Hydrothermal Synthesis Research Articles

Copper-Nanoparticle-Decorated Hydrothermal Carbonaceous Carbon-Polydimethylsiloxane Nanocomposites: Unveiling Potential in Simultaneous Light-Driven Interfacial Water Evaporation and Power Generation.

This study introduces a hydrothermal synthesis method that uses glucose and Cu2+ ions to create a Cu-nanoparticle (NP)-decorated hydrothermal carbonaceous carbon hybrid material (Cu-HTCC). Glucose serves both as a reducing agent, efficiently transforming Cu2+ ions into elemental Cu nanostructures, and as a precursor for HTCC microstructures. An enhanced plasmon-induced electric field resulting from Cu NPs supported on microstructure matrices, coupled with a distinctive localized π-electronic configuration in the hybrid material, as confirmed by X-ray photoelectron spectroscopic analysis, lead to the heightened optical absorption in the visible-near-infrared range. Consequently, flexible nanocomposites of Cu-HTCC/PDMS and Cu-HTCC@PDMS (PDMS=polydimethylsiloxane) are designed as 2 and 3D structures, respectively, that exhibit broad-spectrum solar absorption. These composites promise efficient photo-assisted thermoelectric power generation and water evaporation, demonstrating commendable mechanical stability and flexibility. Notably, the Cu-HTCC@PDMS composite sponge simultaneously exhibits commendable efficiency in both water evaporation (1.47kgm-2h-1) and power generation (32.1mV) under 1 sunlight illumination. These findings unveil new possibilities for innovative photothermal functional materials in diverse solar-driven applications.

On the formation and properties of amorphous and crystalline Li3-yBay/2OCl electrolytes

All-solid-state batteries (ASSBs) have potential to provide higher specific energy, higher power, and longer cycle life than Li-ion batteries (LIBs) for continuously increasing demands of high-performance rechargeable batteries with intrinsic safety. However, one of the barriers for successful design and fabrication of ASSBs is the lack of solid-state electrolytes (SSEs) that can meet multi-functional requirements for ASSBs. To address this issue, the present study investigates hydrothermal synthesis of amorphous and crystalline Ba-doped Li3OCl solid electrolytes and develops the understanding of the relationships between the synthesis conditions and electrochemical properties of the products. It is shown that the formation of an amorphous/crystalline Ba-doped Li3OCl mixture with little hydroxide impurities depends strongly on the hydrothermal reaction temperature, drying temperature, Ba concentration, and rate of removing OH− and H+ ions as steam from water solvated Ba-doped Li3OCl. The key to generate amorphous Li3OCl-based electrolytes with high ionic conductivities (7.65 × 10−3 S/cm) at room temperature is to create non-equilibrium synthesis conditions such as the one identified in this study. The understanding developed in this study will offer critical guidelines for synthesizing amorphous and crystalline Li3OCl-based electrolytes with superior electrochemical properties for ASSBs reliably and reproducibly in the near future.

Laser-Printed Photoanode: Femtosecond Laser-Induced Crystalline Phase Transformation of WO3 Nanorods for Space-Efficient and Flexible Thin-Film Solar Water-Splitting Cells.

Despite its potential for clean hydrogen harvesting, photoelectrochemical (PEC) water-splitting cells face challenges in commercialization, particularly related its harvesting performance and productivity at an industrial scale. Herein, a facile fabrication method of flexible thin-film photoanode for PEC water-splitting to overcome these limitations, based on laser processing technologies, is proposed. Laser-induced graphene, a carbon structure produced through direct laser writing carbonization (DLWC), plays a dual role: a flexible and stable current collector and a substrate for the hydrothermal synthesis of tungsten trioxide (WO3) nanorods (NRs). To facilitate water-splitting, a femtosecond-pulsed laser (fs laser) is focused on the WO3 NRs, converting their crystalline phase from pristine orthorhombic to monoclinic structure without thermal damage. With NiFe layered double hydroxide (LDH) catalyst, the flexible thin-film photoanode exhibits good PEC performance (1.46mAcm-2 at 1.23 VRHE) and retains ≈90% of its performance after 3000 bending cycles. With its excellent mechanical properties, the flexible photoanode can be operated in various shapes with different curvatures, enabling space-efficient PEC water-splitting by loading larger photoanode within a given space. This study is expected to contribute to the advancement of large-scale solar water-splitting cells, introducing a new approach to enhance H2/O2 production and expand its application range.

