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Metal–organic frameworks (MOFs), as porous materials, have great potential for exploring high-performance electrochemiluminescence (ECL) probes. However, the constrained applicability of MOFs in the realm of ECL biosensing is primarily attributed to their inadequate water stability, which consequently impairs the overall ECL efficiency. Herein, we developed a competitive ECL biosensor based on a novel tightest structural ruthenium-based organic framework emitter combining the proximity hybridization-induced catalytic hairpin assembly (CHA) strategy and the quenching effect between the Ru-MOF and ferrocene for detecting paraquat (PQ). Through a simple hydrothermal synthesis strategy, ruthenium and 2,2ʹ-bipyrimidine (bpm) are head-to-head self-assembled to obtain a novel tightest structural Ru-MOF. Due to the metal–ligand charge-transfer (MLCT) effect between ruthenium and the bpm ligand and the connectivity between the internal chromophore units, the Ru-MOF exhibits strong ECL emissions. Meanwhile, the coordination-driven Ru-MOF utilizes strong metal–organic coordination bonds as building blocks, which effectively solves the problem of serious leakage of chromophores caused by water solubility. The sensitive analysis of PQ is realized in the range of 1 pg/mL to 1 ng/mL with a detection limit of 0.352 pg/mL. The tightest structural Ru-MOF driven by the coordination of ruthenium and bridging ligands (2,2ʹ-bipyrimidine, bpm) provides new horizons for exploring high-performance MOF-based ECL probes for quantitative analysis of biomarkers. [ABSTRACT FROM AUTHOR]

Herein, an aromatic ring aldehyde (salicylaldehyde, SL) was grafted onto the biopolymer matrix of the magnetic chitosan (CS/Fe3O4) to yield a recoverable promising adsorbent for the removal of acid red 88 (AR88 dye) from aqueous media. Various characterization methods such as VSM, pHpzc, CHNS, XRD, SEM–EDX, FTIR, and BET were used to determine the physicochemical properties of CS-SL/Fe3O4. A Box-Behnken design (BBD) was adopted to optimize the experimental parameters of A: CS-SL/Fe3O4 dose (0.02–0.1 g), B: [AR88] concentration (10–50 mg/L), C: pH (4–10), and D: contact time (10–90 min) on the adsorption performance of CS-SL/Fe3O4 with the AR88 dye. The Freundlich isotherm and pseudo-second-order kinetic models were applicable to describe the dye adsorption rate of AR888. The maximum dye adsorption capacity (qmax) of the hydrothermally grafted CS-SL/Fe3O4 with AR88 was 137.3 mg/g at a fixed adsorbent dosage (0.09 g) and pH (4.16). Various intermolecular interactions such as electrostatic, π-π stacking, n-π interactions, and H-bonding contribute to AR88 adsorption by CS-SL/Fe3O4. This study introduces a recoverable and a promising magnetic grafted chitosan adsorbent for the removal of an anionic dye from aqueous media. Moreover, this adsorbent can be further applied to the removal of other types of water contaminants in aquatic environmental media. [ABSTRACT FROM AUTHOR]

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In this work, La-doped In2O3 microflowers were successfully prepared by a one-step hydrothermal method. Doping La into the In2O3 lattice causes lattice distortion of In2O3, leading to the change of morphology from cubic to nanosheets. The gas sensing tests show that La doping significantly improves the sensing performance to n-butanol compared to the pristine In2O3. 5% La-In2O3 exhibits the highest sensing response (~ 61.34 to 100 ppm n-butanol) among the various doping amounts of La, which is six times higher than that of the pristine In2O3 (~ 10.12) at the optimal operating temperature of 320 °C. This sample also show short response and recovery times, high selectivity and long-term stability. The enhanced sensing performance is mainly attributed to (1) the tunned bandgap by doping La, which effectively improves the electron transfer ability and produces a thicker electron depletion layer, and (2) the unique morphology and abundant lattice defects of the La-In2O3 samples, providing increased adsorption and reactive sites. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) stands out as an eco-friendly, cost-effective method for generating renewable carbon-based materials from biomass. The HTC process yields products such as hydrochars and carbon dots (CDs), possessed of notable photocatalytic capabilities due to their unique physicochemical features. Additionally, pairing traditional photocatalysts with hydrochar derivatives elevates their performance, rendering them more effective. Recent times have witnessed a surge in interest in these hydrochar based photocatalysts (HC-photocatalysts). Their appeal stems from multiple attributes: impeccable performance, adaptability to visible light, and adjustable physicochemical properties. This review delves deep into the evolving landscape of these HC-photocatalysts, segmenting them into three distinct categories: hydrochars, hydrochar-based CDs (HC-CDs), and hydrochar-based composites (HC-composites). For each category, we dissect their synthesis routes, unravel the photocatalytic mechanisms, and explore various enhancement strategies. We further traverse their versatile applications, spanning environmental treatment, disinfection, energy conversion, and organic synthesis. In the end, we spotlight the prevailing challenges and uncharted territories in the domain of HC-photocatalysts. In essence, this review serves as a guide, furnishing a theoretical foundation and steering directions for future explorations and tangible implementations of HC-photocatalysts. Highlights: Biomass can be converted into highly efficient photocatalysts by HTC. Photocatalytic mechanisms and modifications of hydrochars and HC-CDs are discussed. The roles of carbons in HC-composite photocatalysts are reviewed. HC-photocatalysts have shown various environmental, energy and other applications. Prospects and guidelines for theoretical and application research are listed. [ABSTRACT FROM AUTHOR]

Asphodelus-based CQDs were successfully synthesized in a single step by the hydrothermal synthesis method for detection of β-carotene. TEM, XRD, FTIR, XPS, Zeta potential, UV–Vis absorption and fluorescence measurements were taken to structurally and optically characterize the newly synthesized CQDs. It was determined that the characterized CQDs show high selectivity and sensitivity only to β-carotene among 11 different biomolecules. The detection limit of CQDs for β-carotene was calculated as 8.28 µM. It was determined that the new CQDs respond very quickly and stably without interfering with any other biomolecules. The studies in different pH environments exhibited that CQDs can detect β-carotene at all pH studied. Real sample experiments show that β-carotene can be determined accurately and reliably in practical applications with the novel CQDs. It was thought that the results obtained from this study will make significant contributions to the studies on β-carotene detection, which are limited in the literature. [ABSTRACT FROM AUTHOR]

Cerium oxide, CeO2 nanoparticles (NPs) have been synthesized through various methods to achieve the desired physicochemical properties. However, high temperatures, pressure and long reaction time were involved. In this study, ultra-small CeO2 NPs were successfully synthesized using the hydrothermal method but under a favourably low temperature (70 ℃) for 4 hours using cerium nitrate hexahydrate, Ce(NO3)3 • 6 H2O and sodium hydroxide, NaOH as the precursors while deionized water was used as the solvent. The synthesized ultra-small CeO2 NPs were characterized using field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), ultraviolet visible (UV-Vis) spectrometer, Fourier transform infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) method. The synthesized ultra-small CeO2 NPs were determined to have an average particle size of 3.54 nm, crystallite size of 3.05 nm and a high specific surface area of 185 m2 g-1. UV-Vis spectrum also showed absorption peak at 310 nm and FTIR spectrum intense peak at 447.20 cm-1 indicating the presence of CeO2 NPs. FTIR, EDX and XRD diffraction pattern have proved that the synthesized CeO2 NPs is of high purity. This study has successfully synthesized ultra-small CeO2 NPs with optimal conditions of hydrothermal treatment at 70℃ for 4 hours and a percent yield of ~99%. [ABSTRACT FROM AUTHOR]

