Simple One-step Hydrothermal Synthesis Research Articles

La/SnO2 nanoparticles: Hydrothermal synthesis, structure, and sensing performance in a high relative humidity environment

In this work, a simple one-step hydrothermal synthesis of La doped SnO2 nanocomposites was studied. The structure, morphology, specific surface area, and chemical composition were determined by XRD, SEM, BET, and XPS techniques. The gas sensing performance of SnO2 and La/SnO2 nanocomposites with varied La doping dosages on n-butanol gas was systematically investigated. The results manifested that under the testing environment (50 % relative humidity and 30 °C), La doped SnO2 nanocomposite sensor presented high response (69), excellent selectivity, good repeatability and long-time stability to n-butanol gas at 160 °C. Especially, the 7 mol% La doped SnO2 sensor displayed a 5.9 times higher response to 50 ppm n-butanol than the SnO2 sensor. In comparison with bare SnO2, La doping increased the band gap value of 7 mol% La/SnO2 nanocomposite by 6.23 %, decreased particle size by 11.83 %, and increased the oxygen defect concentration by 6.07 %. Due to the synergistic effect of the above factors, the gas sensing performance of La doped SnO2 nanocomposites towards n-butanol gas was enhanced. Therefore, La doped SnO2 nanocomposites might be a potential gas sensing material for monitoring n-butanol gas at relatively high humidity.

Combination of multiple routes to enhance DSSC performance: Flower-like structure of SnO2 as photoanode and modification with Ag nanoparticle

SnO2 is an attractive photoanode material for dye-sensitized solar cells (DSSCs), but it has many drawbacks and needs to be modified. In this study, flower-like SnO2 particles are firstly prepared by a simple one-step hydrothermal synthesis method respectively, and the effect of hydrothermal reaction time on the growth of the particles is explored. The morphological and structural characterisation reveals that the flower-like particles have a larger specific surface area can provide more adsorption sites for dye molecules and are more suitable for photoanode materials. Then the optimal flower-like SnO2 particles are selected to prepare the photoanode, which is also modified with different concentrations of Ag nanoparticles to successfully introduce the localized surface plasmon resonance (LSPR) effect, and the optimal modification concentration is explored. Conformal characterisation, dye adsorption and light absorption tests revealed that the modification of Ag nanoparticles not only optimises the photoanode conformal structure and improves the dye adsorption, but also works in conjunction with the LSPR effect to improve the light absorption and utilisation, thus increasing the cell efficiency. Many cell performances of DSSC are also greatly improved due to the above work, and the optimal cell performance of DSSC is achieved when the Ag nanoparticles doping concentration is 0.03 M. Compared with the pure flower-like SnO2-based photoanode DSSC, the short-circuit current density of the best Ag nanoparticle-modified DSSC is enhanced by 28.56% to 15.80 mA/cm2, and its efficiency is improved by 20.82%–5.92%.

Electrical and structural engineering of nanoflower-like NiMn-layered double hydroxide by V modulation for high-performance hybrid supercapacitors

This work produced V-doped NiMn-layered double hydroxide(V-NiMnLDH) composite positive electrode material directly on nickel foam using a simple one-step hydrothermal synthesis process. The composite's 3D nanoflower-like design increased spatial utilization, surface area, and active sites for Faradaic redox reactions. The composite material has a specific capacitance of 1551 F g−1 at 1 A g−1 and 85.6 % capacitance retention at 10 A g−1, demonstrating exceptional cycle stability. In addition, we combined V-NiMnLDH with commercial activated carbon to create an asymmetric supercapacitor (ASC) with 63.5 Wh kg−1 energy density and 975 W kg−1 power density. After 5000 charge-discharge cycles, the gadget preserved 89.7 % of its specific capacitance. This material outperforms similar electrode materials in certain performance evaluations. We also used density functional theory (DFT) computations to analyze each element in the V-NiMnLDH composite and explain their electronic density of states contributions. This theoretical framework explains how V doping improves capacitance. Band structure simulations also showed V-NiMnLDH's higher charge transfer and conductivity compared to intermediate products, explaining its extraordinary capacitance performance. Our work combines theoretical and experimental data to advance catalyst design and high-performance energy storage materials.

