Hexamethylenetetramine Research Articles

Structural, Optical, and Catalytic Properties of MgCr2O4 Spinel-Type Nanostructures Synthesized by Sol–Gel Auto-Combustion Method

Spinel chromite nanoparticles are prospective candidates for a variety of applications from catalysis to depollution. In this work, we used a sol–gel auto-combustion method to synthesize spinel-type MgCr2O4 nanoparticles by using fructose (FS), tartaric acid (TA), and hexamethylenetetramine (HMTA) as chelating/fuel agents. The optimal temperature treatment for the formation of impurity-free MgCr2O4 nanostructures was found to range from 500 to 750 °C. Fourier transform infrared (FTIR) spectroscopy was used to determine the lattice vibrations of the corresponding chemical bonds from octahedral and tetrahedral positions, and the optical band gap was calculated from UV–VIS spectrophotometry. The stabilization of the spinel phase was proved by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis. From field-emission scanning electron microscopy (FE-SEM), we found that the size of the constituent particles ranged from 10 to 40 nm. The catalytic activity of the as-prepared MgCr2O4 nanocrystals synthesized by using tartaric acid as a chelating/fuel agent was tested on the decomposition of hydrogen peroxide. In particular, we found that the nature of the chelating/fuel agent as well as the energy released during the auto-combustion played an important role on the structural, optical, and catalytic properties of MgCr2O4 nanoparticles obtained by this synthetic route.

Preparation of Ceria-Coated Silica Nanoparticles and Their Chemical Mechanical Planarization Performance on Si-Face 6H-SiC Substrates

Ceria-coated silica (SiO2/CeO2) composite abrasives were prepared through a novel homogeneous precipitation method using commercial silica (SiO2) sol as the silicon resource and cerium nitrate (Ce(NO3)3) and hexamethylenetetramine (HMT) aqueous mixtures as coating precursors. The phase composition, nano-topography, size distribution, and chemical structure of as-prepared particles were characterized by X-ray diffraction, transmission electron microscopy, Zetasizer Nano ZS90 and Fourier infrared spectra. In addition, the possible coating mechanism was discussed. Then, chemical mechanical planarization behaviors of SiO2 sol, ceria (CeO2) sol, and the novel abrasives and on Si-face (0001) 6H-SiC were investigated by atomic force microscopy. The results indicated that the composite particles were mono-dispersed nano-spheres composed of amorphous SiO2 core and cubic fluorite CeO2 shell, possessing complete core–shell structure and particle size of about 110 nm. CeO2 shell (10 nm) grew on the surface of SiO2 core by formation of Ce–O–Si chemical bonds, forming stable core–shell structure. SiO2/CeO2 composite abrasives provided an exponentially high material remove rate (MRR) of 1207 nm h−1 and an impressive surface finish with roughness average (Ra) 0.216 nm due to its active chemical property and unique structure.

In Situ Neutron Reflectometry Analysis of Interfacial Structure Formation between Phenolic Resin and Silica during Curing.

The structural formation mechanism of phenolic resin-silica interfaces was investigated in situ by neutron reflectometry during curing. There was a 4 nm thick novolac resin adsorption layer on the silica surface before curing. The curing reaction of the novolac resin with hexamethylenetetramine (HMTA) increased the coherent neutron scattering length density of the resin due to the cure shrinkage accompanied by the volatilization of ammonia, which is a byproduct of HMTA decomposition. As curing proceeded at 180 °C, the thickness of the bulk layer increased despite the cure shrinkage, and the thickness of the interfacial layer decreased from 4 to 1 nm. This is attributed to the diffusion of decomposed HMTA fragments generated in the bulk layer into the interfacial novolac adsorption layer during diffusion throughout the bulk layer, incorporating the upper part of the interfacial layer reacting with the fragment into the bulk layer. On the other hand, the fragments could not diffuse into the tightly bound immobile segments of novolac resin in direct contact with the silica surface, retaining the 1-2 nm thick interfacial layer in the cured resin. This structural formation mechanism caused interfacial cross-link inhomogeneity in the cured resin on the silica surface.

