Search Results (3,738)

Traditional oxidative dehydrogenation of n-butene has typically required relatively high operating temperatures (400–500 °C), which has driven increasing interest in the development of catalysts capable of delivering high activity at lower temperatures. In this study, zinc ferrite (ZnFe₂O₄-ST) was successfully synthesized via hydrothermal hydrolysis of Zn–Fe oleate and demonstrated remarkable catalytic performance for the oxidative dehydrogenation of n-butene under mild conditions. At 300 °C, ZnFe₂O₄-ST achieved a conversion of 72.9% with 92.1% selectivity toward 1,3-butadiene, a result that, to the best of our knowledge, ranks among the best reported in the literature. By contrast, ZnFe₂O₄ prepared by conventional coprecipitation (17.2% conversion with 91.3% selectivity) and sol-gel (10.1% conversion with 86.4% selectivity) methods showed much lower activities, highlighting the critical influence of synthesis strategy on catalytic performance. To better understand the origin of these differences, a detailed structural and physicochemical characterization was undertaken using X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), N₂ adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H₂-temperature-programmed reduction (H₂-TPR), temperature-programmed re-oxidation (TPRO), and NH₃-temperature-programmed desorption (NH₃-TPD). These analyses revealed that the as-synthesized ZnFe₂O₄-ST possessed a significantly smaller average particle size, a larger specific surface area, and superior reducibility compared with the other samples. These properties are believed to be the key factors underpinning its outstanding catalytic behavior and provide important insights into the design of efficient low-temperature catalysts for selective oxidative dehydrogenation Full article

In this work, hexagonal wurtzite ZnS nanorods (NRs) and cubic sphalerite ZnS quantum dots (QDs) were synthesized via different methods, and then ZnS NRs/rGO and ZnS QDs/rGO nanocomposites were fabricated by a hydrothermal composite strategy. The structural, morphological, optical and photocatalytic properties of the as-prepared samples were systematically characterized by XRD, TEM, HRTEM, XPS, FT-IR, UV-Vis absorption and PL spectroscopy. The photocatalytic performance of all samples was evaluated by the degradation of methylene blue (MB) under ultraviolet (UV) irradiation, and the cyclic stability of the catalysts was also investigated. The results showed that rGO effectively inhibited the agglomeration of ZnS nanostructures, promoted the separation of photogenerated electron–hole pairs and suppressed their recombination. ZnS QDs/rGO exhibited the optimal photocatalytic performance with an MB degradation efficiency of 98.08% and a first-order rate constant of 2.063 × 10⁻² min⁻¹ after 180 min of UV irradiation, which was significantly higher than pristine ZnS NRs (74.49%, 7.58 × 10⁻³ min⁻¹) and ZnS QDs (88.95%, 1.47 × 10⁻² min⁻¹). Moreover, ZnS NRs/rGO showed superior cyclic stability due to the higher crystallinity of ZnS NRs. The enhanced photocatalytic activity and stability of ZnS/rGO nanocomposites were attributed to the synergistic effect between ZnS and rGO, which increased active sites, facilitated charge transfer and inhibited photocorrosion. This study provides a valuable structural design strategy for the development of high-efficiency ZnS-based photocatalysts for organic dye degradation in water treatment. Full article

NiO electrochromic films have significant potential for applications in smart windows, displays, energy-efficient buildings, and portable electronics, owing to their excellent electrochemical stability, favorable optical modulation performance, and environmental friendliness. However, several challenges remain, such as limited long-term durability, stability under extreme environmental conditions, and the cost-effectiveness of large-scale production. Future research efforts should focus on enhancing the cyclic stability and environmental adaptability of NiO films, developing low-cost fabrication techniques, and advancing multifunctional composite materials for smart devices. This review summarizes recent advances in the preparation and performance optimization of NiO electrochromic films. Several key fabrication methods—including magnetron sputtering, hydrothermal synthesis, electrodeposition, chemical bath deposition, sol–gel processing, and spray pyrolysis—are highlighted, and their effects on film structure, thickness uniformity, and optical properties are analyzed. Furthermore, the critical role of different electrolytes (inorganic, organic, and gel-based) in the electrochromic process is discussed, with a comparative evaluation of their influence on the electrochromic performance of NiO films. This article offers a comprehensive overview of the progress in high-performance NiO electrochromic films and provides theoretical insights and technical support for their broader application in renewable energy and smart home technologies. Full article