Hierarchical nanocomposite of cobalt sulfide nanoflakes-decorated reduced graphene oxide for enhancing the electrocatalytic hydrogen evolution reaction

The hydrogen evolution reaction (HER) driven by electrocatalytic water splitting is attaining prevalent attention for the manufacturing of clean and green hydrogen energy. Herein, we report the simple one-step hydrothermal synthesis of cobalt sulfide nanoflakes decorated with reduced graphene oxide (CoS/rGO) nanocomposites as an effective electrode material for HER. The CoS/rGO nanocomposites exhibited the rGO nanosheet-decorated hierarchically interconnected CoS nanoflakes structure. The CoS/rGO nanocomposites exhibited an excellent HER activity with a low overpotential of 371 mV and a small Tafel slope of 103 mV/dec. More interestingly, the catalytic stability of CoS/rGO nanocomposites is comparatively higher than the pristine CoS NFs. These results suggest that the facile nanocomposites of CoS/rGO could be a prominent catalytic material for effective green hydrogen production.

Preparation and characterization of nanostructured Fe-doped CoTe2 electrocatalysts for the oxygen evolution reaction.

The key step for hydrogen production through water electrolysis is the development of highly efficient and inexpensive oxygen evolution reaction (OER) catalysts. In this work, we report the successful synthesis of a nanostructured Fe-doped cobalt-based telluride (Fe-doped CoTe2) catalyst on Co foam by a simple one-step hydrothermal synthesis method, which shows excellent OER performance. The influences of Fe doping amounts and reaction temperatures on the morphology, structure, composition, and the OER performance of cobalt-based tellurides have been systematically studied. The optimal sample Co@0.3 g FeCoTe2-200 exhibits a low overpotential of 300 mV at a current density of 10 mA cm-2, and a small Tafel slope of 36.99 mV dec-1, outperforming the undoped cobalt telluride catalysts (Co@CoTe2-200). The Co@0.3 g FeCoTe2-200 electrode also reveals a small overpotential degradation of around 26 mV after an 18-hour continuous OER process. These results unambiguously confirm that Fe doping helps improve the OER activity and long-term catalytic stability. The superior performance of nanostructured Fe-doped CoTe2 can be attributed to the porous structure and the synergistic effect of Co and Fe elements. This study provides a new approach for the preparation of bimetallic telluride catalysts with enhanced OER performance, and Fe-doped CoTe2 holds substantial promise for use as a high-efficiency, cost-effective catalyst for alkaline water electrolysis.

Investigation of silver nanowires in Zn2SnO4 spheres for enhanced dye-sensitized solar cells performance

In this paper, 1-D Ag nanowires (AgNW) have been integrated into zinc tin oxide (Zn2SnO4) spheres using a simple one-step hydrothermal synthesis to enhance power conversion efficiency (PCE). Two different amounts of Ag nanowires were applied to assemble a series of dye-sensitized solar cells (DSSCs) and the photovoltaic performance was evaluated. UV–VIS absorption spectra, Mott-Schottky and electrochemical impedance spectroscopy studies demonstrated that the addition of AgNWs can enhance the photoelectrochemical activity and charge injection. We found that 200 µL of AgNW has significantly increased JSC and VOC from 2.0 to 3.83 mA/cm2 and 709–760 mV, respectively, compared to the pure DSSC based on Zn2SnO4.

Enhancing stability of MoS2 catalysts for sulfur-resistant methanation by tuning interlayer interaction

A simple one-step hydrothermal synthesis was developed to modulate the stability of MoS2 for catalytic sulfur-resistant methanation. The methanation performance was optimized by tuning hydrothermal time and solution pH value. The catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy and thermogravimetric and derivative thermogravimetric (TG/DTG) analysis. It was found that both extended hydrothermal time and weak acidic solution value was benefit to prepare the MoS2 catalyst with high stacking layers. TG/DTG analysis indicated that no obvious coke deposition occurred in the MoS2 catalysts during methanation reaction. Moreover, density functional theory (DFT) simulation result proved that with the increase of stacking layers, the electron density between Mo atoms and their neighbor S atoms was strengthened and the interlayer interaction was enhanced. Therefore, the MoS2 catalysts with high stacking layers was stable since they were not easily deactivated by sintering or substitution of active S atoms by O atoms during the reaction.