Thermal Stability and Radiation Tolerance of Lanthanide-Doped Cerium Oxide Nanocubes

The thermal and radiation stability of free-standing ceramic nanoparticles that are under consideration as potential fillers for the improved thermal and radiation stability of polymeric matrices were investigated by a set of transmission electron microscopy (TEM) studies. A series of lanthanide-doped ceria (Ln:CeOx; Ln = Nd, Er, Eu, Lu) nanocubes/nanoparticles was characterized as synthesized prior to inclusion into the polymers. The Ln:CeOx were synthesized from different solution precipitation (oleylamine (ON), hexamethylenetetramine (HMTA) and solvothermal (t-butylamine (TBA)) routes. The dopants were selected to explore the impact that the cation has on the final properties of the resultant nanoparticles. The baseline CeOx and the subsequent Ln:CeOx particles were isolated as: (i) ON-Ce (not applicable), Nd (34.2 nm), Er (27.8 nm), Eu (42.4 nm), and Lu (287.4 nm); (ii) HMTA-Ce (5.8 nm), Nd (6.6 nm), Er (370.0 nm), Eu (340.6 nm), and Lu (287.4 nm); and (iii) TBA-Ce (4.1 nm), Nd (5.0 nm), Er (3.8 nm), Eu (7.3 nm), and Lu (3.8 nm). The resulting Ln:CeOx nanomaterials were characterized using a variety of analytical tools, including: X-ray fluorescence (XRF), powder X-ray diffraction (pXRD), TEM with selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS) for nanoscale elemental mapping. From these samples, the Eu:CeOx (ON, HMTA, and TBA) series were selected for stability studies due to the uniformity of the nanocubes. Through the focus on the nanoparticle properties, the thermal and radiation stability of these nanocubes were determined through in situ TEM heating and ex situ TEM irradiation. These results were coupled with data analysis to calculate the changes in size and aerial density. The particles were generally found to exhibit strong thermal stability but underwent amorphization as a result of heavy ion irradiation at high fluences.

Functionalized nanoclinoptilote as a novel and green catalyst for the synthesis of Mannich bases derived from 4-hydroxy coumarin

In this research, hexamethylene tetraamine propyl silane functionalized nano clinoptilolite (NCP@SiO3PrHMTA) as a novel, green, non-toxic, low cost, heterogeneous, and reusable nanocatalyst was designed, and developed. The structure of the nanocatalyst was fully characterized using various analytical techniques, including; X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and thermo gravimetric–differential thermal analysis (TG-DTA). The prepared nanocatalyst has been used as an efficient and recoverable catalyst for the synthesis of aminocoumarin Mannich bases by the three-component reaction of 4-hydroxycoumarin, aniline and aromatic aldehydes. In the presence of this novel nanocatalyst, aminocoumarin Mannich bases were obtained in excellent yields, high purity, and short reaction times under safe and clean conditions.

Multiple Regulation Effects of Ammonium Acetate on ZnO Growth Process in Chemical Bath Deposition.

Chemical bath deposition method has been used to synthesize a variety of ZnO morphology structures. However, the specificity and interaction of acetate and ammonium ions with ZnO crystal during the growth process remain elusive. This study contributes to understand the roles of ammonium acetate on the growth mechanism of ZnO in Zn(NO3 )2 -HMTA system. The growth process indicates that the nucleation experienced Zn2+ -layered basic zinc salts (LBZs)-ZnO process, while the self-assembled unit changed from urchin-shaped, rod-shaped to a fully coupled twin-shaped structure with increasing ammonium acetate concentration. Ammonium acetate dominates the growth process by combing the ligand-ligand interaction of acetate ions binding to the same Zn-rich (0001) polar surface and ammonium ions regulating hexamethylenetetramine (HMTA) hydrolysis. Relatively regular hexagonal wurtzite structure and a dissolve-renucleation-regrowth process which retains the twin-shaped template and renucleates at the same position are observed at ∼10 mM ammonium acetate. Photoelectrochemistry (PEC) measurements show that the uniform hexagonal ZnO rods (Y-10, the sample named as Y-x (x represents x mM ammonium acetate, herein, x is 10 mM)) have a maximum photocurrent density of 1.54 mA cm-2 at 1.23 V (vs. RHE), much higher than that of the dumbbell-shaped ZnO rods (Y-50, 0.20 mA cm-2 ) at the same voltage. These results provide a further explanation of morphology regulation mechanisms on ZnO synthesis processes and pave the road for more practical applications.

