Hybrid Nanosheets Research Articles

Graphene oxide embedded in Bi2S3 nanosheets by hydrothermal method to enhance thermoelectric performance

Bi2S3 is an inexpensive and non-toxic thermoelectric material with high Seebeck coefficient and low thermal conductivity, which makes it have broad development prospects in the field of thermoelectric materials. In this work, we successfully synthesized Bi2S3/graphene oxide (GO) hybrid nanosheets by a simple hydrothermal synthesis method. Due to the unique structure of the two-dimensional nanomaterial GO, it can be uniformly embedded in the Bi2S3nanosheet matrix. The total thermal conductivity of Bi2S3/GO hybrid nanosheets is astonishingly low as 0.32Wm−1K−1 at 619K, which is 13% lower than that of pure Bi2S3. In addition, the thermoelectric performance of Bi2S3/GO hybrid nanostructures were further improved by changing the doping amount of GO. At 300–650K, the maximum thermoelectric figure of merit (ZT) of Bi2S3/GO(0.5 wt%) is 0.17, and its ZT below 550K is higher than that of pure phase Bi2S3. Bi2S3/GO composites were synthesized by an inexpensive and simple experimental method, which provides a new strategy for optimizing the thermoelectric properties of Bi2S3.

CoP-Embedded Graphitic N-Doped C Nanosheets in Ohmic Contact with S-Deficient CdS Nanocrystals Triggering Efficient Visible-Light Photocatalytic H2 Evolution

Photocatalytic water splitting using semiconductor-based catalysts is a promising avenue to gain H2 fuel from renewable solar energy. Nonetheless, developing earth-abundant and visible-light-responsive photocatalysts for efficient H2 production still remains a huge challenge. In this work, unique two-dimensional hierarchitectures of S-deficient CdS integrated with ultrafine CoP nanocrystals embedding in graphitic N-doped C (CoP-CN) nanosheets are fabricated for the first time. Noticeably, the graphitic CN electron mediator not only enhances the photocatalytic stability of CdS/CoP-CN composites by protecting CoP from external corrosion but also induces the formation of an ohmic junction to boost electron extraction from CdS to CoP efficiently. Meanwhile, the S vacancies in CdS serve as electron traps to further enhance the separation of photogenerated carriers. Such unique CdS/CoP-CN hierarchical hybrid nanosheets exhibited an extraordinary visible-light-induced (λ > 400 nm) photocatalytic H2-evolving performance, delivering a high apparent quantum yield (26.3% at 420 nm) and an excellent H2 generation rate of 54.01 mmol·g–1·h–1, much superior to those of a CdS/CoP Schottky junction, Pt-loaded CdS, and a vast amount of CdS-based photocatalysts ever reported. In addition, the outstanding H2-evolving durability of CdS/CoP-CN composites was verified by cycling and long-term photocatalytic tests. The findings presented here are anticipated to enlighten the rational design and synthesis of highly active photocatalysts with an ohmic junction for application in energy and environment-related domains.

Evaluation of colonic anastomosis healing using hybrid nanosheets containing molybdenum disulfide (MOS2) scaffold of human placental amniotic membrane and polycaprolactone (PCL) in rat animal model.

Anastomosis is a standard technique following different conditions such as obstruction, tumor, and trauma. Obstruction, adhesion, or anastomosis leakage can be some of its complications. To improve healing and prevent postoperative complications, we design a hybrid scaffold containing acellular human amniotic membranes and polycaprolactone-molybdenum disulfide nanosheets for colon anastomosis. The animal model of colocolonic anastomosis was performed on two groups of rats: control and scaffold. The hybrid scaffold was warped around the anastomosis site in the scaffold group. Samples from the anastomosis site were resected on the third and seventh postoperative days for histopathological and molecular assessments. Histopathologic score and burst pressure had shown significant improvement in the scaffold group. No mortality and anastomosis leakage was reported in the scaffold group. In addition, inflammatory markers were significantly decreased, while anti-inflammatory cytokines were increased in the scaffold group. The result indicates that our hybrid scaffold is a proper choice for colorectal anastomosis repair by declining postoperative complications and accelerating healing.

