Template-free Hydrothermal Method Research Articles

Rare earth element Ce-doped floral In2O3 with high sensing performance for n-butanol

Pure In2O3 and the graded flower-shaped In2O3 structures doped with Ce, a rare earth element, were synthesized by an easy-to-operate template-free hydrothermal method, and the high sensing performance of the sensor for n-butanol was investigated. The micro-morphology and elemental compositions of the samples and their valence states were characterized by XRD, SEM, TEM, XPS and other testing methods. The morphological and compositional characterization showed that Ce doping is able to cause lattice distortion, which affects the sensing performance. The gas-sensitive test results revealed that 3 wt% Ce-doped In2O3 has the best sensing performance. At the optimal operating temperature of 320 °C, the response of 3 wt% Ce-In2O3 to 100 ppm n-butanol was as high as 225.63, which was 3.7 times higher than that of the pure In2O3 sensor (60.36). In addition, the Ce-doped In2O3 sensor also exhibited excellent selectivity, repeatability, long-term stability, and large specific surface area (73.1104 m2g-1). This study enhances the understanding of the mechanism of rare earth element doping to improve gas-sensitive properties and provides a new effective strategy for designing high-performance gas-sensitive materials.It also provides new ideas for the efficient detection of the toxic gas n-butanol.

Nanosheet-assembled porous-wall hollow hydroxyapatite microspheres prepared by a template-free hydrothermal method for pH-responsive drug release

Template residues during the preparation of hydroxyapatite (HA) microspheres with hollow structures limit their biological applications to some extent. In this study, the nanosheet-assembled porous-wall hollow HA microspheres were successfully synthesized by a template-free hydrothermal method. SEM and TEM observations revealed that the prepared hollow HA microspheres were about 3–7 μm in diameter and were composed of an interior cavity and a porous shell assembled by nanosheets (consisting of radial nanorods arranged side-by-side). A possible mechanism for the formation of the hollow HA microspheres was proposed based on the time-gradient experiments. Furthermore, the hollow HA microspheres exhibited excellent vancomycin loading capacity (101.3 mg/g) and pH-responsive release properties. This study provides new inspiration for the design and various applications of hollow materials.

Facile synthesis of Ni-doped ZnS nanostructures and their photocatalytic activity to RhB

In this paper, pure ZnS and Ni-doped ZnS nanostructures (Ni–ZnS) were prepared by facile template-free hydrothermal method. The as-prepared Ni–ZnS was characterized by XRD, SEM, EDS, XPS, and UV–Vis DRS. The effects of different Ni doping amounts and hydrothermal reaction temperatures were investigated. The photocatalytic ability was evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the doping of Ni effectively enhanced the photocatalytic activity of pure ZnS. Ni–ZnS exhibited significantly enhanced photocatalytic properties, the reaction rate constant (0.01154 min−1) is higher than that of pure ZnS (0.00218 min−1). Carrier separation efficiency and charge transport efficiency were investigated by transient photocurrent response (TPS) and electrochemical impedance spectroscopy (EIS). Scavenger test was used to determine the role of active species, combining the analysis results of UV–Vis DRS, TPS, and EIS, accordingly the photocatalytic mechanism of Ni–ZnS was proposed.

Tailoring the electric, dielectric and optical properties of template-free hydrothermally synthesized CuO nanostructures via Co doping

