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Novel PtPd alloy nanoparticle-decorated g-C3N4 nanosheets with enhanced photocatalytic activity for H2 evolution under visible light irradiation
摘要： PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g–1 h–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g–1 h–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.
关键词： H2 evolution,PtPd alloy nanoparticles,Photocatalysis,g-C3N4 nanosheets
更新于2025-11-14 17:03:37
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Enhanced Methane Sensing Properties of WO3 Nanosheets with Dominant Exposed (200) Facet via Loading of SnO2 Nanoparticles
摘要： Methane detection is extremely difficult, especially at low temperatures, due to its high chemical stability. Here, WO3 nanosheets loaded with SnO2 nanoparticles with a particle size of about 2 nm were prepared by simple impregnation and subsequent calcination using SnO2 and WO3·H2O as precursors. The response of SnO2-loaded WO3 nanosheet composites to methane is about 1.4 times higher than that of pure WO3 at the low optimum operating temperature (90 °C). Satisfying repeatability and long-term stability are ensured. The dominant exposed (200) crystal plane of WO3 nanosheets has a good balance between easy oxygen chemisorption and high reactivity at the dangling bonds of W atoms, beneficial for gas-sensing properties. Moreover, the formation of a n–n type heterojunction at the SnO2-WO3 interface and additionally the increase of specific surface area and defect density via SnO2 loading enhance the response further. Therefore, the SnO2-WO3 composite is promising for the development of sensor devices to methane.
关键词： methane sensing,SnO2-loaded WO3 nanosheets,exposed (200) facet,heterojunction
更新于2025-11-14 17:03:37
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Tannic acid-derivatized graphitic carbon nitride quantum dots as an “on-off-on” fluorescent nanoprobe for ascorbic acid via copper(II) mediation
摘要： A microwave-assisted hydrothermal route was employed to prepare fluorescent tannic acid (TA)-derivatized graphitic carbon nitride quantum dots. The resulting dots display blue fluorescence (best measured at excitation/emission wavelengths of 350/452 nm) with a quantum yield as high as ~44%. The incorporated TA imparts a fluorescence switching behavior in that very low concentrations of Cu(II) can quench the fluorescence, while (AA) can restore it. It is presumed that AA causes Cu(II) to be transformed to Cu(I). Based on these findings, a fluorometric method was designed for AA detection. The probe allows AA to be detected with a 50 pM limit of detection and a linear analytical range that extends from 0.1 to 200 nM of AA. Real and spiked samples were successfully assayed by the probe to demonstrate its analytical applicability.
关键词： Fluorescence recovery,Metal ions,Graphitic nanosheets,Biomolecules,Polyphenolic compounds,Optical probe,Quantum dots
更新于2025-10-22 19:40:53
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Three-in-one oxygen vacancy: whole visible-spectrum absorption, efficient charge separation and surface site activation for robust CO2 photoreduction
摘要： Exploitation of efficient catalysts to realize solar-driven conversion of inert CO2 into useful fuels confronts big challenges owing to the poor photoabsorption, sluggish charge separation and inefficient surface reactive sites of photocatalysts. Herein, we report a facile and controllable in situ reduction strategy to create surface oxygen vacancies (OVs) on Aurivillius-phase Sr2Bi2Nb2TiO12 nanosheets. Sr2Bi2Nb2TiO12 nanosheets are for the first time prepared by a mineralizer-assisted soft-chemical method, and the introduction of OVs on the surface of Sr2Bi2Nb2TiO12 not only extends photo-response region, but also tremendously promotes separation of photo-induced charge carriers. Moreover, the adsorption and activation of CO2 molecules on the surface of the catalyst are largely enhanced. In the gas-solid reaction system without any co-catalysts or sacrificial agents, OVs-abundant Sr2Bi2Nb2TiO12 nanosheets show an outstanding CO2 photoreduction activity in producing CO with a rate of 17.11 μmol g?1 h?1, ~58 times higher than that of the bulk counterpart, surpassing most previously reported state-of-the-art photocatalysts. Our study provides a three-in-one integrated solution to advance the comprehensive performance of photocatalysts for solar-energy conversion and generation of renewable energy.