A hydrothermal method which can convert free cesium ions into stable pollucite at low temperatures was established in this work, avoiding any evaporation pollution during the disposal of cesium containing waste. Meanwhile, rapid synthesis under hydrothermal conditions was achieved using seed guidance, which shorten the growth time of pollucite crystals to 8 h, and making the treatment and disposal of cesium containing wastewater faster. Standard leaching test results show that the leaching rate of Cs was very low (< 3.5 × 10−7 g·m2·d), it still has good thermal stability at a temperature of 1300 °C, when the cesium content in pollucite reaches 20%. [ABSTRACT FROM AUTHOR]

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]

Aqueous zinc-ion batteries (AZIBs) and supercapacitors (SCs) have wide application prospects in the field of energy storage device due to high-safety, low cost, and environmental friendliness. However, their large-scale application is hampered by the lack of suitable electrode materials. In this work, the smooth CuBi2O4 nanosheets with thickness of about 4–5.5 nm have been prepared by a simple one-step hydrothermal method, and are reported as electrode materials of these two types of devices. Encouragingly, the as-prepared CuBi2O4 nanosheets exhibit fast electronic/ion diffusion, good reversibility and high pseudo-capacitance for AZIBs and SCs. For the AZIBs, CuBi2O4 nanosheets endows high capacity of 186 mAh g−1 after a long-term stability of 800 cycles, Zn storage mechanism is also discussed. For the SCs, it delivers 666.7 F g−1 at 10 A g−1, with 95.8 pct capacitance retention after 7000 cycles. The result suggests a prospect use as electrode material for advanced AZIBs and SCs. [ABSTRACT FROM AUTHOR]

A sample of a catalytic system based on nickel and a carbon-containing material, microcellulose, was obtained using a hydrothermal synthesis method. A catalytic study of the synthesized system in the process of selective hydrogenation of carbon monoxide and carbon dioxide was carried out with calculation of the apparent activation energy. The sample was demonstrated to be highly active in the selective hydrogenation reactions of carbon oxides. A 100% conversion of carbon monoxide and carbon dioxide and selectivity for methane of 90 and 80%, respectively, were obtained. [ABSTRACT FROM AUTHOR]

In this study, we fabricated an efficient and low-cost carbon-doped titania (C–TiO2) counter electrode (CE) as a substitute for platinum (Pt) in dye-sensitized solar cells (DSSCs). By varying different weight ratios, C–TiO2 samples were synthesized through the hydrothermal synthesis method followed by calcination in a tube furnace. The doctor blade coating method was used to deposit thin films of the synthesized samples onto the fluorine-doped tin oxide (FTO) substrates. Structural and morphological properties were studied by using various analytical techniques. Moreover, the electrochemical and photo-conversion characteristics of the fabricated CEs were investigated. Cyclic voltammetry (CV) results of the fabricated CEs showed electrocatalytic activity comparable to the Pt in the DSSCs. Meanwhile, photovoltaic measurement results showed the best-performing 15% C–TiO2 CE having 1.56% power conversion efficiency (PCE) as compared to Pt, which is 2.12%. This study proposed a simple method to fabricate a low-cost and efficient C–TiO2 CE for DSSCs. [ABSTRACT FROM AUTHOR]

Organic pollutants such as dyes and pharmaceutical drugs have become a significant environmental problem due to their unrestricted discharge, especially in water bodies. As a result, an economically viable and environmentally friendly approach to their degradation in water bodies is required and the incorporation of metal tungstate with single metal oxide has attracted attention due to its potential ability towards the photocatalytic degradation of pollutants. The work demonstrates a WO3/g-C3N4/V2O5 nanocomposite synthesized using a facile route wet impregnation method. The results revealed that WO3/g-C3N4/V2O5 nanocomposites are suitable, mainly for their better surface properties, enhanced visible-light absorption, and preferred band positions. Besides that, the degradation of methylene blue (MB) dye is carried out and demonstrated that the complete degradation occurs over 120 min using 10 mg L−1 of WO3/g-C3N4/V2O5 nanocomposite under UV–visible-light irradiation. The scavenger experimental result implies that the photogenerated free electrons and superoxide radials are important role in MB dye degradation. In addition, a possible mechanism is proposed for the photocatalytic activity of WO3/g-C3N4/V2O5 nanocomposite. Moreover, the stability analysis demonstrated that the WO3/g-C3N4/V2O5 nanocomposite can be recycled multiple times. [ABSTRACT FROM AUTHOR]

Resource saving and creation of environmentally safe environment are the guidelines of modern world policy in the field of waste management. This paper considers a possible method of utilization of a by-product of aluminum fluoride production—silica gel—as an alternative high-silica raw material for hydrothermal synthesis of LTA-type zeolites. To obtain synthetic zeolites, industrial silica gel was subjected to sulfuric acid purification and used to obtain one of the hydrogel components—sodium silicate. As a result of investigation of the influence of hydrogel molar composition on the phase composition of the obtained samples, the optimal molar ratios of SiO2:Al2O3, Na2O:Al2O3 and H2O:SiO2 were identified. The phase composition of the obtained samples and morphological pattern were evaluated using X-ray diffraction and scanning electron microscopy techniques. According to the obtained results, the use of hydrogel of composition 1.8SiO2:Al2O3:4Na2O:28H2O allows to obtain a monophase of LTA type zeolite with high ion exchange capacity, the particles of which have a regular cubic shape with the size of the main fraction up to 10 μm. [ABSTRACT FROM AUTHOR]

MoS2 nanosheets consist of multiple S-Mo-S trilayers with large interlayer spacing, which could allow facile Li-ion insertion/extraction. However, MoS2 nanosheets are easily curled and randomly stacked due to high surface energy of 2D nanosheets, which hinders fast ion transportation. In addition, intrinsic electronic conductivity of MoS2 is limited. Therefore, enhancements of both ionic and electronic conductivity of MoS2 are greatly demanded for its application in Li-ion batteries. Here, we report a cost-effective and facile hydrothermal synthesis of 3D nanoflower-like MoS2/C anode materials, which avoids random stacking of nanosheets and improves the electronic conductivity of MoS2. The nanoflower-like MoS2/C exhibits large reversible specific capacity (724 mAh g−1) and high initial coulombic efficiency (79.82%). Moreover, excellent capacity retention (97.98%) after 500-cycle charge/discharge has been achieved at 1 A g−1. [ABSTRACT FROM AUTHOR]

In this work we have narrowed the band gap of orthorhombic sodium tantalate by doping the perovskite structure with 5 and 10% of iron. The hydrothermal method was used in the preparation of the samples. Moreover, the evolution of hydrogen by photocatalytic water splitting is reported for first time for orthorhombic NaTaO3 mono-doped with Fe. The band gap was reduced from 4.08 to 3.24 eV for sodium tantalate doped with 5% of Fe, and up to 2.05 eV for the perovskite doped with 10% of Fe. The highest photocatalytic activity was obtained with the semiconductor that had 5% of Fe. Which was attributable to its smaller particle size, larger specific surface area and lower recombination of electron–hole pairs in contrast with the sample that had 10% of Fe. X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, nitrogen physisorption, ultraviolet–visible diffuse reflectance and photoluminescence spectroscopies were used to analyze the perovskite materials. [ABSTRACT FROM AUTHOR]