Facile template-free hydrothermal method was utilized for preparing CuO nanostructures (NSs) doped with Co element (Cu1-xCoxO (x = 0.0, 0.02, 0.04, 0.06 and 0.08)). A single-phase monoclinic crystal with changing in morphology from rod-to sphere-like nanoparticles was observed. The temperature dependency of DC electrical conductivity revealed that the shallow and deep donor levels are responsible for the DC conduction in low and high temperature ranges, respectively. The Ac electrical conductivity, dielectric constant and dielectric loss were also measured as functions in frequency and temperature. The frequency dependence of the AC conductivity was well represented by the Jonscher's universal power law. The AC conduction was governed by the Correlated Barrier Hopping model where the inter-well and intra-well hopping mechanisms contribute to the electrical conduction in the low and high frequency ranges, respectively. The activation energies and the barrier height decreased while the dielectric constant and dielectric loss increased with increasing the Co content. The relaxation and deformational polarizations predominate and the overall behavior of dielectric constant fits well with the Koops' model. The Cole-Cole plots indicated a decrease in the sample resistance with increasing temperatures and Co concentrations. UV–vis absorption spectra exhibited two peaks at wavelengths 252 and 323 nm. The optical energy gap was calculated using Tauc's equation and decrease from 2.24 to 2.1 eV with increasing the Co concentrations. The effect of Co-doping on CuO was explored for oxygen evolution reaction (OER) and found a decrease in the overvoltage (μ) about 50 mV at 0.08 ratios, which declares that the doping of Co element enhances the electrical conductivity and feasibility for further electrocatalytic improvement.

Design of a new process for the stabilization of FeS-Bi2S3 hybrid nanostructure and its application as a field emitter.

The relentless pursuit for technological advancement has fuelled intensive research into nanoarchitectures as fundamental components of various devices. One-dimensional (1-D) nanomaterials, including nanorods, nanowires, and nanotubes, have garnered significant attention due to their distinctive catalytic, optical, and electronic properties. Metal chalcogenides have emerged as promising candidates for diverse applications ranging from sensing devices to solar cells, particularly bismuth sulphide (Bi2S3). Bi2S3 exhibits unique properties owing to its low work function and anisotropic crystal structure. This work presents a novel approach to synthesize Bi2S3 nanorods and decorate them with FeS to form an FeS-Bi2S3 heterostructure via a one-step, template-free hydrothermal method. The synthesized nanomaterials are evaluated for their field emission characteristics, which are vital properties for numerous electronic applications. By comparing the field emission behaviour of the pristine Bi2S3 and FeS-Bi2S3 heterostructures, insights into the impact of hetero-structuring FeS for field emission performances are elucidated. This study presents insights into tailoring the heterostructure of different transition metals with Bi2S3 and studying their field emission behaviours.

Effect of Co-doping on the electrochromic performance of hexagonal phase WO3 nanorods.

In this study, cobalt-doped hexagonal phase WO3 nanorods were prepared by a template-free hydrothermal method. The effects of varying the cobalt doping concentration on the microscopic morphology and electrochromic properties of hexagonal phase WO3 films were investigated. Films synthesized with the optimal cobalt element doping concentration demonstrate a notable improvement in their electrochromic properties compared to the pure hexagonal phase WO3 films. The film doped with 1.5% Co exhibited excellent cycling stability, retaining 98.55% of its original value after 500 cycles. The introduction of cobalt results in the formation of a nanorod structure with a high specific surface area within the film. This structure provides additional reaction sites for the electrochromic reaction process, thereby enhancing the optical modulation and coloration efficiency of WO3. The resulting films with excellent electrochromic properties provide a convenient and effective means for ion-doped modification of WO3-based electrochromic films.

Selectivity of Control of Oxygen Reduction Reaction over Mesoporous Transition Metal Oxides Catalysts for Electrified Purification Technologies