关键词： Sr2Bi2Nb2TiO12 nanosheets,charge separation,photocatalytic CO2 reduction,oxygen vacancies
更新于2025-09-23 15:23:52
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Colloidally Stable Monolayer Nanosheets with Colorimetric Responses
摘要： Despite the discovery of chromogenic-layered materials for decades of years, fabrication of colloidally stable monolayer organic 2D nanosheets in aqueous media with colorimetric responses is still challenging. Herein reported is the first solution synthesis of chromic monolayer nanosheets via the topochemical polymerization of self-assembled amphiphilic diacetylenes in aqueous media. The polydiacetylene (PDA) nanosheets are ≈3–4 nm thick in solution and only ≈1.9 nm thick in the dried state, while the lateral size can reach several micrometers. Moreover, the aqueous stability endows PDA nanosheets with excellent processability, which can further assemble into films via vacuum filtration or act as an ink for high-resolution inkjet printing. The filtrated films and printed patterns exhibit fully reversible blue-to-red thermochromism, and the film also displays an interesting reversible colorimetric transition in response to near-infrared light, which is not reported for other PDA-only systems. The present colloidal PDA nanosheets should represent a new kind of chromic organic 2D nanomaterials that may be applied as novel building blocks for developing intelligent hybrid materials and may also find diverse sensing, display and/or anticounterfeiting applications.
关键词： colorimetric responses,monolayer nanosheets,colloidal stability,polydiacetylene
更新于2025-09-23 15:23:52
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CsxWO3 nanosheet-coated cotton fabric with multiple functions: UV/NIR shielding and full-spectrum-responsive self-cleaning
摘要： Utilizing fewer functional materials to achieve multifunctional fabrics via facile approaches have been confronting worldwide scientists with an enormous challenge. In this study, a novel multifunctional cotton fabric, combining UV/NIR shielding and full-spectrum-responsive self-cleaning, has been fabricated via self-assembly of CsxWO3 nanosheets based on electrostatic interaction assisted by Poly (diallyldimethylammonium chloride) (PDDA) in aqueous solution. The microstructure of CsxWO3 nanosheets and their self-assembly coating on cotton fabric were characterized and investigated. The functional properties of the CsxWO3-coated cotton fabric, including UV/NIR shielding and photocatalytic self-cleaning were evaluated. The results indicate that the CsxWO3-coated cotton fabric exhibits superb UV/NIR and heat shielding performance with 15.8 °C and 5.9 °C lower than no coverage and coverage by none-treated cotton fabric, respectively. Moreover, the well-coated cotton fabric demonstrates photocatalytic self-cleaning property responsive to the light ranging from UV, Vis to NIR, especially exhibits highly efficient self-cleaning under the respective irritation of full-spectrum, UV and Vis light (color faded completely within 10 h). In summary, the CsxWO3-coated fabrics can achieve multi-functions of UV shielding, heat insulation and self-cleaning by means of a single functional nanomaterial and promise of huge applications in functional textiles.
关键词： full-spectrum self-cleaning,self-assembly coating,UV/NIR shielding,CsxWO3 nanosheets,functional cotton fabric
更新于2025-09-23 15:23:52
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Characterization of M1 and M2 polarization phenotypes in peritoneal macrophages after treatment with graphene oxide nanosheets
摘要： Macrophages play a key role in nanoparticle removal and are primarily responsible for their uptake and trafficking in vivo. Due to their functional plasticity, macrophages display a spectrum of phenotypes between two extremes identified as pro-inflammatory M1 and reparative M2 macrophages, characterized by the expression of specific cell surface markers and the secretion of different cytokines. The influence of graphene oxide (GO) nanosheets functionalized with poly(ethylene glycol-amine) and labelled with fluorescein isothiocyanate (FITC-PEG-GO) on polarization of murine peritoneal macrophages towards M1 and M2 phenotypes was evaluated in basal and stimulated conditions by flow cytometry and confocal microscopy through the expression of different cell markers: CD80 and iNOS as M1 markers, and CD206 and CD163 as M2 markers. Although FITC-PEG-GO did not induce M1 or M2 macrophage polarization after 24 and 48 h in basal conditions, this nanomaterial decreased the percentage of M2 reparative macrophages. We have also compared control macrophages with macrophages that have or have not taken up FITC-PEG-GO after treatment with these nanosheets (GO+ and GO- cells, respectively). The CD80 expression diminished in GO+ macrophages after 48 h of GO treatment but the CD206 expression in GO+ population showed higher values than in both GO- population and control macrophages. In the presence of pro-inflammatory stimuli (LPS and IFN-γ), a significant decrease of CD80+ cells was observed after treatment with GO. This nanomaterial also induced significant decreases of CD206+ and CD163+ cells in the presence of reparative stimulus (IL-4). The CD80, iNOS and CD206 expression was lower in both GO- and GO+ cells than in control macrophages. However, higher CD163 expression was obtained in both GO- and GO+ cells in comparison with control macrophages. All these facts suggest that FITC-PEG-GO uptake did not induce the macrophage polarization towards the M1 pro-inflammatory phenotype, promoting the control of the M1/M2 balance with a slight shift towards M2 reparative phenotype involved in tissue repair, ensuring an appropriate immune response to these nanosheets.
