecules (L-dopa), exhibiting much higher sensitivity than their stacked bulk powders, TPE monomer, and COF model compound. Moreover, the binding affinity of the COF nanosheets toward amino acids can be controlled by increasing the number of azine moieties in the structure. Density functional theory (DFT) calculations reveal that binding affinity control results from the crucial geometric roles and stronger host-guest binding between azine moieties and amino acids. In addition, we demonstrate that minimal loading of the NUS-30 nanosheets in composite membranes can afford excellent performance for biomolecule detection. Our findings pave a way for the development of functional ultrathin 2D COF nanosheets with precise control over the nature, density, and arrangement of the binding active sites involved in enhanced molecule recognition.
关键词： molecular rotors,Covalent organic frameworks,aggregation-induced emission,biomolecular recognition,signal amplification,two-dimensional nanosheets
更新于2025-09-04 15:30:14
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1T-Phase Tungsten Chalcogenides (WS <sub/>2</sub> , WSe <sub/>2</sub> , WTe <sub/>2</sub> ) Decorated with TiO <sub/>2</sub> Nanoplatelets with Enhanced Electron Transfer Activity for Biosensing Applications
摘要： Layered transition metal dichalcogenides (TMDs) have received a great deal of attention due to fact that they have varied band gap, depending on their metal/chalcogen composition and on the crystal structure. Furthermore, these materials demonstrate great potential application in a myriad of electrochemical technologies. Heterogeneous electron transfer (HET) abilities of TMD materials toward redox-active molecules occupy a key role in their suitability for electrochemical devices. Herein, we introduce a promising biosensing strategy based on improved heterogeneous electron transfer rate of WS2, WSe2, and WTe2 nanosheets exfoliated using tert-butyllithium (t-BuLi) and n-butyllithium (n-BuLi) intercalators decorated with vertically aligned TiO2 nanoplatelets. By comparison of all the nanohybrids, decoration of TiO2 on t-BuLi WS2 (TiO2@t-BuLi WS2) results in the fastest HET rate of 5.39 × 10?3 cm s?1 toward ferri/ferrocyanide redox couple. In addition, the implications of decorating tungsten dichalcogenides (WX2) with TiO2 nanoplatelets in enzymatic biosensor applications for H2O2 detection are explored. TiO2@t-BuLi WS2 outperforms all other nanohybrid counterparts and is demonstrated to be an outstanding sensing platform in enzyme-based biosensor with wide linear range, low detection limit, and high selectivity. Such conceptually new electrocatalytic detection systems shall find the way to the next generation biosensors.
关键词： heterogeneous electron transfer,H2O2 detection,nanosheets,TiO2 nanoplatelets,transition metal dichalcogenides
更新于2025-09-04 15:30:14
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Energy Level Engineering in Transition-Metal Doped Spinel-Structured Nanosheets for Efficient Overall Water Splitting
摘要： Unraveling the role of transition-metal doping on affecting the native spinel-structured nanosheets’ water splitting remains a grand challenge. In this work, a series of spinel-structured nanosheets wrapped hollow nitrogen-doped carbon polyhedrons was constructed, and doped transition-metal domains were deliberately introduced on the surface. Theoretical investigations show that their energy level can be finely tuned via direct transition-metal doping engineering. As a prototype, Fe-doped NiCo2O4 nanosheets wrapped hollow nitrogen-doped carbon polyhedron (Fe-NiCo2O4@HNCP) exhibits outstanding bifunctional electrocatalytic performances with low overpotentials (η = 270 mV for OER, η = 84 mV for HER), low Tafel slopes (b = 42 mV dec-1 for OER, b = 47 mV dec-1 for HER), and high durability. The enhanced performance is attributed to the synergistic effects of energy level matching for electron transfer, and partial charge delocalization-induced rich active sites for reactant adsorption via thermodynamic and kinetic acceleration. This work may open a new pathway to design highly active and stable transtion-metal doped electrocatalysts by manipulated energy levels for efficient overall water splitting.
关键词： energy level engineering,water splitting,electrocatalysts,spinel-structured nanosheets,transition-metal doping
更新于2025-09-04 15:30:14