Hydrothermal Synthesis Method Research Articles

Galla chinensis residue-derived carbon dots for sensitive detection of doxorubicin hydrochloride and cell imaging

As an antibiotic, the imbalance of the concentration of doxycycline hydrochloride (DOX) can cause many harms, so real-time detection of the DOX content is crucial. In this study, Galla chinensis residue (GCR) was used as a carbon source, m-phenylenediamine was used as an N-doping agent, and blue-green fluorescent carbon dots (N-GCRCDs) were prepared by a simple hydrothermal synthesis method, with a high quantum yield of 27.31 %. Under optimized conditions, a specific fluorescent probe was established to detect DOX. The addition of DOX resulted in a significant decrease in fluorescence intensity, with a detection range of 5.7–114.9 μM and the detection limit was 1.38 μM. Finally, the feasibility of this method was validated in human urine and the experimental results exhibited a DOX recovery rate of 97.45–104.41 % and an RSD of 0.91–2.64 %. The quenching mechanism was mainly attributed to the inner filter effect and static quenching. Furthermore, the potential application of N-GCRCDs in cells was studied and biocompatibility was evaluated using HepG2 cells, which showed low toxicity at concentrations of 0–50 μg/mL and successful application for HepG2 cell imaging. This study provides reference for resource utilization of GCR and quantitative detection of antibiotics.

The adsorption performance of high crystallinity Na-p zeolites prepared from oil shale ash for the waste water treatment

ABSTRACTS The Na-p type zeolite has been prepared by the alkali fusion hydrothermal synthesis method using the pure oil shale ash (OSA) and mixture of OSA and coal fly ash (CFA) as raw materials, which was used for adsorption of methylene blue (MB). The XRD spectra of zeolite synthesized from pure oil shale residue under different conditions indicated that the optimal experimental conditions were determined as follows: acid leaching concentration of 10%, sodium hydroxide dosage of 7 g, crystallization temperature of 130°C, and crystallization time of 12 h. Under the same conditions, zeolite was synthesized using the mixture of OSA and CFA, and its properties were characterized using XRD, SEM, and BET techniques. The results showed that the specific surface area and crystallinity of the zeolite prepared from the mixture were 59.6 m2/g and 86.32%, respectively, which were higher than that of pure OSA (20.6 m2/g and 64.07%). When 0.05 g of zeolite was added to the 35 mg/L MB solution and adsorbed for 180 min, the removal rates of MB by pure OSA, single-source zeolite and zeolite prepared from the mixture were 27.6%, 83.4%, and 99.2%, respectively. The adjusted R square verified that the pseudo-second-order kinetics and Langmuir isotherm model were the best fitting models. The maximum adsorption capacity (Qmax) of zeolite prepared from the mixture for MB was 55.5 mg/g. The above results proved that the novel material prepared in this study could be a potential effective wastewater treatment material.

Ultrathin, flexible, and high-performance bacterial cellulose/copper nanowires film for broadband electromagnetic interference shielding and photothermal conversion

The swift advancements in wearable electronics, implantable medical devices, fifth-generation mobile communication, unmanned aerial vehicles, and military stealth technology have led to a surge in demand for highly flexible multifunctional films. Consequently, the enhancement of electromagnetic radiation and the requirement for normal operation in extreme environments have posed significant challenges for flexible electromagnetic interference (EMI) shielding films. In this paper, ultra-thin, flexible bacterial cellulose (BC)/copper nanowires (CuNWs) (BCu) films with Janus structure are prepared by the combination of microwave-assisted hydrothermal synthesis and vacuum filtration method, which can be used for broadband EMI shielding and photothermal conversion. BCu films demonstrate exceptional mechanical properties, boasting a tensile strength range from 48.5 to 77.3 MPa, accompanied fracture strain 4.1–5.9 %. When CuNWs mass in Janus film increases to 10 mg, the conductivity of BCu-4 Janus films can reach 4761.90 S cm−1. The ultra-strong EMI shielding effectiveness (SE, above 56.00 dB) is achieved in 6–26.5 GHz for BCu-4 film with an ultra-thin thickness (16 μm). Moreover, the specific EMI SE of BCu-4 is as high as 4294.38 dB mm−1. Furthermore, BCu Janus films exhibit outstanding photothermal conversion performance. A saturation temperature of BCu-4 Janus film reaches as high as 75 °C under irradiation of one sunlight (100 mW cm−2). The facile and collaborative strategy is provided for fabricating ultra-thin, flexible multifunctional Janus films with EMI shielding and photothermal conversion capabilities, addressing EMI problems in modern electronic technology and offering new avenues for applications in various fields.

