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In recent years, functional material surface functionalization has grown into an expanding area of research due to the development and design of advanced systems and devices for key areas in biotechnology, smart sensing, environmental applications and manufacturing. In this work, NdNiO 3 surface was functionalized with octadecylphosphonic acid (ODP) using liquid phase reaction to attain superhydrophobic properties. The resulting ODP modified surface exhibited dual-scale roughness with a stable static contact angle of 170 ± 2°. Electron microscopy micrographs of ODP crystals formed revealed a non-uniform lateral growth characteristics. The presence of ODP hydrocarbon chains was confirmed using Fourier transform infrared spectroscopy with characteristic peaks at 2924 cm −1 and 2851 cm −1 .

In this work, sustainable metal recovery from waste and conversion into Cu-micronutrient-containing N fertilizers was developed utilizing the HNO3 extraction method. For this purpose, solubility diagrams, i.e., polytherms, were constructed of the ternary CO(NH2)2-Cu(NO3)2-H2O and NH4NO3-Cu(NO3)2-H2O systems to determine the corresponding phase equilibria and solid material chemical composition. Copper extraction in the form of water-soluble Cu(NO3)2 was performed from the industrial Cu cable manufacturing waste, using HNO3 concentrations relevant to the industrial conditions (56–58%) at a moderate temperature of 60 °C. Waste dissolution in aqueous NH4NO3 solutions resulted in only partial dissolution of

Sustainable metal recovery from waste is of utmost importance. Zn is a micronutrient that is abundant in many industrial wastes. In this work, the process of converting industrial white pigment waste into a Zn micronutrient containing nitrogen fertilizers was developed utilizing an HNO3 extraction method. For this purpose, solubility diagrams, polytherms, were constructed of the ternary CO(NH2)2–Zn(NO3)2–H2O and NH4NO3–Zn(NO3)2–H2O systems to determine the corresponding phase equilibria and solid material chemical composition. Complex salts containing Zn and two and four urea molecules were observed and the catalytic Zn(NO3)2 effect was observed at the decomposition temperature of CO(NH2)2 during thermal analysis. Two crystalline phases of NH4NO3, namely III and IV, were observed and the corresponding transition temperature decreased with increasing Zn(NO3)2 concentration in solution. Zn extraction in the form of soluble Zn(NO3)2 was performed from the white pigment industrial waste and optimal extraction...

Semiconducting tin sulfide (SnS) was deposited electrochemically from electrolytes containing Sn and S precursors and conditions optimized to maximize its performance as a photoelectrode. Films composed of primarily orthorhombic SnS were electrodeposited on titanium substrates from electrolyte containing 20 mM SnSO4 and 100 mM Na2S2O3 at pH 2.5. For deposition a cathodic pulse of −1.25 V vs Ag/AgCl was applied for 2.75 s followed by a 0.25 s pulse of +0.25 V vs Ag/AgCl repeated for 30–45 min. The films were annealed in argon at 300 °C for 3 h. The addition of SbCl3 ( 5%) the dopants resulted in the formation of secondary phases of Sb and...

A smart ionic co-crystal of urea with KCl and ZnCl2 has been obtained in two polymorphic modifications via mechanochemical and solution methods and proven to be a very efficient urease inhibitor while, simultaneously, able to provide soil nutrients to complement N supply.

Zn–Co oxide films were prepared by electrochemical deposition under potentiostatic conditions. The effects of synthesis conditions on structure, morphology, composition and electrochemical properties of deposited films were studied by atomic absorption spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and photovoltammetry analysis. It has been determined that the as-deposited films are lamellar with intercalated acetate ions, consisting of ZnO and α-Co(OH)2 phases. The annealed films retain the same structure without impurities and consist of wurtzite-type ZnO and spinel-type Co3O4. The photoelectrochemical performance and the specific capacitance of the prepared electrodes were evaluated in 0.1 mol × L−1 NaOH aqueous solutions. The obtained experimental results showed that the values of specific capacitance increase with the increase in the amount of cobalt (hydr)oxide. On the contrary, the photoactivity decreases with the increase in cobalt content in the films.

Face-to-face perfluorophenyl–perfluorophenyl interactions (C6F5···C6F5) are achieved in a disilver metal–organic complex. The C6F5···C6F5 interactions along with argentophilic forces support trans-pentafluorostilbazole to undergo a head-to-head [2 + 2] photodimerization to form a cyclobutane that sustains a fluorinated two-dimensional metal–organic framework.

We examined the degradation of 2-naphthol in a pilot dielectric barrier discharge (DBD) semi-continuously operated non-thermal plasma reactor. Plasma was generated in a quartz tube with the ambient air used as a feed gas for the reactor. The performance of the reactor was evaluated according to the ozone amount produced both in the gas and liquid phase, as well as the overall decomposition efficiency of 2-naphthol. The decomposition kinetics, as well as the intermediary reactive products of 2-naphthol decomposition were determined using the combination of high performance liquid chromatography with ultraviolet detection (HPLC/UV), Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectroscopy (GC/MS) analyses. The overall effectiveness of the process was established according to the degree of total organic carbon (TOC) mineralization, while toxicity tests were performed using Daphnia magna . Ozone production (i.e., its concentration in the gas phase), ranged between 0.39 mg L −1 and 1.52 mg L −1 when varying the discharge power between 5 and 33 W. The decomposition efficiency of 2-napthtol reached 98.6% in 6 min at 33 W based on the HPLC measurements. The FTIR and GC/MS analyses revealed that degradation intermediates consisted mostly of oxygen functional group containing compounds, such as carboxylic acids. Based on the data reported here, we propose a novel dual stage organic wastewater decomposition reactor utilizing excess renewable electricity.

The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnOEvonik TiO2 P25Hombikat TiO2WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA.

