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The efficacy of oxalate–phosphate–amine metal–organic frameworks (OPA-MOFs) as highly efficient slow-release fertilizers in acidic soils is well established. However, a research gap exists concerning the impact of OPA-MOFs on soils with high levels of calcium carbonate. Thus, two distinct types of OPA-MOFs with enhanced specific surface areas were synthesized and utilized in field experiments. A randomized complete block design was employed to evaluate the effect of five different fertilizers on nitrogen (N) and phosphorus (P) contents in wheat at various growth stages cultivated in calcareous soil. The treatments comprised OPA-MOF1, OPA-MOF2, IF1 (urea and triple superphosphate fertilizer), IF2 (ammonium nitrate and triple superphosphate fertilizer), and a control, each with three replications. N and P contents of the wheat plants were assessed at Zadoks growth stages 13 and 40, as well as in the wheat grains. The findings indicated that the highest grain yield was obtained with IF1 (1439.86 kg ha−1), followed by IF2 (1146.83 kg ha−1). In contrast, the OPA-MOF treatments yielded lower grain yields (OPA-MOF1: 1020.64 kg ha−1, OPA-MOF2: 845.06 kg ha−1). Moreover, OPA-MOF1 exhibited a more pronounced effect on the slow release of N and P elements due to its more regular structure, resulting in higher N content during the middle growth stage and a greater grain yield compared to OPA-MOF2.Highlights: The N and P contents were measured at Zadoks growth stages 13, 40, and at the maturity of wheat grains. OPA-MOFs effectively increased nitrogen content in the shoot and grain of wheat. Application of OPA-MOFs can improve yield, biomass, and 1000-seed weight in wheat. OPA-MOF1 showed better performance than OPA-MOF2 in increasing grain P content. OPA-MOFs showed a slower trend in biomass production compared to IF1 and IF2. [ABSTRACT FROM AUTHOR]

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An effective low-cost nano NiO-In2O3 electrode material for oxygen evolution (OER) is presented. Electrochemical studies uncovered electrocatalytic recital in Ascorbic Acid, Hydrogen Peroxide (H2O2), and ethanol. The cubic crystal structure of NiO-In2O3 was revealed by XRD. FT-IR, FE-SEM and HR-TEM studies exploit the structure and morphology of NiO-In2O3. Electrochemistry of NiO-In2O3 uncovered high current density (900mA/cm²) at substantially low overpotential (230mV), realizing its OER recital. On top, high mass activity and turnover frequency by NiO-In2O3 comprehend improved electrical and semiconductive properties in H2O2. The NiO-In2O3 durability beyond 90 hours was estimated by chronopotentiometry (CP). The Impedance analysis (EIS) revealed low charge transfer resistance and high exchange current density. Given electrocatalytic studies, we found a direct relationship between NiO-In2O3 nanocomposite and the degradation of H2O2 compared to its counterparts. Hence, this strategy can be an alternative and potential source of hydrogen and oxygen production at commercial scale. [ABSTRACT FROM AUTHOR]

The addition of 2,5-pyridinedicarboxylic acid (2,5-PDCA) to the Mg-Al LDH coating, which was prepared by one-step hydrothermal synthesis, had extremely enhanced the corrosion protection of AZ31 Mg alloy, although the 2,5-PDCA could not be intercalated into the interlayer spacing. The corrosion current density of 0.05 mol L−1 2,5-PDCA LDH containing LDH coating is 3.18 nA cm−2, reduced by two orders of magnitude compared to the LDH coating without inhibitor, and the corrosion inhibition efficiency of the coating is 98.05%. The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers. The innermost layer is a thick layer that consists of Mg(OH) 2 and the intermediate layer is LDH, which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg. This kind of sediment/LDH/Mg(OH) 2 three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy. [ABSTRACT FROM AUTHOR]

Corrosion products in pressurized water reactors are challenging to study in situ, yet understanding their properties is key to improving reactor performance and radiation reduction. In this study, a hydrothermal synthesis technique was used to produce nickel ferrite (NiFe2O4) particles from goethite (α-FeOOH) and nickel nitrate hexahydrate [Ni(NO3)2 6H2O] in the presence of sodium hydroxide (NaOH). X-ray diffraction was used for phase identification, with scanning electron microscopy used for particle shape and size analysis. By varying the [Ni]:[Fe] ratio of the precursors and synthesis temperature between 100°C to 250°C, a phase diagram was developed to determine the stability field in both composition and temperature for obtaining a single-phase, nonstoichiometric nickel ferrite product. The compositional boundaries of the single-phase region of the diagram are a function of temperature, consistent with the increased solubility and reaction rates at temperatures above 125°C. The single-phase nickel ferrite encompasses [Ni]:[Fe] ratios in a very narrow range at 150°C, only 0.35 to 0.375, but widens as a function of temperature and reaches its greatest breadth at 250°C. At this temperature, a single-phase product is obtained for a range of starting compositions from 0.30 to 0.425. Outside of this window, additional nanoparticles are obtained whose identity and composition vary with both temperature and starting mixture. On the lower nickel content side of the single-phase region, the mixture contains either unreacted goethite (for temperatures below 200°C) or hematite (α-Fe2O3) at 200°C or higher. On the Ni-rich side of the single-phase region, theophrastite [β-Ni (OH)2] was obtained along with the nickel ferrite, at all temperatures studied. The single-phase window was widest at 250°C, resulting in nickel ferrites with a Ni mole fraction between 0.23 and 0.31. [ABSTRACT FROM AUTHOR]

