Hydrothermal Intercalation Research Articles

Electrochemically Intercalated Ti3C2 MXene Bulk for Expanding Interlayer Spacing and Enhancing Supercapacitor Performance.

Tuning the interlayer spacing of 2D MXenes bulk mainly focuses on hydrothermal intercalation, physiotherapy intercalation, and ion exchange intercalation. Nevertheless, the feasibility of electrochemical intercalation technology for expanding the interlayer spacing of Ti3C2 MXene bulk is not yet clear, and further research is required to advance it. Here, we employed an electrochemical intercalation technology to successfully embed metal cations (K+ and Na+) into the interlayer structure of Ti3C2 MXene bulk, expanding the interlayer spacing from ∼10.50 to ∼13.10 Å by K+ intercalation, which can broaden electron/ion transport channels and enhance supercapacitor performance. Compared to the pristine Ti3C2 MXene bulk, the specific capacitance value increased by a factor of 2.8. Moreover, the intercalated MXene also exhibits excellent rate capability, with an increase from 47.32 to 70.20%. This work opens up a new path for the modification of Ti3C2 MXene bulk.

K-doped V2O5 derived from V-MOF precursor as high-performance cathode for aqueous zinc-ion batteries

The safety and low toxicity of aqueous zinc-ion batteries (ZIBs) are piqueing intense scientific interest. Slow reaction kinetics and substantial structural degradation of the cathode materials, however, prevent the creation of ZIBs. As a better cathode for ZIBs, tunnel-structured V2O5 hierarchical with a high preintercalated K cation content (K-V2O5) are proposed here. The K-V2O5 are specifically made using a self-sacrificial template approach that also involves hydrothermal intercalation in a neutral solvent and phase change during annealing. A subsequent H+ and Zn2+ intercalation procedure at various voltage platforms is clarified when tested as cathodes for ZIBs. Prior to the subsequent insertion of Zn2+ into V2O5, the water-solvated H+ first enters tunnel cavities, which partially transforms the V2O5 phase from a tunnel-type structure to a layered-type structure. The pre-intercalated K cations with a high content that act as pillars in the layered-type matrix stabilize the layered structures and widen the migration channels for Zn2+, which can aid in the diffusion of Zn2+ in the V2O5 cathodes.

Mesoporous ZnO: In nanosheets grown on g-C3N4 for improved detection of NO2

The urgent need for real-time detection of toxic and harmful NO2 in the environment has attracted much attention, which requires to improve detection accuracy and portability at low temperature even room temperature. In this work, we reported a mesoporous ZnO:In grown on the side of two-dimensional g-C3N4 by conventional hydrothermal intercalation. At normal mode the sensor exhibits excellent sensitivity at 120 °C, with a response value of 200 for 15 ppm NO2 and a response/recovery time of 18/23 s. At UV assisted mode, the sensor shows improved response value to low concentration of NO2 at room temperature and can achieve instantaneous recovery effect. The reasons for improving the sensitivity, response value, response/recovery time, and cyclic stability of the gas sensor to NO2 are not only related to the abundant mesoporous, large specific surface area, and doping of sensitizer, but also affected by the heterojunction effect of improving the photogenic charge separation efficiency. The strategy of dual-mode operating conditions presented in this work provides an effective design idea for high-sensitivity and efficient NO2 detection devices.

Superlattice-like alternating layered Zn2SiO4/C with large interlayer spacing for high-performance sodium storage

Layered materials are among the most promising anode candidates for sodium-ion batteries, but suffer from limited interplanar spacing and poor electrical conductivity, resulting in unsatisfactory electrochemical performance. Herein, a novel layered composite of Zn2SiO4 and carbon (Zn2SiO4/C) is designed by a simple one-pot hydrothermal intercalation strategy. The Zn2SiO4/C shows unique superlattice-like lamellar configuring that the Zn2SiO4 layers and graphene-like carbon layers are alternately stacked, forming a sandwich-type structure. Such alternating layered contexture endows Zn2SiO4/C with improved conductivity and stability. In addition, the interplanar spacing of the Zn2SiO4/C achieves 1.44 nm, larger than most state-of-the-art layered materials, allowing the fast ion transfer from bulk electrolyte to the inner surface. As such, the Zn2SiO4/C delivers a high reversible Na storage capacity of 374 mAh g−1, and it presents no visible capacity decline during the cycling test. More importantly, even under a very high current density of 20 A g−1, the capacity remains 180 mAh g−1, suggesting an ultrafast energy output within 33 s (≈109 C). The ex-situ studies show that Na storage of Zn2SiO4 obeys a conversion−alloying mechanism, in which it is reduced to Zn, followed by the formation of NaxZn alloy.