Hydrothermal Synthesis of CuO/WO3 Hybrid Bifunctional Composites with Unprecedented Dark Adsorption and Photocatalysis

AbstractThis study presents the synthesis and characterization of Copper Oxide/Tungsten Oxide (CuO/WO3) hybrid bifunctional composites using a hydrothermal approach. X‐ray diffraction (XRD) analysis confirms the successful synthesis of CuO/WO3 hybrids, exhibiting additional peaks corresponding to WO3 phases. Scanning electron microscopy (SEM) images reveal well‐defined, aggregated particles with a nanoscale pattern and uniform distribution of CuO and WO3 throughout the composite. Energy‐dispersive X‐ray spectroscopy (EDX) confirms the stoichiometric composition of CuO/WO3 hybrids. Evaluation of dark adsorption and sunlight‐assisted photocatalysis using methylene blue (MB) dyes shows a remarkable enhancement in efficiency compared to pristine CuO. The CuO/WO3 hybrids exhibit a dark adsorption capacity of 87 % and a photocatalytic degradation efficiency of 95 % under sunlight illumination, outperforming pure CuO. These results underscore the synergistic interaction between CuO and WO3, facilitating efficient pollutant removal. The study elucidates the structural properties and mechanistic insights driving the superior performance of CuO/WO3 hybrid composites, offering promising prospects for advanced water treatment technologies.

Functionalization of silver nanoparticles coating cotton fabrics through hydrothermal synthesis for improved antimicrobial properties

Deposition of silver nanoparticles (AgNPs) on the surfaces of cotton fabric (CF) is an approach for producing antimicrobial textile products. CF-AgNPs composites were fabricated ex situ using a simple hydrothermal synthesis of AgNPs, while the fabric was surface modified using a plasma to improve adhesion prior to coating. The morphology and chemical composition of CF-AgNPs nanocomposites were examined using UV–vis spectrophotometry (UV–vis), x-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Study results show uniform deposition of AgNPs on cotton fabrics. The CF-AgNPs composite material exhibits excellent laundering durability and antimicrobial performance against Gram-positive, Staphylococcus aureus and Gram-negative, Escherichia coli pathogens. These findings indicate that the developed fabric can be used in a wide range of biomedical applications, health care and various packaging systems.

The Interplay of Electronic Configuration and Anion Ordering on the Magnetic Behavior of Hydroxyfluoride Diaspores.

We report a new nickel hydroxyfluoride diaspore Ni(OH)F prepared using hydrothermal synthesis from NiCl2·6H2O and NaF. Magnetic characterization reveals that, contrary to other reported transition-metal hydroxyfluoride diaspores, Ni(OH)F displays weak ferromagnetism below the magnetic ordering temperature. To understand this difference, neutron diffraction is used to determine the long-range magnetic structure. The magnetic structure is found to be distinct from those reported for other hydroxyfluoride diaspores and shows an antiferromagnetic spin ordering in which ferromagnetic canting is allowed by symmetry. Furthermore, neutron powder diffraction on a deuterated sample, Ni(OD)F, reveals partial anion ordering that is distinctive to what has previously been reported for Co(OH)F and Fe(OH)F. Density functional theory calculations show that OH/F ordering can have a directing influence on the lowest energy magnetic ground state. Our results point toward a subtle interplay between the sign of magnetic exchange interactions, the electronic configuration, and anion disordering.