Introduction: The use of abundant feedstocks, such as water and air, in manufacturing of value-added products is important in achieving the UN’s Sustainable Development Goals.1 In this context, electrified direct synthesis of chemicals from oxygen in the air is of special interest since it avoids greenhouse gas emissions if the electricity used to drive the synthesis comes from sustainable sources such as solar- and wind-power. The controlling of oxygen reduction path over catalysts incorporation with oxygen evolution reaction as auxiliary reaction enables the electrosynthesis of value-added chemicals, oxygen and hydroxyl radical. The development of cheap materials e.g., mesoporous transition metal oxides, is urged to replace the expensive and scarce of platinum group metal (PGM)-based catalysts, with the ability to provide competitive reaction rate in alkaline media.2 Experimental: A template-free hydrothermal method is developed for the synthesis of mesoporous NiO and NiCo2O4. The materials’ physicochemical properties are characterized by X-ray diffraction, physisorption, electron microscopy, selected electron area diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties and electrocatalytic oxygen activity are evaluated via cyclic voltammetry and electrochemical impedance spectra in alkaline electrolyte using a standard three electrodes electrochemical working station equipped with (ring) rotating disk electrode (RDE/RRDE) techniques.The catalysts coated on carbon fiber paper (CFP) are used as electrode assembled with anion exchange membrane in two-electrodes-electrochemical cell for device test. NiO- and NiCo2O4-modified CFP are used as cathode and anode, respectively, for constructing electrochemical generator of hydroxyl radical. 50 mL min-1 O2 flow was maintained in catholyte to enable oxygen saturation. 20 mg L-1 rhodamine B (RhB)was fed into cathode. Off-line UV-vis measurements were used for RhB quantification. In Electrochemical oxygen purifier, NiCo2O4-modified CFP are used as electrodes. 0.1 - 3 M KOH aqueous solutions were used as anolyte and air-saturated catholyte. The volume of produced oxygen on the anode after 2 h was collected and measured by a water displacement method. Results and Discussion: A facile template-free hydrothermal synthesis is developed for bifunctional oxygen electrocatalysts (OER and ORR) of NiO and NiCo2O4. Physicochemical characterization shows that both NiO and NiCo2O4 are mesoporous with the pore size within a range of 2 - 8 nm and specific surface areas of 60 and 120 m2 g-1, respectively. In addition, NiO and NiCo2O4 possess cubic crystal structures with the corresponding crystal sizes of ~6.0 and 9.3 nm.Electrochemical analysis shows that mesoporous NiCo2O4 has about two times larger capacitance and eight times smaller charge transfer resistance compared to NiO. NiCo2O4 shows higher electrocatalytic activity in OER and selectivity to water as the terminal product of ORR. On the contrary, ORR over NiO yielded hydroxyl radicals, as a product of a Fenton-like reaction of H2O2. The product selectivity in ORR is used to construct two electrolyzers of electrified purification of oxygen and generation of hydroxyl radicals. The optimization of configuration of hydroxyl radical generator enables the degradation of RhB up to 90% after 1 hour, and the electrochemical oxygen purifier shows high efficiency of about 100%. Significance: It is demonstrated that the synthesized mesoporous transition metal oxides via a simple template-free hydrothermal route, and the materials can be used as alternatives to PGM-based electrocatalysts for driving electrochemical cell towards to various products. The work also clearly shows how the composition and structure of catalysts affect the oxygen reactions, and the selectivity of ORR used for producing value-added chemicals coupling with OER. It is shown that the established electrochemical oxygen purifier and hydroxyl radical generator have a high conversion efficiency. Schematic 1. (a) Scheme of operation of the hydroxyl radical generator, (b) the degradation efficiency and rate constants as function of current densities; (c) Scheme of the oxygen purifier, and (d) the generated oxygen volume as a function of working power of the electrochemical cell with different anolyte concentrations. Acknowledgements: This work was supported by the competence center FunMat-II funded by the Swedish Agency for Innovation Systems (Vinnova, grant no 2016-05156), the Swedish Energy Agency (project no 42022-1), and Swedish Research Council (VR 2019-05577, Flexible metal-air primary batteries). Reference: 1 United Nations. Transforming our world: The 2030 agenda for sustainable developement. (UN General Assembly, New York, 2015).2 Yang, Y. et al. Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies. Chem. Rev. 6, 6117–6321 (2022). Figure 1

CeO2 nanorods with bifunctional oxygen vacancies for promoting low-pressure photothermocatalytic CO2 conversion with CH3OH to dimethyl carbonate