Edge-rich MoS2 nanosheets anchored on layered Ti3C2 MXene for highly efficient and rapid catalytic reduction of 4-nitrophenol and methylene blue

In this work, we report a simple one-step hydrothermal synthesis strategy for depositing edge-rich MoS2 nanosheets on conductive layered Ti3C2 MXene, and demonstrate the formed MoS2/Ti3C2 heterostructure has significant active site exposure and effective charge carrier flow. The resulting MoS2/Ti3C2 exhibits enhanced activity and excellent stability for the catalytic reduction of 4-nitrophenol (4-NP). The optimal MoS2/Ti3C2 catalyst displays a high pseudo-first-order rate constant of 0.61 min−1, a conversion efficiency of 96.2% within 5 min and almost unchanged activity after six consecutive reaction cycles, which is better than the pristine MoS2 nanosheets. Moreover, the MoS2/Ti3C2 catalyst achieves a pseudo-first-order rate constant as high as 0.779 min−1 for the catalytic reduction of methylene blue (MB). This study opens up new opportunities for the design and development of cost-effective, efficient and reusable alternatives to noble metal catalysts based on molybdenum disulfide for environmental applications.

Preparation of BiFeO3 and its photoelectric performance as photoanode of DSSC

BiFeO3 was prepared by using a simple one-step hydrothermal synthesis method. The key factor is to rapidly cool the product after the hydrothermal reaction in order to suppress the formation of Bi2Fe4O9 and Bi25FeO40 phases. Different cascade structures of TiO2 and BiFeO3 with controllable dopants(Pr, Al) and concentrations were also prepared on the FTO. The J-V test showed that the photoelectric conversion efficiency of the conventional TiO2 photoanode was increased from 2.54% to 3.21%. However, the J-V tests of Bi0.98Pr0.02FeO3, BiFe0.95Al0.05O3 and Bi0.98Pr0.02Fe0.95Al0.05O3 indicated that their photoelectric conversion efficiencies were up to 3.97%, 4.07%, and 4.99% respectively.

Novel voltammetric detection of norfloxacin in urine and blood serum using a flexible Ni foam based Ni-Co-MOF ultrathin nanosheets derived from Ni-Co-LDH

Trace level valuation of analytes by the costless method is a thriving force to construct a viable sensor. Here, the proposed norfloxacin (NFC) sensor has been developed electrochemically using nickel-cobalt metal-organic frameworks (Ni-Co-MOF) nickel foam (NF). Here, a sphere-like structure assembled with nanosheets of Ni-Co-MOF NF was obtained by a simple one-step hydrothermal synthesis. Then, to obtain ultrathin nanosheets of Ni-Co-MOF NF by immersing the obtained NF in DMF. The formation of ultrathin nanosheets was confirmed and explained by physical characterization like XRD, SEM and RAMAN studies. The prepared Ni-Co-MOF was further used to analyze the electrochemical oxidation of NFC using cyclic voltammetry and differential pulse voltammetry method with a working potential 0 to 1.25 V. Acquired DPV results at Ni-Co-MOF NF showed a respectable linear range of 0 To 69 μM, lower LOD of 0.02229 and 0.0944 μM, the higher sensitivity of 9.4 and 38.74 μA/μmol/L and reproducibility. Also, fabricated Ni-Co-MOF NF was additionally used to determine the commercially available norfloxacin tablet in urine and blood serum samples with satisfactory results.

Infrared emission characteristic and microwave loss property of aluminum doped zinc oxide nanoparticles

Aluminum doped zinc oxide (AZO) nanoparticles with different doping concentrations were prepared by a simple one-step hydrothermal synthesis method. The crystal structure, morphology, infrared absorption, infrared emission and microwave loss properties of the AZO nanoparticles were analyzed in detail. With the increase of the aluminum doping concentration, the crystal plane spacing does not change much, while the grain size increases gradually, and the thickness of the flakes and the average size of the particles have no significant change. With the increase of the Al doping concentration, the infrared emissivity of AZO tends to decrease first and then increase, among which the AZO infrared emissivity with Zn-ion ratio of 95:5 is the lowest. The electromagnetic parameters of AZO with a mole doping ratio of 93:7 were carried out at a frequency range of 2–18 GHz, the real part (ε′) and imaginary part (ε″) of the complex permittivity varies between 4.3-4.5 and 0.2–0.4, respectively, the dielectric loss tangent (tanδ) varies between 0.04 and 0.09.