An Overview of Hydrothermally Synthesized Titanate Nanotubes: The Factors Affecting Preparation and Their Promising Pharmaceutical Applications

Recently, titanate nanotubes (TNTs) have been receiving more attention and becoming an attractive candidate for use in several disciplines. With their promising results and outstanding performance, they bring added value to any field using them, such as green chemistry, engineering, and medicine. Their good biocompatibility, high resistance, and special physicochemical properties also provide a wide spectrum of advantages that could be of crucial importance for investment in different platforms, especially medical and pharmaceutical ones. Hydrothermal treatment is one of the most popular methods for TNT preparation because it is a simple, cost-effective, and environmentally friendly water-based procedure. It is also considered as a strong candidate for large-scale production intended for biomedical application because of its high yield and the special properties of the resulting nanotubes, especially their small diameters, which are more appropriate for drug delivery and long circulation. TNTs’ properties highly differ according to the preparation conditions, which would later affect their subsequent application field. The aim of this review is to discuss the factors that could possibly affect their synthesis and determine the transformations that could happen according to the variation of factors. To fulfil this aim, relevant scientific databases (Web of Science, Scopus, PubMed, etc.) were searched using the keywords titanate nanotubes, hydrothermal treatment, synthesis, temperature, time, alkaline medium, post treatment, acid washing, calcination, pharmaceutical applications, drug delivery, etc. The articles discussing TNTs preparation by hydrothermal synthesis were selected, and papers discussing other preparation methods were excluded; then, the results were evaluated based on a careful reading of the selected articles. This investigation and comprehensive review of different parameters could be the answer to several problems concerning establishing a producible method of TNTs production, and it might also help to optimize their characteristics and then extend their application limits to further domains that are not yet totally revealed, especially the pharmaceutical industry and drug delivery.

A novel type-II–II heterojunction for photocatalytic degradation of LEV based on the built-in electric field: carrier transfer mechanism and DFT calculation

Heterojunctions play a crucial role in improving the absorption of visible light and performance of photocatalysts for organic contaminants degradation in water. In this work, a novel type-II–II Ag2CO3/Bi2WO6 (AB) heterojunction was synthesized by hydrothermal reaction and in situ-precipitation methods. The mechanisms of charge transfer and carrier separation at the interface of heterojunctions and the influence on the photocatalytic activity were investigated. The degradation of levofloxacin (LEV) under visible light irradiation was employed to evaluate the photocatalytic performance of AB. The results showed that 85.4% LEV was degraded by AB, which was 1.38 and 1.39 times higher than that of Bi2WO6 and Ag2CO3, respectively. The work functions of the different crystal planes in the AB heterojunction, which was calculated by density functional theory, are a significant difference. The Fermi energy (Ef) of Ag2CO3 (− 6.005 eV) is lower than Bi2WO6 (− 3.659 eV), but the conduction band (CB) is higher. Therefore, using AB heterojunctions as an example, the research explored the mechanism of type-II–II which CB and Ef of one semiconductor cannot simultaneously surpass those of another material, based on the built-in electric field theory. Through this analysis, a deeper understanding of type-II heterojunctions was achieved, and providing valuable insights into the behavior of this specific heterojunction system.

Preparation of Heterogeneous Fenton Catalysts Cu-Doped MnO2 for Enhanced Degradation of Dyes in Wastewater

Herein, a series of heterogeneous Fenton catalysts, Cu doped MnO2 (CDM), with different Cu/Mn molar ratios were prepared via a hydrothermal reaction. Meanwhile, detailed characterizations were used to study the structures of CDM, and it is amazing that the morphology of CDM changed from nanowires to nanoflowers with an increasing amount of Cu doped. Apart from this, both the specific surface area and oxygen vacancy increased obviously with the increasing Cu/Mn molar ratio. Then, the degradation of different dyes was utilized to evaluate the catalytic activity of different CDM with H2O2 used as the oxidizing agent, and the 50%-CDM with the highest content of Cu doped displayed the best catalytic activity. Herein, the degradation efficiency (D%) of Congo red (CR) solution with low concentration (60 mg/L) reached 100% in 3 min, while the D% of CR solution with a high concentration (300 mg/L) reached 99.4% after 5 min with a higher dosage of H2O2. Additionally, the 50%-CDM also displayed excellent reusability, for which the D% values were still higher than 90% after the 14th cycles. Based on the structure characteristics and mechanism analysis, the excellent catalytic capacity of 50%-CDM was due to the combined influence of large specific surface area and abundant oxygen vacancy. Thus, a promising heterogeneous Fenton catalyst was developed in this study, which proved the treatment efficiency of actual dye wastewater.