A facile synthetic method (in as little as four hours) for simultaneously loading high amounts of titania (Si/Ti = 3) and Pd0 co-catalyst (0.1 wt.% per gram of total catalyst) in cubic mesoporous MCM-48 material was developed at room temperature. The solar simulated photocatalytic hydrogen evolution from photocatalysts containing Pd0 and TiO2 nanoclusters in periodic cubic MCM-48 and aperiodic mesoporous silica was compared. The results indicate that the periodicity of the mesoporous silica support, the oxidation state of Pd, the location and dispersion of Pd0 have a significant impact on the photocatalytic activity. Periodic cubic MCM-48 mesoporous silica containing Pd0 in close contact with titania exhibit superior hydrogen evolution rates compared to Pd0-TiO2 containing aperiodic mesoporous silica. The highly ordered and open three-dimensional mesoporous cubic MCM-48 support has high surface area and facilitate good dispersion and close contact of titania and Pd0. At very low loadings of 0.1 wt.% of Pd, hydrogen yield was found to be 560 μ mol h−1, which is among the highest reported in the literature for Pd0 containing TiO2 based materials under solar simulated conditions. The results suggest that the pore architecture of the support is also an important parameter that governs the photocatalytic activity. In addition, the Pd0-mesoporous materials in general possess higher activity than Pd2+ containing mesoporous materials. The photocatalysts were extensively characterized by a variety of techniques such as powder X-ray diffraction (XRD), nitrogen sorption analysis, transmission and scanning electron microscopic studies, photoluminescence, diffuse reflectance spectroscopy (DRS), CO Chemisorption, and X-ray photoelectron spectroscopy (XPS).

Polyamide (PA) incorporated CdSe–CdS films were deposited using sorption–diffusion method. A single precursor – K2SeS2O6 was used as both sulfur and selenium source. In aqueous solution, SeS2O62− diffused into the polymer where it reacted with Cd2+ ions to form cadmium chalcogenide particles. Crystallinity of the composite material was analyzed via XRD and both CdSe and CdS were detected within the material at all deposition conditions of temperature and SeS2O62− – chalcogenization – exposure time. A complex surface speciation was obtained using XPS analysis. Formation of the protonated amide species was observed in combination with the adsorbed SO42− on the surface of the polymer confirming that SeS2O62− and its decomposition products hydrolyzed to form cadmium chalcogenides and H2SO4. A significant red shift in UV–vis spectrum was observed with the increasing chalcogenization time of PA, whereas Cd2+ solution temperature had very little effect on the apparent thickness and the optical properties of the composite materials. SEM surface analysis revealed sub-micron particles deposited on top of the PA–CdSe–CdS composite materials in continuous overlapping films, showing a possible dual crystal growth mechanism.

Graphene oxide (GO) has been recognized as an important intermediate compound for a potential low-cost large-scale graphene-like film fabrication. In this work, graphene oxide multilayer films deposited on glass substrate were reduced using different thermal reduction methods, including low-temperature annealing, flame-induced and laser reduction, and the corresponding surface morphology and structural properties were investigated. These graphene oxide thermal reduction methods strongly affected surface morphology and differently facilitated structural and chemical transformations of graphene oxide. As evidenced by Raman measurements, thermal annealing and laser reduction of graphene oxide produced more ordered graphene-like structure multilayer films. However, surface morphological differences were observed and attributed to the different de-oxidation mechanisms of GO. This Letter provides an important systematic comparison between the GO reduction methods and thermally-driven structural changes they provide to the reduced GO multilayer films obtained.

Design and manufacture of high nitrogen content sulfur-containing fertilizers is of crucial importance in sustainable food and energy crop production. The availability of large elemental sulfur amounts in oil refining and natural gas processing facilities, in combination with decreasing sulfur deposition into soil from natural and anthropogenic sources in a bioavailable sulfate form, calls for innovative engineering solutions that bridge this gap via sustainable sulfur processing. Diurea sulfate-based liquid and compound solid granulated fertilizers were synthesized in this work, and their resulting physicochemical properties were determined. First, phase compositional information on the 2CO(NH2)2·H2SO4–CO(NH2)2–H2O ternary system was measured, and high nitrogen content, ∼15:1 N:S ratio liquid fertilizer grades, were established. Next, diurea sulfate granulation experiments using (i) dolomite, (ii) byproduct material after the phosphoric acid extractive production, CaSO4·0.5H2O, and (iii) dolomite combine...

We present a novel high throughput photocatalyst efficiency assessment method based on 96-well microplates and UV-Vis spectroscopy. We demonstrate the reproducibility of the method using methyl orange (MO) decomposition, and compare kinetic data obtained with those provided in the literature for large conventional photoreactors. To demonstrate the example of the method capabilities, we rapidly screened the effects of salts, potentially present in wastewater, on kinetic rates of MO decomposition, and briefly discuss the obtained data comparing it with the existing literature obtained using conventional photoreactors.

Current climate and atmospheric chemistry models assume that all sea spray particles react as if they are pure NaCl. However, recent studies of sea spray aerosol particles have shown that distinct particle types exist (including sea salt, organic carbon, and biological particles) as well as mixtures of these and, within each particle type, there is a range of single-particle chemical compositions. Because of these differences, individual particles should display a range of reactivities with trace atmospheric gases. Herein, to address this, we study the composition of individual sea spray aerosol particles after heterogeneous reaction with nitric acid. As expected, a replacement reaction of chloride with nitrate is observed; however, there is a large range of reactivities spanning from no reaction to complete reaction between and within individual sea spray aerosol particles. These data clearly support the need for laboratory studies of individual, environmentally relevant particles to improve our fundamental understanding as to the properties that determine reactivity.