The present work was designed to synthesize Ag2O-supported MgO/rGO nanocomposites (NCs) via green method using Phoenix leaf extract for improved photocatalytic and anticancer activity. Green synthesized Ag2O-supported MgO/rGO NCs were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman, ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) spectroscopy, and gas chromatography–mass spectroscopy (GC–MS) was applied to examine the chemical components of the Phoenix leaf extract. Characterization data confirmed the preparation of MgO NPs, Ag2O-MgO NCs, and Ag2O-MgO/rGO NC with particle size of 26–28 nm. UV–vis study exhibited that the band gap energy of MgO NPs, Ag2O-MgO NCs, and Ag2O-MgO/rGO NC were in the range of 3.53–3.43 eV. The photocatalytic results showed that the photodegradation of Rh B dye of Ag2O-supported MgO/rGO NCs (82.81%) was significantly higher than pure MgO NPs. Additionally, the biological response demonstrates that the Ag2O-supported MgO/rGO NCs induced high cytotoxicity against MCF-7 cancer cells for 24 h and 48 h compared with both pure MgO NPs and Ag2O-MgO NCs. This study suggests that the adding of Ag2O and rGO sheets played significant role in the enhanced photocatalytic and anticancer performance of MgO NPs. [ABSTRACT FROM AUTHOR]

Recent development and expansion in electrochemical water splitting processes have driven the research community to explore an efficient, economical and eco-friendly electrocatalyst. Within this domain, the electrocatalytic oxygen evolution reaction (OER) presents a notable challenge due to its inherent inefficiency arising from a sluggish four-electron transfer process. In the present study, we investigated a hydrothermal technique for synthesizing an electrocatalyst featuring MnO-embedded CoFe2O4 spinel oxide, which is firmly anchored onto a nickel foam (NF) substrate. The electrocatalyst demonstrated impressive performance, exhibiting exceptional stability over an 82-h endurance test. A significantly smaller overpotential was required for OER, achieving a notable decrease of 179 mV. Furthermore, it displayed a Tafel value of approximately 68 mV dec−1 at current density of 10 mA cm−2 for OER, underscoring its exceptional electrocatalytic performance. In light of these compelling findings, the current research has introduced a feasible, environmentally friendly, and potentially high-impact strategy towards the development of cost-effective transition metal-based catalysts, highly suitable for use as electrodes in electrochemical water splitting applications. [ABSTRACT FROM AUTHOR]

In this study, the 2-step hydrothermal synthesis of pure phase analcime zeolite from the combination of glass powder waste and aluminium anodizing waste was carried out, to contribute to the reduction of disposal of these industrial residues in sanitary landfills. Population growth has intensified industrial activities worldwide, increasing the generation of waste with a high potential for environmental impact. Currently, the reuse of solid wastes has become an alternative for the development of materials with greater added value. Placket Burman statistical design was used to identify the variables of greater statistical relevance in the synthesis process, aiming at future optimization. Crystallization time and temperature were verified as the most relevant variables in the synthesis, while calcination time and calcination temperature in the alkaline fusion step were the variables with less relevance. The results revealed the formation of single-phase analcime, reaching a crystallinity of up to 75% and a specific surface area of 43.3 m2.g−1. Scanning electron microscopy analysis showed the presence of particles with trapezoidal morphology, typical of analcime zeolite. Zeta potential measurement revealed an isoelectric point in pH 2.6, an important parameter in case of application in wastewater treatment. The investigated experimental conditions also enabled the formation of other zeolites, e.g., Na-P1, cancrinite, and sodalite, demonstrating that the combination of glass powder waste and aluminium anodizing waste can be used to obtain different zeolitic phases. Consequently, products with greater added value can be obtained, contributing to sustainability in the aluminium and glass industries. [ABSTRACT FROM AUTHOR]

Pure and Co (10 mol %)-doped α-Fe2O3 (Hematite) nanostructures have been effectively synthesized by hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) have been used for the analysis of crystallography, morphology and functional groups of synthesized samples. The banding nature of synthesized samples is analyzed by Fourier transform infrared spectroscopy (FTIR). Powder XRD results reveal the formation of rhombohedral structured α-Fe2O3 nanostructures. Effect of dopant and synthesis conditions, such as precursor change and time duration of heating temperature has been investigated on the morphology of pure and Co (10 mol %)-doped α-Fe2O3 nanostructures. It has been observed that the addition of dopant, change of precursor and time duration of the heating temperature of hydrothermal treatment can effectively control the morphology of NPs. Methylene dye (MB) has been used as a test contaminant in aqueous solution to determine the photo-catalytic potential of Fe2O3 nanostructures under visible light. [ABSTRACT FROM AUTHOR]

Cerium vanadate/modified bentonite (CeVO4/mbt) nanocomposite with different composition percentages was synthesized through a simple one-step hydrothermal method at 180 ℃, and then its photocatalytic activity was evaluated by decolorizing methylene blue (MB) in an aqueous solution under light exposure. In order to increase the surface area as an important parameter in photocatalytic processes, bentonite was modified by ball mill method. The structural and optical properties of the synthesized composites were determined by XRD, FT-IR, DRS, FESEM, EDS, and BET measurements. XRD and EDS results confirmed the successful synthesis of pure CeVO4. FESEM images and EDS mapping showed a proper distribution of rice-like CeVO4 nanoparticles on bentonite. The removal efficiency of MB with only 0.1 g of CeVO4/mbt nanocomposite in 15 min was about 99%, which is significant compared to neat bentonite and pure CeVO4 with efficiency of 30% and 57%. The mentioned nanocomposite followed the first-order kinetics, had a reaction rate constant equal to 0.1483 min–1, and showed acceptable stability in five consecutive cycles. [ABSTRACT FROM AUTHOR]

The investigation of electrode materials for urea level determination (non-enzymatic) is advantageous to monitor patient's clinical health and prevention of milk adulteration. Chalcogenides have prospective applications in electrocatalysis because of their fast charge transfer and large specific surface area in terms of non-enzymatic sensing via redox reactions, which is of great significance. However, despite their tremendous relevance, they continue to present significant problems. To address this issue, a new parkerite-type compound, Ni3Bi2Se2, was synthesized using the capping agent sodium laurel sulfate through a hydrothermal process. The physical characterization of the ternary chalcogenide Ni3Bi2Se2 was done by X-ray photoelectron spectroscopy, scanning electron microscopy, powder X-ray diffraction, and photoluminescence. The analytical performances of the suggested sensor electrode, including sensitivity, the limit of detection (LOD), limit of quantification (LOQ), stability, and durability, were obtained by various electrochemical techniques. The lower limit of detection (LOD-6.05 µM), sensitivity (10.9 mA µM−1 cm−2) and lower limit of quantification (LOQ-18.35 µM) were derived using the calibration curve. Moreover, it provides accurate results when detecting urea in human urine samples. The prepared electrode shows outstanding sensitivity, selectivity, superior reproducibility, and long-term stability. [ABSTRACT FROM AUTHOR]