Green Synthesis of Luminescent Carbon Dots from Ficus benghalensis Aerial Roots for Bioimaging.

In this work, carbon quantum dots (CQDs) were prepared using a one-step hydrothermal green synthesis method from a low-cost and eco-friendly renewable biomass, specifically the Ficus benghalensis aerial roots (FB-AR). For the past two decades, CQDs have been noted for their tunable emission spectrum, quantum yield, biocompatibility, photostability, and unique optoelectronic properties such as photoluminescence (PL), and fluorescence. The synthesized Ficus benghalensis carbon quantum dots (FB-CQDs) were characterized for their physical, structural, and chemical properties using XRD, Raman, HRTEM, XPS, FTIR, TG-DTG, UV-visible, and photoluminance analysis. XPS analysis confirmed the presence of phytoconstituent functionalities and the composition of components. The FB-CQDs, which exhibit long-range emissions, have potential applications in various biological and therapeutic fields. Their bioimaging capability is tested in Escherichia coli bacteria. However, despite their promising characteristics, the FB-CQDs showed no antibacterial inhibition against Escherichia coli and Staphylococcus aureus, likely due to its carbonization temperature.

Chemical synthesis, structural and magnetic properties of Al-doped neodymium orthoferrite

Crystalline and single phase of Al doped orthoferrite with stoichiometry NdFe1-xAlxO3 was synthesized by a hydrothermal method. The effect of Al doping on the structure features was investigated by powder X-ray diffraction (PXRD) technique. In this sense, Rietveld refinement was applied in refining the PXRD data. Scanning electron microscopy (SEM) was used to characterize the morphology. And from image analyses show a sub-micron particle size distributions for all samples. Using hydrothermal synthesis method, a micro-sized particle distribution is reached. Measurement of magnetic hysteresis loops showed that the highest coercivity (Hc) obtained was 5.2 kOe for the sample with x=2. Compared to previous results using sol-gel synthesis, the hydrothermal method used in this study showed improved magnetization properties.

Sulfur dioxide gas sensor based on vanadium oxide doped TiO2 nanopaper

Abstract The gas sensor based on TiO2 nanomaterials is promising for both industry and daily life because of its simple fabrication, low cost, high sensitivity, and easy application to micro-devices. However, its selectivity is relatively low and strongly influenced by the environment, thus limiting its practical application. In this work, we prepared TiO2 nanopaper by methods of hydrothermal synthesis and conventional paper preparation. To improve the selectivity, we added V2O5 by immersing the as-prepared nanopaper in an ammonium metavanadate (NH4VO3) solution evenly dispersed in ethanol. Nanopaper is a random array of long nanowires and nanofibers, which retains its shape and structure at high temperature, unlike pure nanowires, due to its high porosity and mechanical stability. V2O5 leads to a selective sensing performance with high catalytic activity for SO2 gas. The surface structure of the sensing material and its porosity were characterized by SEM, XRD, XPS. The improved sensing material exhibited a high response of about 22.6 for 100 ppm SO2 and a fast response and recovery of 9 s and 14 s, respectively. It also exhibited good reproducibility and selectivity in other interfering gases. Furthermore, the long-term sensing performance in the atmospheric environment was maintained for about 50 days.