Fresh mineral aerosol has recently been found to be effective cloud condensation nuclei (CCN) and contribute to the number of cloud droplets in the atmosphere due to the effect of water adsorption on CCN activation. The work described here uses experimental water adsorption measurements on Na-montmorillonite and illite clay to determine empirical adsorption parameters that can be used in a recently derived theoretical framework (Frenkel–Halsey–Hill Activation Theory, FHH-AT) that accounts for the effect of water adsorption on CCN activation. Upon fitting the Frenkel–Halsey–Hill (FHH) adsorption model to water adsorption measurements, we find FHH adsorption parameters, AFHH and BFHH, to be 98 ± 22 and 1.79 ± 0.11 for montmorillonite and 75 ± 17 and 1.77 ± 0.11 for illite, respectively. The AFHH and BFHH values obtained from water adsorption measurements differ from values reported previously determined by applying FHH-AT to CCN activation measurements. Differences in FHH adsorption parameters were attributed to different methods used to obtain them and the hydratable nature of the clays. FHH adsorption parameters determined from water adsorption measurements were then used to calculate the critical super-saturation (sc) for CCN activation using FHH-AT. The relationship between sc and the dry particle diameter (Ddry) gave CCN activation curve exponents (xFHH) of −0.61 and −0.64 for montmorillonite and illite, respectively. The xFHH values were slightly lower than reported previously for mineral aerosol. The lower exponent suggests that the CCN activity of hydratable clays is less sensitive to changes in Ddry and the hygroscopicity parameter exhibits a broader variability with Ddry compared to more soluble aerosols. Despite the differences in AFHH, BFHH and xFHH, the FHH-AT derived CCN activities of montmorillonite and illite are quite similar to each other and in excellent agreement with experimental CCN measurements resulting from wet-generated clay aerosol. This study illustrates that FHH-AT using adsorption parameters constrained by water adsorption is a simple, valid method for predicting CCN activation of fresh clay minerals and provides parameters that can be used in atmospheric models to study the effect of mineral dust aerosol on cloud formation and climate.

Several remarkable observations regarding structure, (surface) composition and visible light induced photocatalytic activity of Bi-promoted Anatase photocatalysts are reported. First, XPS characterization data show that compositions of mixed Bi-Ti-oxide phases obtained by hydrothermal treatment at 180 °C of aqueous solutions of ethanol, titanium n-butoxide, and bismuth nitrate, are surface enriched with a specific fraction of metallic-like bismuth. Second, the formation of highly dispersed nanoparticles of platinum on these composites by photo-deposition is accompanied by significant morphological changes. Third, the platinum functionalized, bismuth-promoted Anatase composites exhibit extraordinary photocatalytic activity in the photocatalytic degradation of organic compounds (acid orange 7 and salicylic acid, respectively) upon illumination at 447 nm, higher than observed for P25 upon UV illumination in similar reactor configuration. An optimized Pt-Bi-Ti-Ox composite consists of 1 wt% Pt and 5 wt% Bi. The high activity of the composite is discussed on the basis of the crystalline morphology and surface composition

The catalytic activity and hydrocarbon selectivity in electrochemical carbon dioxide (CO2) reduction on cuprous oxide (Cu2O) derived copper nanoparticles is discussed. Cuprous oxide films with [100], [110] and [111] orientation and variable thickness were electrodeposited by reduction of copper(ii) lactate on commercially available copper plates. After initiation of the electrochemical CO2 reduction by these oxide structures, the selectivity of the process was found to largely depend on the parent Cu2O film thickness, rather than on the initial crystal orientation. Starting with thin Cu2O films, besides CO and hydrogen, selective formation of ethylene is observed with very high ethylene-to-methane ratios (∼8 to 12). In addition to these products, thicker Cu2O films yield a remarkably large amount of ethane. Long term Faradaic efficiency analysis of hydrocarbons shows no sign of deactivation of the electrodes after 5 hours of continuous experiment. Online mass spectroscopy studies combined with X-ray diffraction data suggest the reduction of the Cu2O films in the presence of CO2, generating a nanoparticulate Cu morphology, prior to the production of hydrogen, CO, and hydrocarbons. Optimizing coverage, number density and size of the copper nanoparticles, as well as local surface pH, may allow highly selective formation of the industrially important product ethylene.

TiO2–SiO2 mixed oxide materials were hydrothermally synthesized and the photocatalytic degradation of phenol under UV-irradiation was evaluated. We also demonstrated that varying the co-solvent, modulates the structural properties of the materials. In particular, the use of non-polar co-solvents such as toluene seemed to increase the crystallinity, surface area, and pore diameter while the crystallite size of titania seemed to change little. A comprehensive characterization using surface and bulk techniques evidenced the role of porosities, crystallinity, and Ti–O–Si linkages of the mixed oxides as significant factors that contribute to the degradation of phenol. The TiO2–SiO2 mixed oxide material prepared using only ethanol as the solvent showed 24% degradation of phenol after 120 min of irradiation whereas other mixed oxide materials degraded phenol more efficiently (57% to 100%) in the same duration of time. The higher photocatalytic activities of the mixed oxide materials prepared using non-polar solvents is attributed to a combination of factors that include higher Apparent Surface Coverages of Ti–O–Si heterolinkages, larger pore sizes, and most importantly higher crystallinities of the titania phase. Larger pore sizes enabled better transport of reactant molecules and products to and from the active sites (Ti–O–Si heterolinkages) and the higher crystallinities of the titania phase helped in minimizing the electron–hole recombination in these photocatalysts, and thus resulted in high degradation efficiencies.