Cobalt oxide micro flowers derived from hydrothermal synthesised cobalt sulphide pre-catalyst for enhanced water oxidation

The rational design and development of the low-cost and efficient electrocatalysts towards oxygen evolution reaction (OER) are greatly influenced by the exposed surface area and structure of the electrocatalyst. Herein, we show a flower-like cobalt oxide/cobalt sulphide nanosheet electrocatalyst via a simple and cheap one-step hydrothermal synthesis for electrochemical water oxidation. Tuning the sulphur concentration influences the crystal formation and structural direction to achieve flower-like morphologies that greatly improves the surface area to benefit the OER. The best OER electrocatalysts were achieved on the CoS (1:0.5) electrode, which can deliver a current density of 10 mA cm−2 at a small overpotential of 383 mV, a low Tafel slope (38 mV dec−1) and remains constant for over 24 h. Mechanism study shows that during OER, the cobalt sulphide acts as a pre-catalyst and produces more active cobalt oxide phases with higher Co valence state when undergoing oxidation. This innovative design demonstrates the catalytic activity and overall efficiency which can be applied as an efficient non-noble metal electrocatalyst for OER.

Effect of zeolite amount on the properties of Pt/(AlSBA-15 + Beta zeolite) micro-mesoporous catalysts for the hydroisomerization of n-heptane

The composite (AlSBA-15 + Beta zeolite) materials were prepared using a simple one-step hydrothermal synthesis, aiming to investigate the effect of the ratio AlSBA-15 : zeolite on their physicochemical properties. The resulting micro-mesoporous materials (SBB) containing from 14 to 25 wt% of zeolite were used as supports for Pt catalysts in hydroisomerization of n- heptane (n-C7). Obtained catalysts were characterized by means of nitrogen sorption, XRD, Py–IR, 27Al MAS NMR, CO chemisorption, TEM and SEM. It was found, that the textural properties of the micro-mesoporous materials were comparable to pure AlSBA-15. It also appeared that the introduction of zeolite into AlSBA-15 at the synthesis stage affected the total acidity of the composite materials. Both the total acidity and strength of acid sites depended on AlSBA-15: zeolite ratio. The results of n-C7 hydroconversion showed that catalysts containing 14 and 25 wt% of zeolite provided the highest yield of the most desired, high-octane number products. The most promising Pt/AlSBA-15 + BEA catalysts (i.e. containing 14 and 25 wt% of Beta) allows to improve research octane number from 0 to the 65–70 points.

One-step hydrothermal synthesis of hierarchical nanosheet-assembled Bi2O2CO3 microflowers with a {001} dominant facet and their superior photocatalytic performance

Using citric acid (CA) and 1,5-naphthalenedisulfonic acid (NDSA) as the structure-directing agent, a hierarchical flower-like Bi2O2CO3 product is successfully prepared via a simple one-step hydrothermal synthesis, which is spirally assembled by the {001} facet-dominated nanosheets. It is testified that the additive CA plays an important inducing role in forming the chemical composition of Bi2O2CO3, the nanosized sheet-type subunits, and the exposure of the {001} facet, while the NDSA greatly improves the dispersity and porous structure of the Bi2O2CO3 microflower. Due to the nano-size effect and distortion of surface Bi-O bonds, the Bi2O2CO3 microflower could be excited by the visible light to exhibit a superior photocatalytic performance in the degradation of tetracycline (TC). Besides, it is found the exposed {001} facet of Bi2O2CO3 would preferentially generate holes during the illumination process, thus enhancing the photooxidative activity of the Bi2O2CO3 microflower. Finally, the structural and optical features of the Bi2O2CO3 microflower have been discussed in detail, and its photocatalytic mechanism has also been proposed in this work.