β-BaTi2O5 (β-BT2) nanorods were obtained for the first time by a simple hydrothermal method from a dried gel precursor. The influence of NaOH solution concentration sfrom 0.1 M to 2 M on crystallisation and microstructure was discussed. β-BT2 nanorod with a single-crystal structure exhibited obvious piezoelectric response and piezocatalytic capability for rhodamine B. The degradation of RhB by β-BT2 nanorods under ultrasonic irradiation demonstrated that β-BT2 was a potential piezocatalyst. The proposed strategy can serve as a valuable reference for the synthesis of β-BT2 nanorods and their application in piezocatalysis. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate the sample and low coast hydrothermal synthesis of a nanocomposite of Bi2O3/MoSe2 for hybrid photocatalyst. The structure of as-synthesized samples was characterized by using several techniques, including XRD spectroscopy, Raman spectroscopy, XPS, SEM, BET, and UV-visible absorption spectroscopy. The nitrogen adsorption–desorption measurements show that the samples have a mesoporous texture with slits like pores. The Bi2O3/MoSe2 nanocomposite had BET surface areas of 36.439 m2/g, which were more than those of Bi2O3 (18.342 m2/g) and MoSe2 (12.923 m2/g). Under visible illumination, the photocatalytic activities of pure samples (Bi2O3 and MoSe2) and the hybrid Bi2O3/MoSe2 sample for the disintegration of methylene blue were assessed. The results show that the Bi2O3/MoSe2 sample showed the highest photocatalytic degradation efficiency (i.e. 96.5% after an exposure time of 80 min). The increased photocatalytic activity is due to the mixed sample's high crystallinity and surface area, as well as the small particle size. [ABSTRACT FROM AUTHOR]

The carbon nanotubes attached mesoporous Ag3O4-coated NiO nanosheets were prepared successfully through hydrothermal method. The structural, morphological and electrochemical properties of the prepared nanocomposite have been studied. The X-ray diffraction and Raman analysis confirms the presence of NiO, Ag3O4 and carbon nanotubes in the prepared sample. HRTEM images clearly show the coating of Ag3O4 on the NiO and attachment of carbon nanotubes. BET surface area analysis confirms the mesoporous nature of the prepared composite. The cyclic voltammetric (CV), galvanostatic charge-discharge (GCD) and impedance analysis were made to explore the electrochemical nature of the composite. Cyclic voltammograms reveals the maximum specific capacity of 415.86 mAh g−1 at the scan rate of 3 mV s−1 and GCD analysis exhibits the specific capacity of 416.63 mAh g−1 at 1 A g−1. The prepared nanocomposite retained 97% of maximum capacity even after 1500 cycles. [ABSTRACT FROM AUTHOR]

Lead ions (Pb2+) are heavy metal environmental pollutants that can significantly impact biological health. In this study, the synthesis of a ternary nanocomposite, ErVO 4 /P@g-C 3 N 4 /SnS 2 , was achieved using a combination of hydrothermal synthesis and mechanical grinding. The as-fabricated photoelectrochemical (PEC) sensor was found to be an ideal substrate for Pb2+ detection with high sensitivity and reliability. The ErVO 4 /P@g-C 3 N 4 /SnS 2 /FTO was selected as the substrate because of its remarkable and reliable photocurrent response. The Pb2+ sensor exhibited a low detection limit of 0.1 pM and a broad linear range of 0.002–0.2 nM. Moreover, the sensor exhibited outstanding stability, selectivity, and reproducibility. In real-time applications, it exhibited stable recovery and a low relative standard deviation, ensuring reliable and accurate measurements. The as-prepared PEC sensor was highly stable for the detection of Pb2+ in different water samples. This promising characteristic highlights its significant potential for use in the detection of environmental pollutants. [Display omitted] • ErVO 4 /P@g-C 3 N 4 /SnS 2 was prepared by the sonochemical assisted hydrothermal method. • ErVO 4 /P@g-C 3 N 4 /SnS 2 /FTO was used for the photocatalytic detection of Lead. • A remarkably lower detection limit of 0.1 pM is achieved. • The practical feasibility of the photo driven sensor was evaluated in water samples. [ABSTRACT FROM AUTHOR]

This research introduces a novel approach for developing an improved method for removing thorium ions (Th(IV)), termed as electrosorption, by fusing the principles of electricity and adsorption. The methodology involves utilizing a phosphate – incorporated graphitic carbon nitride (g-C 3 N 4 /P) electrode, synthesized via a hydrothermal – calcination process with urea as a precursor and bis (2-ethylhexyl) phosphoric acid (D2EHPA) as a dopant. Static batch experiments were conducted to explore the influence of various parameters, including voltages, initial Th(IV) concentrations and operational time, on the electrosorption of Th(IV). Characterization analysis including XRD, FT-IR, FESEM-EDS and XPS were conducted to validate the successful integration of phosphate into the g-C 3 N 4 structure. The g-C 3 N 4 /P electrode demonstrated impressive adsorption capacity for Th(IV) electrosorption in an aqueous solution containing an initial concentration of Th(IV) at 100 mg.L−1. It was observed that applying a potential as low as −0.2 V resulted in significantly increase in the Th(IV) removal with 92.23 % (> 300 mg.g−1) within 30 minutes of duration, compared to cases without the electrochemical assistance (65.41 mg.g−1). Through FT-IR and XPS analyses, the adsorption mechanism was clarified as follows: (1) the negatively charged g-C 3 N 4 /P electrode attracted Th(IV) ions through electrostatic interaction; and (2) Th(IV) ions was coordinated with exposed oxygen (O), nitrogen (N) and phosphorus (P) atoms via complexation. In the context of real wastewater scenarios involving rare earth residue, encompassing Ce(III), La(III), Nd(III) and Pr(III) ions, the g-C 3 N 4 /P electrode showcased good capabilities in selectively adsorbing Th(IV). Additionally, the electrode synthesized in this study displayed considerable regenerative capabilities, sustaining a commendable removal ratio of approximately 70 % over five successive cycles. These findings underscore the promising potential of g-C 3 N 4 /P electrode for thorium removal through electrosorption applications. [Display omitted] • The hydrothermal synthesis of phosphate-incorporated g-C 3 N 4 electrode was performed. • Maximum adsorption capacity reached 341.93 mg.g−1 at −0.2 V within 30 min. • Electrosorption encompassed electrostatic attraction and Th(IV) complexation via P, N and O functional groups in C 3 N 4 /P. • C 3 N 4 /P exhibited the highest Th distribution (8487.09 mL.g−1) compared to coexisting ions in an actual residue sample. [ABSTRACT FROM AUTHOR]