Methane, a highly hazardous gas mixture when exposed to open flames, is commonly encountered in coal mines. Its primary component is CH₄, making the detection of its concentration, especially under diverse environmental conditions, highly significant. In this study, La_0.7Gd_0.3Fe_0.9Co_0.1O₃ nanomaterials were prepared using an ultrasound-assisted hydrothermal method. Through dual-site synergistic regulation involving Gd doping at the A-site and Co doping at the B-site, rapid detection of CH₄ at low temperatures was achieved. At 150 ${}^{\circ }$C, the sensor demonstrated a significantly enhanced response to 100 ppm CH₄, with a sensitivity of 10.22. This value represents an approximately tenfold improvement over that achieved with pure LaFeO₃. In addition, the sensor responded rapidly to the gas exposure within 6.3 s and recovered within 5.4 s, respectively, at the same gas concentration. Such swift recovery capabilities enable reliable detection across multiple environmental conditions. Moreover, the sensor not only shows excellent repeatability but also maintains a high response value of 9 even under highly humid conditions (95% RH). The performance enhancement is attributed mainly to lattice distortion induced by A-site doping and the increased active sites provided by B-site doping. The development of this sensor lays a foundation for future CH₄ detection and industrial safety applications. Full article

In the present manuscript, the influence of reaction time on the hexagonal-to-monoclinic phase transition in hydroxyapatite (HAp) nanofibers synthesized via a low-temperature modified hydrothermal method at 100 °C is investigated. The resulting nanofibers were highly crystalline and stoichiometric, with a Ca/P ratio of approximately 1.67. Comprehensive structural and functional characterization, combining X-ray diffraction with Rietveld refinement, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), and resonance-tracking piezoresponse force microscopy (RT-PFM), was employed to elucidate the role of the non-centrosymmetric monoclinic P2₁/b phase in governing HAp’s structural and piezoelectric properties. The analyses indicated a time-dependent phase evolution from hexagonal (P6₃/m) to monoclinic (P2₁/b), with exclusive formation of the hexagonal phase at 6 h and a clearly dominant monoclinic fraction (73.56%) after 24 h. Nanofibers synthesized for 48 h comprised approximately 98% monoclinic HAp and exhibited elongated morphologies with an average length of 354.82 nm and diameter of 45 nm. RT-PFM measurements confirmed a pronounced piezoelectric response associated with the monoclinic phase, yielding an effective piezoelectric coefficient (d_eff) of 19.85 pm/V. In vitro MTT assays demonstrated that the high monoclinic content did not compromise biocompatibility, as cell viability and cytotoxicity met the requirements of ISO 10993 and ASTM F895 standards. These findings offer new insights into how monoclinic ordering governs the piezoelectric behavior of HAp and suggest a promising strategy for enhancing its performance in biomedical applications. Full article

This review summarizes scientific advances about the sonochemical synthesis of starch nanoparticles (St-NPs) for the food industry, as well as nutraceutical and drug delivery applications. High-intensity ultrasonication (HIU) has been explored as a versatile and environmentally friendly alternative to conventional methods for synthesizing St-NPs with high yields (>90%), controlled size (~100 nm), and minimal effluent generation. Thus, HIU has been explored (pre- or post-treatment) to mitigate the inherent disadvantages (high-cost, low yields, and environmental impact) of hydrothermal gelatinization, acid/alkaline hydrolysis, enzymatic hydrolysis, enzyme branching, water-in-oil and oil-in-water emulsions, non-solvent nanoprecipitation, extrusion, high-pressure homogenization, high-energy milling, and cold plasma. Conventional sources of starch (corn [normal, waxy, high-amylose] and potato) and other unconventional sources (tubers [cassava, yam, malanga], seeds and grains [sorghum, barley, quinoa, lotus], breadfruit, pinhao seed, Araucaria angustifolia) have been subjected to single or assisted sonochemical protocols to obtain St-NPS with unique structural, physicochemical, and technological properties. The physical–mechanical effects of ultrasonication (cavitation, heat, and pressure) directly promote surface functionalization (i.e., esterification, pore formation) and impact the St-NPS’s particle size, double-helix structure, enzymatic-resistance properties, crystallinity, and intra- and intermolecular arrangements. Pickering additives in food systems, colloids in beverages, nanocomposites in biofilms for food packaging, and nanocarriers for drug and nutraceutical delivery (oral and transdermal) have been the most reported applications. Full article