Methenamine Prophylaxis for Recurrent Urinary Tract Infections in a Tertiary Referral Center

Methenamine hippurate (MH) is a urinary antiseptic, indicated for prophylaxis of recurrent urinary tract infections (UTIs) but with only few and limited studies regarding its efficacy. To help address this knowledge gap we reviewed our experience with MH for UTI prophylaxis, focusing on women with recurrent uncomplicated UTIs. The University of Kentucky electronic health record was queried to identify adults who were prescribed MH from the urology clinic between January 2013 and January 2019. Charts were reviewed to assess patient-reported UTI frequency, demographics and relevant health factors. Treatment success was defined as 0-1 UTI in 6 months or 0-2 UTIs in 1 year. Of 670 patients prescribed MH, 508 did not meet inclusion criteria. The most common reasons for exclusion were complicated UTI, no return visit, treatment nonadherence and insufficient followup time. The primary study population was 162 women with recurrent uncomplicated UTIs: 41 premenopausal and 121 postmenopausal. Success rates with MH were 83% and 77%, respectively. Success rates were not significantly associated with age, diabetes, immune suppression, high-tone pelvic floor dysfunction or (if postmenopausal) vaginal estrogen use. Exploratory study of patients using intermittent catheterization showed success in 20 of 30 patients (67%). MH had high success rates for premenopausal and postmenopausal women with recurrent uncomplicated UTIs. Patients using catheters had lower success rates. Prospective trials would strengthen the evidence to guide decisions for treatment and insurance coverage.

One-pot synthesis of yolk-shell Cu/Cu2O nanospheres with tunable morphologies for assisting photocatalytic hydrogen evolution

We report a facile, one-pot synthesis of spherical Cu/Cu 2 O yolk-shell nanocrystals (Cu/Cu 2 O YSNSs) with tunable morphologies and explored their applications for assisting photocatalytic hydrogen evolution. The success of current synthesis relies on the reduction of Cu(NO 3 ) 2 by ascorbic acid in the presence of octadecyl trimethylammonium chloride (OTAC) and hexamethylenetetramine (HMTA). It is found that the variation of OTAC concentration would lead to the formation of Cu/Cu 2 O YSNSs with tunable morphologies. The as-prepared Cu/Cu 2 O YSNSs are further anchored by TiO 2 nanoparticles (Degussa P25) to construct Cu/Cu 2 O/TiO 2 nanocomposites for applications in photocatalytic H 2 evolution under simulated sunlight irritation. The resulting metal-semiconductor nanostructures have remarkable photocatalytic activity in H 2 evolution from water-methanol mixtures, with the product rate being almost 97 times greater than that of the pure P25 catalysts. Such improvement should be attributed to the unique hollow structure and the presence of multi-valent copperish species. The current study describes a feasible one-pot strategy to synthesize copperish oxide nanocrystals with tunable yolk-shell morphologies and validates their promising use in as co-catalyst for photocatalytic hydrogen evolution to illustrate the advantage from both the structure and composition. Yolk-shell Cu/Cu 2 O nanospheres with tunable morphologies are prepared in high purity via a one-pot method. By anchoring with TiO 2 nanoparticles (P25), they exhibit excellent photocatalytic activity (~97 times greater than P25 in hydrogen production rate) and long-term durability towards photocatalytic hydrogen evolution, illustrating the structural and morphological advantages.