Increasing world population, urbanization, and industrialization have led to an increase in demand in production and consumption, resulting in an increase in industrial solid wastes and pollutant levels in water. These two main consequences have become global problems. The high Si and Al content of solid wastes suggests that they can be used as raw materials for the synthesis of zeolites. In this context, when the literature studies conducted to obtain synthetic zeolites are evaluated, it is seen that hydrothermal synthesis method is generally used. In order to improve the performance of the hydrothermal synthesis method in terms of energy cost, synthesis time, and even product quality, additional methods such as alkaline fusion, ultrasonic effect, and microwave support have been developed. The zeolites synthesized by different techniques exhibit superior properties such as high surface area and well-defined pore sizes, thermal stability, high cation exchange capacity, high regeneration ability, and catalytic activity. Due to these specific properties, zeolites are recognized as one of the most effective methods for the removal of pollutants. The toxic properties of heavy metals and dyes in water and their carcinogenic effects in long-term exposure pose a serious risk to living organisms. Therefore, they should be treated at specified levels before discharge to the environment. In this review study, processes including different methods developed for the production of zeolites from industrial solid wastes were evaluated. Studies using synthetic zeolites for the removal of high levels of health and environmental risks such as heavy metals and dyes are reviewed. In addition, EPMA, SEM, EDX, FTIR, BET, AFM, and 29Si and 27Al NMR techniques, which are characterization methods of synthetic zeolites, are presented and the cation exchange capacity, thermodynamics of adsorption, effect of temperature, and pH are investigated. It is expected that energy consumption can be reduced by large-scale applications of alternative techniques developed for zeolite synthesis and their introduction into the industry. It is envisaged that zeolites synthesized by utilizing wastes will be effective in obtaining a green technology. The use of synthesized zeolites in a wide variety of applications, especially in environmental problems, holds great promise. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) have versatile applications in luminescence, whereas identifying optimal synthesis conditions has been challenging due to numerous synthesis parameters and multiple desired outcomes, creating an enormous search space. In this study, we present a novel multi-objective optimization strategy utilizing a machine learning (ML) algorithm to intelligently guide the hydrothermal synthesis of CQDs. Our closed-loop approach learns from limited and sparse data, greatly reducing the research cycle and surpassing traditional trial-and-error methods. Moreover, it also reveals the intricate links between synthesis parameters and target properties and unifies the objective function to optimize multiple desired properties like full-color photoluminescence (PL) wavelength and high PL quantum yields (PLQY). With only 63 experiments, we achieve the synthesis of full-color fluorescent CQDs with high PLQY exceeding 60% across all colors. Our study represents a significant advancement in ML-guided CQDs synthesis, setting the stage for developing new materials with multiple desired properties. Optimizing the synthesis for efficient luminescent materials requires consideration of a large number of parameters. Here, the authors realize high quantum yield full-color carbon quantum dot using an iterative machine-learning experimental strategy. [ABSTRACT FROM AUTHOR]

The paper discusses experimental results concerning the probable inheritance of the secondary structure of the polypeptide chain of wool keratin used as a biotemplate by titanium dioxide through topochemical reaction and crystal nucleation during crystallization under hydrothermal conditions. Sheep wool fibers were impregnated with a solution containing titanium hydroxocomplexes. Samples of native wool, wool-TiO2 hybrid material, and TiO2 crystalline powders were characterized using X-ray diffraction, IR spectroscopy, thermal analysis (DSC and TG), and scanning electron microscopy. X-ray studies revealed that diffuse halos characteristic of the secondary structure of wool (containing α-spiral and β-folded keratin configurations) at 2θ = 8.7° and 19.6° are preserved both for hydrothermally impregnated wool and after annealing at 600°C and 800°C, albeit with a shift towards smaller angles of 2θ = 6.3° and 13.2°. This suggests stretching of keratin fibers during hydrothermal impregnation and preservation of crystallinity domains of the secondary structure in annealed samples, representing a mixture of well-crystallized phases of anatase and rutile. The interpretation of this effect is based on the assumption that TiO2 crystallization centers are located along the turns of the α-helix or folds of the β-structure, replicating these structures in a certain spatial arrangement. Nucleation is attributed to the interaction of monomeric forms of titanium hydroxocomplexes with carbonyl and carboxyl groups of the polypeptide chain, followed by growth of anatase and rutile crystallites via olation/oxolation reactions under hydrothermal conditions. [ABSTRACT FROM AUTHOR]

Two new cadmium(II) complexes [Cd0.5(HL)(bpa)0.5(H2O)]n·0.5nbpa and [Cd2(HL)2(L)(bpe)2]n·nH2L [H2L = 3-hydroxyisonicotinic acid, bpa = 1,2-bi(4-pyridyl)ethane, bpe = 1,2-bi(4-pyridyl)ethene] were synthesized by the reaction of a H2L and auxiliary N-containing ligands with Cd(II) ions under hydrothermal conditions. Obtained complexes were studied by elemental analysis, IR spectroscopy, powder XRD and X-ray crystallography. The thermal stability and luminescent properties of two complexes were investigated. [ABSTRACT FROM AUTHOR]

A nanocomposite of Ce-doped ZnO/r-GO was synthesized using a conventional hydrothermal method. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of cyclobenzaprine hydrochloride (CBP). The properties of the composite were extensively analyzed, including its morphology, structure, and electrochemical behavior. This study investigates the application of a modified glassy carbon electrode for the detection of CBP, a muscle relaxant used to treat musculoskeletal diseases that cause muscle spasms. The electrode is modified with Ce-doped ZnO/r-GO. Various detection methods, such as cyclic voltammetric and square wave techniques (SWV), were utilized. The composite material showed high effectiveness as an electron transfer mediator in the oxidation of CBP. The electrode showed a good response for SWV evaluations in CBP identification, with a minimum detection limit of 1.6 × 10−8 M and a wide linear range from 10 × 10−6 M to 0.6 × 10−7 M, under ideal conditions. The rate constant for charge transfer (ks) and the estimation of the electrochemical active surface area were obtained. A developed sensor exhibited desirable selectivity, long-lasting stability, and remarkable reproducibility. A sensor was used to analyze water, human serum, and urine samples, resulting in positive recovery results. [ABSTRACT FROM AUTHOR]

Synthesis of nitrogen-doped carbon dots (N-CDs) using urea and ascorbic acid as carbon sources is addressed in this study using a microwave-assisted hydrothermal technique. The samples were characterized by ultraviolet, photoluminescence (PL) and transmission electron microscopy analyses, which confirmed the formation of CDs. Besides PL properties, the peroxidase-like catalytic activity of the CDs and N-CDs was also compared. Interestingly, the N-CDs exhibit higher peroxidase-like catalytic activity than pure CDs and can be used to detect H2O2. Additionally, we synthesized several N-CD ratios and evaluated their peroxidase-like catalytic activity. [ABSTRACT FROM AUTHOR]