Herein, we present a simple method for fabricating plasma polymerized hexamethyldisiloxane films (pp-HMDSO) possessing superhydrophobic characteristics via arc discharge. The pp-HMDSO films were deposited on a soda–lime–silica float glass using HMDSO monomer vapor as a precursor. A detailed surface characterization was performed using scanning electron microscopy and atomic force microscopy. The growth process of the pp-HMDSO films was investigated as a function of deposition time from 30 to 300 s. The non-wetting characteristics of the pp-HMDSO films were evaluated by means of contact angle (CA) measurements and correlated with the morphological characteristics, as obtained from microscopy measurements. The deposited films were found to be nano-structured and exhibited dual-scale roughness with the static CA values close to 170°. Fourier transform infrared spectroscopy analysis was carried out to investigate chemical and functional properties of these films. Methyl groups were identified spectroscopically to be present within the pp-HMDSO films and were proposed to result in the low surface energy of material. The synergy between the dual-scale roughness and low surface energy resulted in the superhydrophobic characteristics of the pp-HMDSO films. A possible mechanism for the pp-HMDSO film formation is proposed.

The surface photochemistry of nitrate, formed from nitric acid adsorption, on hematite (α-Fe2O3) particle surfaces under different environmental conditions is investigated using X-ray photoelectron spectroscopy (XPS). Following exposure of α-Fe2O3 particle surfaces to gas-phase nitric acid, a peak in the N1s region is seen at 407.4 eV; this binding energy is indicative of adsorbed nitrate. Upon broadband irradiation with light (λ300 nm), the nitrate peak decreases in intensity as a result of a decrease in adsorbed nitrate on the surface. Concomitant with this decrease in the nitrate coverage, there is the appearance of two lower binding energy peaks in the N1s region at 401.7 and 400.3 eV, due to reduced nitrogen species. The formation as well as the stability of these reduced nitrogen species, identified as NO(-) and N(-), are further investigated as a function of water vapor pressure. Additionally, irradiation of adsorbed nitrate on α-Fe2O3 generates three nitrogen gas-phase products including NO2, NO, and N2O. As shown here, different environmental conditions of water vapor pressure and the presence of molecular oxygen greatly influence the relative photoproduct distribution from nitrate surface photochemistry. The atmospheric implications of these results are discussed.

Sustainable, low temperature methods of natural gas activation are critical in addressing current and foreseeable energy and hydrocarbon feedstock needs. Large portions of natural gas resources are still too expensive to process due to their high content of hydrogen sulfide gas (H2S) in mixture with methane, CH4, altogether deemed as sub-quality or “sour” gas. We propose a unique method for activating this “sour” gas to form a mixture of sulfur-containing hydrocarbon intermediates, CH3SH and CH3SCH3, and an energy carrier, such as H2. For this purpose, we computationally investigated H2S mediated methane activation to form a reactive CH3SH species via direct photolysis of sub-quality natural gas. Photoexcitation of hydrogen sulfide in the CH4+H2S complex results in a barrier-less relaxation via a conical intersection to form a ground state CH3SH+H2 complex. The resulting CH3SH can further be heterogeneously coupled over acidic catalysts to form higher hydrocarbons while the H2 can be used as a fuel. This process is very different from a conventional thermal or radical-based processes and can be driven photolytically at low temperatures, with enhanced controllability over the process conditions currently used in industrial oxidative natural gas activation. Finally, the proposed process is CO2 neutral, as opposed to the currently industrially used methane steam reforming (SMR).

A hydrothermal method based on the use of hydrogen peroxide is described to grow a homogeneous layer of tungsten oxide (WO3) on a platinum (Pt) film supported on a silicon wafer. WO3 growth is highly selective for Pt when present on silicon in a patterned arrangement, demonstrating that Pt catalyzes decomposition of the WO3 precursor in solution. The obtained Pt/WO3 interface yields high photocurrents of 1.1 mA/cm(2) in photoelectrochemical water splitting when illuminated by a solar simulator. The photocurrents are significantly higher than most previously reported values for hydrothermally grown layers on indium-tin oxide and fluorine-tin oxide glasses. The selective growth method thus provides new options to effectively implement WO3 in photoelectrochemical devices.

Organic acids in the atmosphere are ubiquitous and are often correlated with mineral dust aerosol. Heterogeneous chemistry and the uptake of organic acids on mineral dust particles can potentially alter the properties of the particle. In this study, heterogeneous uptake and reaction of formic acid, HCOOH, the most abundant carboxylic acid present in the atmosphere, on oxide and clays of the most abundant elements, Si and Al, present in the Earth's crust are investigated under dry and humid conditions. In particular, quantitative adsorption measurements using a Quartz Crystal Microbalance (QCM) coupled with spectroscopic studies using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy are combined to allow for both quantification of the amount of uptake and identification of distinct adsorbed species formed on silica, alumina, and kaolinite particle surfaces at 298 K. These oxides and clay particles show significant differences in the extent and speciation of adsorbed HCOOH due to inherent differences in surface -OH group reactivity. Adsorbed water, controlled by relative humidity, can increase the irreversible uptake of formic acid. Interestingly, the resulting layer of adsorbed formate on the particle surface decreases the particle hydrophilicity thereby decreasing the amount of water taken up by the surface as measured by QCM. Atmospheric implications of this study are discussed.