Synthesis of functionalized janus hybrid nanosheets for one-step construction of pickering emulsion and selective photodegradation of water-soluble dyes

Recently, Pickering emulsions stabilized by photocatalytic nanomaterials have become a hotspot in the field of catalysis due to their high interfacial activity. However, since most photocatalytic nanomaterials are extremely hydrophilic, using them as stabilizers is unconvenient for Pickering emulsions construction. Herein, a novel magnetic Janus nanosheets (JMPSN/α-FeOOH) with Janus SiO2 nanosheets as the carrier and iron oxyhydroxide (α-FeOOH) as the catalyst species, respectively, was successfully fabricated through a simple synthetic strategy, which could act as an environmental-friendly Pickering emulsion emulsifier and catalyst simultaneously. We demonstrated that JMPSN/α-FeOOH exhibited good emulsifying properties of various oil phases. Morever, JMPSN/α-FeOOH in the formed Pickering emulsion-based photocatalytic system displayed significantly enhanced photocatalytic efficiency in degradation of dyes as compared to traditional non-emulsified systems while maintaining the stability of Pickering emulsion under constant irradiation. JMPSN/α-FeOOH could also quickly respond to external magnetic fields so as to achieve rapid recovery of catalyst, and catalyst still showed high catalytic activity after many catalytic cycles. Finally, a convenient and promising synthesis strategy for preparing Janus catalyst with low toxicity was proposed, which provided a guidance on how to effectively use the emulsion system stabilized by Janus catalyst to improve the degradation efficiency of various pollutants.

Combined experimental and DFT investigation of temozolomide sensing properties of 2D− 2D interface of rich oxygen vacancies of WO3−x and sulfur-doped g-C3N4 nanosheets hybrids composites

Temozolomide (TMZ) is one of the most effective anticancer drug and higher the risk of side effects, used in overdosage in cancer treatment. It is a major concern to determine the appropriate level of the anticancer drug by a more conventional method. In the present study, the first developed 2D− 2D interface of rich oxygen vacancies of WO3 −x and sulfur-doped g-C3N4 nanosheets hybrids composites (2D–2D/RWNs-SCN) was synthesized using a facial microwave-assisted route to detection of temozolomide (TMZ) in pharmaceutical sample. The samples’ morphological, two-dimensional rich oxygen vacancies of WO3 −x nanosheets (2D RWNs) and sulfur-doped g-C3N4 nanosheets (2D SCN) were investigated using field emission-scanning electron microscopes (FE-SEM). The 2D–2D/RWNs-SCN modified screen-printed carbon electrodes (SPCEs) were utilized for reducing TMZ in a 0.1 M phosphate-buffered solution (pH 7.0). The 2D–2D/RWNs-SCN achieved a higher reduction current against TMZ than the bare SPCE, CN/SPCE, SCN/NSs/SPCE, and 2D RWNs/SPCE. With optimized sensing parameters, the limit of detection was estimated to be 0.0019 μM, with a high sensitivity of 18.2855 μA μM− 1 cm− 2. To corroborate our experimental observations qualitatively, we have first time performed detailed density functional theory simulations to explore the charge transfer and bonding mechanism of TMZ on 2D RWNs and 2D–2D/RWNs-SCN surface. The higher binding energy of TMZ and enhanced charge transfer from TMZ to 2D–2D/RWNs-SCN owing to the 2D–2D interface possess superior charge-transfer kinetics, resulting in higher TMZ sensing performance, which supports our experimental observations. The hybrid nanocomposites are successfully applied to the determination of TMZ in the presence of pharmaceutical samples.

One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications.