The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol is a kind of highly-attractive route for CO2 conversion to high value-added chemicals. However, a key core problem is how to more effectively activate CO2. Here, we adopt simple template-free hydrothermal method to prepare CeO2 nanorods with oxygen vacancies and introduce light energy into the thermal catalysis system for promoting low-pressure photothermalcatalytic CO2 with methanol direct conversion to DMC. The SEM, HRTEM, XRD, XPS, N2 adsorption-desorption isotherm, CO2-TPD, EPR, Raman, photoluminescence spectra and UV-Vis-IR DRS characterizations are carried out to analyze the microscopical properties including the crystal phases, chemical states, structural features, optical properties for building up the intrinsic relationship with macroscopic performance. Our findings reveal that oxygen vacancies can not only act as photo-produced charge trapping center to prevent the recombination of photoinduced electrons and holes, but also promote CO2 adsorption and activation abilities through Lewis acid-base interaction. Finally, the detailed action mechanism for photothermalcatalytic CO2 conversion with methanol to DMC is proposed. This work should provide new ideas and insights for achieving the CO2 conversion into high value-added long-chain chemicals.

Fabrication of novel PN-heterojunction CuS/TiO2 nanocomposite for the photocatalytic degradation of rhodamine B dye under visible light irradiation

ABSTRACT. In the current study, a novel visible light-active photocatalyst CuS/TiO2 nanocomposite was synthesized by a template-free hydrothermal method. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of synthesized nanocomposites and the structural characteristics of synthesized nanoparticles were characterized and confirmed by the X-ray diffraction (XRD) technique. The morphology and particle size of synthesized nanocomposites were measured by a field emission scanning electron microscope (FESEM), which revealed an average particle size of around 30 nm. The optimized efficiency of the fabricated photocatalyst was assessed for the photodegradation of rhodamine B (RhB) dye. It was observed that the photodegradation efficiency of CuS/TiO2-Y composites having a molar ratio of 1:1 for RhB was found to be 89.54% under visible light irradiation.
 KEY WORDS: CuS/TiO2 nanocomposite, Heterojunction structure, Rhodamine B, Photodegradation, Visible light irradiation
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1553-1564. DOI: https://dx.doi.org/10.4314/bcse.v37i6.19

Novel template free synthesis of high surface area mesoporous ceria and adaptive neuro fuzzy interference system (ANFIS) modelling for Cr(VI) adsorption

The search for sustainable and ecofriendly mesoporous materials with high surface area is intensively desired for catalytic applications. Herein, we explore a template-free hydrothermal method for synthesizing mesoporous Cerium Oxide (meso-CeO2) nanoparticles as an adsorbent, for the removal of toxic hexavalent chromium Cr(VI) from water. The morphology and structure of synthesized nanomaterials were characterized using various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), UV–visible spectrophotometer (UV–Vis), Fourier transform infrared spectroscopy (FTIR), and Brunauer, Emmett, and Teller(BET) analysis. The BET analysis confirmed CeO2 possess a high surface area of 270 m2/g, a 4.5 nm pore diameter, 0.22 cm3/g pore volume, and a stable mesoporous structure. The synthesized meso-CeO2, exhibited efficient removal (99.8% at pH 5) of Cr (VI) from water within 60 min at room temperature. The meso-CeO2 material demonstrated reusability for up to 5 cycles. The removal of Cr (VI) using meso-CeO2 followed Pseudo-second order kinetics (R2 > 0.99) and showed a good fit with the Freundlich isotherm model. Moreover, adaptive neuro fuzzy inference system (ANFIS) models were employed on 320 experimental data sets to predict the adsorption process accurately. Overall, this study highlights the potential of meso-CeO2 nanoparticles as a promising adsorbent for effective water remediation of heavy metal contaminants like Cr (VI).

Flower-like tin oxide membranes with robust three-dimensional channels for efficient removal of iron ions from hydrogen peroxide

Membrane technology has become the mainstream process for the production of electronic grade hydrogen peroxide (H2O2). But due to the oxidation degradation of the organic membranes (e.g. polyamide) by the strong oxidative radicals (e.g. OH) generated via the activation of H2O2 by iron ions (Fe3+), the short effective lifetime of membranes remains a challenge. Inorganic nano tin oxide (SnO2) has great potential for the removal of Fe3+ in strongly oxidative H2O2 because of its ability to stabilize H2O2 and preferentially adsorb Fe3+. Herein, we have designed for the first time a flower-like robust SnO2 membrane on the ceramic support by in situ template-free one-step hydrothermal method. The three-dimensional loose pore structure in the membrane built by interlacing SnO2 nanosheets endows the SnO2 membrane with a high specific surface area and abundant adsorption sites (OH). Based on the coordination complexation and electrostatic attraction between the SnO2 surface and Fe3+, the membrane shows a high Fe3+ removal efficiency (83%) and permeability (24 L·m−2·h−1·MPa−1) in H2O2. This study provides an innovative and simple approach to designing robust SnO2 membranes for highly efficient removal of Fe3+ in harsh environments, such as strong oxidation conditions.