Environmentally friendly, high near-infrared reflection green pigments for thermal insulation

In this paper, TiO2 and MgAl-LDHs were coated on yellow pigment hydroxyl iron oxide (FeOOH) with sol-gel and hydrothermal synthesis method respectively to prepare loaded yellow pigment (FT8M0.25). Then, phthalocyanine blue (CuPc) was combined with FT8M0.25 to prepare composite green pigment (FT8M0.25Px). The results indicate the FT8M0.25Px has the structural characteristics of hydrotalcites and CuPc. The surface of FeOOH pigment has a clear TiO2 coating layer and MgAl-LDHs flake structure. KPFM analysis indicate that there is electron transfer between the interfaces of pigments. According to the analysis of color performance and near-infrared reflectance (NIR), the FT8M0.25P0.13 (a*=-12.98) is greener than that of Cr2O3 (a*=-6.65). The NIR of FT8M0.25P0.13 is as high as 73.54 %. The visible light absorption spectrum characteristics determine the color of the pigments, and there is electron transfer between the interfaces of each group. The formation of multi-level interfaces and the resulting multiple light reflections increase the reflectivity of the pigment. The developed coating achieved a considerable temperature difference of 20 °C before and after the coating surface with excellent photostability and reusability, which makes it possible for pigments to replace chromium containing pigments and be used as energy-saving cold pigments.

Preparation of Soybean Dreg-Based Biochar@TiO2 Composites and the Photocatalytic Degradation of Aflatoxin B1 Exposed to Simulated Sunlight Irradiation.

Aflatoxin B1 (AFB1) is a highly toxic carcinogen severely harmful to humans and animals. This study fabricated SDB-6-K-9@TiO2 composites via the hydrothermal synthesis method to reduce AFB1. The structural characterization results of the photocatalytic composites showed that TiO2 was successfully loaded onto SDB-6-K-9. The different photocatalytic degradation conditions, photocatalyst kinetics, recycling performance, and photocatalytic degradation mechanism were investigated. Photocatalysis with 6 mg of 4%SDB-6-K-9@TiO2 in a 100 μg/mL AFB1 solution presented a reduction of over 95%, exhibiting excellent performance, high stability, and reusability even after five cycles of photocatalytic experiments. Active species trapping experiments confirmed that holes (h+) played the most critical role. After structural analysis and identification of the photocatalytic degradation products, the photodegradation path and photocatalytic oxidation mechanism of 4%SDB-6-K-9@TiO2 were postulated. The results show a new way to improve TiO2's photocatalytic performance, providing a certain theoretical basis for the effective AFB1 reduction.

Synthesis and Characterization of LaMnO3 Prepared by Hydrothermal Synthesis Method

Abstract LaMnO3 powders were prepared by hydrothermal synthesis method by varying citric acid to metal ions. The ratio of citric acid to metal ions is one of the parameters that have an affect on purity of LaMnO3 prepared by hydrothermal method. It is necessary to control the parameter to obtain the good quality of the final product of LaMnO3. LaMnO3 with variation molar ratio of citric acid to metal ion (CA/M) of 0, 1 and 4 were prepared. To determine the morphology, crystall structure, and phase composition, the powders were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) techniques. The obtained results revealed that the morphology of sample CA/M = 0 has rod-like shape, CA/M = 1 was in the formed of irregular fine particles that stuck together and formed agglomerates, while the spherical morphology with various diameters were formed in the sample CA/M = 4. The XRD analysis demonstrated that sample CA/M = 1 had a single phase while in sample CA/M = 0 and CA/M = 4 others phase were detected such as La (OH)3 and La2O3. There was a change in crystall structure of the LaMnO3 phase in each sample due to the presence of citric acid. The peaks position in sample CA/M = 0, 1, dan 4 exhibit orthorhombic, rhombohendral and cubic structure with space group of Pnma, R -3c and Pm-3m respectively.

Synergistic enhancement of lithium iron phosphate electrochemical performance by organic zinc source doping and crystalline carbon layer capping

In this study, lithium iron phosphate (LFP) is prepared as cathode material by hydrothermal synthesis method and the combined effect of doping and capping is applied to co-modify it. We thoroughly investigate how Zn2+ doping and PA capping layer affect the crystal structure, microscopic morphology, and electrochemical properties of LFP cathode materials. The experimental results show that when co-modified with 5 % Zn2+ doping combined with 7 % PA capping layer, the resulting cathode material exhibits a discharge specific capacity of 165.5 mAh g−1, and the capacity retention rate can still be maintained at a high level of 98.6 % after 200 charge–discharge cycles.