Cytotoxicity and apoptosis response of hexagonal zinc oxide nanorods against human hepatocellular liver carcinoma cell line

Hexagonal zinc oxide nanorods (ZnO-NRs) were prepared via solution process using zinc nitrate hexahydrate (Zn(NO3)2·6H2O, 0.25 M), hexamethylenetetramine (HMT) and sodium hydroxide at low concentration (4 × 10-3 M in 100 ml of distilled water) and refluxed at 100 °C for an hour. The HMT was used because its act as a template for the nucleation and growth of zinc oxide nanorods. The X-ray diffraction patterns (XRD) clearly reveal that the grown product is pure zinc oxide. The diameters and lengths of the synthesized nanorods lie between 200 and 250 nm and 2–3 μm respectively as observed from the field emission scanning electron microscopy (FESEM). The chemical functional properties was analyzed by Fourier Transform infra-red (FTIR) spectroscopy. This study was designed to show the possible effect of ZnO-NRs in human liver cancer (HepG2) cells. It induces cytotoxicity via reactive oxygen species (ROS), mitochondrial membrane potential. For gene expression analysis, it induces apoptotic gene marker P53, Bax, caspase3, Bcl2 genes. Based on analysis and observations, it concludes that the ZnO-NRs were utilized for toxicity at dose dependent via ROS generation against human hepato cellular liver carcinoma cell line.

Surfactant-assisted synthesis of MoO3 nanorods and its application in photocatalytic degradation of different dyes in aqueous environment

The fabrication of an effective photocatalytic material for environmental applications is an active research area. In this research, MoO3 nanorods using different surfactants were fabricated using a facile hydrothermal method. Structural properties, surface morphology, chemical composition, and optical properties of the fabricated photocatalysts were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and UV–visible diffused reflectance spectroscopy. The α-MoO3 hexagonal prism shaped nanorods prepared by hexamethylenetetramine (HMTA) exhibited excellent photocatalytic activity for the decomposition of methylene blue (MB), rhodamine B (RhB) and alizarin (AZ) dyes under the irradiance of visible light as compared to other photocatalysts. Moreover, MoO3-HMTA sample showed higher degradation efficiency for MB (98%), RhB (90%) and AZ (74%) dyes within 120 min of light exposure. In addition to this, MoO3-HMTA photocatalysts demonstrated good stability in aqueous environment after five consecutive cycles. The scavenger’s effect and degradation mechanism of MB, RhB & AZ dyes is also explained with highly efficient photocatalyst material (MoO3-HMTA). The enhanced photocatalytic efficiency of prepared material was found due to rapid transition of charge carriers, reduced recombination of photogenerated electrons and holes because of good morphology.

Synthesis and crystal structure of di-aqua-bis-(hexa-methyl-enetramine-κN)bis-(thio-cyanato-κN)cobalt(II)-hexa-methyl-ene-tetra-mine-aceto-nitrile (1/2/2).

The crystal structure of the title solvated coordination compound, [Co(NCS)2(C6H12N4)2(H2O)2]·2C6H12N4·2C2H3N, consists of discrete complexes in which the Co2+ cations (site symmetry ) are sixfold coordinated by two N-bonded thio-cyanate anions, two water mol-ecules and two hexa-methyl-ene-tetra-mine (HMT) mol-ecules to generate distorted trans-CoN4O2 octa-hedra. The discrete complexes are each connected by two HMT solvate mol-ecules into chains via strong O-H⋯N hydrogen bonds. These chains are further linked by additional O-H⋯N and C-H⋯N and C-H⋯S hydrogen bonds into a three-dimensional network. Within this network, channels are formed that propagate along the c-axis direction and in which additional aceto-nitrile solvent mol-ecules are embedded, which are hydrogen bonded to the network. The CN stretching vibration of the thio-cyanate ion occurs at 2062 cm-1, which is in agreement with the presence of N-bonded anionic ligands. XRPD investigations prove the formation of the title compound as the major phase accompanied by a small amount of a second unknown phase.