The development of renewable woods for power generation can help improve the energy efficiency of buildings, and promote the concept design and implementation of "smart buildings". Here, with specific chemical treatment and hydrothermal synthesis, we demonstrated the practical value of natural wood for thermoelectric power generation in smart buildings. The prepared wood-based thermoelectric sponges show high Seebeck coefficients of 320.5 and 436.6 µV/K in the vertical and parallel directions of the longitudinal channel of wood. After 500 cycles of the compressive strain at 20%, the corresponding Seebeck coefficients increase up to 413.4 and 502.1 µV/K, respectively, which is attributed to the improved contact and connection between tellurium thermoelectric nanowires. The Seebeck coefficients are much larger than those of most reported inorganic thermoelectric materials. Meanwhile, the thermoelectric sponges maintain excellent thermoelectric and mechanical stability. We further modeled the application value of wood-based thermoelectric sponges in smart buildings for power generation. Relatively high thermoelectric electricity can be obtained, such as in Beijing with over 1.5 million kWh every year, demonstrating the great potential in thermal energy harvest and energy supply. [ABSTRACT FROM AUTHOR]

Microgravity offers an enticing synthetic knob for materials scientists to explore—however, this environment creates major challenges in hardware development that can turn a simple 3-day experiment into a 3-year long nightmare. This paper provides an overview of engineering an autoclave, compatible with NASA's Solidification Using a Baffle in Sealed Ampoules (SUBSA) furnace, to enable microgravity hydrothermal synthesis—an acceleration-sensitive technique that processes aqueous samples above the boiling point of water. Hydrothermal synthesis is a universal chemical transformation technique that is used to produce a range of advanced materials with applications in alternative energy, healthcare, and the food industry. In this work, we use the synthesis of graphene hydrogel as a case study to verify our hardware design on Earth before launching to the International Space Station for microgravity testing. The design addresses pertinent challenges which include enabling thermal expansion while preventing air bubble formation in solution and implementing a pressure fail-safe above the maximum operating temperature. Our goal in presenting this autoclave design is to provide a step forward towards commercial-of-the-shelf microgravity hardware. [ABSTRACT FROM AUTHOR]

A hydrothermal synthesis method was developed to produce high crystallinity ZSM-5 zeolite using coal gasification coarse slag (CGCS) as the raw material. Instead of the expensive NaOH(s.), Na2SiO3(s.) was utilized to activate, depolymerize, and recombine Si and Al elements in the CGCS. The mother liquor circulation technology was employed to recover and reuse raw materials and residual reagents (Na2SiO3(aq.) and TPABr), reducing waste emissions and enhancing resource utilization efficiency. The synthesized ZSM-5 had a specific surface area of 455.675 m2 g−1, pore volume of 0.284 cm3 g−1, and pore diameter of 2.496 nm. The influence of various factors on the morphology and crystallinity of ZSM-5 was investigated, resulting in the production of ZSM-5 with higher specific surface area and pore volume. Adsorption experiments showed that WU-ZSM-5 exhibited a removal efficiency of 85% for ammonia nitrogen (NH4+-N(aq.)), validating its effectiveness in coal chemical wastewater purification. The mother liquor recycling technology enabled zero-emission utilization of solid waste resources and improved the utilization rate of alkali and template to 90%. These results demonstrate the potential application of the developed method in the efficient treatment of coal chemical wastewater. [ABSTRACT FROM AUTHOR]

In this study, we report on the electrochemical properties of hydrothermally synthesized MoS2 composites for use in lithium-ion batteries. A widespread method was modified for facile synthesis of pristine MoS2 and its composites with PEDOT:PSS, rGO, or both. The electrochemical performance of the materials was investigated using cyclic voltammetry and galvanostatic charge-discharge measurements. The addition of rGO significantly enhances the specific capacity and stability of MoS2, with the MoS2/rGO composite exhibiting specific capacity in the second cycle of 748 mA·h·g−1 and a capacity retention of 63% through the 400th cycle. The composites exhibited a phenomenon of capacity increase after reaching a minimum, with this effect being most pronounced in the case of MoS2/rGO. This composite reached its lower capacity value at the 143rd cycle (211 mA·h·g−1), and then recovered to 224% of the minimum capacity (472 mA·h·g−1). We attribute this behavior to an increase in the availability of active particles over the course of cycling by milling the active components into smaller and thus more accessible species of Li2S and S. The intensity of the effect of rGO is due to its intrinsically large surface area and two-dimensional layered structure, which enhances the distribution of redox-active particles within the material layers and prevents agglomeration. Our results contribute to the existing evidence of the improved electrochemical performance of MoS2 in Li-ion batteries with layered graphitic compounds and provide promising avenues for further research of the unique behavior of conversion materials. [ABSTRACT FROM AUTHOR]

Design of experiments is a powerful planning technique that optimizes processes and reduces experimental variability. This research aims to optimize the hydrothermal synthesis of TiO2 nanotubes with a high specific surface area (SSA). A 22 factorial design was applied to investigate the influence of temperature and time on nanotube formation, achieving SSA above 350 m2 g−1. A Doehlert design combining SSA with morphology reveals closely related responses and a defined maximum surface. Microscopy shows that nanotube formation is favored at lower temperatures and longer treatment times, with the optimal condition at 120 °C for 36 h. Higher temperatures yield cauliflower-like nanostructures and provide insight into how synthesis conditions affect the morphology and nanoparticle properties. XRD and Raman spectroscopy analysis revealed that, although the anatase phase played a vital role in nanotube formation, the materials exhibited a combination of crystalline phases, including the discovery of an unidentified phase. [ABSTRACT FROM AUTHOR]

Simple hydrothermal method can be applied for synthesizing rod shape Gd2O3:Eu3+ phosphors. X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy are used for the characterizations of samples. Increase of Eu3+ concentration in Gd2O3:Eu3+ can cause red shift in the charge transfer band (CTB) of Eu – O. The nature of Eu3+ surroundings is asymmetric. It is ascertained from PL emission studies. The calculation of second order crystal field parameter from PL spectra corroborates the asymmetric environment of Eu3+. PL emission and decay lifetime studies confirm the existence of quenching due cross-relaxation. The quantum yield for Y2O3:Eu3+ (19 at.%) under 265 nm excitation is found to be 7%. [ABSTRACT FROM AUTHOR]

Usage of cost effective synthesis methods are inevitable due to increasing economic conditions worldwide. In this study, zinc oxide nano-structures were synthesized by low cost chemical methods. Outcomes of X-ray diffraction analysis revealed dominating plane was c-axis for ZnO seed layer and nano-rods deposited by sol–gel spin coating and chemical bath deposition method (CBD), respectively. However, a-axis plane dominance was observed for ZnO nano-rods prepared by hydrothermal method. Scanning electron microscopy offered the surface morphology of granular structure and well aligned compact ZnO nano-rods by sol–gel and CBD, respectively. Conversely, randomly oriented ZnO nano-rods were found by hydrothermal method. Presence of zinc and oxygen in the samples was confirmed by EDS results. Optical band gap of 3.29 eV, 3.25 eV and 3.21 eV were obtained by sol–gel, CBD and hydrothermal method, respectively. Likewise, photoluminescence results were also analyzed for all the samples. The super-hydrophobic state with water contact angle (WCA) of 150° was observed for ZnO nano-rods by CBD. However, hydrophilic and hydrophobic state was detected for ZnO seed layer and nano-rods with WCA of 70° and 118°, respectively. The super-hydrophilic state was also noticed after the induction of Ultra-Violet (UV) light. The WCA reduction rate of the values 0.067 and 0.17 were estimated for ZnO nano-rods. Furthermore, CA recovery time was also measured. The UV sensing photo-response was evaluated among seed layer and nano-rods, and better result was produced by ZnO nano-rods by CBD. [ABSTRACT FROM AUTHOR]