Direct synthesis of low-silica ZSM-48 zeolite via seed-assisted hydrothermal synthesis with 1,6-hexanediamine as template

ZSM-48 zeolite is characteristic of 10-member ring (10-MR) one-dimensional tubular channel structure and finds extensive applications in catalytic hydroisomerization reactions. Here we developed an efficient synthetic strategy for low-silica ZSM-48 zeolite with a SiO2/Al2O3 ratio at 30∼176 via a seed-assisted hydrothermal synthesis method, overcoming the limit that 1,6-hexanediamine (HDA) template can only be used to synthesize high-silica (i.e., SiO2/Al2O3 ratio >200) zeolites. A two-step crystallization procedure coupled with zeolite seed-assisted synthesis strategy was enrolled to realize well crystallized ZSM-48 zeolites, in which the zeolite nuclei are sufficiently produced at the nucleation temperature at 100 °C for 24 h with the aid of zeolite seeds, and the zeolite growth is proceeded at the crystallization temperature at 160 °C for 48 h. The morphology and particle size of low-silica ZSM-48 have been manipulated by adjusting the synthetic parameters, such as the alkalinity and silicon source of aluminosilicate gel for zeolite, the crystallization manner (static or dynamic crystallization), as well as the presence of additive (i.e., sodium chloride). The as-synthesized ZSM-48 zeolite exhibits a significantly high acid content of 0.194 mmol/g, highlighting its potential as an excellent acidic support for hydroisomerization catalysts. The cost-effective and environmentally friendly synthesis strategy, which is anticipated to expand the application of alkylamine organic templates in the synthesis of low-silica ZSM-48 zeolite.

Direct synthesis of Cu-TiO<sub>2</sub>-SBA-16 photocatalysts and its application for the oxidative desulfurization of fuel oil model

In this study, the Cu-TiO2-SBA-16 photocatalytic materials were successfully prepared by direct hydrothermal synthesis method. The products were characterized by X-ray diffraction (XRD), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS) methods. The analysis illustrated that Cu-TiO2 nanocrystals were successfully incorporated into the SBA-16 mesopores. The photocatalytic activity of these Cu-TiO2-SBA-16 mesoporous materials have been tested by the oxidative desulfurization reaction of dibenzothiophene (DBT) using H2O2 as an oxidant under UV light irradiation. The results showed that the Cu-TiO2-SBA-16 mesoporous materials prepared at the Cu/Ti mole ratios of 0.05 showed higher photocatalytic activity than the rest due to the decrease in band gap energy.

Poly(3,4-ethylenedioxythiophene)-Coated Vanadium-Doped MnO2 Nanorods for High-Performance Flexible Aqueous Zinc-Ion Battery Cathode.

Manganese-based aqueous zinc-ion batteries (AZIBs) are considered promising cathode materials for large-scale energy storage applications due to their low cost and high safety. However, the primary constraints on achieving high specific capacity and cycling stability are the inherent low conductivity and suboptimal structural stability of the AZIB cathodes. Herein, we report a high-performance poly(3,4-ethylenedioxythiophene) (PEDOT)-coated vanadium-doped MnO2 nanorod (NR) electrode for AZIBs. First, vanadium-doped MnO2 (V-MnO2) NRs were synthesized by a simple hydrothermal synthesis method. The V-MnO2 NRs were further encapsulated with a nanolayer of PEDOT through an in situ polymerization process, which was subsequently treated with sulfuric acid to achieve a smooth surface. The V doping creates oxygen vacancies within the MnO2, allowing for the rapid embedding and diffusion of Zn2+. The PEDOT nanolayer greatly enhances the conductivity and structural stability of the V-MnO2. Benefiting from the unique features, an optimal composite NRs electrode exhibits a high specific capacity of 250 mAh g-1 at 0.4 A g-1, a high energy density (388 Wh kg-1 at 151 W kg-1), and excellent stability over 5000 cycles at 3 A g-1. In addition, the flexible pouch cell assembled with the electrode shows good stability under bending. Given the positive outcomes, the material holds great potential for use as a cathode in next-generation flexible energy storage systems.