The development of low-temperature, high-efficiency catalysts for the catalytic elimination of chlorinated volatile organic compounds (CVOCs) remains a significant challenge. Investigating the influence mechanism of catalyst physicochemical properties on chlorobenzene oxidation performance and degradation pathways is particularly important. CuO/WO₃ catalysts were developed using a hydrothermal method in this work. The effects of simultaneous or separate addition of ammonium sulphate and ammonium persulphate on the catalytic performance of the CuO/WO₃ series catalysts were investigated. The results showed that the introduction of ammonium sulphate alone can facilitate the formation of CuWO₄, thereby increasing the chemisorbed oxygen concentration of the CuO/WO₃, and making the overall structure of the catalyst looser and increasing the active sites on the catalyst surface. As the optimal catalyst, CuO/WO₃-2 exhibited 55.9% of chlorobenzene conversion and 32.9% of CO₂ selectivity at 500 °C. Interestingly, although the surface acidity in this work seemed to be one of the reasons for promoting the chlorobenzene oxidation, it could be clearly found that the strong solid acidity of WO₃ was actually a key factor in inhibiting the chlorobenzene oxidation. Finally, based on in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis, the primary mechanism for chlorobenzene oxidation on CuO/WO₃ catalysts proceeds through a sequential conversion: chlorobenzene was first transformed into phenolic intermediates, followed by quinone compounds, maleates, aldehydes, bidentate carbonates, and ultimately carbonate species. Full article

Dichloromethane, as a widely used highly volatile industrial solvent, has neurotoxicity and hepatotoxicity and is suspected of being a carcinogen to humans. Therefore, it is necessary to develop a detection method that is more convenient for users, responds faster and is more efficient than traditional analytical techniques. In cataluminescence (CTL) technology, as a promising alternative, the performance of CTL sensors critically depends on the design of high-performance sensitive materials. In this study, by rationally designing two typical metal–organic frameworks (MOFs), UIO-66 (zirconium-based) and HKUST-1 (copper-based), UIO-66/HKUST-1 nanocomposites for dichloromethane CTL detection were prepared by using a simple hydrothermal method. The experimental results show that when the composition ratio of UIO-66 is 2%, this composite exhibits the strongest CTL response to dichloromethane. Under optimized conditions, this sensor exhibits high selectivity, excellent stability (RSD = 3.98%), and a rapid response advantage for dichloromethane. The response time and recovery time are 5 and 19 s, respectively. It shows a good linear relationship within the concentration range of 8.4–84 ppm, along with a detection limit as low as 1.71 ppm. Analysis indicates that the enhanced performance stems from the formation of high-concentration oxygen vacancies and significantly strengthened synergistic effects at the UIO-66/HKUST-1 composite. This increases the concentration of surface reactive oxygen species, thereby providing more active sites for catalytic reactions. This work provides a robust and efficient sensing strategy for dichloromethane detection. Full article

Lithium manganese iron phosphate [LiMn_xFe_1−xPO₄ (x ≤ 0.5)]-based cathode materials were synthesized via a hydrothermal method to investigate their composition effect on structure and electrochemical performance. The X-ray diffraction results confirmed a single-phase olivine structure (Pnma) for all the compositions, with minor lithium phosphate (Li₃PO₄) impurities detected at high manganese (Mn) contents (x ≥ 0.4). The morphological evolution from small particles with low Mn content to compact rod-like particles at x = 0.3 indicates optimized crystal growth and improved interparticle connectivity. Electrochemical testing revealed that the discharge capacity initially increased with the substituted Mn content to a maximum of 140 mAh g⁻¹ at 0.5 C for LiMn_0.3Fe_0.7PO₄/C with remarkable cycling stability. This high capacity is attributed to the activation of Fe²⁺/Fe³⁺ and Mn²⁺/Mn³⁺ redox couples and the minimal formation of electrochemically inactive phases. Further Mn incorporation (x > 0.3) caused structural distortion, Li₃PO₄ formation, and overall capacity loss. Codoping with Mg (LiMg_0.05Mn_xFe_1−xPO₄) improved stability but lowered discharge capacity owing to the electrochemical inactivity of Mg²⁺ and impurity formation. Notably, an optimal x value of ~0.3 exhibited an effective balance between high energy density, rate capability, and structural integrity in Mn-doped LiFePO₄ cathodes for next-generation lithium-ion batteries. Full article