Hydrothermal intercalation for the synthesis of novel three-dimensional hierarchically superstructured carbons composed of graphene-like ultrathin nanosheets

Hierarchical superstructured carbons (HSCs) assembled by low-dimensional fibers or sheets have held a great prospect in energy applications on account of their stable intersecting carbon network, large accessible surface area and optimized ion transfer. However, the synthesis of HSCs with well-defined nanostructure is still a challenge. Herein, a novel HSC is developed on the basis of constructing sandwich-type alternate layered carbon/Zn2SiO4 composite by an intercalation growth strategy. This type of HSC is assembled by graphene-like ultrathin carbon nanosheets with a thickness less than 1 nm (2–3 carbon layers), and displays rigid and stable 3D network owing to the interconnected self-supported nanosheets. The in-depth investigation reveals that the growth of HSC complies with a unique “octopus model”, and both the homogeneous and heterogeneous reaction conditions are applicable for the synthesis system. More importantly, the as-constructed superstructure can be coated on the surface of any SiO2-containing substrates, which offers an avenue to design superstructured carbons with various morphologies. With combination of the large accessible surface area and optimized nanostructure for ion transfer and electron immigration, the as-prepared HSC demonstrates superior performance in electronic double-layer capacitor.

Large-area, flexible broadband photodetector based on WS2 nanosheets films

High performance, flexible broadband photodetectors based on two-dimensional materials have attracted extensive research interest due to their potential applications. However, these reported flexible photodetectors are generally fabricated into micron-nano devices due to the limited size of two-dimension material, with a narrow spectrum detection range, which has seriously hindered their applications in large-area, broadband photodetector. Herein, we have prepared WS2 nanosheets film via typical hydrothermal intercalation and vacuum filtration methods to fabricate a large-area, flexible broadband photodetector. The fabricated devices respond to a broadband wavelength from visible light to near-infrared light (532–1064 nm), and exhibit a responsivity of 4.04 mA/W and a detectivity of 2.55 × 109 Jones at 532 nm irradiation. Moreover, even in an arbitrary bending condition, our fabricated photodetectors show consistently stable photoresponse characteristics. All the results indicate that our stratagem in this work will be a more convenient and practical guidance for the future flexible optoelectronic devices.

Graphene–like tungsten sulphide nanosheets prepared by hydrothermal intercalation/exfoliation route and its application for photodetector

Herein, yields of graphene-like two-dimensional (2 D) tungsten sulphide (WS2) nanosheets was fabricated by a feasible hydrothermal intercalation exfoliation route. It was also characterised by X-Ray Diffraction, Raman spectrum and scanning electron microscope to verify the yield and quality of as-prepared WS2 nanosheets. In addition, the prepared 2 D WS2 nanosheets was used for photoelectrochemical (PEC) type photodetector to explore its photoresponse properties. The results of the PEC tests indicate the prepared WS2 nanosheets possess preferable photoresponse activity that the photocurrent density can reach to 3 μA cm−2 at the bias of 0.5 V. The stability measurements demonstrate it has remarkable work stability with no obvious photocurrent decreasing after 40 cycles. Besides that, the as-prepared WS2 nanosheets demonstrate good self-powered ability in the PEC system, it can work under the bias of 0 V without external power source and exhibited excellent photoresponsivity about 3.75 μA W−1. The high photoresponse properties and prominent self-powered ability of PEC-type photodetector based on WS2 nanosheets, which can be attributed to the excellent photoelectric conversion capability of the prepared high quality 2 D WS2 nanosheets as well as the unique solid liquid contact mechanism of PEC-type photodetector. With the advance of stable ability and extraordinary photoresponse performance, which make it more promising in practical application.

Ni-MOF coating MoS2 structures by hydrothermal intercalation as high-performance electrodes for asymmetric supercapacitors

Two-dimensional metal-organic frameworks and nanoflowers of the MoS2 form a composite structure as an electrode material for high-performance supercapacitor application. MoS2 expands in the accordion-type Ni-MOF layers, and -S- joins the two materials to form a Ni-MOF coating MoS2 composite structure. The composite material MoS2@Ni-MOF combines the structural characteristics of the Ni-MOF and MoS2, and effectively improves the electrochemical performance. The basic skeleton structure of the MoS2@Ni-MOF material remains unchanged, showing a remarkable specific capacitance of 1590.24 F·g−1 at a current density of 1.0 A·g−1 and an excellent cycle stability (retention rate of 87.97% after 20,000 cycles at current of 5.0 A·g−1). Due to the special composite structure of MoS2@Ni-MOF, the as-assembled MoS2@Ni-MOF//AC assymmetric supercapacitor (ASC) device exhibits a maximum energy density of 72.93 Wh·kg−1 at a power density of 375 W·Kg−1. These excellent electrochemical properties indicate that the MoS2@Ni-MOF has potential applications in energy storage devices.