The combination of two-dimensional materials and metal nanoparticles (MNPs) allows the fabrication of novel nanocomposites with unique physical/chemical properties exploitable in high-performance smart devices and biosensing strategies. Current methods to obtain graphene-based films decorated with noble MNPs are cumbersome, poorly reproducible, and difficult to scale up. Herein, we propose a straightforward, versatile, surfactant-free, and single-step technique to produce reduced graphene oxide (rGO) conductive films integrating "naked" noble MNPs. This method relies on the instantaneous laser-induced co-reduction of graphene oxide and metal cations, resulting in highly exfoliated rGO nanosheets embedding gold, silver, and platinum NPs. The production procedure has been optimized, and the obtained nanomaterials are fully characterized; the hybrid nanosheets have been easily transferred onto lab-made screen-printed electrodes preserving their nanoarchitecture. The Au@rGO-, Ag@rGO-, and Pt@rGO-based electrodes have been challenged to detect caffeic acid, nitrite, and hydrogen peroxide in model solutions and real samples. The sensors yielded quantitative responses (R2 ≥ 0.997) with sub-micromolar limits of detections (LODs ≤ 0.6 μM) for all the analytes, allowing accurate quantification in samples (recoveries ≥ 90%; RSD ≤ 14.8%, n = 3). This single-step protocol which requires low cost and minimal equipment will allow the fabrication of free-standing, MNP-embedded rGO films integrable into a variety of scalable smart devices and biosensors.

One-step preparation of ZnTi-LDH/graphene nanosheet hybrids in supercritical ethanol based on an exfoliation-reassembly strategy and their enhanced photocatalytic performance

This study proposed a one-step preparation method for ZnTi-layered double hydroxide (ZnTi-LDH)/reduced graphene oxide (rGO) nanosheet hybrids in a supercritical ethanol system. After treating pristine ZnTi-LDH and rGO in the supercritical state of ethanol (268 °C, 10 MPa) for 1 h, nanocomposites composed of LDH nanosheets (7–10 nm in thickness) and rGO were obtained. Based on the conversion of ethanol between supercritical and conventional states, this method achieves the exfoliation of LHD nanosheets and reassembly with rGO in one step. This method promotes the generation of oxygen vacancies (OVs) favorable for electron-hole pair separation on the LDH/rGO surface. In the photocatalytic degradation of organic dyes, the degradation rate constants of LDH/rGO composites for Rhb and AO7 are 2.9 and 3.3 times that of pristine LDH, respectively. The enhanced photocatalytic activity was attributed to the OVs on the LDH/rGO surface, the positively charged LDH nanosheets, and the electrical conductivity of rGO.

Construction of Nitrogen-Doped Biphasic Transition-Metal Sulfide Nanosheet Electrode for Energy-Efficient Hydrogen Production via Urea Electrolysis.

Urea-assisted hybrid water splitting is a promising technology for hydrogen (H2 ) production, but the lack of cost-effective electrocatalysts hinders its extensive application. Herein, it is reported that Nitrogen-doped Co9 S8 /Ni3 S2 hybrid nanosheet arrays on nickel foam (N-Co9 S8 /Ni3 S2 /NF) can act as an active and robust bifunctional catalyst for both urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), which could drive an ultrahigh current density of 400mA cm-2 at a low working potential of 1.47V versus RHE for UOR, and gives a low overpotential of 111mV to reach 10mA cm-2 toward HER. Further, a hybrid water electrolysis cell utilizing the synthesized N-Co9 S8 /Ni3 S2 /NF electrode as both the cathode and anode displays a low cell voltage of 1.40V to reach 10mA cm-2 , which can be powered by an AA battery with a nominal voltage of 1.5V. The density functional theory (DFT) calculations decipher that N-doped heterointerfaces can synergistically optimize Gibbs free energy of hydrogen and urea, thus accelerating the catalytic kinetics of HER and UOR. This work significantly advances the development of the promising cobalt-nickel-based sulfide as a bifunctional electrocatalyst for energy-saving electrolytic H2 production and urea-rich innocent wastewater treatment.

Bandgap Tunable Oxynitride LaNb2 O7-x Nx Nanosheets.