Hydrothermal Synthesis of SnO2 with Different Morphologies as Sensing Materials for HCHO Detection.

Morphology regulation is an effective strategy for improving the sensor sensitivity of transition metal oxide nanostructures. In this work, SnO2 with three different morphologies (nanorods, nanoparticles, and nanopillars) has been synthesized by a simple one-step solvothermal process with the addition of various solute ratios at 180 °C for 6 h for detecting formaldehyde (HCHO) at the optimum working temperature of 320 °C. Compared to nanorods and nanopillars, the created SnO2 nanoparticles exhibit a much faster response time and sensitivity than other samples, showing the fastest recovery time (18 s) with the highest sensitivity of 6-100 ppm of the HCHO gas. The sensing mechanism of the sensors is investigated by Brunauer-Emmett-Teller (BET) methods and X-ray photoelectron spectroscopy (XPS) analysis, revealing that the pore size distribution and amount of OV and OC improve the charge transfer and HCHO adsorption of nanoparticle sensors. Such an effect of morphology control on sensing performance paves an idea for the development of different structure-based HCHO sensors.

Green and sustainable degradation of ofloxacin in Fe3O4/clinoptilolite electro-Fenton system under neutral condition

BackgroundIn order to overcome the drawbacks of the pH value adjustment and Fe2+addition of traditional electro-Fenton in refractory organic wastewater treatment, we set up an electro-Fence system (FCC-EF) with multiple functions of adsorption, catalysis, and green regeneration for efficient and green degradation of ofloxacin (OFLO) wastewater under neutral condition. MethodsThe Fe3O4/clinoptilolite catalyst with adsorption function was prepared by hydrothermal synthesis method, and then characterized by energy dispersive spectrometer (EDS), transmission electron microscopy (TEM) and X-ray Diffractometer (XRD). The Fe3O4/clinoptilolite's chemical composition and oxidation state was investigated by X-ray photoelectron spectros (XPS). The degradation of OFLO and the total organic carbon (TOC) were determined through HPLC and a TOC analyzer, respectively. FindingsThe results indicate that in multi-cycle operation under current density of 6 mA·cm−2 and pH = 7, FCC-EF has a 100 % removal rate for OFLO and 80.4 ± 0.2 % removal rate for TOC at 165 min, while no iron ions are detected. The internal cycling of Fe3+/Fe2+ within Fe3O4 crystals is performed in FCC-EF. The green regeneration of Fe3O4/clinoptilolite and the efficient degradation of OFLO in multi-cycle operation could be simultaneously achieved under neutral condition.

Calcination-free crystallization of rare earth double tungstate Na(La1 − xEux)(WO4)2 by sacrificial-template hydrothermal reaction, restrained concentration quenching, and optical thermometry

Calcination-free crystallization of rare earth double tungstate Na(La1 − xEux)(WO4)2 by sacrificial-template hydrothermal reaction, restrained concentration quenching, and optical thermometry

Self-assembly of NiFe-LDH@Ni3S2 sub-nanosheets catalyst for overall water splitting

The development of water splitting catalysts for generating high-purity hydrogen in large-scale is still facing challenges in terms of improving efficiency and stability. Herein, Ni3S2-coated NiFe layered double hydroxides sub-nanosheets with a hierarchical heterostructure (NiFe-LDH@Ni3S2) were prepared on nickel foam (NF) by a strategy of continuous hydrothermal synthesis. The introduction of S2− broke the hydrogen bonds between NiFe-LDH layers and separated into sub-nanosheets with a thickness of only about 1 nm, which enlarged the active areas of NiFe-LDH@Ni3S2/NF by a factor of 5.7. The coexisting charge channels Ni-O-Ni and Ni-S-Ni in the material enhanced the electrochemical activity, resulting in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) overpotentials as low as 179 mV and 116 mV at 10 mA cm−2 in 1.0 M KOH. Moreover, after a 50-hour chronopotentiometry test at 50 mA cm−2, the overpotential for OER and HER decreased only 0.013 V and 0.059 V, respectively. Furthermore, under the conditions of simulating industrial hydrogen production with an electrolyte of 6.0 M KOH and a temperature of 75 °C, after a 140-hour test for durability, the current density decreased only 0.75% at the cell voltage of 1.70 V.