Membrane coupling with electrochemical processes has proven to be an effective way for wastewater treatment. However, it still suffering from high energy consumption and low operational stability. Three different forms nanosheet-MoO3 were prepared by hydrothermal synthesis method via adjusting various additives to ammonium heptamolibdate. MoO3 loaded porous Ti membranes was employed as anode to constitute fixed-bed electrocatalytic reactor (FBER) for synthetic dye wastewater treatment to overcome the drawback of three different forms. The electrochemical properties of MoO3/Ti membranes were investigated, results showed that the MoO3/Ti membranes with hexadecyltrimethylammonium bromide (CTAB) additive exhibited the best electrochemical performance. Meanwhile, three MoO3/Ti membranes were used to constitute FBER for 100 mg l−1 MO wastewater treatment, the MO and COD removal rate of MoO3/Ti without additive, MoO3/Ti with CrCl3 additive and MoO3/Ti with CTAB additive were 78.6% and 65.3%, 83.2% and 72.9%, 90.3% and 81.6%, respectively. Furthermore, the energy consumption of MoO3/Ti with CTAB additive was only 0.76 kWh·kg−1·COD. After 3 repeated stabilities experiment of 12 h MO wastewater treatment, the removal rate of MO and COD remained above 97.2% and 88.6%. In sum, the FBER exhibits a great potential in the dye wastewater treatment with high efficiency and excellent stability. [ABSTRACT FROM AUTHOR]

With high theoretical specific capacity and favorable electrochemical properties, CuS is considered to be the ideal cathode material for hybrid Mg-Li ion batteries. However, the traditional CuS cathodes exhibit inferior rate performance and poor cycle stability, which limits the development and application of CuS. In this work, CuS@MoS2 with core–shell structure was prepared by two-step hydrothermal synthesis. When utilized for hybrid Mg-Li batteries, CuS@MoS2 displayes high special capacity and stable cycling performance. At current density of 50, 100 and 300 mAg−1, the first discharge capacity is 337.40, 276.28 and 254.58 mAhg−1 which are all higher than those of single CuS and MoS2. More importantly, the discharge capacity of core–shell CuS@MoS2 can remain 104.70 mAhg−1 at 100 mAg−1 after 50 cycles. These performance improvements are contributed to rich reaction sites and high conductivity of mixed metal sulfides. Furthermore, core–shell structure could relieve the volumetric change and remain structure stability for active materials. In conclusion, core–shell CuS@MoS2 could offer a new strategy for the design of high-performance cathode. [ABSTRACT FROM AUTHOR]

Mesoporous zinc-manganese oxide decorated carbon nanocomposites, as promising low-cost candidates for chromate(VI) sorption, were developed via a one-pot facile route based on battery wastes. The improved-based carbon composite with (ZnMn 2 O 4 +MnO(OH)/Mn 2 O 3 ·H 2 O/C (I-C)) was produced by in-situ hydrothermal growth. Furthermore, the treated composite of carbon with adding ZnSO 4 solution (ZnMn 2 O 4 /C (T-C)). Nanocomposites were characterized comprehensively using FTIR, XRD, HR-TEM, XPS, EDX, and BET analyses. The T-C nanocomposite showed a significant enhancement of chromate sorption by 1.5 fold in comparison with I-C in terms of maximum capacity and equilibrium time. Langmuir and pseudo-second-order fit the experimental data well. The sorption process is spontaneous, endothermic, and governed by entropic. The interaction mode was elucidated via FTIR, XRD, and XPS data, unveiling a synergistic ion-pair sorption and redox mechanism. Elution and sorbent regeneration were successfully achieved using HCl (0.2 M) with high durability over seven cycles. Finally, both nanocomposites, especially T-C, demonstrated exceptional efficiency and selectivity in removing high levels of Cr(VI) from wastewater from tannery industries. [Display omitted] • Two mesoporous ZnMn 2 O 4 /carbon nanocomposites were hydrothermally synthesized from zinc-carbon batteries wastes. • The pure spinal structure of ZnMn 2 O 4 /carbon nanocomposite improves the efficiency by ⁓1.50 time. • The Langmuir capacities are 3.64 and 5.50 mmol/g for I-C and T-C, respectively at pH 0 2.5. • FTIR, XRD and XPS data reveal a synergistic ion-pair sorption and redox mechanism. • Outstanding selectivity for Cr(VI) sorption from industry tanneries effluents. [ABSTRACT FROM AUTHOR]