Template-free hydrothermal preparation of IR-blue light upconverting NaYF4: Yb, Eu phosphors

Highly efficient IR-blue light up-converting NaYF4: Yb3+, Eu2+ phosphors have been prepared by a template-free hydrothermal method under mild and reductive experimental conditions. It has been demonstrated that for a fixed reaction time and temperature (150°C/4h), the α→β NaYF4 conversion can be accurately controlled by modifying the F/Y ratio. UC emission spectroscopy reveals that IR-blue light emission efficiency is greatly improved when β-NaYF4 phase predominates. Under the experimental conditions set in this work, reaching full α→β conversion just by increasing fluoride content entails the co-crystallization of the secondary phase YF3 1.5NH3, but far from causing a detrimental effect on the optical properties, it has been found that the samples where both β-NaYF4 and YF3 1.5NH3 phases coexist, exhibit outstanding optical properties.

Analyzing the role of Ni dopant to change the structural, optical and photocatalytic properties of SnO2 nanoparticles

SnO2 and 5 wt% Ni doped SnO2 nanoparticles (SnO2:Ni NPs) were successfully synthesised by a template-free hydrothermal method. X-ray diffraction (XRD) patterns depicted polycrystalline nature of the NPs in rutile-type cassiterite phase with dominant (110) and (101) Bragg diffraction peaks. Rietveld refinement of XRD patterns supported single phase tetragonal crystal structure having space group P42/m n m. With Ni doping, crystallite size of NPs decreased from 39 nm to 35 nm whereas lattice strain increased from 3.56 × 10−3 to 3.99 × 10−3. This is attributed to the substitution of Sn4+ ion by Ni2+ ions. The morphology of the SnO2 NPs also changed from regular spherical shape to elongated irregular shape upon Ni doping. The dominant Raman peak obtained at 634 cm−1 matched with the signature peak for rutile SnO2 (Raman A1g mode). Further, we observed disappearance of E g mode due to Ni doping, which indicated the formation of oxygen vacancies. Also, XPS analysis indicated an increase of oxygen vacancy concentration in the doped NPs due to charge imbalance between Sn4+ and Ni2+. The direct optical band gap of SnO2 increased from 3.97 eV to 4.11 eV when doped with 5 wt% Ni and it is ascribed to Burstein–Moss effect. Irrespective of higher optical band gap of SnO2:Ni NPs, they showed enhanced photocatalytic activity to degrade Rhodamine B (RhB) dye molecules under UV-visible irradiation. The first order kinetic reaction rate constants for degradation of RhB were found to be 0.014 min−1 and 0.045 min−1 in case of SnO2 and SnO2:Ni NPs respectively. The enhanced photocatalytic activity in SnO2:Ni NPs is explained by relating to the formation of more oxygen vacancies and chemisorptions of O2 and H2O molecules followed by generation of radicals. This work demonstrates the superiority of SnO2:Ni NPs for use as photocatalytic material for industrial waste water treatment.

H2S Sensing Characteristics of NiO Nanopetal Film

NiO is one of the most candidate materials for hydrogen sulfide (H2S) sensing due to its catalytic activity for the oxidation reaction of H2S, and high affinity of Ni in the NiO to S for the H2S adsorption. Porous NiO nanopetal film composed of interconnected thin nanosheets was grown by a facile template-free hydrothermal method at the relatively low temperature of 105 °C, and its H2S sensing characteristics was investigated in the temperature range of 25 °C to 400 °C. The NiO nanopetal film based device showed a reliable response to wide range of concentration from 10 ppm to 500 ppm H2S ambient at 400 °C. The sensor started to exhibit the responsivity to 500 ppm H2S gas at 200 °C. The maximum responsivity of the sensor with NiO nanopetals was 400% for 500 ppm H2S exposure at 300 °C. The NiO nanopetal film grown by the simple low-cost hydrothermal synthesis has high potential in applications of chemical, medical, energy, and food industries.