Influences of thickness, scanning velocity and relative humidity on the frictional properties of WS2 nanosheets

Distinguishing with the traditional cantilever mechanics method, we propose the extended cantilever mechanics method to calibrate the lateral calibration factor by using the normal spring constant obtained from atomic force microscopy (AFM) but not the Young’s modulus and the width of the cantilever, before the influences of thickness, scanning velocity and humidity on the frictional properties are investigated via friction measurement performed by the lateral force mode (LFM) of AFM. Tungsten disulfide (WS2) nanosheets were prepared through hydrothermal intercalation and exfoliation route, and AFM and Raman microscope were used to investigate the frictional properties, thickness and crystalline structure. The friction force and coefficient decrease monotonically with the increase of the nanosheet’s thickness, and the friction coefficient minimum value is close to 0.012 when the thickness larger than 5 nm. The friction property variation on the nanosheet’s thickness can be explained by the puckering effect of tip-sheet adhesion according thickness dependence of bending stiffness in the frame of continuum mechanics. The friction force is a constant value 1.7 nN when the scanning speed larger than the critical value 3.10 μm s−1, while it logarithmically increases for the scanning speed less than the critical value. It is easy to understand through the energy dissipation model and the thermally activated effect. The friction force and friction coefficient increase with the relative humidity at the range of 30%–60%, and the latter is at the range of 0.010–0.013. Influence of relative humidity is discussed via the increasing area of the water monolayer during the water adsorption process. The research can not only enrich nanotribology theory, but also prompt two dimensions materials for nanomechanical applications.

Photoresponse improvement in liquid-exfoliated SnSe nanosheets by reduced graphene oxide hybridization

The SnSe/reduced graphene oxide (SnSe/RGO) hybrid was synthesized by a simple hydrothermal reduction method using tin selenide (SnSe) nanosheets (NSs) and graphene oxide (GO), in which the two-dimensional SnSe NSs were peeled off by hydrothermal intercalation and exfoliation process, and GO was synthesized through an improved Hummers’ method. The characterization techniques including scanning electron microscopy and transmission electron microscopy verified a large-size SnSe NSs and SnSe/RGO hybrid. Meanwhile, X-ray diffraction and Raman spectra were carried out and confirmed the inherent optical and physical properties of SnSe NSs. In addition, the photoelectrochemical tests were carried out and proved that the photoresponse performances of as-prepared SnSe/RGO hybrid were greatly improved compared to that of sole SnSe NSs. When the bias potential was 0.8 V, the photocurrent density of SnSe/RGO hybrid was about 6.42 μA/cm2, which was approximately four times that of sole SnSe NSs (about 1.58 μA/cm2). Meanwhile, SnSe/RGO hybrid possessed faster photoresponse compared to sole SnSe NSs. The improvement in photoresponse performance is due to the hybridization of SnSe/RGO with good conductivity and the coupling between SnSe/RGO and SnSe NSs, which would be beneficial to promote the effective separation of photo-generated electron–hole pairs. Our results show that SnSe/RGO hybrid has a good application prospect in the field of photodetection.

Synthesis of SnSe nanosheets by hydrothermal intercalation and exfoliation route and their photoresponse properties

Two dimensional Tin Selenide (SnSe) nanosheets (NSs) have been prepared via a facile hydrothermal intercalation and exfoliation route. Morphological test verifies high yield of SnSe NSs with good quality. Additional X-ray diffraction pattern and Raman spectra are carried out and confirm the exfoliated SnSe nanosheet is pure and well crystalized. AFM measurement, along with the SEM images and Raman shifts, reveals few-layers SnSe nanosheet has been successfully obtained after hydrothermal intercalation and exfoliation route. Photoelectrochemical tests also demonstrate the photocurrent density of SnSe NSs is greatly improved compare to that of bulk SnSe. Photocurrent density of exfoliated SnSe NSs can achieve 16μA/cm2 when the applied potential is 0.8V, which is nearly four times higher than that of bulk SnSe. This work demonstrates that the two-dimensional SnSe NSs may have a great potential application in photovoltaic devices.