A study of copper selenide (CuxSe) thin film deposition on PA 6 polymer surface via adsorption/diffusion method and the resulting surface properties is presented. A two stage process used to deposit these thin films involves (a) selenization in 0.1 M K2SeS2O6 at pH 2.15 and 60 °C followed by (b) treatment with 0.34 M Cu(II) and 0.06 M Cu(I) salt solution at 80 °C. Resulting chemical and physical properties of CuxSe films were investigated using XRD, XPS, SEM and sheet resistivity measurements. XRD data showed a complex mixture of CuxSe phases with peaks due to the elemental Se present at longer exposures. Thin film bulk elemental composition varied with the exposure time whereas XPS analysis showed surface to be slightly copper enriched. Additionally, mostly CuSe bonds were observed on the surface with minor oxidation products. SEM crossectional analysis showed distinct CuxSe film formation on PA 6 surface with thickness of ∼1–5 μm. Finally, it was found that sheet resistance of 150 ± 10 Ω/□ was achieved after 120 min of selenization for all samples and remained constant after longer exposures

Silver sulfide (Ag2S), an efficient solar light absorber, was synthesized using a modified chemical bath deposition (CBD) method and polyamide 6 (PA) as a host material via solution phase reaction between AgNO3 and Na2S2O3. X-ray diffraction (XRD) data showed a single, α-Ag2S (acanthite), crystalline phase present while surface and bulk chemical analyses, performed using X-ray photoelectron (XPS) and energy dispersive (EDS) spectroscopies, showed 2:1 Ag:S ratio. Direct and indirect bandgaps obtained from Tauc plots were 1.3 and 2.3 eV, respectively. Detailed surface chemical analysis showed the presence of three distinct sulfur species with majority component due to the Ag2S chemical bonds and minority components due to two types of oxygen–sulfur bonds. Conductivity of the resulting composite material was shown to change with the reaction time thus enabling to obtain controlled conductivity composite material. The synthesis method presented is based on the low solubility of Ag2S and is potentially green, no by-product producing, as all Ag2S nucleated outside the host material can be recycled into the process via dissolving it in HNO3.

Single particle analysis of individual sea spray aerosol particles shows that cations (Na(+), K(+), Mg(2+), and Ca(2+)) within individual particles undergo a spatial redistribution after heterogeneous reaction with nitric acid, along with the development of a more concentrated layer of organic matter at the surface of the particle. These data suggest that specific ion and aerosol pH effects play an important role in aerosol particle structure in ways that have not been previously recognized.

Ag/ZnO powders were synthesized through a precipitation method, using poly(ethylene oxide)-block-poly(propylene oxide) as stabilizer. X-ray diffraction patterns of all prepared powders showed a mixed phase of Ag and ZnO. The existence of metallic Ag on the surface of all prepared ZnO powders was confirmed by X-ray photoelectron spectroscopy. Their photocatalytic activities were investigated through the degradation of a methylene blue solution under blacklight illumination. The Ag/ZnO prepared from the Zn2+ solution containing 7 mol% of Ag+ had the highest photocatalytic activity and this also showed better photocatalytic activity than a commercial ZnO powder.

This work investigates water droplet behavior on superhydrophobic (water contact angle value of 162 ± 1°) SiO2 nanocomposite films subjected to repetitive icing/deicing treatments, changes in SiO2 nanocomposite film surface morphology and their non-wetting characteristics. During the experiment, water droplets on SiO2 nanocomposite film surface are subjected to a series of icing and deicing cycles in a humid (~ 70% relative humidity) atmosphere and the resulting morphological changes are monitored and characterized using atomic force microscopy (AFM) and contact angle measurements. Our data show that the formation of the frozen or thawed water droplet, with no further shape change, on superhydrophobic SiO2 nanocomposite film, is obtained faster within each cycle as the number of the icing/deicing cycles increases. After 10 icing and deicing cycles, the superhydrophobic SiO2 nanocomposite film had a water contact angle value of 146 ± 2° which is effectively non-superhydrophobic. AFM analysis showed that the superhydrophobic SiO2 nanocomposite film surface area under the water droplet undergoes gradual mechanical damage during the repetitive icing/deicing cycles. We propose a possible mechanism of the morphological changes to the film surface that take place during the consecutive icing/deicing experiments.

Despite the widespread use of the anabolic androgen trenbolone acetate (TBA) in animal agriculture, evidence demonstrating the occurrence of TBA metabolites such as 17β-trenbolone (17β-TBOH), 17α-trenbolone (17α-TBOH), and trendione (TBO) is relatively scarce, potentially due to rapid transformation processes such as direct photolysis. Therefore, we investigated the phototransformation of TBA metabolites and associated ecological implications by characterizing the photoproducts arising from the direct photolysis of 17β-TBOH, 17α-TBOH, and TBO and their associated ecotoxicity. LC-HRMS/MS analysis identified a range of hydroxylated products that were no longer photoactive, with primary photoproducts consisting of monohydroxy species and presumptive diastereomers. Also observed were higher-order hydroxylated products probably formed via subsequent reaction of primary photoproducts. NMR analysis confirmed the formation of 12,17-dihydroxy-estra-5(10),9(11),dien-3-one (12-hydroxy-TBOH; 2.2 mg), 10,12,17-trihydroxy-estra-4,9(11),dien-3-one (10,12-dihydroxy-TBOH; 0.7 mg), and a ring-opened 11,12-dialdehyde oxidation product (TBOH-11,12-dialdehyde; 1.0 mg) after irradiation of ∼14 mg of 17β-trenbolone. Though unconfirmed by NMR, our data suggest that the formation of additional isomeric products may occur, likely due to the reactivity of the unique 4,9,11 conjugated triene structure of trenbolone. In vivo exposure studies employing Japanese medaka (Oryzias latipes) indicate that low concentrations of 17α-TBOH photoproduct mixtures can alter ovarian follicular development, and photoproducts alter whole-body 17β-estradiol levels. Therefore, direct photolysis yields photoproducts with strong structural similarity to parent steroids, and these photoproducts still retain enough biological activity to elicit observable changes to endocrine function at trace concentrations. These data indicate that environmental transformation processes do not necessarily reduce steroid hormone ecotoxicity.