关键词： Graphene oxide nanosheets,Macrophage polarization,Peritoneal macrophages,Cytokine profiling
更新于2025-09-23 15:23:52
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Detection of divalent copper with improved accuracy by dual suppression of electrochemiluminescent recovery
摘要： This work is to construct an electrochemiluminescent (ECL) sensor with improved accuracy for the detection of Cu2+. The improved accuracy is achieved by utilizing a reaction system to realize Cu2+ dose-dependent dual suppression of ECL recovery from gold nanoparticle-graphitic carbon nitride nanosheet nanohybrid (Au-CNNS) film. The ECL sensor shows sensitive response to Cu2+ in the concentration range of 5 nM to 500 nM with an enlarged slope, and high specificity attributed to the high affinity of CNNS-Cu2+ complex and the high catalytic activity of Cu(NH3)6 2+ to decompose H2O2 in the reaction system. The proposed ECL sensor with improved accuracy may prove valuable in future biomedical applications.
关键词： dual suppression,electrochemiluminescent sensor,copper,graphitic carbon nitride nanosheets
更新于2025-09-23 15:23:52
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Facile synthesis of thin black TiO2 ? x nanosheets with enhanced lithium-storage capacity and visible light photocatalytic hydrogen production
摘要： In combination of a facile and scalable solvothermal method and solid-phase reduction reactions, a novel two-dimensional black TiO2 ? x nanosheet (TiO2 ? x NS) with high specific surface area of 108 m2 g?1 and nearly total solar spectral absorption capability have been successfully prepared. With careful characterizations, the novel TiO2 ? x NS showed enhanced electrochemical performance and visible-light photocatalytic activity than those of their white TiO2 nanosheet (TiO2 NS) precursors. The black TiO2 ? x NS electrode delivered a reversible specific capacity of 160 mA h g?1 even after cycling at 0.5 C (1 C = 190 mA h g?1) for 300 times, which was significantly higher than the corresponding white TiO2 NS electrode (104 mA h g?1). Meanwhile, the TiO2 ? x NS also exhibited enhanced ability of visible-light photocatalytic hydrogen production than that of the white TiO2 NS. It is expected that making white TiO2 NS into black ones is an effective way to design the photocatalysts with visible light response and the anodes with long lifetime and high rate performance in lithium ion batteries. The novel black TiO2 ? x NS could find potential applications in the field of environmental management and energy storage and conversion.
关键词： Solvothermal method,Photocatalysis,Black TiO2 ? x nanosheets,Anodes
更新于2025-09-23 15:23:52
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Direct patterned growth of intrinsic/doped vertical graphene nanosheets on stainless steel via heating solid precursor films for field emission application
摘要： Vertical graphene nanosheets (VGNs), normally consisting of one to several graphene layers vertically aligned on substrates, are promising in a variety of applications including field electron emitters, gas sensors and energy storage devices. Herein, we report a simple, green, easily scalable and cost-effective strategy of growing both intrinsic and nitrogen (N)-doped VGNs on stainless steel (SS) just by heating the solid thin layers of glucose and/or urea in a resistance-heating furnace. It is interesting that VGNs mainly grow on the roughened regions, which can be attributed to the more nucleation and catalyzing sites on such regions than smooth SS. Meanwhile, the N doping concentration can be adjusted by varying the urea addition. Field electron emission measurement indicates that the obtained N-doped VGNs exhibit excellent field emission with a relatively low turn-on electric field strength (~2.6 V μm?1 at the current density of 10 μA cm?2), large field enhancement factor (~9428) and high stability.
关键词： Green synthesis,Nitrogen doping,Vertical graphene nanosheets,Field electron emission,Direct patterned growth
更新于2025-09-23 15:23:52