Non-antibacterial methods for the prevention and treatment of recurrent lower urinary tract infections

Urinary tract infections are widespread throughout the world and occupy one of the leading places among infectious diseases. Antibacterial methods are the basis of modern treatment standards. At the same time, a widespread increase in antibiotic resistance of the main uropathogens is currently observed. In clinical practice, recurrent lower urinary tract infections are increasingly common. Following this, the main task of the doctor is to maximize the recurrence-free interval. Given the obvious negative collateral effect of long-term antibiotic prophylaxis, specialists are increasingly turning to alternative methods. Non-antibacterial preventive measures are aimed at key links in the pathogenesis of the disease, such as counteracting the penetration and adhesion of uropathogens, as well as stimulating the immune system of the macroorganism. The available physicians' toolkit includes pharmacological agents (d-mannose, methenamine hippurate, estrogens, non-steroidal anti-inflammatory drugs, probiotics, intravesical glycosaminoglycans, immunostimulants and vaccines), natural uroantiseptics (medicinal herbs and cranberry products), as well as behavioural therapy. The main advantages of non-antibacterial methods for the treatment and prevention of lower urinary tract infections are environmental friendliness. It is associated with the absence of a negative effect on the commensal flora, as well as a reduction in the risk of developing antibiotic resistance. The current guidelines provide very limited information on the application of this approach to treatment. Published studies indicate the high potential of non-antibacterial methods, some of which are comparable in effectiveness to standard therapy. However, the quality of studies and the lack of drug use standards do not allow including this approach in the existing guidelines. The need for new, high-quality clinical trials is evident.

Antibiotics Use and Subsequent Risk of Colorectal Cancer: A Swedish Nationwide Population-Based Study.

BackgroundAntibiotics use may increase colorectal cancer (CRC) risk by altering the gut microbiota, with suggestive evidence reported. Our study aims to investigate antibiotics use in relation to subsequent CRC risk.MethodsThis is a nationwide, population-based study with a matched case-control design (first primary CRC cases and 5 matched, cancer-free controls). Complete-population data, extracted from Swedish national registers for the period 2005-2016, were used to calculate odds ratios and 95% confidence intervals.ResultsWe included 40 545 CRC cases and 202 720 controls. Using the full dataset, we found a positive association between more frequent antibiotics use and CRC, excluding antibiotics prescribed within 2 years of diagnosis attenuated results toward the null. In site-specific analyses, excluding the 2-year washout, the positive association was confined to the proximal colon (adjusted odds ratio for very high use vs no use = 1.17, 95% confidence interval = 1.05 to 1.31). For rectal cancer, an inverse association, which appears to be driven by women, was observed. Quinolones and sulfonamides and/or trimethoprims were positively associated with proximal colon cancer, whereas a more general inverse association, across antibiotics classes, was observed for rectal cancer. We found no association between methenamine hippurate, a urinary tract antiseptic not affecting the gut microbiota, and CRC risk.ConclusionsThis register-based study covering the entire population of Sweden found a robust association between antibiotics use and higher risk of proximal colon cancer and an inverse association with rectal cancer in women. This study strengthens the evidence from previous investigations and adds important insight into site-specific colorectal carcinogenesis.

Hexamethylenetetramine concentration effect on CaWO4 for electrochemical hydrogen evolution reaction activity

Hexamethylenetetramine (HMT) assisted calcium tungstate nanostructures were successfully synthesized through co-precipitation method. The phase and material confirmation of scheelite type calcium tungstate nanostructures with tetragonal unit cell (a = 5.193 and c = 11.255) were done by employing X-ray diffraction (XRD). All the prepared electrocatalysts such as CW1, CW2 and CW3 crystallite sizes were 29.01, 24.86 and 17.40 nm respectively. The calculated band gap values were found to be 3.31, 3.31 and 3.27 eV for CW1, CW2 and CW3 materials respectively. Different morphology such as ball like and dumbbell shaped calcium tungstate were revealed by scanning electron microscopy (SEM). Surfactant largely plays a significant role to reduce nanostructures agglomeration. The specific surface area, pore volume and diameter of 0.1 M hexamethylenetetramine (HMT) assisted calcium tungstate nanostructure was about 24.7 m2/g, 0.141 cc/g and 3.365 nm. The surface area of the calcium tungstate nanostructures drastically enhanced hydrogen evolution reaction (HER) performance as recognized by linear sweep voltammetry. The overpotential values of CW1, CW2 and CW3 electrodes were 123, 115 and 102 mV respectively. Solution resistance (Rs) and charge transfer resistance (Rct) of synthesized materials was finding out by electrochemical impedance spectroscopy and all prepared electrocatalyst estimated values were 1.07, 1.25, 1.34 Ω and 4.06, 1.62, 0.76 Ω respectively. The stability of 0.1 M hexamethylenetetramine (HMT) assisted CaWO4 was analyzed by 16 h and it exhibited excellent robustness without any decay. The synthesized CaWO4 material exhibited superior hydrogen evolution reaction (HER) activity and the prepared electrodes was capable electro catalysts in water splitting applications.