• Mordenite zeolite is crystallized using bamboo leaves silica ash for the first time. • Three distinct morphologies are observed from parametric crystallization study. • The zeolite morphology affects the hierarchical micro/mesoporosity and surface acidity. • The modernite catalyst is active in acetalization of benzaldehye and glycerol. • 80.2 % of glycerol is converted to dioxolane and dioxane products at 180 °C for 10 min. Bamboo leaves ash (BLA) is a cheap and sustainable silica source but under-utilized. In this work, mordenite zeolites with various morphologies synthesized from BLA are reported. Our strategy involves merely mixing of silicate and aluminate solutions where parametric crystallization study successfully captured three mordenite synthesis recipes. The prepared solids are then characterized with XRD, SEM, XRF, FTIR, TGA/DTG, N 2 sorption and TPD-NH 3 before their catalytic behavior is tested in acetalization. Mordenites with three distinct shapes (nanostick, intergrown bulky ball, nanorod) are successfully synthesized via parametric crystallization study. Some mordenite zeolites contain hierarchical micro/mesoporosity which is beneficial in acetalization of benzaldehye and glycerol. The nanorod-like mordenite is the best catalyst (80.2 ± 2.4 % conversion, 54.4 ± 0.3 % selective towards 2-benzyl-4-hydroxymethyl-1,3-dioxolane) and its catalytic performance is better than those of classical homogeneous and zeolite catalysts with high recyclability. [Display omitted] [ABSTRACT FROM AUTHOR]

The (BiO) 2 CO 3 /BiOCl heterojunction holds promise for photocatalytic purification of antibiotics, which is primarily attributed to the type-II and Z-scheme photocharge separation mechanisms. However, it lacks a report on S-scheme heterojunction for efficiently promoting photocharge separation and retaining powerful redox capability. In this study, a 2D/2D S-scheme (BiO) 2 CO 3 /BiOCl (denoted as (BC/BL) 1) heterojunction was prepared through the hydrothermal synthesis method. The as-synthesized (BC/BL) 1 exhibited a significantly enhanced photocatalytic activity, with a degradation rate of tetracycline hydrochloride (TC-HCl) reaching 95.3% after 60 minutes. Its kinetic constant of photodegradation surpassed that of (BiO) 2 CO 3 and BiOCl by 20.8 and 3.8 times, respectively. A series of characterizations revealed that the improved photocatalytic activity of the (BC/BL) 1 sample stemmed from the formation of a built-in electric field at the intimate interface, which strongly drove the photogenerated carriers to achieve the S-scheme separation. This study highlights the potential application prospects of photocatalyst (BC/BL) 1 in antibiotic degradation. • 2D/2D (BiO) 2 CO 3 /BiOCl heterojunction photocatalysts were achieved. • The (BiO) 2 CO 3 /BiOCl displays a remarkably improved photocatalytic activity. • The enhanced principle for TC-HCl photocatalytic removal was discussed in detail. [ABSTRACT FROM AUTHOR]

Photocatalysis has proven to be a green technology that possesses the synergy between addressing climate change and combating air pollution. Compared with traditional photocatalysts, Cerium oxide (CeO 2) holds distinct advantages such as low-cost, and high affinity for Ce3+/Ce4+ redox pair. This study presents a systematic investigation into the modification of CeO 2 morphologies via optimized one-step hydrothermal synthesis method with low-temperature control. The findings reveal that CeO 2 nanorods exhibited the notable photocatalytic performance, achieving 71.8% NO degradation while generating a mere 4.1% of toxic byproducts. Additionally, the promising CO and CH 4 yields from CO 2 conversion were 4.11 and 3.67 µmol g–1 h–1, respectively. The improvement in photocatalytic activity is attributed to the relationship between the specific surface area and the defects within the CeO 2 nanorods structure. Furthermore, CeO 2 nanorods also emerged as promising candidates for superior and sustainable photocatalytic CO 2 conversion, demonstrating high stability, with only 0.7% and 1.1% reduction in CO and CH 4 yields after four successive photocatalytic cycles. This study underscores the potential of CeO 2 nanorods in advancing green technologies for clean energy and contributes valuable insights to the field of practical zero emissions strategies. [Display omitted] • CeO2 morphologies were synthesized using optimized hydrothermal method. • Influencing factors for CeO2 morphologies were discussed. • Surface area and oxygen vacancies enhanced photocatalytic performance. • CeO 2 nanorods demonstrated highest performance for photocatalysis of NO and CO 2. • Plausible photocatalytic mechanism of CeO2 nanorods for NO and CO2 is presented. [ABSTRACT FROM AUTHOR]

In the present work, we investigated a one-step hydrothermal synthesis of copper bismuthate (CBO) and Sn doped (SCBO). The properties of CBO have been enriched by doping of Sn, which has been inclined to modify screen printed carbon electrode for the electrochemical determination of chloramphenicol (CMP). The dopant Sn with CBO was varied [(SCBO-1), (SCBO-5), (SCBO-10)] with comparison analysis done to choose highly conducting composite. The doping of Sn over CBO is highly a new strategy in detecting CMP which showed improved electrical conductivity with the dopant variation. Among, the different dopant variations, SCBO-5 demonstrated enhanced electrochemical response towards CMP when compared with the other dopant variations. Highly enriched actives sites at SCBO-5/SPCE resulted with a low detection limit of 0.007 µM and a sensitivity about 5.7 µAµM-1cm-2 with linear range of 0.09 µM to 475.73 µM. The decrease in particle size with improved surface area deliberately influenced the detection range and the sensitivity with improved electrochemical performances. The fabricated hybrid material with cost effective materials is highly significant over other high cost preparation materials. The substitution of Sn substantially increases both the electrical conductivity and electro catalytic activity of CBO which is strongly agreed by the electrochemical performance. [ABSTRACT FROM AUTHOR]