Chromium containing mesoporous silica materials were synthesized via a modified Stober synthesis at room temperature. The chromium ion loading and the effect of counter ion in the synthesis were studied in detail. The mesoporous materials were extensively characterized by powder X-ray diffraction (XRD), N2 physisorption, Atomic Absorption Spectroscopy (AAS), Fourier-Transform-Infrared Spectroscopy (FT-IR), Diffuse Reflectance Spectroscopy (DRS UV–Vis), hydrogen Temperature-Programmed Reduction (H2-TPR), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM) studies. A transition from Ia View the MathML source3¯d cubic phase to p6mm hexagonal or wormhole phases was noted as more amounts of chromium were incorporated into the siliceous materials. Chromium species present in the silica matrix include monochromate, polychromate, and chromium oxide (Cr2O3) clusters.

We report a facile method for the synthesis of 4-mercaptobenzoic acid (MBA) stabilized CdS-trititanate nanotube (CdS-TNT) composite materials. The resultant materials were well characterized by powder X-Ray Diffraction (XRD), N2 physisorption, Raman spectroscopy, UV–Visible Diffuse Reflectance spectroscopy (DRS), Fourier-Transform Infra-Red (FT-IR) spectroscopy, Photoluminescence (PL) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Atomic Absorption Spectroscopy (AAS), and Transmission Electron Microscopy (TEM). The photocatalytic performances of these materials were evaluated by monitoring the amount of hydrogen evolved from water under visible light irradiation. The amount of hydrogen evolved from MBA stabilized CdS-TNT composite materials were higher compared to MBA stabilized CdS, suggesting an important role of the TNT support. The enhanced photocatalytic hydrogen generation in MBA stabilized CdS-TNT composite materials compared to CdS-MBA might have arisen from the effective charge separation in CdS-TNT composite materials, which was further supported by PL studies.

Return of the Steroid Trace levels of organic contaminants enter aquatic ecosystems from a variety of sources, including runoff of from agricultural lands. When these compounds and their metabolites break down, it is generally assumed that they become inert and pose less ecological risk. Qu et al. (p. 347 , published online 26 September) tracked the sunlight-mediated transformation of metabolites of trenbolone acetate (TBA)—a common growth-promoting steroid given to beef cattle—across a number of conditions in the laboratory and in the field. When the degradation products were exposed to dark conditions following photodegradation, they surprisingly reverted back to TBA metabolites, including analog steroidal compounds similar to TBA with unknown biological effects.

Ag3PO4 was synthesized by the precipitation method using three different types of phosphate salts (Na3PO4, Na2HPO4, and NaH2PO4) as a precipitating agent. Hydrolysis of each phosphate salt gave a specific pH that affected the purity and morphology of the prepared Ag3PO4. The Ag3PO4 prepared from Na2HPO4 showed the best photocatalytic activity induced by visible light to degrade methylene blue dye. During the photocatalytic process, Ag3PO4 decomposed and produced metallic Ag, and this evidence was confirmed by the X-ray diffraction technique and X-ray photoelectron spectroscopy. The photocatalytic efficiency decreased with the number of recycles used. This Ag3PO4 photocatalyst also degraded another cationic dye, rhodamine B, but did not degrade reactive orange, an anionic dye. The degraded products produced by the photocatalysis had lower toxicities than the untreated dyes using Chlorella vulgaris as a bioindicator

In this work, amorphous hydrogenated carbon (a-C:H), SiO x containing a-C:H (a-C:H/SiO x ) and nitrogen-doped a-C:H/SiO x (a-C:H:N/SiO x ) thin films were deposited on chromium thin film coated glass using a closed drift ion beam source. Acetylene gas, hexamethyldisiloxane and hydrogen or 20% nitrogen/hydrogen mixture were used as precursors. Resulting hydrogenated carbon thin film surface morphology as well as their cohesive and adhesive properties were studied using progressive loading scratch tests followed by optical microscopy analysis. Surface analysis was also performed using atomic force microscopy via topography, surface morphology parameter, height distribution histogram and bearing ratio curve based hybrid parameter measurements. The a-C:H/SiO x and a-C:H:N/SiO x thin films showed better mechanical strength as compared to the conventional a-C:H films. X-ray photoelectron spectroscopy was used to determine the chemical composition of these films. It showed increased amounts of silicon and absence of terminal oxygenated carbon bonds in a-C:H:N/SiO x thin film which was attributed to its improved mechanical properties.

The influence of Ti–O–Si hetero-linkages in the degradation of Rhodamine B (RhB) dye over TiO2–SiO2 xerogels is exemplified by XPS analysis. We demonstrate a relationship between the percentage surface content of Ti–O–Si and the rate of photocatalytic degradation of RhB. Our detailed surface investigation revealed that the overall degradation of RhB is enhanced due to the high surface percentage content of Ti–O–Si species, high crystallinity of titania phase, and its effective dispersion on a high surface area porous silica support.

This review discusses modern developments in CO2 surface chemistry by focusing on the work published since the original review by H.J. Freund and M.W. Roberts two decades ago (Surface Science Repor ...

Methyl mercaptan, CH3SH, is an industrial waste as well as the reactive product of several H2 and H2S induced catalytic hydrogenation processes of COS and CS2. Its coupling into value added products is of great importance in monetizing sour natural gas. In the present work, the full theoretical cycle of catalytic CH3SH coupling to form ethene was investigated by means of density functional theory (DFT) using chabazite as a model catalyst with emphasis on the first C-C bond formation. Calculated thermodynamics were compared with those of analogous and well established CH3OH processes to identify the similarities and differences in the reactive pathways. With few exceptions, CH3SH catalytic transformations are of higher free energy when compared to those of CH3OH. The trimethylsulfonium ion, TMS, isostructural with that of the trimethyloxonium ion, TMO, is shown to be a key reactive intermediate and a thermodynamically stable species leading to ethene formation.