The present study utilized zinc-tin nanoflowers (ZT-NFs) in a batch adsorption treatment process to effectively remove cadmium from synthetic wastewater. The batch adsorption strategy was optimized using the univariate approach to enhance the efficiency of the adsorption process. The dominant parameters examined in the optimization experiments were pH/volume of buffer solution, nanoflower amount, and sample agitation type/period. After determining the optimal batch adsorption conditions, equilibrium studies were performed by adding cadmium to synthetic wastewater at concentrations in the range of 1.0 – 40 mg/L. The quantification accuracy for cadmium was improved by developing the calibration plot with spiked sample matrix. The equilibrium data were subjected to mathematical modelling utilizing the Langmuir adsorption isotherm model. The calculated isotherm constants indicated a well-fitted isotherm model to the experimental data. The reported ZT-NFs-based adsorptive removal strategy was effectively employed to remove cadmium from synthetic wastewater. [ABSTRACT FROM AUTHOR]

Utilizing Aloe vera gel (AVG) extracts as reducing agents, the hydrothermal synthesis of dual-functional iron oxide nanoparticles (Fe2O3 NPs) offers a straightforward and environmentally friendly approach. AVG extract, rich in polyphenol complexes and antimicrobial compounds, serves both as a reducing agent for ferric chloride in aqueous solutions and as a stabilizing agent for the resulting nanoparticles. This method showcases the potential of natural plant biomolecules in nanoparticle synthesis. UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), vibrating sample magnetometry (VSM) and energy dispersive X-ray spectroscopy (EDX) were used to characterise the Aloe vera gel –Fe2O3 nanoparticles (AVGF NPs). The pattern on the XRD indicated the production of crystalline material, which matched JCPDS card no. 89–0596 precisely. Nondestructive XRD analysis indicated a rhombohedral phase crystalline structure, whereas scanning electron microscopy revealed a spherical form. Surface morphology images exhibited that the NPs have sphere-shaped with a size in the range 10–40 nm and magnetic measurements is a high saturation magnetization value of 73.9 emu were synthesised. Bragg's reflection speaks indicated that the rhombohedral phase structure of AVGF NPs. The thermal stability and functional groups analysis results indicated that the presence of the AVG on the Fe2O3 surface. Moreover, the AVGF NPs had different coloring reflectance on the solution to confirm by absorption spectra. These findings suggest that the formation of AVGF NPs in producing great stable, fluorescence lifetime (26.21 ns), more lasting magnetic characteristics ideal for a variety scenarios primarily effective antimicrobial properties against Gram-positive bacteria and potential conversion of hazardous Cr6+ to less harmful Cr3+ and promising AVGF catalyst efficacy for methylene blue discoloration. [ABSTRACT FROM AUTHOR]

Giant Nb deposits hosted by alkaline igneous rocks worldwide are characterized by hydrothermal and/or metamorphic modifications after magmatic crystallization. However, the impact of secondary processes on Nb mineralization in alkaline igneous rocks remains controversial. In this study, U–Pb ages, elemental, and Nd isotope compositions of titanite from a series of Nb-rich dyke swarms in the Ziyang region of South Qinling (China) have been investigated to unveil Nb remobilization and enrichment histories during magmatic and hydrothermal processes. Three types of titanite are documented: magmatic, deuteric, and hydrothermal. The magmatic titanite (Ttn I) grains are euhedral wedge-shaped, while the deuteric type (Ttn II) occurs as coronas on magmatic ilmenite. The hydrothermal titanite (Ttn III) occurs as either bead-like clusters within the cleavage planes of chloritized biotite or as anhedral grains (lesser than 200 μm in diameter) coexisting with hydrothermal actinolite, chlorite, fluorite, and/or REE-rich oxides. The magmatic titanite grains from the most primitive igneous rocks have U–Pb ages of 455 ± 25 Ma and are characterized by high levels of Nb2O5 (up to 1.4 wt%) and other high field strength elements (HFSE, up to 1.3 wt% ZrO2), rare earth elements (REE), and V, and high mean crystallization temperatures (880 ± 40 °C), suggesting that they nucleated and crystallized in a high-T and Nb-rich alkaline magma during the Early Paleozoic. The gradual decrease in V, Sr, and Ba in Ttn I from mafic to intermediate dykes exemplifies the role of fractionation on magmatic enrichment of Nb (mean of 170 ppm and 7300 ppm for Ttn I in mafic and intermediate dykes, respectively) and other incompatible elements (e.g., Ta, Zr, Hf, Sn, Y, and REE) in the residual melt. The deuteric and hydrothermal types of titanites in each lithology have lower concentrations of HFSE (e.g., Nb mean of 140 ppm and 860 ppm for Ttn II in mafic and intermediate dykes, respectively), Sn, LREE, and Y but higher Al, F, V, Sr, and HREE contents than their magmatic counterpart. The deuteric and hydrothermal types of titanite have U–Pb ages of 420 ± 25 Ma and 232 ± 49 Ma, respectively, supporting two distinct hydrothermal events at Ziyang. The magmatic and deuteric types of titanite have similar ranges of εNd(t) values (+ 1.4 to + 3.5 and + 2 to + 4.2, respectively), indicative of a common source for these two generations. The hydrothermal titanite also has comparable εNd(t) values (+ 0.8 to + 2.7) to the magmatic and deuteric types, indicating a minimal external contribution to Nd (and by analogy Nb as well) from the late hydrothermal fluids. The deuteric and late hydrothermal F-rich fluids in Ziyang dyke swarms both remobilized the dispersed Nb in magmatic ilmenite, amphibole, and biotite to form secondary titanite (Ttn II, III), which is beneficial to the metallurgical extraction of this critical metal. Therefore, both magmatic fractional crystallization and hydrothermal remobilization contributed to Nb mineralization. [ABSTRACT FROM AUTHOR]

The present work involves the design and validation of an electrochemical sensor for precise and selective sensing of nicotinamide adenine dinucleotide (NADH). The designed electrochemical sensor consists of TCNQ and Pd-Co@NC nanocomposite–modified electrodes (TCNQ-Pd-Co@NC/CPE). The designed electrode was validated by cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy (EIS). The results revealed potent electrocatalytic activity towards NADH oxidation and sensing. Cyclic voltammetry revealed the superior capability of TCNQ-Pd-Co@NC-based carbon paste electrode in electron transfer than TCNQ-Co@NC/CPE and TCNQ/CPE, validating better conductivity of TCNQ-Pd-Co@NC/CPE for NADH sensing. Amperometry study provided a wide linear range of 10 to 250 µM for NADH detection with a low detection limit (LOD) of 5.17 µM and a sensitivity of 21.5 µA mM. EIS study revealed the lowest Rct value of 12.5 × 102 for TCNQ-Pd-Co@NC/CPE compared to TCNQ-Co@NC/CPE and TCNQ/CPE, demonstrating high electron transfer capability and thus sensitivity towards NADH. Besides this, the modified TCNQ-Pd-Co@NC-based carbon paste electrodes offered exceptional selectivity, reproducibility, and stability over time. Therefore, designed TCNQ-Pd-Co@NC nanocomposite–based carbon paste electrodes can be efficiently used for precise and selective NADH sensing. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSCs) have gained recognition as a promising indoor photovoltaic technology, drawing considerable attention for their ability to convert light into electricity. In this study, we present a straightforward one-step hydrothermal synthesis method for producing cobalt sulfide nanoparticles decorated with reduced graphene oxide (CoS2/RGO) nanocomposites, serving as an efficient counter electrode (CE) material for DSSCs. The CoS2/RGO nanocomposites exhibited a chain-like structure formed by RGO nanosheet-decorated spherical particles interconnected with CoS2. Demonstrating excellent electrocatalytic activity with a low Epp (peak-to-peak separation) value, the CoS2/RGO nanocomposites outperformed pristine CoS2 nanoparticles. Moreover, the power conversion efficiency of the CoS2/RGO hybrid structure-based CE surpassed that of the pristine CoS2 nanoparticles. These findings suggest that the facile synthesis of CoS2/RGO nanocomposites holds great promise as an electrode material for effective CEs in DSSC applications. [ABSTRACT FROM AUTHOR]