Synthesis‐structure‐catalysis relations in CHA zeolites applied for selective catalytic reduction of NOx with ammonia

Microporous aluminosilicate zeolites are useful industrial catalysts. However, their hydrothermal synthesis is a multistep process with complicated and unclear reactions, limiting their rational functional design. Herein, we compare the formation pathway and the structural and catalytic properties of several CHA zeolites to obtain fundamental knowledge for intentionally controlling the catalytic function of zeolites. Three CHA zeolites were synthesized using different starting silica/alumina sources in the presence of tetraethylammonium hydroxide as an inexpensive organic structure‐directing agent. FAU zeolite and an amorphous synthesis gel prepared using two different methods were used as starting materials. The obtained CHA zeolites were applied for exhaust gas purification (selective catalytic reduction of NOx with ammonia, NH3‐SCR), and their structural characteristics and formation pathways were investigated using a combination of analytical methods. Stepwise gel preparation (SGP), which divides the compositional control of the amorphous synthesis gel, promotes the decomposition of the initial additive (zeolite seed), resulting in the formation of CHA zeolites with abundant micropores and paired Al sites. This structural feature obtained using the SGP method improves the catalytic durability of the NH3‐SCR reaction. The present relationship, including different crystallization phenomena, structures, and catalytic abilities, provides useful insights into rational zeolite synthesis and its application.

Tuning the morphology and crystal phase of Ru nanocatalysts for efficient hydrogen evolution

Regulation of crystal phase of Ru nanocatalysts has been identified as an effective approach in regulating the bonding strength of reaction intermediates to Ru and improving the intrinsic activity of Ru-based catalysts during electrocatalytic hydrogen evolution reaction (HER). Here, we reported that the morphology and crystal phase of Ru nanocatalysts could be facilely regulated by halide anions in hydrothermal synthesis. Structural characterization revealed that halogen anions directed the anisotropic growth of hcp Ru, stabilized Ru crystals from aggregation, and increased the abundance of grain boundaries. As a result, The Ru polycrystalline networks exhibited excellent HER activity and durability with a smaller Tafel slope of 21 mV dec−1 and overpotential (η50) of 18 mV. This work sheds light on the shape and phase control of nanocrystals and future design of high-efficient non-Pt electrocatalysts with enhanced HER performance.

Degradation of Levofloxacin by Electroactivated Sodium Persulfate on Carbon Cloth Cathode Modified with Cerium-Based Metal Organic Frameworks (Ce-MOF) Derivatives

Levofloxacin (LFX), which is difficult to degrade effectively due to its molecular stability, has become an problem that needs to be solved urgently. The advanced oxidation technology of persulfate has received increasing attention from researchers. In this study, a Ce-MOF derivative (Ce-MOF-T) was prepared by hydrothermal synthesis and calcination, which synergistically responded to electroactivation to generate sulfate radicals for the efficient degradation of LFX. It has been proven that electrical activation and the Ce-MOF derivatives work together to generate sulfate radicals and effectively degrade LFX. Ce-MOF-550-modified carbon cloth was used as the cathode and a platinum electrode as the anode, the concentration of LFX was 20 mg·L−1, the loading of Ce-MOF-550 was 15 mg, pH = 5, the concentration of sodium persulfate (PMS) was 0.3 g·L−1, the current density was 100 A·m−2, and the degradation rate was 82.05% after 1 h of reaction and 95% after 3 h of reaction. After five cycle tests, the degradation rate was still higher than 75.00%, indicating that the material had good stability. In addition, the degradation of LFX was consistent with a quasi-primary kinetic reaction with apparent rate constants of 2.26 × 10−2 min−1.