Tin(II) sulfide (SnS) is considered to be a promising optoelectronic material due to its narrow band gap, strong optical absorption, low cost and nontoxic and chemically inert characteristics. As an inherently stable compound, SnS surfaces are expected to be hydrophobic by nature. However, exposure of pristine SnS surfaces to air inevitably leads to surface oxidation which can affect the mineral’s dissolution, reactivity, optical and electronic properties as well as hydrophobicity. In the present study, water adsorption measurements on oxidized SnS thin films were performed using horizontal attenuated total reflection Fourier transform infrared (HATR-FTIR) spectroscopy. X-ray photoelectron spectroscopy (XPS) analysis allowed for characterization of the SnS surface composition before water vapor exposure and identification of any changes that occurred to the surface after water vapor exposure. XPS results are consistent with water adsorption occurring on SnS surfaces containing hydroxyl and carbonate group...

Heterogeneous chemistry of nitrogen dioxide with lead-containing particles is investigated to better understand lead metal mobilization in the environment. In particular, PbO particles, a model lead-containing compound due to its wide spread presence as a component of lead paint and as naturally occurring minerals, massicot and litharge, are exposed to nitrogen dioxide at different relative humidity. X-ray photoelectron spectroscopy (XPS) shows that upon exposure to nitrogen dioxide the surface of PbO particles react to form adsorbed nitrates and lead nitrate thin films with the extent of formation of nitrate relative humidity dependent. Surface adsorbed nitrate increases the amount of dissolved lead. These reacted particles are found to have an increase in the amount of lead that dissolves in aqueous suspensions at circumneutral pH compared to unreacted particles. These results point to the potential importance and impact that heterogeneous chemistry with trace atmospheric gases can have on increasing solubility and therefore the mobilization of heavy metals, such as lead, in the environment. This study also show that surface intermediates, such as adsorbed nitrates, that form can yield higher concentrations of lead in water systems. In the environment, these water systems can include drinking water, ground water, estuaries and lakes.

Reactions between CO(2) and reduced sulfur compounds (RSC), H(2)S and CH(3)SH, were investigated using ground and excited state density functional theory (DFT) and coupled cluster (CC) methods to explore possible RSC oxidation mechanisms and CO(2) activation mechanisms in the atmospheric environment. Ground electronic state calculations at the CR-CC(2,3)/6-311+G(2df,2p)//CAM-B3LYP/6-311+G(2df,2p) level show proton transfer as a limiting step in the reduction of CO(2) with activation energies of 49.64 and 47.70 kcal/mol, respectively, for H(2)S and CH(3)SH. On the first excited state surface, CR-EOMCC(2,3)/6-311+G(2df,2p)//CAM-B3LYP/6-311+G(2df,2p) calculations reveal that energies of

The dependence of electrooxidation on experimental conditions of organic molecules was investigated to optimize the production of hydrogen from potential wastewater sources using low voltage sources (∼1 V dc). Electrooxidation on platinum, gold, and stainless steel anodes with hydrogen production on the cathode was investigated using several different organic reductants, including: methanol, ethanol, glycerol, isopropanol, propanal, glycerol, glucose, sucrose, citric acid, and propionic acid. The electrolyte pH was varied from 2 to 12 in a 1 M Na2SO4 supporting solution. At 1 V, glycerol, citric acid, ethanol and methanol were found to yield the highest currents at low pH values (pH 2 and 7) on platinum electrode, glucose on gold electrode at pH 12 in 1 M Na2SO4 solution produced the highest total current density at 1 V with measured Faradaic efficiency for 1 M glucose of 70%. The hydrogen energy production efficiency was 86%. Practical limitations of glucose oxidation at optimum experimental conditions are discussed. Highlights: We determined optimal conditions for organic wastewater electrooxidation at 1 V. 3 mA/cm2 current density for glucose on Au electrode at 0.5 M and pH 13 obtained. Faradaic efficiency of H2 production was ∼70% for glucose on the Au electrode. These experiments are an alternative to the conventional water photoelectrolysis.

Metal oxide based minerals naturally contain transition metal impurities isomorphically substituted into the structure that can alter the structural and electronic properties as well as the reactivity of these metal oxides. Natural α-Al(2)O(3) (corundum) can contain up to 9.17% (w/w) Fe(2)O(3) and 1.81% (w/w) of Cr(2)O(3.) Here we report on changes in the structural and electronic properties of undoped and doped α-Al(2)O(3) (0001) surfaces using periodic density functional theory (DFT) methods with spin unrestricted B3LYP functional and a local atomic basis set. Both structural and electronic properties are altered upon doping. Implications for doping effects on photochemical processes are discussed.As metal oxides are major components of the environment, including atmospheric mineral aerosol, DFT was also used to study the effect of transition metal impurities on gas/surface interactions of a model acidic atmospheric gas molecule, carbon monoxide (CO). The theoretical results indicated that the presence of Fe(3+) and Cr(3+) impurities substituted on the outer layer of natural corundum surfaces reduces the propensity toward CO adsorption relative to the undoped surface. However, CO-surface interactions resemble that of bulk α-Al(2)O(3) when the impurity is substituted below the first surface layer. The presence and location of the mineral dopant was found to significantly alter the structural and electronic properties and gas/surface interactions studied here.

Chromium (Cr) thin films were deposited on float glass using electron beam (e-beam) physical vapor deposition and radio frequency (RF) magnetron sputtering techniques. Surface morphology of these Cr films was studied using atomic force microscopy (AFM). The e-beam deposited Cr films consisted of isolated surface mounds while in RF sputtered samples, these mounds combined to form larger islands. Lower surface adhesive properties were observed for e-beam deposited films, as determined from AFM force–distance curves, presumably due to the nanostructural differences. Similar amounts of adsorbed atmospheric carbonaceous contaminants and water vapor were detected on samples deposited using both methods with e-beam deposited samples having additional carbide species, as determined by X-ray photoelectron spectroscopy data. The dominant crystallographic plane in both e-beam deposited and RF sputtered Cr thin films was (110) of body-centered cubic Cr metal structure as determined from X-ray diffraction data. Weak (211) reflection was also observed in RF sputtered samples and was attributed to a different thin Cr film condensation and growth mechanism which resulted in nanostructural differences between films deposited using two different methods.