Bandgap tunable lanthanum niobium oxynitride [LaNb2 O7-x Nx ](1+x)- nanosheet is prepared by the delamination of a Ruddlesden-Popper phase perovskite oxynitride via ion-exchange and two-step intercalation processes. The lanthanum niobium oxynitride nanosheets have a homogeneous thickness of 1.6nm and exhibit a variety of chromatic colors depending on the nitridation temperature of the parent-layered oxynitride. The bandgap energy of the nanosheets is determined by ultraviolet photoemission spectroscopy, Mott-Schottky, and photoelectrochemical measurements and is found to be tunable in the range of 2.03-2.63eV. Furthermore, the oxide/oxynitride superlattice structures are fabricated by face-to-face stacking of 2D crystals using oxynitride [LaNb2 O7-x Nx ](1+x)- and oxide [Ca2 Nb3 O10 ]- nanosheets as building blocks. Moreover, the superlattices-like restacked oxynitride/oxide nanosheets hybrid exhibits unique proton conductivity and dielectric properties strongly influenced by the oxynitride nanosheets and enhanced photocatalytic activity under visible light irradiation.

Density functional theory studies on graphene/h-boron nitride hybrid nanosheets for supercapacitor electrode applications.

Pristine graphene (C32), hexagonal boron nitride (h-BN), and graphene/h-BN hybrid nanosheets were examined using density functional theory calculations in order to find their suitability as an electrode material for supercapacitor applications. The stability of the structure, charge density, electronic properties, and quantum capacitance of pristine graphene and graphene/h-BN hybrid nanosheets were studied. The structural optimization results reveal that all the nanosheets are stable with zero transverse displacement of atoms along the z-direction. Further, replacing the C-C pair with B-N altered the average bond length and angle, thereby maintaining structural stability. The interaction between graphene and h-BN is higher for C16B8N8 compared to other hybrid nanosheets because of the delocalized distribution of the electron density cloud. The doping of the B-N pair into the graphene nanosheet shifts the Fermi level into either the valence band or the conduction band based on the concentration of the B-N pair. Meanwhile, the effective mass is increased and is relatively high for the hybrid nanosheets with a localized state. The pristine B16N16 nanosheet exhibits a quantum capacitance of 31.539 μF cm-2, while among the hybrid nanosheets, the C4B14N14 nanosheet exhibits a maximum quantum capacitance of 22.518 μF cm-2, and from the outcomes, they are suitable as an electrode for asymmetric supercapacitors.

Coupled W-Co2P hybrid nanosheets as a robust bifunctional electrocatalyst for hydrazine-assisted hydrogen production.

Herein, we put forward a novel electrode by electrochemically integrating metal W species and Co2P nanosheets onto nickel foam (W@Co2P/NF), which delivers excellent bifunctional activity for both the HER and HzOR. The hydrazine assisted water electrolyzer provides a small cell potential of 0.18 V at 100 mA cm-2 and stability for hydrogen generation, which is superior to most of the other bifunctional materials.

Hierarchical PdNi alloy nanochains coupled with Ni(OH)2 nanosheets to enhance CO-poisoning resistance for the methanol oxidation reaction.

Hybridizing Pd-based electrocatalysts with Ni-based species has been recognized as an effective pathway to enhance the catalytic performance for the methanol oxidation reaction (MOR). However, doping Ni-based species with heterogeneous valences into Pd nanocrystals still remains challenging, although heterogeneous valence Ni species may result in improved properties of Pd from different aspects. Herein, a facile one-pot synthetic method is reported to simultaneously introduce alloyed Ni0 into Pd lattices and couple hydroxy Ni2+ species with a Pd surface, generating 1D porous PdNi alloy nanochains@Ni(OH)2 nanosheet hybrids (PdNi NCs@Ni(OH)2 NSs). Borane-tert-butylamine (C4H14BN) plays the key role in realizing the formation of Ni-based species with heterogeneous valence. On one hand, it works as a reducing agent to facilitate the doping of alloyed Ni0 into the lattice of Pd nanochains. On the other hand, it raises the solution pH value and converts the remaining [Ni(CN)4]2- into Ni(OH)2 nanosheets. Each component of the PdNi NCs@Ni(OH)2 NSs plays an important role: Pd serves as the active site, alloyed Ni0 modifies the electronic structure of Pd, and Ni(OH)2 provides abundant OHads species to strengthen the anti-poisoning capability, thus greatly enhancing the activity, CO-tolerance, and durability for the MOR.