Facile one-step hydrothermal synthesis and room-temperature NO2 sensing application of α-Fe2O3 sensor

An alpha-iron oxide (α-Fe2O3) film-sensor prepared by a simple one-step hydrothermal synthesis technique demonstrates a high selectivity and sensitivity toward NO2 at room-temperature (27 °C). The XRD pattern of the as-synthesized sensor endows polycrystalline nature and hematite crystal structure. The gas sensing properties of α-Fe2O3 sensor are investigated against various target gases viz. hydrogen (H2), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon dioxide (CO2), liquefied petroleum gas (LPG), and carbon monoxide (CO). Due to a high specific surface area, special structure, and high electron contributing power over other tested gases, α-Fe2O3 sensor exhibits a high response, with good response/recovery time for NO2 gas. The α-Fe2O3 sensor shows 86% response for 100 ppm concentration of NO2 gas with excellent response/recovery time (31/32 s) and reported. The α-Fe2O3 sensor performance is measured for various concentration levels of NO2 gas. The theoretically proposed gas sensing mechanism also suggests a better response of the α-Fe2O3 sensor to NO2 gas over other gases. The room-temperature sensing operation, high selectivity, moderate repeatability and short response/recovery time with cost-effectiveness followed scalable synthesis of α-Fe2O3 sensor would decidedly useful for social and commercial benefits.

Hierarchically Nanostructured Fe₃O₄/C Composite as a Promising Magnetic Targeted Drug Nanocarrier.

Nanostructured Fe₃O₄/C composites are very attractive for high-performance magnetic targeted drug carriers. Herein, Fe₃O₄/C composite nanospheres with good dispersity are prepared by a simple one-step hydrothermal synthesis and subsequent heat treatment in Ar. The composite nanospheres consist of clustered primary nanoparticles, and exhibit a hierarchical architecture with a high specific surface area of 119.3 m² g-1. The Fe₃O₄/C composite nanospheres show a high saturation magnetization value of 101 emu g-1 and good biocompatibility. In particular, the composite nanospheres deliver a large loading content (85.8%) of epirubicin hydrochloride (EPI), resulting from their unique composition and microstructure. More importantly, the release of EPI from the EPI-loaded magnetic carrier (Fe₃O₄/C-EPI) may be enhanced by both a slightly acidic environment and a rotating magnetic field induced by a simple motor-driven magnet system. The above favorable properties make the hierarchical Fe₃O₄/C composite sample a promising candidate for magnetic targeting nanocarriers of EPI.

Sandwich-like SnS2/Graphene/SnS2 with Expanded Interlayer Distance as High-Rate Lithium/Sodium-Ion Battery Anode Materials

SnS2 materials have attracted broad attention in the field of electrochemical energy storage due to their layered structure with high specific capacity. However, the easy restacking property during charge/discharge cycling leads to electrode structure instability and a severe capacity decrease. In this paper, we report a simple one-step hydrothermal synthesis of SnS2/graphene/SnS2 (SnS2/rGO/SnS2) composite with ultrathin SnS2 nanosheets covalently decorated on both sides of reduced graphene oxide sheets via C-S bonds. Owing to the graphene sandwiched between two SnS2 sheets, the composite presents an enlarged interlayer spacing of ∼8.03 Å for SnS2, which could facilitate the insertion/extraction of Li+/Na+ ions with rapid transport kinetics as well as inhibit the restacking of SnS2 nanosheets during the charge/discharge cycling. The density functional theory calculation reveals the most stable state of the moderate interlayer spacing for the sandwich-like composite. The diffusion coefficients of Li/Na ions from both molecular simulation and experimental observation also demonstrate that this state is the most suitable for fast ion transport. In addition, numerous ultratiny SnS2 nanoparticles anchored on the graphene sheets can generate dominant pseudocapacitive contribution to the composite especially at large current density, guaranteeing its excellent high-rate performance with 844 and 765 mAh g-1 for Li/Na-ion batteries even at 10 A g-1. No distinct morphology changes occur after 200 cycles, and the SnS2 nanoparticles still recover to a pristine phase without distinct agglomeration, demonstrating that this composite with high-rate capabilities and excellent cycle stability are promising candidates for lithium/sodium storage.