Zeolite has good physicochemical properties such as adsorption, cation exchange, molecular sieving and catalysis to be widely used as selective scavengers of heavy metals from liquid effluents. In this paper, the synthesis method of 13X zeolite using fine granite dust (FGD) resulting from granite processing has been investigated. Both alkaline fusion method (770–830 °C, 80 min) and hydrothermal process (95–100 °C, 8–12 h) were selected and applied to the synthesize of 13X zeolite. A major disadvantage of synthesis of zeolite by using alkaline fusion method is high sintering temperature. The sintering temperature was lowered from 1300 to 800 °C by putting FGD into water and maintaining for 5 min to remove crystalline quartz which has low reactivity. On the other hand, it is important to find rational sintering temperature at which albite is decomposed more easily than kalifeldspar in FGD because 13X zeolite is chemically concerned with sodium (Na). For this, reaction heats of kalifeldspar and albite were calculated at the temperature range of 770–830 °C. As a result, it was proved that albite has the possibility to be dissolved thermodynamically more easily than kalifeldspar, but the difference between the heat effects of albite and kalifeldspar is not altered too much in proportion to the increase of temperature. Eventually, 13X zeolite has been successfully synthesized from FGD with low energy and all the other stone processing waste can be recycled by this method. [ABSTRACT FROM AUTHOR]

Improving the electrochemical performance of electrode materials via structural design is critical in developing energy storage technologies. In this investigation, a nanoarray electrode composed of Co–Ni layered double hydroxide (Ni–Co LDH) nanosheets and Ni2SnO4 nanosheets (Ni2SnO4 NSs) stabilized on Ni foam (NF) is developed utilizing an in-situ growth method to its electrochemical properties in supercapacitors can be evaluated. The Ni2SnO4 was created in the first stage using a light hydrothermal reaction as the core. The Ni–Co LDH was then hydrothermally immobilized using the electrode, which had been made as a skeleton. The structural and textural study of the material was described using energy dispersive X-ray analysis (XRD), Fourier transforms infrared (FT–IR), field-emission scanning electron microscopy, and transmission electron microscopy. When the developed Ni–Co LDH/Ni2SnO4/NF electrode is compared to the Ni2SnO4/NF electrode, the electrochemical result shows a specific capacitance of up to 3,924 F g−1 at 1 A g−1 in a 2 mol L−1 KOH electrolyte, as well as a capacitance retention of 95% after 3000 cycles. Unsymmetrical supercapacitors made of Ni–Co LDH/Ni2SnO4/NF and activated carbon demonstrated exceptional electrochemical properties, including high rate capability, high energy, and power density (91.03 Wh kg−1 and 9.0 kW kg−1, respectively), and long cycle life. Due to its unique core/shell structural system, which facilitates ion diffusion and offers a fast electron transport kinetic model and good strain lodging, the rising pseudocapacitive behaviors render it an intriguing candidate for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Hydrothermally reduced chemical method synthesis of rGO-TiO2 nanocomposites (NCs) with varied concentrations of graphene oxide (GO) from 1 to 5 wt% was investigated for its morphological, structural, chemical bonding, structural defects, optical and electrochemical properties. Formation of rGO-TiO2 NCs was confirmed from SEM and EDX analysis where the average particle size of TiO2 nanoparticles dispersed over reduced graphene oxide (rGO) sheets increased from 46.2 to 71.2 nm. The diffraction peaks study from XRD reveals the TiO2 phase in the anatase structure which is well supported by Raman results presenting the vibrational modes of Eg (1), Bg (1), A1g+B1g (2), and Eg (2) located at 146.1, 392.1, 513.2, and 638.1 cm−1. The average crystallite size of rGO-TiO2 NCs varied from 37.6 to 39.8 nm and lattice strain decreased from 0.0014 to 0.00135. The presence of the combination of Ti–O–Ti and Ti–O–C vibrational signatures indicates the effective interaction between Ti and C and the chemical bond formation between TiO2 and rGO which is justified by X-ray photoelectron spectroscopy. Electrochemical measurements showed that the specific capacitance of rGO-TiO2 NCs varied from 204.7 to 276.4 F g−1 at a 5 mV s−1 scan rate with the maximum specific capacitance obtained for 5% rGO-TiO2 NC. The lowest charge transfer resistance was recorded for 5% rGO-TiO2 NC (63.86 Ω) which is consistent with the maximum specific capacitance achieved. Moreover, corrosion studies reveal that corrosion potential becomes more positive with more rGO content obtaining a maximum of 0.297 V in 5% rGO-TiO2 NC. [ABSTRACT FROM AUTHOR]

Cyano-bridged layered coordination polymer [Cu8(dpe)4(CN)8]·2dpe·H2O (1) is prepared by the hydrothermal reaction of CuCN and dpe (dpe = 1,2-di-4-pyridylethylene) in the presence of Cs3K[Re6S8(CN)6]·2H2O. The [Cu8(dpe)4(CN)8] complex is an isomer of the earlier described [Cu2(CN)2(dpe)] with a 3D framework structure. The structure of 1 is triclinic, space group, a = 11.9229(8) Å, b = 11.9549(8) Å, c = 14.1984(10) Å, α = 102.019(2)°, β = 102.370(2)°, γ = 104.151(2)°, V = 1842.8(2) Å3, Z = 1, dcalc = 1.647 g/cm3. The Cu atoms in 1 have a triangular coordination environment formed by N atoms of the bridging dpe molecule and N and C atoms of the ambidentate bridging CN ligands. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting stands as a promising method for harnessing energy from renewable sources. However, substantial overpotential required for sluggish oxygen evolution reaction (OER) hampers its widespread adoption. In this study, a CuSe@PPy hybrid is being created by hydrothermally layering polypyrrole on top of CuSe. This hybrid electrocatalyst outperforms both pure CuSe and PPy in terms of OER efficiency. Structural and morphological analyses, including powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller (BET), confirm that the synthesized CuSe@PPy composite exhibits high crystallinity, nanostructured granular morphology, and a hexagonal structure with a large surface area. Evaluation of its electrocatalytic performance for water oxidation in a 1 M KOH alkaline medium reveals CuSe@PPy hybrid's exceptional durability, achieving 35 mA cm−2 for 100 h. This durability is attributed to PPy coating on its surface, which facilitates efficient electron conduction. Coupling of PPy with CuSe leads to reduced overpotential (248 mV), a lower Tafel slope (30 mV/dec), and decreased charge transfer resistance (2.16 Ω), enhancing OER efficiency. By modifying surface of CuSe with a conducting polymer like PPy, this study underscores potential for improving performance in various applications, including photoelectron-catalytic research and stabilizing material activity. [ABSTRACT FROM AUTHOR]