We report the facile synthesis of hierarchical spiked cobalt selenide (Co_0.85Se) microcrystals grown on nickel foam (NF) via a hydrothermal method followed by selenization. Derived from cobalt hydroxyl fluoride (Co(OH)F) microcrystals, the resulting Co_0.85Se structures exhibit a robust architecture with well-defined spikes that offer abundant active sites and promote efficient charge transfer, thereby enhancing their electrocatalytic bifunctional activity toward the oxygen evolution reaction (OER) and urea oxidation reaction (UOR). The Co_0.85Se/NF electrode delivers low overpotentials of 357 mV for OER and 236 mV for UOR at 100 mA cm⁻². Furthermore, it exhibits a small Tafel slope (34.3 mV dec⁻¹) and excellent durability for 24 h at 100 mA cm⁻² during UOR. This simple and cost-effective strategy highlights the potential of hierarchical spiked Co_0.85Se microcrystals as highly efficient electrocatalysts for urea-assisted OER and related sustainable energy conversion applications. Full article

Groundwater recharge by faults is often ignored in current hydrothermal potential assessment approaches. This omission may cause a significant discrepancy between the estimated potential and the actual potential in areas adjacent to faults. To address this gap, this study proposes a novel approach for assessing hydrothermal potential that incorporates the influence of faults. This approach was applied to investigate the hydrothermal potential in the main urban area of Yichang, China. The data obtained from the traditional methods and the novel approach were evaluated through comparison with field pumping test data. The findings indicate that the estimates from both methods generally align with the actual potential in most areas. However, significant discrepancies emerge between the estimated and actual potential in zones proximate to faults. Specifically, the traditional method yielded an estimate 60–75% lower than the field measurements. In contrast, the novel approach reduced this deviation by 20%, demonstrating its superior accuracy in fault zones. This study demonstrates the superior performance of the proposed approach over traditional methods for characterizing the heterogeneous distribution of hydrothermal resources in fault-developed zones. Full article

With increasing worldwide attention to green and sustainable energy, thermal infrared remote sensing technology has gained significant popularity for detecting geothermal anomalies, as it can overcome the limitations of traditional ground surveys. This study explores the potential application of thermal infrared images in geothermal exploration within the Datong Basin. We mainly utilized Landsat-8 images to obtain the actual land surface temperature (LST), hydrothermal alteration, and linear structures of the Datong Basin. Radiative transfer equation algorithm (RTE), principal component analysis (PCA), and interactive interpretation method were applied in this study. The results show that LST retrieval through the RTE method accurately reveals geothermal anomalies in the Datong Basin. Five areas with distinct high-LST values were identified as geothermal anomaly zones based on field investigation, including Xiejiatun, Gushancun, Taipingpu, Shuitongsi, and Wenjiayao–Yuanjialiang. Effective estimation of hydrothermal alteration zones (dominated by clays, OH⁻/H₂O, and carbonates) in the basin was achieved using the PCA method and band combinations. In total, 394 linear structures were obtained through interactive interpretation, including 45 concealed structures. All of these linear structures were associated with deep-seated faults. The basin’s primary controlling structures are the Yunmen Mountain piedmont fault (F1-1) and the northern margin of Xiong’er Mountain faults (F1-2 and F1-3), with F1-1 and F1-3 playing a key role in regional thermal regulation. The high-LST premium geothermal target zones of Shuitongsi and Gushancun were identified based on remote sensing interpretations and geothermal geological conditions. Furthermore, strong consistency was verified between the remote sensing predictions and four deep drilling temperature field measurements. This study confirms that remote sensing is an effective approach for geothermal potential identification, providing a scientific basis for future sustainable resource exploration in other regions. Full article