Controllable Synthesis of Magnetic Composite Derived from MIL-88D and Study on Adsorption Properties of Cu2+

In this paper, MIL-88D (Fe) with spindle shape was prepared by the hydrothermal synthesis method, a metal oxide with a new structure was obtained by calcination at different temperatures as a precursor, and a magnetic iron oxide composite was prepared successfully. At the same time, it was used as an adsorption material for the adsorption of heavy metal ions Cu2+. The influence of the initial pH value and adsorption time on the adsorption effect was investigated, the adsorption kinetics and adsorption isotherm were further fitted, and the adsorption mechanism was preliminarily analyzed. The results show that the magnetic iron oxide composites have a good adsorption capacity for Cu2+. The pH value is an important parameter that affects the adsorption effect. The adsorption of Cu2+ by magnetic iron oxide composites reached adsorption equilibrium in 30 min. The adsorption of Cu2+ by magnetic iron oxide composites conforms to the second-order reaction kinetics and Langmuir adsorption isotherm equation, which indicates that the adsorption process mainly occurs through chemisorption and typical single-molecular-layer adsorption.

An europium complex assembled by a flexible derivative of imidazole-4,5-dicarboxylic acid as a fluorescence turn-off chemosensor to detect Cr(VI) anions

A new europium(III) CP [Eu(HBBIDA)(H2O)]n (1) (H4BBIDA = 1,1′-(butane-1,4-diyl)bis(1H-imidazole-4,5-dicarboxylic acid) was successfully constructed by hydrothermal synthesis method and detailed characterization was performed. Crystal structure analysis reveals that CP 1 presents a 2D layered structure composed of cage-like SBUs with a TiS2 topological network. CP 1 can maintain framework integrity in an air environment below 260 °C, as well as in a certain pH range of acid-base aqueous solutions and common organic reagents, showing better thermal and chemical stability. Fluorescence measurements show that CP 1 exhibited excellent sensing activities toward CrO42− and Cr2O72− anions through fluorescence quenching, and their average quenching Ksv values of 3.99 × 103 M−1 (CrO42−) and 4.36 × 103 M−1 (Cr2O72−) and the LOD of 3.30 × 10−6 M (CrO42−) and 3.02 × 10−6 M, which makes it very suitable for the detection of hexavalent chromium anions contaminants in aqueous solutions. Furthermore, possible sensing mechanisms have been studied and discussed in detail, and the results show that static photocompetitive absorption should be the primary cause for the fluorescence quenching of the sensor.

RGO loaded Fe3O4 strategy to construct high toughness PAM hydrogel for electromagnetic shielding

With the continuous development of electronic products, polymers with EM shielding have received widespread attention. In this study, Fe3O4@RGO was prepared by the hydrothermal synthesis method, which solved the problems of Fe3O4 precipitation and RGO stacking. Using it as a precursor, Fe3O4@RGO/PAM conductive hydrogel was prepared. The research shows that the conductivity of this hydrogel reaches 16.2 S/m at a thickness of 0.3 cm, and the maximum EMI SE is 27.1 dB. Among them, RGO can form a conductive framework, and Fe3O4 can optimize the impedance matching and provide additional magnetic loss. The combined effect of the two makes the hydrogel have excellent EMI SE. In addition, PAM-based hydrogels have good thermal stability, crystallinity, water content, and mechanical properties.

Impact of various metal promoters on the propane dehydrogenation performance of cobalt-based catalysts

Large-scale exploitation of natural gas and shale gas has spurred the development of the propane dehydrogenation technology. While cobalt-based catalysts, known for their low cost and low toxicity, effectively activate C–H bonds, they are often deactivated because of coke formation. In this study, we prepared SBA-15 molecular sieves using a hydrothermal synthesis method and developed a series of Co-based catalysts supported on SBA-15 with various metal promoters (denoted Co-X/SBA-15, where X = Mn, Fe, Mg, Zn, or La) via an incipient wetness impregnation method. Characterization techniques and activity evaluation results revealed that the Co–O–Mg structure in the Co-Mg/SBA-15 catalyst stabilizes the primary Co2+ active site and hinders the reduction of the CoOx species. The incorporation of Mg enhances the total alkalinity of the catalyst, facilitating propane adsorption and propylene desorption, leading to superior activity and stability. Although the addition of La improved propylene selectivity, it did not significantly enhance propane conversion. Conversely, the introduction of Mn, Fe, and Zn into the catalyst inhibited the reaction.