High-performance proton exchange membrane employing water-insoluble hybrid formed by chemically bonding phosphotungstic acid with polydopamine

Heteropolyacids can retain water in a proton exchange membrane to increase proton conductivity at high temperatures and low humidity; however, their high solubility in water leads to leaching, which limits their further application. Herein, we used phosphotungstic acid (HPW) and polydopamine (PDA) particles to prepare a water-insoluble PDA/HPW hybrid (PDW) via hydrothermal reaction. The amino groups of PDA in PDW chemically bonded to HPW and acted as an anchor for HPW. The proton conductivity of the sulfonated poly(ether ether ketone) (SPEEK) composite membrane containing 15wt% PDW (SPEEK/PDW-15) in liquid water was 0.052 S⸱cm–1 at 25 ℃, which was 63% higher than that of the SPEEK control membrane (0.032 S⸱cm–1). The SPEEK/PDW-15 composite membrane also showed stable proton conductivity during 80 days of testing while immersed in water.

Hydrothermal synthesis of kesterite CZTSSe nanoparticles for highly efficient thin film

CZTSSe kesterite nanoparticles have been investigated for the efficient. The hydrothermal method has been used to prepare the material. The various characterization like X-ray diffraction (XRD), Raman scattering, Scanning Electron Microscopy (SEM) for (UV–Vis) ultraviolet–visible spectrophotometry and (EDS) energy-dispersive X-ray spectroscopy and of the prepared nano particles have been studied. Furthermore, numerical analysis of the synthesized material has also been investigated to optimize the performance for more characterization at the device level. For the optimization purpose, we have modelled a device structure of the hybrid buffer layer and optimized its physical parameters for the efficient. Theoretical efficiency is found to be 18.46 % for the prepared model. The results of this study show that Cu2ZnSn (S, Se)4 could be used as an absorbent layer for efficient solar cell.

Magnetron Sputtered SnO₂ Layer Combined with NiCo−LDH Nanosheets for High‐Performance All‐Solid‐State Supercapacitors

AbstractNickel‐cobalt layered double hydroxide (NiCo−LDH) has attracted much attention because of its excellent electrochemical properties and regulability. And it is a potential pseudocapacitive electrode material, which is commonly used in supercapacitors and lithium‐ion batteries. Its application in the field of supercapacitors can improve the energy density, power density and cycle life of devices. However, NiCo−LDH still faces some challenges, such as poor electrical conductivity and the capacity attenuation caused by agglomeration of layered structures, which require further research and optimization. In this paper, SnO2 films were prepared on carbon cloth (CC) by magnetron sputtering method, and Ni−Co LDH nanosheets were grown by hydrothermal reaction to obtain NiCo−LDH@SnO2 composites. Due to the synergistic effect between NiCo−LDH and SnO2, NiCo−LDH@SnO2 composites exhibit high Cs and good cyclic stability. In addition, an all‐solid‐state flexible asymmetric supercapacitor (ASC) was assembled with activated carbon (AC) anodes, showing good specific capacitance(Cs) and energy density. And a high initial capacitance can still be retained after 10,000 cycles. This paper shows that NiCo−LDH@SnO2 shows excellent application potential in supercapacitors.

Impact of surfactant groups on the corrosion inhibition properties of superhydrophobic membranes on X80 steel

Fe2O3/Fe3O4 composite films were successfully prepared on the surface of X80 steel through hydrothermal synthesis and annealing treatments. Subsequently, the oxidised films were modified using surfactants such as decanoic acid (DA), decyl silane triol (DS) and perfluorodecyl silane triol (FDS), resulting in the creation of three distinct films exhibiting superhydrophobic properties. The effects of the hydrophilic and hydrophobic groups of surfactants on the superhydrophobic films of X80 steel were analysed using electrochemical methods, surface analysis techniques and theoretical calculations. The results showed that all three superhydrophobic films exhibited excellent corrosion resistance, with the order being DA > FDS > DS after 72 h of immersion in acidic conditions (pH = 6, 60 °C). Theoretical calculations showed that the adsorption performance of carboxyl groups was superior to that of silyl alcohol bonds, whereas fluorination of hydrophobic groups helped to enhance the adsorption capacity of hydrophilic groups. This not only reveals the key role of surfactants in the preparation of superhydrophobic membranes but also provides a theoretical basis for the preparation of superhydrophobic membranes on carbon steel surfaces.