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Metala??organic framework nanosheets for enhanced performance of organic photovoltaic cells
摘要： Metal-organic nanosheets (MONs) are an emerging class of two-dimensional materials whose diverse and readily tunable structures make them ideal for use in optoelectronic applications. Here, liquid exfoliation is used to synthesize ultrathin zinc-porphyrin based MONs with electronic and optical properties ideally suited for incorporation into a polythiophene-fullerene (P3HT-PCBM) organic solar cell. Remarkably, the addition of MONs to the photoactive layer of a photovoltaic device results in a power conversion efficiency of 5.2%, almost twice that for reference devices without nanosheets with a simultaneous improvement of Jsc, Voc and FF. Our analysis indicates that the complimentary electronic, optical and structural properties of the MONs allows them to act as a surface to template the crystallization of P3HT leading to a doubling of the absorbance, a tenfold increase in hole mobility and reduced grain size. These results demonstrate the potential of MONs as a tunable class of two-dimensional materials for enhancing the performance of a broad range of organic solar cells and other electronic devices.
关键词： Metal-organic nanosheets,organic photovoltaic cells,power conversion efficiency,liquid exfoliation,zinc-porphyrin
更新于2025-09-19 17:13:59
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Noble-metal-free MoS2 nanosheet-coupled MAPbI3 photocatalyst for efficient and stable visible-light-driven hydrogen evolution
摘要： We report that MoS2 nanosheets (MoS2 NSs) as an cocatalyst in situ coupled with MAPbI3 leads to a highly efficient composite photocatalyst for visible-light-driven photocatalytic H2 evolution. The most efficient MAPbI3/MoS2 NSs exhibits a high H2 evolution rate (206.1 μmol h-1) in MAPbI3-saturated HI solution, which is 121 times higher than that of pristine MAPbI3 (1.7 μmol h-1) and greatly superior to that of MAPbI3/Pt/C (68.5 μmol h-1), and the composite is very stable for H2 evolution in 156 h reaction.
关键词： photocatalyst,MoS2 nanosheets,visible-light-driven,MAPbI3,hydrogen evolution
更新于2025-09-19 17:13:59
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Bionanosensor based on N-doped graphene quantum dots coupled with CoOOH nanosheets and their application for in vivo analysis of ascorbic acid
摘要： Herein, we employ 3D nitrogen-doped porous graphene frameworks (3D NPG) as raw material to prepare emissive nitrogen doped graphene quantum dots (r-NGQDs) via chemical oxidation method. The as-prepared fluorescent r-NGQDs was integrated with CoOOH nanosheets to construct a sensing platform for in vivo ascorbic acid (AA) analysis. Initially, the fluorescence emission intensity of r-NGQDs was quenched by CoOOH nanosheets based on the inner filter effect (IFE). Then the quenched intensity of r-NGQDs and CoOOH nanosheets system was enlightened by the addition of AA, since AA could consume CoOOH nanosheets through redox reaction, leading to the release of r-NGQDs and fluorescence restoration. Moreover, the restored fluorescence intensity of r-NGQDs is highly dependent on the concentration of AA which endows them as a quantitative analysis of AA with a limit of detection (LOD) reach up to1.85 μM (n = 3) in aqueous solution. Finally, the as constructed bionanosensor was further employed for in vivo analysis of AA in living rat brain microdialysate with basal value up to 9.4 ± 1.4 μM (n = 3).
关键词： Nitrogen-doped porous graphene,Graphene quantum dots,Ascorbic acid,In vivo,CoOOH nanosheets
更新于2025-09-16 10:30:52
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Plasmon Ag and CdS quantum dot co-decorated 3D hierarchical ball-flower-like Bi <sub/>5</sub> O <sub/>7</sub> I nanosheets as tandem heterojunctions for enhanced photothermal–photocatalytic performance
摘要： Plasmon Ag and CdS quantum dot co-decorated three-dimensional (3D) hierarchical ball-flower-like Bi5O7I nanosheets as tandem heterojunction photocatalysts are synthesized by oil bath, photoreduction and hydrothermal processes. The formation of a tandem heterojunction structure facilitates the migration and spatial separation of photogenerated electron–hole pairs. Plasmon Ag nanoparticles can generate hot electrons to enhance the photothermal performance due to the surface plasmon resonance (SPR) effect. The unique 3D hierarchical ball-flower-like Bi5O7I nanosheets can provide a number of surface active sites and allow incident light to be reflected multiple times within the Bi5O7I nanosheets, thus improving the light utilization. Under the protection of Bi5O7I nanosheets, CdS quantum dots which are deposited by a hydrothermal strategy can effectively avoid photocorrosion. In addition, the introduction of Ag nanoparticles and CdS quantum dots extends the photoresponse to the near infrared (NIR) region. The photocatalytic degradation rate of Bi5O7I/Ag/CdS composites with a CdS content of 5.76 wt% exhibits the best photocatalytic activity, which is several times higher than that of pristine Bi5O7I. The photocatalytic hydrogen evolution is about 10 times higher than that over Bi5O7I nanosheets. Moreover, the photothermal efficiency of Bi5O7I/Ag/CdS is also improved obviously. The results of cyclic experiments show that the composite photocatalysts have high stability. The outstanding photocatalytic and photothermal performance is attributed to the formation of tandem heterojunctions favoring the separation of charge carriers, the 3D hierarchical structure of Bi5O7I offering adequate surface active sites, and the SPR effect of Ag promoting the photothermal effect. These novel Bi5O7I/Ag/CdS tandem heterojunctions may provide a new insight into the synthesis of other photocatalysts with synergistic photocatalytic–photothermal effects.