Synthesis of Ag-doped SnO2 nanoflowers and applications to room temperature high-performance NO2 gas sensing

SnO2 has attracted much attention in the field of gas sensors due to its unique structure and properties. In this work, SnO2 nanoflowers doped by Ag structures were prepared by a facile hydrothermal synthesis method. Ag doping not only increases the number of oxygen vacancies in the composite, but also alters the carrier migration behavior and significantly increases the carrier concentration, promoting the electron transport rate. Additionally, Ag doping enhanced the conductivity and catalytic activity of the composite, making it highly selective for NO2. At room temperature (RT), Ag-doped SnO2 sensor exhibit excellent gas-sensitizing properties. At the NO2 concentration of 100 ppm at RT (25 °C, 25 % RH) the prepared 2 at% Ag-SnO2 sensor has a response value of 73.0 (Ra/Rg), a response time of 1.4 s, and a detection limit as low as 10 ppb. Its long-term stability is up to 90 days. Doping is an effective way to improve gas sensing performance. It solves the disadvantages of low sensitivity and poor selectivity of SnO2.

Comprehensive Review of Li-Rich Mn-Based Layered Oxide Cathode Materials for Lithium-Ion Batteries: Theories, Challenges, Strategies and Perspectives.

Lithium-rich manganese-based layered oxide cathode materials (LLOs) have always been considered as the most promising cathode materials for achieving high energy density lithium-ion batteries (LIBs). However, in practical applications, LLOs often face some key problems, such as low initial coulombic efficiency, capacity/voltage decay, poor rate performance and poor cycle stability. It seriously shortens the lifespan of lithium-ion batteries and hinder the large-scale commercial application of LLOs. Herein, firstly, the basic theories of LLOs were systematically reviewed, including the structural characteristics, the working mechanism of LLOs, the preparation methods of LLOs (liquid phase co-precipitate method, sol-gel method, hydrothermal synthesis method, solid phase method, low heat solid-phase method, high temperature solid-state method etc.), and electrochemical characteristics of LLOs (first charge discharge characteristics and reversible efficiency, cycling performance, high and low temperature performance and thermal stability etc.). Then, key challenges faced by LLOs were systematically discussed. Finally, the LLOs modification strategies used to address these challenges (element doping, surface modification, defect engineering, structural and morphological control etc.) were elaborated in detail. This important review provides potential insights and directions for further improving the electrochemical performance of LLOs, and provides a necessary theoretical basis for accelerating the large-scale commercial application of LLOs. It possesses important scientific research value and far-reaching social significance.

Cu-doped Ni3S2 electrocatalyst for glycerol oxidation coupling to promote hydrogen evolution reaction

Hydrogen energy is becoming increasingly important as a clean and efficient form of energy. Glycerol oxidation synergistic electrocatalytic hydrogen evolution technology is an electrochemical process that integrates anodic glycerol oxidation reaction (GOR) and cathodic hydrogen production. Compared with the oxygen evolution reaction (OER) required in the electrolysis of water for hydrogen production process, this technology can not only reduce the energy consumption of the whole reaction, but also obtain valuable by-products while producing hydrogen. In this study, we successfully prepared a copper-doped Ni3S2 (Cu-Ni3S2@NF) electrode material loaded on a nickel foam carrier by a two-stage hydrothermal synthesis method, and applied it to the bifunctional electrocatalytic reaction of GOR and hydrogen evolution reaction (HER). After a series of in-depth electrochemical performance tests, it was confirmed that 0.1Cu-Ni3S2@NF showed lower overpotential requirements when performing GOR and HER, requiring only 1.41 V relative to the reversible hydrogen electrode (RHE) to drive a current density of 100 mA cm−2 for GOR, and only 0.56 V vs. RHE to achieve the same current density for HER. Moreover, the electrode material still maintains good stability under long-term operation. Among them, the Faraday efficiency (FE) of glycerol oxidation to formate is more than 85 %, while the FE of HER is not less than 93 %.