Ship‐in‐bottle preparation of multi‐SO3H functionalized ionic liquid@MIL‐100(Fe) for acid‐catalyzed ring‐opening of epoxides

AbstractThe fact that the homogeneous acid catalysts are usually separated difficulty than heterogeneous catalysts from the reaction media, the opportunity to combine the advantages of both homogeneous and heterogeneous catalytic systems by immobilizing ILs within the pores of a porous solid support host is an alternative method. In this research, a multi‐SO3H functionalized ionic liquid derived from hexamethylenetetramine (HMTA) and 1,3‐propane sultone was entrapped inside the pores of MIL‐100(Fe) through the ship‐in‐bottle method and utilized for heterogeneous acid‐catalyzed ring‐opening of epoxides under solvent‐free conditions. The physicochemical properties of prepared catalyst were fully elucidated by various methods. FT‐IR spectroscopy and elemental analysis approved the successful incorporation of modified groups within the MIL‐100(Fe) cavities. The concentration of acid sites was measured via the acid–base titration which exhibited the 0.9 mmol/g H+ in the catalyst structure. Also, thermogravimetric analysis (TGA) profile showed the loosing of modified groups at 300–600°C. Moreover, X‐ray diffraction (XRD) analysis showed that the MIL‐100(Fe) structure was retained after modification and nitrogen adsorption–desorption analysis (BET method) manifested the decrease in surface area caused by incorporation of ionic liquid. The fabricated catalyst exhibited high catalytic efficiency in methanolysis of styrene oxide (99% conversion in 3 h) under ambient conditions and used without a substantial drop in product yield in further rounds.

Spectroscopic and pair distribution evidence for hexamethylenetetramine (HMT) as adsorbents and absorbents of nano-ceria

Spectroscopic and pair distribution evidence for hexamethylenetetramine (HMT) as adsorbents and absorbents of nano-ceria

Mass fabrication of 2D nanostructure (ZnO) in chemical growth solution using tip induced lithography

ABSTRACT The present article reports an accelerated growth technique for fabrication of 2D assembly of ZnO nanostructure and investigated the impact of concentration variance on their grown morphology. The combination of zinc nitrate hexahydrate [Zn (NO3)2 · 6H2O] and hexamethylenetetramine (HMTA) is employed as growth solution having pH value of 6.0. The assembly of 2D nanostructures grown on microtip is accelerated by introducing the ultrafine discharge in the chemical growth solution. The synthesis, deposition, and growth time were limited to 20 seconds only. After deposition and growth, annealing heat treatment was applied at 95°C for 45 minutes to eliminate any impurities or crystal defects. The structural/morphological characterization through FESEM confirms that the fabricated nanostructure is of 2D nanosheet-like at lower molar concentration (0.10 M). Nevertheless, at higher concentration (0.20 M), the grown morphology changes to marigold flower-like structure with porousness in its crystal structure. The chemical characterization through EDX confirms the dominance of the ZnO in the fabricated nanostructure. The XRD results confirm the phase pure hexagonal wurtzite structure of ZnO with an average crystalline thickness of ≈27 nm. The availability of functional group and molecular fingerprint corresponds to ZnO stretching is identified by FTIR while elemental composition and their chemical states were analyzed by XPS.