The low-temperature (α-/β-/γ-/δ-MnO2/CeO2-Nanorod) catalysts have been synthesized using the hydrothermal method followed by wet-impregnation and anaylzed in the Inconel reactor for selective catalytic reduction of NO using NH3 as a reducing agent. The catalysts were characterized by the Brunauer-Emmett characterized catalysts–Teller, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy-Energy dispersive X-ray spectroscopy, transmission electron microscopy and Raman spectroscopy. The characterization analysis of the catalysts revealed that the α-MnO2/CeO2-Nanorod has the highest specific surface area, surface Ce3+ and Mn4+, and oxygen storage capacity among all the catalysts. The activity results exhibited that in the 50–450 °C temperature range, the α-MnO2/CeO2-Nanorod has the maximum NO conversion and N2 selectivity. It showed the highest NO conversion (75%) and N2 selectivity (86%) at 250 °C. As the amount of α-MnO2 increased in the α-MnO2/CeO2-Nanorod catalyst, the NO conversion with N2 selectivity exceeded 94.25% and 95%, respectively. [ABSTRACT FROM AUTHOR]

KAlPO4F was prepared hydrothermally at 453 K, a time-saving method using cheap reagents. The white solid was characterized by different methods such as powder X-ray diffraction, thermal analysis, SEM and UV–Vis diffuse reflectance. The compound was successfully tested for the removal of methyl violet (MV), a hazardous dye. Experiments were carried out as a function of contact time, initial concentration, temperature and pH. The amount of dye uptake was found to vary with increasing initial solution pH and maximum adsorption was observed at pH 10; the equilibrium was attained in 270 min. The amount of dye uptake (mg/g) was found to increase with increase in dye concentration and contact time. The pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models were applied to fit the experimental data to elucidate the kinetic adsorption. The pseudo-second-order model was the best to describe the adsorption process. Different models analyzed the equilibrium isotherms; the applicability for the experimental data follows the order: Freundlich > Langmuir > Temkin. The thermodynamic parameters: ΔH° (39.034 kJ mol−1), ΔS° (134 J K−1 mol−1) and ΔG° (− 367.01 J mol−1) indicated that the adsorption process is endothermic and spontaneous with increasing disorder at the solid–solution interface. [ABSTRACT FROM AUTHOR]

Acid-washed coal fly ash (AW-CFA) was subjected to wet grinding activation followed by hydrothermal crystallization to synthesize P zeolite (FAZ-P). The FAZ-P obtained at 120 °C for 24 h exhibited a maximum relative crystallinity of 93.15% and was employed for the adsorption of Cr3+, Ni2+, and Co2+ from aqueous solutions. The zeolitization of coal fly ash (CFA) leads to an increase in specific surface area to 44.00 m2/g, resulting in the formation of nano-sized P zeolite crystals with uniformly narrow fissures and sizes within the range of 10–30 nm. Adsorption experimental results indicate that FAZ-P exhibits maximum adsorption capacities of 49.03 mg/g for Cr3+, 22.20 mg/g for Ni2+, and 27.25 mg/g for Co2+. The adsorption equilibrium data for both mixed and single-metal ion solutions conform to the Langmuir model, with the affinity sequence for heavy metal ions being Cr3+ > Co2+ > Ni2+. The pseudo-first-order and pseudo-second-order kinetic models effectively described the adsorption behavior of Cr3+, Ni2+, and Co2+. Increasing the initial pH value of the solution significantly enhanced the adsorption capacity of the adsorbent for heavy metal ions. The removal mechanism of metal ions involves both adsorption and ion exchange processes. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic. This study utilizes solid waste pollutant coal fly ash as a raw material, synthesizing coal fly ash-based P zeolite through wet mechanical grinding activation and hydrothermal crystallization. The synthesized zeolite exhibits excellent heavy metal adsorption performance, offering the potential for resource utilization of coal fly ash and sustainable industrial applications through waste-to-waste processing. [ABSTRACT FROM AUTHOR]

A layered ZnO@MnO2 nanocomposite was synthesized by hydrothermal techniques at a reaction temperature of 120°C for a reaction time of 12 h. Structural (x-ray diffraction), functional (Fourier transform infrared [FTIR] spectroscopy), and morphological (field-emission scanning electron microscopy) characterization confirm the formation of a ZnO@MnO2 nanostructure with high purity and layer-like morphology. The electrochemical performance of the ZnO@MnO2 nanocomposite was analysed by fabricating a symmetric supercapacitor device. The ZnO@MnO2 nanocomposite displayed good current rate capability and excellent capacitance of 839.9 F/g at a current density of 0.3 A/g. The energy density of the supercapacitor cell was 74.6 Wh/kg at a power density of 149.3 W/kg with remarkable long-term cycling stability of 92% after 10,000 cycles. The ZnO@MnO2 layered composite electrode is promising for high-energy-density supercapacitor applications due to its superior electrochemical performance. [ABSTRACT FROM AUTHOR]

The development of catalysts for treating hazardous organic effluents contained in wastewater via the light-induced advanced oxidation processes (AOPs) has been at the forefront of recent research. The heterogeneous photo-Fenton process is one of the most effective AOPs used in the abatement of wastewater pollutants. However, there is a frequent requirement for acidic pH and ultraviolet (UV) irradiation, both of which hinder its industrial viability. Thus, there is a demand for a stable solar light-activated photo-Fenton catalyst capable of operating under near-neutral pH. This is the first demonstration of the mesoporous FeNbO4 used for solar-driven photocatalytic reaction under an oxidative environment at near neutral pH. The present work reports the preparation of pure-phase mesoporous FeNbO4 with a high specific surface area through a wet chemical technique. The cationic surfactant tetradecyl trimethylammonium bromide (TTAB) has been employed as the structure-directing agent in the present synthesis that produces a mesoporous structure with a surface area of 97 m2/g, an average pore diameter of ~ 6.5 nm and an average pore volume of 0.139 cm3/g. The synthesized mesoporous FeNbO4 has been characterized by thermo-gravimetric analysis (TGA), Fourier Transform Infrared Spectrophotometer (FTIR), X-ray diffractometer (XRD), Branauer-Emmett-Teller analysis (BET), transmission electron microscope (TEM), and UV-vis spectroscopy. Our synthesized material exhibits high activity towards the degradation of organic dyes in the presence of H2O2 under natural sunlight irradiation in an optimized catalytic scheme. The complete degradation of the mixture of dyes was achieved by direct sunlight irradiation at near natural pH (5.7) in the presence of a catalyst (3 g/L) and 50 mM H2O2 for 1 h. The present article also reports the measurement of its point zero surface charge and the role of reactive species in the degradation of organic dyes. The synthesized material has been found to be a promising, stable, and recyclable photo-Fenton catalyst for the removal of organic pollutants from wastewater under solar light irradiation and near neutral pH. [ABSTRACT FROM AUTHOR]