Effect of Polymer Addition on the Structure and Hydrogen Evolution Reaction Property of Nanoflower-Like Molybdenum Disulfide

Nano-structured molybdenum disulfide (MoS2) catalysts have been extensively developed for the hydrogen evolution reaction (HER). Herein, a novel hydrothermal intercalation approach is employed to fabricate nanoflower-like 2H–MoS2 with the incorporation of three polymers, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyethylenimine (PEI). The as-prepared MoS2 specimens were characterized by techniques of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), together with Raman and Fourier transform infrared spectroscopy (FTIR). The HER properties of these lamellar nanoflower-like composites were evaluated using electrochemical tests of linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The existent polymer enlarges the interlayer spacing of the lamellar MoS2, and reduces its stacked thickness. The lamellar MoS2 samples exhibit a promoting activity in HER at low additions of these three polymers (0.04 g/g MoS2 for PVA and PEI, and 0.08 g/g MoS2 for PVP). This can be attributed to the fact that the expanded interlayer of MoS2 can offer abundant exposed active sites for HER. Conversely, high additions of the polymers exert an obvious interference in the HER activity of the lamellar MoS2. Compared with the samples of MoS2/PVP–0.08 and MoS2/PEI–0.04, the MoS2/PVA–0.04 composite exhibits excellent activity in HER, in terms of higher current density and lower onset potential.

Ecosustainable Development of Novel Bio-inorganic Hybrid Materials as UV Protection Systems for Potential Cosmetic Applications.

A new organoclay, bio-inorganic hybrid material, was successfully prepared following the "green chemistry" principles, exploiting microwave irradiation (as an alternative energetic source) in both the solvent-free synthesis of the organic filler (UVB filter) and in its hydrothermal intercalation in a sodium Bentonite clay (renewable natural inorganic source at low temperature). The organic filler is a benzylidene camphor derivative with the same cationic moiety as the well- known UV filter camphor benzalkonium methosulfate. The aim of the research was the ecosustainable development of a new UV protection model, suitable for use in cosmetic and pharmaceutical products, with potential advantages of stability, efficiency and safety compared to the commercially available UVB sunscreens. The organically modified clay was thoroughly investigated using X-ray diffraction (XRD), infrared spectroscopy (IR), thermo gravimetric analysis and differential thermal analysis (DTA). Results confirmed the complete intercalation of the organic filler in the interlayer region of the smectite clay, leading to a new bio-inorganic hybrid material with potential for cosmetic and pharmaceutical applications in the UV protection field, as confirmed by preliminary photochemical studies. This work represents the first example in the use of Na-Bentonite cationic clay (usually employed as rheological additive) as hosting agent of the synthesized quaternary UVB filter, as well as in the complete MW-assisted preparation of the organoclay, starting from the synthesis of the organic UV sunscreen to its hydrothermal intercalation.

Effective photocatalytic decolorization of methylene blue utilizing ZnO/rectorite nanocomposite under simulated solar irradiation

Preparation of a nanometer zinc oxide/rectorite (ZnO/REC) composites photocatalyst based on natural rectorite was conducted using a hydrothermal intercalation method. The structure, thermal property, and surface morphology of ZnO/REC were characterized by X-ray diffractor (XRD), thermogravimetric analysis (TGA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM) techniques. The photocatalytic activity of ZnO/REC was evaluated by photocatalytic decolorization of methylene blue (MB) in aqueous solution as a model pollutant under simulated sunlight irradiation. The HRTEM results revealed that well-dispersed and uniform ZnO/REC nanocomposites with diameters of 10nm were embedded in rectorite. The ZnO/REC nanocomposite exhibited high photocatalytic activity under simulated solar irradiation. After 2h of irradiation by simulated solar light, over 99% of methylene blue solution (15mg/L) was decolorized with 0.9g/L of the photocatalyst. The ZnO/REC was reusable, which meant that the adsorption photocatalytic decolorization process could be operated at a relatively low cost. Since this process does not require the addition of hydrogen peroxide but uses sunlight, it can be developed as an economically feasible and environmentally friendly method to decolorize or treat dye wastewater using solar.

Photoresponse properties of ultrathin Bi 2 Se 3 nanosheets synthesized by hydrothermal intercalation and exfoliation route

Abstract The photoresponse properties of Bi 2 Se 3 nanosheets prepared by a simple hydrothermal intercalation and exfoliation route are studied. Photoelectrochemical results indicate that the as-prepared Bi 2 Se 3 nanosheets devices have excellent sensitivity, high-speed and good reproducibility as a photodetector, which are superior to the bulk Bi 2 Se 3 . Especially, the response time, responsivity, and external quantum efficiency are found to be about 0.7 s, 20.48 mA/W, and 8.36 η 0 , respectively. It is proposed that the two-dimensional nanostructure of Bi 2 Se 3 can be effectively used in high performance nanoscale photodetectors.