Fast detection of Staphylococcus aureus using thiol-functionalized WS2 quantum dots and Bi2O2Se nanosheets hybrid through a fluorescence recovery mechanism.

Ultrafast and sensitive detection of Staphylococcus aureus (S. aureus), a harmful Gram-positive human pathogenic bacterium, by two-dimensional layered materials continues to be a challenge. Herein, we have studied the sensing of S. aureus using a tungsten disulfide (WS2) quantum dot (QD) and bismuth oxyselenide (Bi2O2Se) nanosheet (NS) hybrid through their unique optical functionalities. The WS2 QDs of a mean diameter of 2.5 nm were synthesized by liquid exfoliation. Due to the quantum confinement and functional groups, the WS2 QDs exhibit high fluorescence (FL) yield under UV excitation. The addition of Bi2O2Se NSs resulted in the adsorption of WS2 QDs on their surface, resulting in quenching of the FL emission due to nonfluorescent complex formation between the WS2 QDs and Bi2O2Se NSs. A specific sequencing single-standard DNA (ssDNA) aptamer, which identifies and explicitly binds with S. aureus, was attached to the defect sites of the WS2 QDs for selective detection. The thiol-modified ssDNA aptamers attach covalently to the WS2 QD defect sites, which was confirmed by Raman and X-ray photoelectron spectroscopy (XPS). The interaction of S. aureus with the aptamer functionalized WS2 QDs weakens the van der Waals interaction between the WS2 QDs and Bi2O2Se NSs, which results in the detachment of the WS2 QDs from the Bi2O2Se NS surface and restores the FL intensity of the WS2 QDs, thus allowing the efficient detection of S. aureus. Similar measurements with non-targeted bacteria show that the system is quite selective towards S. aureus. Our FL-based biosensor has a linear response in the range of 103-107 CFU mL-1 (colony formation unit mL-1) with a detection limit of 580 CFU mL-1. We have observed a fast response time of 15 minutes for sensing, which is superior to the previous reports. The proposed system was tested in human urine and can detect S. aureus in human urine samples selectively, proving its potential in real-life applications. The reported approach is versatile enough for sensing other biomolecules and metal ions by choosing suitable receptors.

Assembling a high-performance asymmetric supercapacitor based on pseudocapacitive S-doped VSe2/CNT hybrid and 2D borocarbonitride nanosheets

High performance asymmetric supercapacitor assembled using the S-VSe2/CNT positrode and BCN negatrode.

Salt-assisted pyrolysis of carbon nanosheet and carbon nanoparticle hybrids for efficient microwave absorption

MOF-derived carbon materials with unique structures are prepared by salt-assisted pyrolysis and exhibit excellent microwave absorbing performance with an effective absorption bandwidth of 6.23 GHz at lower fill ratios of 7%.

Ultrafine ZnCo2O4 QD-incorporated carbon nitride mediated peroxymonosulfate activation for norfloxacin oxidation: performance, mechanisms and pathways.

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are being actively investigated as a potential technology for water decontamination and many efforts have been made to improve the activation efficiency of PMS. Herein, a 0D metal oxide quantum dot (QD)-2D ultrathin g-C3N4 nanosheet (ZnCo2O4/g-C3N4) hybrid was facilely fabricated through a one-pot hydrothermal process and used as an efficient PMS activator. Benefiting from the restricted growth effect of the g-C3N4 support, ultrafine ZnCo2O4 QDs (∼3-5 nm) are uniformly and stably anchored onto the surface. The ultrafine ZnCo2O4 possesses high specific surface areas and shortened mass/electron transport route so that the internal static electric field (Einternal) formed in the interface between p-type ZnCo2O4 and the n-type g-C3N4 semiconductor could speed up the electron transfer during the catalytic reaction. This thereby induces the high-efficiency PMS activation for rapid organic pollutant removal. As expected, the ZnCo2O4/g-C3N4 hybrid catalysts significantly outperformed individual ZnCo2O4 and g-C3N4 in catalytic oxidative degradation of norfloxacin (NOR) in the presence of PMS (95.3% removal of 20 mg L-1 of NOR in 120 min). Furthermore, the ZnCo2O4/g-C3N4-mediated PMS activation system was systematically studied in terms of the identification of reactive radicals, the impact of control factors, and the recyclability of the catalyst. The results of this study demonstrated the great potential of a built-in electric field-driven catalyst as a novel PMS activator for the remediation of contaminated water.