This study reports the precise synthesis of red-emitting gold–silver bimetallic nanoclusters (Au-AgNCs) via a one-pot hydrothermal method using thiolactic acid as both the ligand and reducing agent. The Au-AgNCs possess an average diameter of 1.85 nm and exhibit strong fluorescence emission at 687 nm. Furthermore, they display notable assembly-induced emission enhancement (AIEE) properties. Upon assembly with bovine serum albumin (BSA), their fluorescence quantum yield significantly increases from 2.50% to 7.78%. Then Au-AgNCs@BSA assembly was employed as a ratiometric fluorescence sensor for the detection of chlortetracycline (CTC). In the presence of CTC, the original red emission of the assembly at 687 nm remained stable, while a new blue emission emerged at 420 nm and intensified progressively with CTC concentration. The ratio of the two emission intensities (I₄₂₀/I₆₈₇) exhibited an excellent linear correlation with CTC concentration over the range of 0.10 to 15 μM, with a limit of detection (LOD) of 20 nM. Notably, the sensor demonstrated exceptional selectivity for CTC, showing negligible response to common interfering substances such as metal ions, anions, amino acids, and crucially, other tetracycline antibiotics (tetracycline, oxytetracycline, and doxycycline). The practical applicability of the sensor was validated through the determination of spiked CTC in real water samples, achieving satisfactory recovery rates. In conclusion, this work accomplishes two key objectives: the development of novel AIEE-active Au-Ag bimetallic nanoclusters and the design of an efficient ratiometric sensing strategy. This approach enables the highly selective and sensitive detection of CTC, offering a promising tool for environmental monitoring. Full article

CeO₂ particles were synthesized via a hydrothermal method to investigate the influence
of precursor molarity and reaction time on their structural, optical, and adsorption characteristics. Ce(NO₃)₃·6H₂O served as the cerium source, while PVP and Triton X-100
acted as surfactants to regulate nucleation and particle growth. XRD and Raman analyses
confirmed the formation of single-phase cubic fluorite CeO₂, whereas FTIR spectra verified
the presence of Ce–O bonding. SEM observations revealed that a decreasing precursor
molarity led to smaller and more uniform particles, while prolonged reaction times enhanced crystallinity. UV–Vis DRS and XPS analyses indicated that both the band gap
(3.06–3.12 eV) and the Ce³⁺/Ce⁴⁺ ratio were governed by oxygen vacancies, demonstrating defect-mediated redox behavior. Adsorption studies using methyl orange (MO) dye followed pseudo-second-order kinetics (R² > 0.99), indicating chemisorption as the dominant mechanism. The CP1-8 sample exhibited the highest dye removal efficiency (87%) under acidic conditions (pH < pHPZC). These findings demonstrate that controlled hydrothermal synthesis enables precise tuning of CeO₂ morphology, defect density, and surface chemistry, yielding efficient adsorbent materials for environmental remediation applications. Full article

Monitoring the hydrochemistry of groundwater and the H-O isotopes in the Jingpo Lake volcanic area, China, is fundamental to studying the mechanisms of volcanic and seismic events, as well as the associated hazards. To study the hydrogeochemistry of fluids in the Jingpo Lake volcanic area, water samples from seven sites were tested for hydrogeochemistry, H-O isotopes, and radon (Rn) content. The genesis and evolution of the groundwater system were elucidated through an integrated approach employing Gibbs diagrams, ionic ratio analyses, reservoir temperature estimation (silica–enthalpy method), and inverse geochemical modeling with PHREEQC. The results showed that the dominant water chemistry type was HCO₃⁻, primarily influenced by volcanic rock weathering and deep hydrothermal activity. Spring and well water were influenced by cation exchange, adsorption, and rock weathering dissolution. The H-O isotope composition and radon content indicate that atmospheric precipitation is the main source of supply, while well water is influenced by deep fluids. According to the Na-K-Mg triangle diagram, most of the groundwater was shallow and immature, whereas the well water was partially balanced. The temperature of the geothermal water was controlled by the geothermal gradient, depending on its occurrence and circulation depth. Additionally, the equilibrium temperature of the thermal reservoir was calculated using the silica–enthalpy equation method, with the concentrations of dissolved components in the water taken into account. The temperature of the thermal reservoir of the well water and the depth of groundwater circulation were estimated. The original reservoir temperature in the study area was calculated to range from 108 °C to 156 °C, with a geothermal water-to-shallow groundwater mixing ratio of between 71% and 85%. The estimated shallow temperature ranged from 64.9 °C to 74.9 °C. These hydrogeochemical signatures reflect active water–rock interactions and the contribution of deep-seated geothermal fluids, providing robust evidence for ongoing geothermal activity in the Jingpo Lake volcanic system. The findings enhance our understanding of the recent geological evolution and present-day hydrothermal processes of this potentially active volcanic field, which establishes a crucial hydrogeochemical baseline for future monitoring and hazard assessment studies. Full article