Ordered ZnO nanorod arrays were hydrothermally synthesized on a patterned GaN substrate formed by a nanosphere lithography method. Firstly, polystyrene (PS) nanospheres were used to self-assemble a close-packed monolayer on the surface of water. Then the monolayer was transferred onto a GaN substrate. Subsequently, magnetron sputtering of SiO2 was used to reduce the size of PS nanospheres and cover the interstitial space between PS nanospheres by SiO2 at the same time. After removing the PS nanospheres, periodic seed sites were accomplished on the GaN substrate for ZnO growth. Finally, ordered ZnO nanorod arrays, perpendicular to the substrate, were grown on GaN substrates by a hydrothermal method. This work provides a potential low-cost hydrothermal method for the preparation of ordered semiconductor nanorod arrays. [ABSTRACT FROM AUTHOR]

Supercapacitive properties of Co/ZnCo oxide composite with a core-shell nanostructure (Co3O4/ZnCo2O4) prepared directly onto a nickel foam substrate by a two-step hydrothermal method were investigated. The synthesized core-shell structure consisted of some ~40-100 nm in thick flaky ZnCo2O4 deposits coated onto the surface of Co3O4 nanorods measuring ~150 nm in diameter. The specific capacitance value of the Co3O4/ZnCo2O4 core-shell nanostructure synthesized by hydrothermal at 130 °C for a ZnCo2O4 deposition time of 2 h can attain 1804 F g-1 at a scan rate of 5 mV s-1. Furthermore, the core-shell structured electrode still exhibited a relatively good capacitance retention of more than 93% after 3000 CV cycles due to the superior structural support of Co3O4 scaffolds. The Co3O4/ZnCo2O4 core-shell structure exhibits excellent electrochemical performances and, as such, is one of the more promising active materials in pseudocapacitor applications. [ABSTRACT FROM AUTHOR]

Coal Fly ash is an industrial waste produced from coal-based thermal power plants. Of the total amount of fly ash generated, a small fraction is used as a supplement to Portland cement and rest of the fly ash is used as landfill. One of the novel ways of utilizing coal fly ash is through zeolitization, zeolites being hydrated aluminosilicates, and coal fly ash a rich source of alumina and silica. Coal fly ash obtained from the thermal power plant of NTPC Kaniha is subjected to alkaline hydrothermal treatment and the resulted zeolite is characterized for chemical analysis, crystal structure, thermal stability, FTIR studies, ion exchange capacities, etc. After zeolitization surface area of the product increases due to the formation of more pores and channels and also there is an increase in its crystallinity. When subjected to temperature its crystallinity first increases and then decreases and after a particular temperature the crystalline character almost vanishes. The resulted zeolite is found to be NaP1 zeolite with a high ion exchange capacity. High cation exchange (CEC) values ensure the adsorption of heavy metals by zeolites which can be used for the treatment of wastewater and industrial waste material. Thus zeolites can be hydrothermally synthesized from an industrial waste like coal fly ash at a much cheaper cost of production. The synthesized zeolite can be used for cation exchange, adsorption catalysis, and a host of other industrial applications. [ABSTRACT FROM AUTHOR]

• A hydrothermal route to form carbon nanodots (CNDs) from different isomers. • The synthesis was performed using o -, m -, and p -phenylenediamine as precursors. • The effect of solvent type on quantum yield of CND suspensions was investigated. • The solvent polarity significantly influences the fluorescence of CND suspensions. • We provide a promising approach to engineering highly fluorescent CNDs. In this work, we have developed a novel fabrication technique for preparing N-functionalized carbon nanodots (CNDs) through one-pot hydrothermal route using various isomers, exhibiting highly intense fluorescence under blue light illumination. Three types of isomers, o -, m -, and p -phenylenediamine (PD), serving as the carbon and nitrogen sources were employed where the N/C atomic ratio in the CNDs structure was precisely tuned within the range of 20.2–25.7 at.% via tailoring the isomer precursors. The application of the m -PD precursor resulted in implanting the "lattice N" functionalities while the o -PD precursor enabled the formation of N-oxide groups. The CND suspensions in highly-polarity solvents (e.g., water and ethanol) emit intense fluorescence with ultrahigh quantum yield (QY: 85‒99%), whereas the fluorescence from the CND suspensions in propylene glycol methyl ether acetate is significantly quenched. The ultrahigh QY is majorly due to an intense radiative emission mechanism induced by the substitutional N atoms (via high electron-withdrawing) and N- and O-rich edge groups as the major contributors for boosting the affinity to high-polar solvents. Given the widespread applications of quantum dots as high-performance nanomaterials, this study paves the way for engineering N-functionalized CNDs to be used in optical, sensing, energy storage/conversion, and biological devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Selective catalytic oxidation of ammonia (NH 3 -SCO), as the main technology for treating ammonia leaks from diesel engines, converts excess NH 3 into harmless N 2 and H 2 O through catalysts. Catalysts follow different reaction mechanisms during the reaction process, which can be broadly classified into four types according to the reaction pathways and characteristic intermediates. The current research hotspots of ammonia oxidation catalysts are to improve the ammonia oxidation rate in the low temperature region of the catalyst and widen the catalytic temperature window, to improve the N 2 selectivity of the catalyst and reduce the side reaction products, and to improve the catalyst stability, including cycling stability and hydrothermal stability. There are many factors affecting the three catalyst properties, and this paper summarizes the effective strategies to improve the performance of acidity, redox performance, and hydrothermal stability such as modification/doping, selection of support, creation of novel nanostructures and crystal planes, and optimization of preparation methods, so as to expect inspiration for the design and future research of NH 3 -SCO catalysts. [Display omitted] • The review article summarizes four reaction mechanisms for NH 3 -SCO. • The review describes the conditions under which catalysts are applied to diesel vehicle exhausts. • The review article summarizes the factors and strategies that affect catalyst performance. • The review article outlines the challenges in NH 3 -SCO catalyst research and suggests future research directions. [ABSTRACT FROM AUTHOR]