Surfactant-assisted lamellar structuration of tunable Co-based hybrid nanosheets

Formation of tunable cobalt-based hybrid lamellar nanosheets using a bottom-up approach.

Pd nanoparticles decorated ultrathin 2D metal-organic framework nanosheets with enhanced peroxidase-mimic activity and colorimetric assay of glucose.

In addition to size, shape and morphology, enzyme-mimetic property could be efficiently regulated by controlling composition, forming complexes or hybrids, and surface modification. Herein, Pd nanoparticles with an average diameter of 2.52 nm were decorated on ultrathin 2D copper(ii)-porphyrin derived metal-organic framework (MOF) nanosheets by a simple reduction method for catalytic activity regulation. In comparison with other nanozymes, the as-synthesized Pd modified 2D MOF hybrid nanosheets (Pd@Cu-TCPP(Fe)) presented excellent peroxidase-mimic activity, exhibiting an even superior catalytic ability towards H2O2 with a Michaelis-Menten constant as low as 2.33 mM. Based on a cascade reaction between glucose oxidase and Pd@Cu-TCPP(Fe), a colorimetric method for the detection of glucose was established and validated with a wide linear range (0.2-8.0 mM), good recovery (89.5-94.2%) and nice reproducibility (3.65%). All these features guaranteed its excellent ability for glucose determination in human cerebrospinal fluids. This study could offer a valuable reference for constructing novel optical biosensors.

CdTe QD-decorated GO nanosheet heterojunction for efficient photocurrent generation and photocatalytic activity.

Cadmium telluride quantum dot (CdTe QD)-decorated graphene oxide (GO) nanosheets are promising heterojunctions for the environmental remediation of organic pollutants in water. However, assembling these two materials is a challenge. For this purpose, we have developed a one-step approach for the decoration of QDs onto the surface of GO nanosheets/intercalation of QDs into GO nanosheets through self-assembly, resulting in the formation of sandwiched hybrid heterojunctions. After synthesis, the samples were analysed for variations in their structural, morphological, compositional, optical and photoelectrochemical characteristics using various analytical tools. Interlinking QDs and GO nanosheets enhanced the photocurrent generation (∼5.8 μA cm-2), resulting in faster electron transfer by delaying the decay time (58.25 ms). A higher rate constant value (k = 0.135 min-1) was obtained for degrading 93% MB dye in 20 min. This work demonstrates a cost-effective strategy for constructing CdTe QDs/GO nanosheet hybrid heterojunctions for potential application in the field of photocatalysis.

Long-Term Antifogging Coating Based on Black Phosphorus Hybrid Super-Hydrophilic Polymer Hetero-Network.

The antifogging coating based on super-hydrophilic polymer is regarded as the most promising strategy to avoid fogging but suffers from short-term effectiveness due to antifogging failure induced by water invasion. In this study, a black phosphorus nanosheets (BPs) hybrid polymer hetero-network coating (PUA/PAHS/BPs HN) was prepared by UV curing for the first time to achieve long-term antifogging performance. The polymer hetero-network (HN) structure was composed of two novel cross-linked acrylic resin and polyurethane acrylate. Different from physical blending, a covalent P-C bond between BPs and polymer is generated by UV initiated free radical reaction, resulting in BPs firmly embedded in the polymer HN structure. The BPs enriched on the coating surface by UV regulating migration prevent permeation of water towards the inside of the coating through its own good water-based lubricity and water absorption capacity. Compared with the nonhybrid polymer HN, PUA/PAHS/BPs HN not only has higher hardness and better friction resistance properties, but also exhibits superior water resistance and longer antifogging duration. Since water invasion was greatly reduced by BPs, the PUA/PAHS/BPs HN coating maintained antifogging duration for 60 min under a 60 °C water vapor test and still maintained long-term antifogging performance after being immersed in water for 5 days.