Degradation of the O-phenylphenol Fungicide in Water by Unconventional CeO2-WO3 Photocatalysts

Background: Water pollution due to emerging contaminants such as pesticides, pharmaceutics and/or plasticizers, is a serious environmental problem strictly connected to the safety of human and ecosystem life. For this reason, the development of high-performing (photo)catalysts for water purification is crucial. Objective: In recent years, the synergistic effects in Advanced Oxidation Processes (AOPs) can perform better strategies to remove recalcitrant contaminants from water. In this contest, the (photo)catalytic activity of CeO2-WO2materials for the degradation of the orto-phenylphenol fungicide comparing the photocatalytic, the Fenton and the photo-Fenton-like processes, has been examined. Methods: The samples were synthetized through deposition-precipitation mediated with the hexamethylenetetramine (HMTA) surfactant. The chemico-physical properties of the materials were examined by Raman, UV-Vis Diffuse Reflectance (Uv-vis DRS) and X-Ray photoelectron (XPS) spectroscopies, N2 adsorption-desorption measurements and transmission electron microscopy (TEM). The (photo)catalytic measurements were made through a home-made photoreactor irradiated by a solar lamp. The degradation of the fungicide was measured by UV-vis spectroscopy. Results : An efficient heterojunction was formed between the CeO2 and the WO2 oxides, which provided a good degradation percentage of the pesticide (65%) employing the solar photo-Fenton-like reaction that was the best performing process among the three investigated AOPs. The addition of WO3on CeO2 facilitated the ionic exchange between the Ce and the W ions, boosting the redox properties of cerium oxide. Conclusions: The strong interaction between CeO2 and WO3 and the peculiar properties of this unconventional composite pave the way to its use as a promising material for water depollution.

Nickel-Doped ZnO Nanowalls with Enhanced Electron Transport Ability for Electrochemical Water Splitting.

This article reports on the growth of 3 mol% nickel (Ni)-doped zinc oxide nanowalls (ZnO NWLs) using the hydrothermal method. Morphological investigation as well as electrical conductivity of the undoped and Ni-doped ZnO NWLs was also discussed. The surface roughness of the formed ZnO NWLs was reduced after Ni-doping. The pore size of Ni-doped ZnO NWLs can be controlled by changing the concentration of hexamethylenetetramine (HMT). As the HMT concentration increased, the pores became larger with increasing surface roughness. The electrical conductivity of the electron-only device based on the Ni-doped ZnO NWLs was higher than that of the undoped one, and it was decreased with increasing the HMT concentration. Our results reveal that Ni-doping and adjustment of the HMT concentration are two key approaches to tune the morphology and electrical properties of ZnO NWLs. Finally, the undoped and Ni-doped ZnO NWLs were used as the catalyst for electrochemical water splitting. The Ni-doped ZnO NWLs with the HMT concentration of 1 mM showed the highest electrochemical performance, which can be attributed to the increased surface area and electrical conductivity.

Columnar nitrogen-doped ZnO nanostructured thin films obtained through atomic layer deposition

The present study was aimed to develop nitrogen-doped nanostructured ZnO thin films. These films were produced in a sequential procedure involving the atomic layer deposition technique, and a hydrothermal process supported by microwave heating. Employing the atomic layer deposition technique, through self-limited reactions of diethylzinc (DEZn) and H2O, carried out at 3.29 × 10−4 atm and 190 °C, a high-quality ZnO seed was grown on a Si (100) substrate, producing a textured film. In a second stage, columnar ZnO nanostructures were grown perpendicularly oriented to the silicon substrate on those films, using a solvothermal process in a microwave heating facility, employing Zn(NO3)2 as zinc precursor, while hexamethylenetetramine (HMTA) was used to produce the bridging of Zn2+ ions. The consequence of N-doping concentration on the physicochemical properties of ZnO thin films was studied. The manufactured films were structurally analyzed by scanning electron microscopy and x-ray diffraction. Also, x-ray photoelectron spectroscopy, Raman, and UV–vis spectroscopies were used to provide further insight on the effect of nitrogen doping. The N-doped films displayed textured wurtzite-like structures that changes their preferential growth from the (002) to the (100) crystallographic plane, apparently promoted by the increase of nitrogen precursor. It is also shown that nitrogen-doped films undergo a reduction in their bandgap, compared to ZnO. The methodology presented here provides a viable way to perform high-quality N-ZnO nanostructured thin films.