Multi-functional fluorinated NiTiO3 perovskites for CO2 photocatalytic reduction, electrocatalytic water splitting, and biomedical waste management

Multi-functional F-doped NiTiO3 structures with high stability were prepared by a template-free hydrothermal method. A multi-technique approach including several physicochemical techniques was employed to describe the morphology, electronic properties, and structural characters. The F-doped NiTiO3 catalyst showed a much higher CO2 to CH4 photocatalytic conversion rate (2.6 μmol g−1 h−1) than pristine NiTiO3 (1.6 μmol g−1 h−1), highlighting the key role of F impurities in suppressing the charge carriers recombination. In addition to the higher efficiency and reusability than Pt/C reference electrode toward electrocatalytic water splitting, a lower Tafel slope was recorded for the F-doped structure (81.2 mV dec−1). This implies significant improvement in the reaction kinetics, arising from the synergistic effects between the F sites and bulk constituents to supply more desired active electronic states. The capability of the structures for the biomedical wastewater (containing the Caco-2 cancer cells) treatment was also explored. According to several biochemical assays, the fluorinated material shows a promising performance against the tumor cells at its IC50 concentration, 0.15 μg/mL, in a typical hospital wastewater. Our results pave the way for developing novel multi-functional photoactive titanate perovskites aiming at future clean energy transition.

Boosting the Hydrogen Evolution Reaction Performance of P-Doped PtTe2 Nanocages via Spontaneous Defects Formation.

PtTe2 , a member of the noble metal dichalcogenides (NMDs), has aroused great interest in exploring its behavior in the hydrogen evolution reaction (HER) due to the unique type-II topological semimetallic nature. In this work, a simple template-free hydrothermal method to obtain the phosphorus-doped (P-doped) PtTe2 nanocages with abundant amorphous and crystalline interface (A/C-P-PtTe2 ) is developed. Revealed by density functional theory calculations, the atomic Te vacancies can spontaneously form on the basal planes of PtTe2 by the P doping, which results in the unsaturated Pt atoms exposed as the active sites in the amorphous layer for HER. Owing to the defective structure, the A/C-P-PtTe2 catalysts have the fast Tafel step determined kinetics in HER, which contributes to an ultralow overpotential (η=28mV at 10mAcm-2 ) and a small Tafel slope of 37mVdec-1 . More importantly, benefiting from the inner stable crystalline P-PtTe2 nanosheets, limited decay of the performance is observed after chronopotentiometry test. This work reveals the important role of the inherent relationship between structure and activity in PtTe2 for HER, which may bring another enlightenment for the design of efficient catalysts based on NMDs in the near future.

Improvement of surface properties of metal doped-CeO2 nanospindle catalysts for direct synthesis of dimethyl carbonate from CO2 and methanol

To utilize carbon dioxide (CO2) which is the main greenhouse gas, this study developed effective metal doped-CeO2 nanospindle catalysts for conversion of CO2 and methanol into dimethyl carbonate (DMC). Ce0.9M0.1O2 nanospindles (where M is a transition metal, i.e., Zr, Fe, Cu and Co) were prepared by a template-free hydrothermal method. The substitution of different valence and size cations, including Zr4+, Fe3+, Cu2+ and Co2+, for Ce4+ sites in the fluorite CeO2 lattice induced the defect formation of surface-active sites of exposed Ce3+ and oxygen vacancies through the charge compensation and redox pair reactions. Ce0.9Fe0.1O2 solid solution with well-preserved spindle shaped morphology showed the highest catalytic performance by giving DMC yield at 3.56 mmol.gcat−1 with 100% DMC selectivity. The improvement of catalytic activity was attributed to the higher proportion of surface defect sites and variation of acid-base properties caused by the integration of Fe dopants into CeO2 ionic system.