Hydrothermal exfoliated molybdenum disulfide nanosheets as anode material for lithium ion batteries

Ultrathin MoS2 nanosheets were prepared in high yield using a facile and effective hydrothermal intercalation and exfoliation route. The products were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the high yield of MoS2 nanosheets with good quality was successfully achieved and the dimensions of the immense nanosheets reached 1 μm–2 μm. As anode material for Li-ion batteries, the as-prepared MoS2 nanosheets electrodes exhibited a good initial capacity of 1190 mAh·g−1 and excellent cyclic stability at constant current density of 50 mA·g−1. After 50 cycles, it still delivered reversibly sustained high capacities of 750 mAh·g−1.

Preparation, characterization and photoelectrochemical property of ultrathin MoS2 nanosheets via hydrothermal intercalation and exfoliation route

A simple but effective hydrothermal intercalation and exfoliation route is developed to prepare ultrathin MoS2 nanosheets in high yield. The morphologies and microstructures of as prepared products are characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy and atomic force microscopy. It is found that zerovalent lithium is readily intercalated between the layers of MoS2 using ethylene glycol as both reductant and solvent in hydrothermal process. Subsequently ultrathin MoS2 nanosheets with good quality are obtained by the removing of lithium via the exfoliating process in water. The obtained ultrathin MoS2 nanosheets exhibit preferable photoelectrochemical and photoresponse activity under the illumination of simulated sunlight compared to bulk MoS2. Our results indicate that ultrathin MoS2 nanosheets have promising applications in photo-electrochemistry, heterogeneous catalysis, sensors and optoelectronic nanodevices.

Large-scale production of ultrathin topological insulator bismuth telluride nanosheets by a hydrothermal intercalation and exfoliation route

A convenient hydrothermal intercalation/exfoliation method for large-scale manufacturing of bismuth telluride (Bi2Te3) nanosheets is reported here. Lithium cations can be intercalated between the layers of Bi2Te3 using the reducing power of ethylene glycol in the common hydrothermal process, and high quality Bi2Te3 nanosheets with thickness down to only 3–4 nm are obtained by removing lithium in the following exfoliating process. Scanning electron microscopy, transmission electron microscopy and Raman spectrum characterizations confirm that the high yield of Bi2Te3 nanosheets with good quality were successfully achieved and the sizes of the immense nanosheets reached 200 nm width and 1 μm length. This hydrothermal intercalation/exfoliation method is general, as it has been extended to other layered materials, such as Bi2Se3 and MoS2. Our results suggest a simple route for the large-scale production of thin and flat Bi2Te3 nanosheets, which may be beneficial to further electronic and spintronics applications.

In‐situ Synchrotron X‐ray Diffraction Study of the Formation of Cubic Li2TiO3 Under Hydrothermal Conditions

AbstractSynchrotron powder X‐ray diffraction (PXRD) has been used to study in‐situ the hydrothermal intercalation of lithium ions in titania powder following the reaction TiO2 + 2 LiOH → Li2TiO3 + H2O. Syntheses were performed in a sapphire capillary at temperatures between 133 and 230 °C. By sequential Rietveld refinement of the PXRD data, the particle growth of the metastable cubic α‐Li2TiO3 compound was determined as a function of the reaction time, as well as the transformation of the cubic α‐phase to its stable monoclinic β‐modifications at a temperature above the critical point of water. The reactions were presumed to be controlled by nucleation and crystal growth, and therefore the Avrami‐Erofe'ef equation was applied to model the reaction mechanisms of this intercalation process and an activation energy of 66(7) kJ/mol was determined.

Preparation of Nano-Laminated Composite by Electrophoretic Deposition

Electrophoretic deposition (EPD) has been widely studied in preparing clay-modified electrodes (CMEs) and in assembly of nano-laminated composite that mimics nacre. In this paper, the hydrothermal intercalation and EPD were combined to prepare CMEs with a uniform and continuous polymer/clay composite film of brick-and-mortar nano-laminated structure. X-ray diffraction, scanning electronic microscopy and thermal gravimetric analysis were employed to characterize the structure and composition of the films. Stability of aqueous suspension, temperature for hydrothermal intercalation and deposition time, etc. were systematically studied and discussed.