The novel Fe-loaded porous hydrothermal biochars (FeKHCs) were successfully prepared by two-step synthesis of hydrothermal pretreatment and pyrolysis at different temperatures and used to remove tetracycline (TC) from wastewater. The biochar synthesized at 900 °C (FeKHC900) showed the highest specific surface area (SSA) (1487.55 m2/g) and porosity volume (V total) (0.9951 cm3/g), which was significantly affected by hydrothermal pretreatment and K 2 C 2 O 4 activation. K 2 C 2 O 4 favored the micropores formation, which was beneficial to TC adsorption. Thus, FeKHC900 had the largest sorption amount of 606.52 mg/g for TC and outstanding performance for the other three antibiotics. Moreover, Fixed-bed column adsorption experiments proved that FeKHC900 has good dynamic adsorption performance (425.93 mg/g). The slightly reduced sorption amounts in different initial pH, coexisting ions, and humic acid (HA) indicated that FeKHC900 has a high resistance to interference and selective adsorption ability. Batch experiments revealed that TC adsorption was dominated by chemisorption, and the main mechanism referred to π-π interactions, pore-filling, H-bonding, and complexation. This work shares a simple and effective strategy for fabricating magnetic porous hydrothermal biochar as an efficient adsorbent to treat antibiotics. [Display omitted] • Novel FeKHCs was prepared by two-step synthesis of hydrothermal and pyrolysis • K 2 C 2 O 4 favored for the micropores formation of FeKHCs • The Q max of TC sorption onto FeKHC900 was 606.52 mg/g • FeKHC900 presented excellent dynamic adsorption capacity for TC • TC adsorption were dominated by π-π interactions and pore-filling [ABSTRACT FROM AUTHOR]

Considering industrialization and the rising amounts of wastewater, effective water treatment has become a matter of great importance. Adsorption and photocatalysis show superior results compared to conventional water purification methods. Since they are economical and environmentally friendly, many recent studies are focused on developing efficient materials for application in adsorption and photocatalysis. Zeolite is a good sorbent for many metal ions due to its specific porous structure, but it shows low adsorption capacity towards Ni 2+ and Cr3+ ions [1]. In order to improve its adsorption efficiency, zeolite and hydroxyapatite-based composite was synthesized in this study. Hydroxyapatite shows a significantly higher adsorption capacity for Ni 2+ ions compared to natural zeolite. On the other hand, titanium dioxide is a widely used photocatalyst, but it suffers from high recombination rate and possess low efficiency under solar light. These limitations can easily be overcome by coupling TiO2 with a conducting polymer [2]. Among many conducting polymers, one of the most promising is polyaniline (PANI) since it is stable, economical, and easy to synthesize. In this work, TiO2/PANI composites with different amount of PANI (0, 1, 3, 5 wt.%) were synthesized. Zeolite/hydroxyapatite (Zeo/HAp) composite was obtained by the hydrothermal crystallization of calcium hydroxyapatite in the presence of natural zeolite clinoptilolite at 160°C for 4 hours. TiO2/PANI composites were obtained by physical mixing of hydrothermally synthesized TiO2 and PANI, produced using the chemical oxidative polymerization. X-ray powder diffraction (XRPD) analysis was used to determine the phase composition of the obtained composites using an Ital Structure APD2000 diffractometer. Particle size distribution analysis was performed using Mastersizer 2000 (Malvern Panalytical) and Zetasizer Nano S (Malvern Panalytical). The adsorption property of the obtained Zeo/HAp sample was examined towards Ni 2+ and Cr3+ ions. Photocatalytic properties of the prepared TiO2/PANI composites were investigated towards degradation of toxic textile azo dye Reactive Orange 16 (RO16). XRPD analysis showed that the composites were successfully prepared. The diffractogram of Zeo/HAp adsorbent confirmed the presence of clinoptilolite and hydroxyapatite in microcrystalline form. All four photocatalysts crystalized in preserved anatase structure of TiO2 with crystallites less than 50 nm, according to the XRPD analysis. Particle size analysis showed that all the prepared composites were stable in aquatic suspension without further tendency to agglomerate over time. Most of particles had size around 100 μm in the Zeo/HAp composite. Interestingly, it was revealed that the PANI had impact on particle size distribution in TiO2/PANI composites: with an increase in PANI content, the average particle size increased from 213 nm for pure TiO2 to 360 nm for TiO2/5 % PANI. After 24 hours, Zeo/HAp composite adsorbed 42.4 % Ni 2+ ions and 94.8% Cr3+ ions meaning that the adsorption capacity of Zeo/HAp composite is 2.7 times bigger for Ni 2+ ions and 1.8 times bigger for Cr3+ ions compared to natural zeolite clinoptilolite. TiO2/PANI composites demonstrated significantly better adsorption properties during process of photocatalysis comparing to pure TiO2. The best photocatalytic activity was reached by TiO2/1 % PANI which almost completely (99.8 %) degraded the dye after 120 min under simulated solar light. In summary, micro-sized Zeo/HAp and nano-sized TiO2/PANI composites were successfully obtained. Both, Zeo/HAp adsorbent and TiO2/PANI photocatalysts showed better outcomes in water purification compared to the natural zeolite clinoptilolite and the pure TiO2. [ABSTRACT FROM AUTHOR]