Facile Synthesis of Organic Template-Free Chabazite Zeolite-Coated Kaolin Ceramic Membrane for Continuous Separation of Cerium from Aqueous Solutions

Developing an organic template-free zeolite coated on a low-cost ceramic support is essential to reduce the overall cost of the membrane for heavy metal separation. In this study, a low-cost and highly durable kaolin-supported zeolite-coated composite membrane was fabricated and tested for removal of cerium metal ions from its aqueous solution. Different strategies were followed to fabricate the composite membrane through the organic template-free hydrothermal synthesis method, such as coating the ceramic tubes solely on the interior surface, exterior surface, and both sides. The results obtained from X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy indicated that the hydrothermal synthesis route produced pure, ultrafine, and uniform particles of chabazite zeolite with a cation exchange capacity of 3.96 meq/g. The effect of coating on the membrane surface(s) was investigated by measuring the weight increment, porosity, pore size, and pure water permeability; the results revealed that the ceramic tube coated on both sides has the highest amount of zeolite loading, that is, 1.82 ± 0.18 g, along with a porosity of 30.50 ± 0.50%, a water permeability of 1.74 L/m2 h bar, and an average pore diameter of 36 nm. The average pore diameter of the composite membrane (both-side-coated tubes) obtained from BET analysis (34 nm) was in good agreement with the pore size (36 nm) estimated through the pure water permeability test. Furthermore, the performance of the composite membrane coated on both sides was evaluated toward removing cerium ions from aqueous solutions. The effect of applied pressure, pH, and concentration of the feed solution was investigated. During the cross-flow filtration tests, the permeate flux decline was not observed for all the applied pressures. More than 99.9% removal of cerium was achieved under the different conditions of feed concentration and pH. This study establishes the application of the prepared composite membrane for cerium removal from aqueous solutions.

Comparison study of WO3 thin film and nanorods for smart window applications

The WO3 thin films were deposited at oxygen partial pressure of 8x10-4 mbar. A template-free straightforward hydrothermal method is employed to produce vertical alignment hierarchical WO3 nano-architectures on clear conducting substrates (3x2.5 cm2 in size and slides resistance 4 O). After being deposited at ambient temperature, the samples were air annealed at 400 °C for 4 h. The optical, electrochromic, surface and structural morphology behavior of the deposited material after annealing were studied using XRD, Raman, FTIR, SEM, electrochemical analyzer and UV–Visible spectrometer characterization methods. After annealing at 400 °C for 4 h in air, every characteristic peak are matched to a monoclinic (crystalline) WO3 phase. The Nano flower array achieved a considerable coloration efficiency (24.09 cm2/s) and low cathodic peak current (−2.03 mA) compare to the Tungsten trioxide thin film produced by the DC magnetron sputtering method. The vertically oriented geometry and the porosity space between the Nano flower, which improve H+ diffusion and provide a considerable contact area for charge-transfer processes, are primarily responsible for the improved electrochromic properties.

Facile template-free synthesis of 3D cluster-like nitrogen-doped mesoporous carbon as metal-free catalyst for selective oxidation of H2S

Construction of metal-free carbon-based materials for efficient sulfur resource recovery in pollutant H2S is very critical for both applied environmental catalysis and fundamental material exploration. Herein, we report a template-free hydrothermal method to prepare hierarchical nitrogen-doped mesoporous carbon (HNMCs) materials with abundant nitrogen sites and large BET surface area. The representative HNMC-800 achieves a H2S conversion of ∼100% and sulfur selectivity of ∼95% at 150 °C in H2S selective oxidation. Moreover, HNMCs catalysts are resistant to sulfur poisoning, displaying good catalytic durability, with no significant loss of sulfur yield in the run of 80 h, outperforming the pure active carbon, g-C3N4, and commercial Fe2O3. This work provides the possibility of utilizing hierarchical nitrogen-doped carbon materials as metal-free catalysts for the selective oxidation of H2S.