关键词： tandem heterojunctions,photothermal–photocatalytic performance,Bi5O7I nanosheets,CdS quantum dot,Plasmon Ag
更新于2025-09-16 10:30:52
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NiPS <sub/>3</sub> nanosheets for passive pulse generation in an Er-doped fiber laser
摘要： With the rapidly increasing demands of industrial material processing, biomedical sensing, light detection, and high-speed communication, various novel two-dimensional (2D) materials have been synthesized and employed in ultrafast fiber laser generation due to their advantages of easy processing characteristics, desirable structures and excellent nonlinear optical properties. However, finding an efficient 2D material-based saturable absorber (SA) with the capacity of both high stability and excellent working property performance remains a challenge. Herein, high-quality NiPS3 crystals, from the metal phosphorus trichalcogenide (MPT3) family, were synthesized by a modified chemical vapor transport (CVT) method and a few-layer NiPS3 nanosheet SA was easily obtained using a direct liquid-phase exfoliation method. Different from other 2D materials, ultrathin NiPS3 nanosheets display a good stability. Moreover, a passively Q-switched operation and dual-wavelength mode-locked pulse output were proposed based on a NiPS3-SA erbium-doped fiber (EDF) laser. In the passively Q-switched operation, the maximum peak power was 6.40 mW with a maximum pulse energy of 29.66 nJ. It is also worth noting that dual-wavelength pulse output was achieved in passively mode-locked pulse generation. These results not only supply other choices of SAs for pulse generation, but also provide guidance to extend other possible applications of the MPT3 family for nonlinear optics.
关键词： mode-locked,Q-switched,NiPS3 nanosheets,ultrafast fiber laser,saturable absorber
更新于2025-09-16 10:30:52
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Synthesis of bilayer graphene nanosheets by pulsed laser ablation in liquid and observation of its tunable nonlinearity
摘要： Bilayer graphene nanosheets (B-GNSs) have been synthesized from dry-cell graphite electrode by using facile laser ablation in liquid technique in ambient condition. The plasma plume generated on incidence of ns pulsed Nd:YAG laser fundamental radiation of 1064 nm has facilitated the transformation of bulk graphite (BG) into B-GNSs via liquid carbon phase within 30 min of laser irradiation, and the layer number is are found to be increased with further increase in laser ablation time. The thickness dependent coherent nonlinear optical (NLO) response of the synthesized materials in aqueous dispersion has been determined by spatial self-phase modulation technique. The oxygen-containing surface defects in multilayer GNSs (M-GNSs) have led to scarcity in amount of e-h pairs in compared to that in B-GNSs. Therefore, a better NLO polarization has been observed in B-GNSs in compared to that of M-GNSs. Moreover, the thickness dependent thermal conductivity and hydrodynamic performance of GNSs-water dispersion has led to the observation of tunable NLO response with change in temperature as well as with the intensity of pump laser. The experimental findings obtained in this work may be considered as a key step towards fabrication of graphene from graphitic waste materials for development of future nonlinear photonics devices.
关键词： Waste material,Nonlinear optical properties,Optical properties,Spatial self-phase modulation,Laser ablation,Graphene nanosheets
更新于2025-09-16 10:30:52
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Study of the photocatalytic performance and carrier migration of reduced graphene oxide-modified infrared-responsive photocatalyst β-NaYF4:Yb3+, Er3+@BiOCl-rGO
摘要： To further enhance the photocatalytic performance of BiOCl, a facile hydrothermal reduction reaction was used to synthesize the reduced graphene oxide- (rGO-) modified ternary compound photocatalyst β-NaYF4:Yb3+, Er3+@BiOCl-rGO (NYF–Bi-rGO). rGO prepared using a hydrothermal method showed good conductivity. Furthermore, the specific surface area of NYF-Bi-rGO was 20-fold larger than that of NYF, which is a quality that could prove highly advantageous for use in pollutant adsorption. In addition, the ternary photocatalytic system produced by rGO increased the absorption intensity of NYF-Bi in the visible light region, and caused a red-shift of the entire absorption cross-section. In particular, analysis of carrier migration showed the introduction of rGO promoted the separation of the photoelectron-hole pairs of BiOCl, inhibited its recombination and improved the photocatalytic efficiency of the ternary photocatalyst NYF-Bi-rGO.