Developing an inexpensive non-noble metal catalyst is essential in the electrochemical water reduction. However, to choose the support for hydrogen-producing catalyst is still a problem that needs to be solved. Herein, we report a novel route combining powder metallurgy and hydrothermal synthesis to fabricate Ni/MoS2 catalysts for boosting the hydrogen evolution reaction performance. Powder metallurgy produces the suborbicular pores on the surface and inside Ni once the sintering temperature reaches 1000 °C. The hollow MoS2 nanoparticles are successfully modified on the surface of porous Ni by hydrothermal synthesis. The hollow structure of MoS2 nanoparticles provides more active sites for electrochemical reaction and the porous Ni matrix with the porosity of 16.5% exhibits higher electronic conductivity, which endows the Ni/MoS2-1000 catalyst with an excellent hydrogen evolution reaction activity. The Ni/MoS2-1000 shows a low overpotential of 229 mV at the current densities of 10 mA·cm-2 with a small Tafel slope of 76 mV·dec-1. This study provides guidelines on the large-scale synthesis of nanostructured electrocatalysts with porous Ni as the support. [ABSTRACT FROM AUTHOR]

Cupric oxide (CuO) sphere structures by hydrothermal synthesis are investigated for non-enzymatic glucose sensors. Firstly, different CuO spheres are synthesized on ITO/glass substrates to analyze the catalytic ability to glucose. Copper acetate, copper nitrate trihydrate, and various amount of ammonia water are used to self-assemble CuO spheres. The experimental results indicate that by using precursor of copper nitrate trihydrate and 5 ml ammonia water, CuO spheres have high sensitivity of 2128.44 μAmM−1 cm−2 to glucose. Besides, it has good linear range between 0.5–2.5 mM glucose concentration. The structure has more gaps between each nanoleaf and more reaction sites to react with glucose. Furthermore, the current variation of the working electrode after adding other interferences is negligible. It also has great anti-interference ability. Superior performances of the CuO spheres to glucose can help more accurately and quickly detecting diabetes. [ABSTRACT FROM AUTHOR]

• One-step hydrothermal method of synthesizing of Ag/TiO 2 nanofibers was developed. • Silver incorporation can self-assembly onto the TiO 2 NFs after the optimal calcination, constructing the heterostructure. • Ag/TiO 2 nanofibers possess the enormous potential of photocatalyst used in pollutant removal and hydrogen evolution. Photocatalysis has been regarded as a promising process for pollution removal and green energy. TiO 2 nanofibers synthesized by the hydrothermal method presents high crystalline and performs excellently due to the efficient charge transport. For practical use, we designed an autoclave with a 1,000 cm3 of Teflon-liner inside and stainless steel outside for the hydrothermal synthesis of Ag/TiO 2 NFs. Various parameters of the process, including reaction temperature, doping concentration, and calcination temperature, were investigated to provide a reliable and optimal process. Through the hydrothermal reaction, TiO 2 particles transformed into sodium titanate nanorods, and further refilled the hollow channel. With the proton exchange using diluted hydrochloric acid, the precipitated Ag nanoparticles were leached but appeared again on the surface of Ag/TiO 2 nanofibers after the calcination. Silver incorporation enhanced the absorption in the visible region and precipitated onto the TiO 2 NFs surface after the optimal calcination, constructing the heterostructure. It dominated the photocatalytic performance of pollutant degradation and water splitting. The unveiling of silver surface precipitation gives a clear illustration in the scaled-up hydrothermal method of Ag/TiO 2 , providing an efficient way for nanomaterial fabrication. [Display omitted] [ABSTRACT FROM AUTHOR]

• Composite of MIL-100(Fe)@SBA-15 (1) was synthesized with the hydrothermal method. • Several analyses confirmed the successful synthesis of the composite 1. • Composite 1 showed high surface area in comparison with its component. • Composite 1 showed high adsorption efficiency towards mixed dye solutions. MIL-100(Fe)@SBA-15 (1) was synthesized as a composite material using SBA-15 and precursors of MIL-100(Fe) with the hydrothermal method. The structural characteristics, surface area, and morphology of the synthesized materials were measured by several analyses. The BET surface area increased from 797 m2 g−1 for SBA-15 to 1564 m2 g−1 for composite 1. The synthesized materials, SBA-15, MIL-100(Fe), and composite 1 , were used for removal of methylene blue (MB), rhodamine B (RB), methyl orange (MO), and alizarin yellow R (AY) organic dyes from aqueous solution. Results revealed that composite 1 (25 mg) could adsorb most of the dyes with a maximum adsorption capacity of 38,32,30, and 41 mg g−1 for MB, RhB, MO, and AY solutions (50 mL,50 mg L−1), respectively. Moreover, composite 1 showed ultrafast and high adsorption efficiency to removal mixed cationic and anionic dye solutions. The isotherm, kinetic and thermodynamic studies for adsorption of MB solution with the composite 1 were evaluated and discussed thoroughly. Herein we suggest composite 1 as a novel adsorbent with high commercial potential for wastewater treatment because of easy preparation, good structure stability, and simultaneous adsorption of several dye solutions in a short time. [ABSTRACT FROM AUTHOR]