Constructing a 2D/2D Bi2O2CO3/Bi4O5Br2 heterostructure as a direct Z-scheme photocatalyst with enhanced photocatalytic activity for NOx removal

As a direct Z-scheme photocatalyst, a two-dimensional/two-dimensional (2D/2D) Bi2O2CO3/Bi4O5Br2 (BOC/BOB) heterostructure was fabricated by stacking the ultrathin nanosheets of Bi2O2CO3 and Bi4O5Br2 via a simple one-step hydrothermal synthesis process. The atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) results show that the heterostructure was successfully formed by coupling the ultrathin nanosheets of BOC and BOB. By optimizing the content of BOC, we found that the 30% BOC/BOB composite can exhibit a superior photocatalytic activity (53.2%) for NOx removal under simulated solar light illumination, which is much higher than that of single-phase BOC (20.4%) or BOB (37.9%). The results from trapping experiments and DMPO-ESR spin-trapping measurements demonstrate that both O2– and OH are the main active species during the photocatalytic reaction process. According to the DFT calculations, a Z-scheme heterojunction is formed between the BOC and BOB ultrathin nanosheets, in which the photo-induced electrons in BOC are combined with holes in BOB. This process can effectively hinder the recombination of photo-induced charge carriers in the BOC/BOB nanocomposites and resulting in the enhancement of charge separation efficiency. This work may shed light on developing more efficient photocatalysts by designing the 2D/2D Z-scheme heterostructures using ultrathin nanosheets.

A simple one-step hydrothermal synthesis of cobalt[sbnd]nickel selenide/graphene nanohybrid as an advanced platinum free counter electrode for dye sensitized solar cell

A nanohybrid comprises of cobalt-nickel selenide (Co0.50Ni0.50Se) nanoparticles dispersed on graphene nanosheets (GN) has been synthesized by a simple one-step hydrothermal method to use as a counter electrode for dye sensitized solar cell (DSSC). The structural changes and the corresponding electrocatalytic properties in terms of cathodic peak current density and charge transfer resistance at the electrode/electrolyte interface for Co0.5Ni0.5Se/GN nanohybrid with respect to the mass ratio between Co0.5Ni0.5Se nanoparticles and graphene nanosheets have been investigated. Co0.5Ni0.5Se/GN0.50 exhibits higher electrocatalytic activity and lower charge transfer resistance than other Co0.5Ni0.5Se/GN nanohybrids and std. platinum (Pt) counter electrodes. Finally, the DSSC fabricated with Co0.5Ni0.5Se/GN0.50 as the counter electrode delivered photo-conversion efficiency (PCE) of 9.42%, which is higher than that of DSSC fabricated with Co0.5Ni0.5Se (7.59%) and std. Pt (7.68%) counter electrodes. This improved electrochemical performance and higher PCE incited by the synergistic effect of Co and Ni in Co0.5Ni0.5Se nanoparticles, as well as Co0.5Ni0.5Se and graphene, could make Co0.5Ni0.5Se/GN0.50 nanohybrid as a promising low-cost Pt-free counter electrode for DSSC.

Hydrothermal synthesis of flower-like Cu2MoS4/g-C3N4 composite and its adsorption performances for Rhodamine B

Abstract Waste water treatment with adsorbents has become one of the most effective methods. In this work, we have reported the preparation of the flower-like Cu2MoS4/g-C3N4 composites. The Cu2MoS4 nanosheets were arranged in a flower-like structure by a simple one-step hydrothermal synthesis method and attached to g-C3N4 nanosheets. The as-prepared flower-like Cu2MoS4/g-C3N4 composites was found to have potential for the adsorption of RhB in aqueous solution. The microstructure of the product was analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscope (XPS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET). The effects of the ratio of the composite material, the initial concentration of the dye and the contact time were explored. The Langmuir maximum adsorption capacity of the flower-like Cu2MoS4/g-C3N4 composites for RhB was reached 420.2 mg/g. Moreover, the adsorption process is consistent with the pseudo second-order kinetic model, the Langmuir isotherms model and the Freundlich isotherms model.