关键词： Photocatalytic degradation,Characterization,BiOCl nanosheets,Reduced graphene oxide (rGO)
更新于2025-09-16 10:30:52
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Rapid, facile, reagentless, and room-temperature conjugation of monolayer MoS2 nanosheets with dual-fluorophore-labled flares as Nanoprobes for ratiometric sensing of TK1 mRNA in living cells
摘要： Direct loading of fluorophore-labeled DNA molecules (named as flares) on gold nanoparticles (AuNPs) is a controllable and straightforward approach for intracellular imaging of target DNA molecules. However, the modification of AuNPs with flares requires a tedious and time-consuming procedure, additional reagents, or adenosine-rich DNA molecules. Here, we developed a rapid, simple, reagentless, and room-temperature approach for the modification of monolayer molybdenum disulfide nanosheets (M-MoS2 NSs) with dual-fluorophore-labeled flares, which were implemented for ratiometric imaging of TK1 mRNA in living cells. The duplexes were prepared by hybridizing thiolated single-stranded DNA (ssDNA) to 6-carboxyfluorescein (FAM)- and 5-carboxytetramethylrhodamine (TAMRA)-labeled flares. Fabrication of the nanoflares was conducted by conjugating the formed duplexes to the surface sulfur vacancy sites of the M-MoS2 NSs. The time for preparing the nanoflares was found to be completed within 1 h. In the nanoflares, FAM stays away from TAMRA, leading to inefficient fluorescence resonance energy transfer (FRET). The presence of perfectly matched DNA (DNApm) molecules induces the liberation of the flares from the nanoflares. The liberated flares fold into hairpin-shaped structures, causing high FRET efficiency from FAM to TAMRA and efficient FAM-TAMRA static quenching. Following this mechanism, the nanoflares provided an effective platform for ratiometric sensing of DNApm molecules with the limit of detection (at a signal-to-noise ratio of 3) of 8 nM and the linear range of 25?500 nM. Confocal microscopy experiments demonstrated that the nanoflares can be used to ratiometrically image TK1 mRNA in HeLa and MCF-7 cells.
关键词： ratiometric sensing,monolayer MoS2 nanosheets,TK1 mRNA,dual-fluorophore-labeled flares,living cells
更新于2025-09-16 10:30:52
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Large-scale synthesis of crystalline g-C <sub/>3</sub> N <sub/>4</sub> nanosheets and high-temperature H <sub/>2</sub> sieving from assembled films
摘要： Poly(triazine imide) (PTI), a crystalline g-C3N4, hosting two-dimensional nanoporous structure with an electron density gap of 0.34 nm, is highly promising for high-temperature hydrogen sieving because of its high chemical and thermal robustness. Currently, layered PTI is synthesized in potentially unsafe vacuum ampules in milligram quantities. Here, we demonstrate a scalable and safe ambient pressure synthesis route leading to several grams of layered PTI platelets in a single batch with 70% yield with respect to the precursor. Solvent exfoliation under anhydrous conditions led to single-layer PTI nanosheets evidenced by the observation of triangular g-C3N4 nanopores. Gas permeation studies confirm that PTI nanopores can sieve He and H2 from larger molecules. Last, high-temperature H2 sieving from PTI nanosheet–based membranes, prepared by the scalable filter coating technique, is demonstrated with H2 permeance reaching 1500 gas permeation units, with H2/CO2, H2/N2, and H2/CH4 selectivities reaching 10, 50, and 60, respectively, at 250°C.
关键词： PTI,high-temperature,nanosheets,crystalline g-C3N4,hydrogen sieving
更新于2025-09-16 10:30:52
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Photocatalytic producing dihydroxybenzenes from phenol enabled by gathering oxygen vacancies in ultrathin porous ZnO nanosheets
摘要： As an energy-efficient and environmental friendliness method, solar sunlight-driven photo-oxidation catalysis process for organic chemicals synthesis has gained enormous attention, but still faces huge challenge in developing highly-efficient photocatalysts material. Two-dimensional materials engineering and surface defect engineering of photocatalysts both provide an effective strategy to improve the catalytic activity. Inspired by these pathway, we design and synthesize ultrathin porous ZnO nanosheets featuring abundant oxygen vacancies specific to producing dihydroxybenzenes based on a photocatalytic oxidation process. Several valid characterizations had been employed to discern the structural character of the obtained model catalyst, revealing that the resultant ZnO sheets afford an average thickness of 3 nm, and abundant surface porosity, thereby contributing to the rich oxygen vacancies. Such a structure could generate a synergistic effect to enhance the optical absorption and improve the transportation rate of photogenerated charge carriers from the materials design. As expected, the specific ultrathin ZnO nanosheets exhibited a greatly-improved photocatalytic activity for oxidation of phenol to dihydroxybenzenes (31.5% conversion & almost 76.7% selectivity of DHB), near 3 and 4 times higher, respectively than its counterparts that one with few oxygen vacancies and Bulk-ZnO. Impressively, the obtained catalyst showed durable catalytic activity without any activity loss during the five recycling. Finally, the feasible oxidation mechanism was proposed and testified by the controlled scavenger experiments. This study provides a novel reference on how to design high-performance photocatalytic material.
关键词： oxygen vacancies,ZnO,ultrathin nanosheets,oxidation of phenol,photocatalytic
更新于2025-09-12 10:27:22