Image, graphical abstract Zeolites as heterogenous catalysts have continuously attracted researchers' interest due to the potentials for industrial biomass conversion. However, combining hierarchical structure and uniformly dispersed active sites in crystalline zeolites catalysts remains challenging. In this study, in-situ hydrothermal synthesis of Sn-MFI/MCM-41 composites were investigated with hexadecyl trimethylammonium bromide (CTAB) as the structure-directing agent by a stepwise heating. The resulting catalyst was characterized with hexagonal mesochannels, high BET area and crystalline MFI domains. Compared with previously reported tin-containing zeolites, enhanced glucose conversion and fructose selectivity was observed on the resulting Sn-MFI/MCM-41 materials, giving a fructose selectivity of 84%. • Sn-MFI/MCM-41 composites were hydrothermally prepared. • Temperature-gradient strategy was used to introduce MFI domains into mesoporous framework. • Sn-MFI/MCM-41 composites exhibited excellent catalytic performance for glucose isomerization to fructose. [ABSTRACT FROM AUTHOR]

Bone and tooth enamel surface are made up of different crystallographically hydroxyapatite (HA), whereby bone comprises a(b)-planes of HA whilst tooth enamel comprises c-planes of HA. The reason behind the difference between HA orientations in both tissues are still yet to be discovered. We report the fabrication of anisotropic coatings of a-plane oriented HA according to the following process: (i) synthesis of a-plane oriented HA powders via a hydrothermal reaction and (ii) fabrication of a-plane oriented HA coatings via a Drop-on-Demand (DoD) micro-dispensing technique. Two types of HAs with high a-plane orientation degree of 72.2 and 75.6% (HA10 and HA84, respectively) was synthesised for the DoD coatings. The HA84 coating demonstrated more uniform and flatter surface than HA10 coating. The heat treatment of HA10 and HA84 coatings prepared with mesh-sieved particles led to a low adhesion strength for the substrates. However, the orientation degrees of those coatings (96.0 and 94.6%, respectively) were higher than the coatings without mesh-sieving. [ABSTRACT FROM AUTHOR]

This study describes the hydrothermal synthesis of cupric oxide nanoparticles (CuO NPs) using Mint extract agent. A mixture of 0.1 M copper nitrate and a mint extract was hydrothermally treated at a temperature of 180 °C for two hours. Meanwhile, the Mint leaf extract had reduced the copper ions of the nanoparticles after five minutes, resulting in dark-green precipitation. The structural and optical properties of the nanoparticles were studied using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and UV-Vis spectroscopy. The nanoparticles showed a simple cubic structure with a crystallite size range of 22 nm ‒ 25 nm. According to the UV-Vis spectrum, an absorption peak was observed at 346 nm. The antibacterial activity was checked against Escherichia coli (E-coli) and Bacillus subtilis (B-subtilis) cultures by which the inhibition zones were found to be 35 mm and 38 mm, respectively. It is concluded that the CuO NPs have a good ability to resist microbes. [ABSTRACT FROM AUTHOR]

This study describes the hydrothermal synthesis of cupric oxide nanoparticles (CuO NPs) using Mint extract agent. A mixture of 0.1 M copper nitrate and a mint extract was hydrothermally treated at a temperature of 180 °C for two hours. Meanwhile, the Mint leaf extract had reduced the copper ions of the nanoparticles after five minutes, resulting in dark-green precipitation. The structural and optical properties of the nanoparticles were studied using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and UV-Vis spectroscopy. The nanoparticles showed a simple cubic structure with a crystallite size range of 22 nm ‒ 25 nm. According to the UV-Vis spectrum, an absorption peak was observed at 346 nm. The antibacterial activity was checked against Escherichia coli (E-coli) and Bacillus subtilis (B-subtilis) cultures by which the inhibition zones were found to be 35 mm and 38 mm, respectively. It is concluded that the CuO NPs have a good ability to resist microbes. [ABSTRACT FROM AUTHOR]

The development of exceptionally active and stable electrocatalysts for the urea oxidation reaction (UOR) is a current research topic of interest. In this work, NiO/NiCr2O4 nanocomposites with different CrNi ratios (denoted as NiO/NiCr2O4-m, m = 1, 2, 3) were synthesized by a facile one-pot hydrothermal mothed without any template followed by a thermal treatment in N2 at 600 °C. The NiO/NiCr2O4-2 catalyst exhibited a large electrochemical surface area, which provided numerous accessible active sites and electronic transmission channels for the UOR. At a low catalyst loading of 50 μg cm–2, NiO/NiCr2O4-2 electrode delivered a current density of 994 mA cm−2 mg−1 (49.7 mA cm−2 ) in an electrolyte of 1.0 M KOH with 0.33 M urea at the potential of +0.5 V vs Ag/AgCl. The catalyst showed excellent redox characteristics and better stability compared to catalysts with other ratios of NiO/NiCr2O4, pure NiO and NiCr2O4 prepared similarly. Benefiting from the synergistic effect of NiO and NiCr2O4, multicomponent catalysts, particularly NiO/NiCr2O4-2, have demonstrated excellent electrocatalytic activities and are considered as promising candidates for direct urea fuel cells. [ABSTRACT FROM AUTHOR]