In this study, heterogeneous interactions of H2O and HNO3 on goethite, α-FeOOH, a component of mineral dust aerosol, are investigated with simultaneous QCM measurements and ATR-FTIR spectroscopy. Laboratory synthesized α-FeOOH of varying sizes (microrods and nanorods) when exposed to gas phase H2O and HNO3 results in the uptake of these gases. This combined approach of QCM measurements and ATR-FTIR spectroscopy allows for both quantification of the amount of uptake and spectroscopic data that provides information on speciation of adsorbed products. The results show that, in the case of H2O, both microrods and nanorods take up water and that the total amounts of water, when normalized to surface area, are similar. However, for HNO3 uptake, the saturation coverage of total and irreversibly bound HNO3 on microrods was observed to be higher than that on nanorods, a size effect which is attributed to surface structural changes that occur as a function of particle size. Furthermore, an investigation of the beha...

We report a green and facile approach for the preparation of carbon-modified (C-modified) TiO2 composite materials by hydrothermal synthesis followed by pyrolytic treatment. The resultant materials were characterized by powder X-ray diffraction (XRD), nitrogen physisorption studies, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). The photocatalytic performances of these materials were evaluated by calculating the amount of hydrogen evolved from the decomposition of water under solar simulated irradiation conditions. An improvement was achieved from no H2 evolution at all with the bare TiO2, to an evolution of 0.21 mL g−1 h−1 from a composite material modified with an optimum carbon loading of 3.62%. These results suggested that the interaction of carbon with predominantly rutile form of TiO2 can promote shallow trapping of photogenerated electrons in the oxygen vacancies. This phenomenon consequently enhances the photocatalytic activity by minimizing charge carrier recombination, a characteristic demonstrated by fluorescence quenching of the TiO2 emission.

An important unsolved problem in materials science is prediction of the thermodynamic stability of organic crystals and their solubility from first principles. Solubility can be defined as the saturating concentration of a molecule within a liquid solvent, where the physical picture is of solvated molecules in equilibrium with their solid phase. Despite the importance of solubility in determining the oral bioavailability of pharmaceuticals, prediction tools are currently limited to quantitative structure–property relationships that are fit to experimental solubility measurements. For the first time, we describe a consistent procedure for the prediction of the structure, thermodynamic stability and solubility of organic crystals from molecular dynamics simulations using the polarizable multipole AMOEBA force field. Our approach is based on a thermodynamic cycle that decomposes standard state solubility into the sum of solid-vapor sublimation and vapor-liquid solvation free energies ΔGsolubilityo=ΔGsubo+ΔGsolvo, which are computed via the orthogonal space random walk (OSRW) sampling strategy. Application to the n-alkylamides series from aeetamide through octanamide was selected due to the dependence of their solubility on both amide hydrogen bonding and the hydrophobic effect, which are each fundamental to protein structure and solubility. On average, the calculated absolute standard state solubility free energies are accurate to within 1.1 kcal/mol. The experimental trend of decreasing solubility as a function of n-alkylamide chain length is recapitulated by the increasing stability of the crystalline state and to a lesser degree by decreasing favorability of solvation (i.e. the hydrophobic effect). Our results suggest that coupling the polarizable AMOEBA force field with an orthogonal space based free energy algorithm, as implemented in the program Force Field X, is a consistent procedure for predicting the structure, thermodynamic stability and solubility of organic crystals.

Nanocrystalline Ag-doped ZnO powders were synthesized directly from an aqueous solution of zinc acetate dihydrate and silver nitrate in the presence of poly(ethylene oxide)- b -poly(propylene oxide), (PEO) 19 - b -(PPO) 3 , and sodium hydroxide at 70 °C. The ZnO powders had an urchin-like shape without any dopant and this turned to an agglomerated rod-like structure when the Ag loading was less than or equal to 0.5 mol%. If the Ag content was further increased, the urchin-like shape reappeared. This may occur because the Ag aggregates at the grain boundary. The finding that the diameter of the urchin-like shape decreases as the Ag concentrations increase, can be explained by the pinning effect of the Ag particles as obstacles that inhibit the grain migration and grain growth. An increase of the photocatalytic efficiency for degrading methylene blue increases with the Ag loading up to 1.0 mol% while the best of the antibacterial activity against Staphylococcus aureus was found at 0.5–0.8 mol% of Ag. However, the different Ag loadings in the ZnO powders had no effect on the antibacterial effect on Escherichia coli .

We have prepared organic nanocrystals of [2.2]paracyclophane (pCp) and tetrakis(4-pyridylcyclobutyl)[2.2]paracyclophane (tpcp) via sonochemistry. Both nanocrystals exhibit an enhanced fluorescence compared to dilute solution, while the tpcp nanocrystals also demonstrate a red-shifted fluorescence.

Nanodot and nanopillar structures and precisely controlled reproducible fabrication thereof are of great interest in common nanoelectronic devices, including photonic crystals and surface plasmon resonance instruments. In this work, fabrication process of the silicon nanopillar structures is described. It includes self-organization of gold and chromium clusters at thickness close to that of one atomic diameter to serve as etching masks followed by the reactive ion etching to form silicon nanopillars. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to characterize self-organized gold and chromium clusters as well as the final silicon nanopillars. This method was found to produce silicon nanopillars of sub-10 nm lateral dimensions and the diameter-to-height aspect ratio of up to 1:14.