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General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Energie, Energy, Combustibles, Fuels, Combustibles de remplacement. Production et utilisation, Alternative fuels. Production and utilization, Hydrogène, Hydrogen, Métal transition, Transition metal, Metal transición, Platinoïde, Platinoid, Platinoide, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Hydrogénation, Hydrogenation, Hidrogenación, Hydrure, Hydrides, Hidruro, Hétérocycle, Heterocyclic compound, Heterociclo, Liquide, Liquid, Líquido, Protection environnement, Environmental protection, Protección medio ambiente, Ruthénium, Ruthenium, Rutenio, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réactivité chimique, Chemical reactivity, Reactividad química, Stockage hydrogène, Hydrogen storage, Structure, Estructura, Substitution, Substitución, Heterocyclic compounds, Liquid organic hydride, and Ruthenium catalysts

The effect of the type of heteroatom in the structure on the recyclability of possible candidate compounds for application as LOC (liquid organic carriers) was studied by comparing the rate and selectivity obtained in hydrogenation of carbazole, dibenzothiophene, dibenzofuran and fluorene. The effect of a partial saturation of the compound on its hydrogenation yield and reaction pathway was also considered by studying hydrogenation of 1,2,3,4-tetrahydrocarbazole. Using Ru black catalyst, the rate of hydrogenation was found to decrease in order; dibenzofuran > 1,2,3,4-tetrahydrocarbazole > carbazole » fluorene. No reaction was observed in the hydrogenation of dibenzothiophene under the conditions studied which was attributed to the immediate poisoning of ruthenium metal by sulphur compounds. The rate of hydrogenation of fluorene was around 3 times lower as compared to carbazole and over 8 times lower as compared to that of dibenzofuran under the same reaction conditions. With the exeption of S containing dibenzothiophene, the presence of the heteroatom in the structure was found to be beneficial in terms of increasing the rate of hydrogen loading step. Additionally, a higher reaction rate was obtained in the hydrogenation of the partially saturated 1,2,3,4-tetrahydrocarbazole as compared to the substrate carbazole. The structure and stability of intermediates was found to be significantly influenced by the type and presence of a heteroatom in the structure. A stable octahydro-intermediate was observed only with N-heterocycles, whereas a stable hexahydro-intermediate was produced in the polyaromatic hydrocarbon-fluorene. Additionally, the theoretically obtained lowest total enthalpies using DFT calculations agreed well with the stable intermediates observed experimentally in the hydrogenation of fluorene. Theoretical DFT differences in enthalpies also indicated the products of hydrogenolysis of perhydro-dibenzofuran to be the most favourable products of its hydrogenation, which agreed well with the experimental observations. Overall, taking into account the recyclability of LOC, substitution of carbon with a N heteroatom was demonstrated to be one of the promising approaches to improve the kinetics of the hydrogen loading step.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Métal transition, Transition metal, Metal transición, Argent, Silver, Plata, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dopage, Doping, Energie, Energy, Energía, Matériau hybride, Hybrid material, Material híbrido, Protection environnement, Environmental protection, Protección medio ambiente, Rayonnement solaire, Solar radiation, Radiación solar, Transfert électron, Electron transfer, Transferencia electrón, Energy level control, Organic/inorganic hybrid solar cells, Photoexcited electron transfer, and Silver doping

The photoexcited electron transfer rate represents one of the most important properties required for photovoltaic devices. However, the fabrication of solar cells with a faster electron transfer remains a technological challenge. Regulating the energy level alignment of acceptor-donor system by the incorporation of foreign ions is one of the most promising strategies to achieve this aim. Herein we demonstrate that the incorporation of silver ions into TiO2 nanocrystals results in a remarkable reduction of energy offset between the conduction band edge of acceptor and the lowest unoccupied molecular orbital of donor. In particular, the electron transfer life time was shortened from 30.2 to 18.3 ps, i.e., almost 40% faster than pure TiO2 acceptor, thus leading to a notable enhancement of power conversion efficiency by almost 38% in organic/inorganic hybrid solar cells. The reduction of the 'excess' energy offset accelerates the electron transfer, which is expected to have an important role in applications of solar energy conversion and photon detectors.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Métal transition, Transition metal, Metal transición, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Durabilité, Durability, Durabilidad, Oxygène, Oxygen, Oxígeno, Palladium, Paladio, Pile combustible, Fuel cell, Pila combustión, Platine, Platinum, Platino, Platinoïde, Platinoid, Platinoide, Protection environnement, Environmental protection, Protección medio ambiente, Préparation, Preparation, Preparación, Réduction chimique, Chemical reduction, Reducción química, Structure, Estructura, Yttrium, Ytrio, Core-shell-shell structure, and Oxygen reduction reaction

A core-shell-shell structure Pd-Y-Pt/C catalyst was prepared using a controlled surface reaction method. The structure was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques. Nano-scale yttrium was formed as a shell located as the middle layer of the catalyst. Electrochemical evaluation of the Pd-Y-Pt/C with less than 7% of Pt showed an improved performance toward oxygen reduction reaction (ORR) compared to Pt/C (20wt.% Pt). Accelerated degradation tests (ADT) indicated that the addition of Y improved catalyst stability compared to Pt/C and Pd-Pt/C core-shell catalysts under various experimental conditions. This was due to the Y middle layer created approximate half-filled metal-metal d bond between Pt (or Pd) and Y. This catalyst utilized the core-shell-shell structure to minimize the Pt usage, and Y middle shell to improve stability.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Alcool, Alcohol, Composé benzénique, Benzenic compound, Compuesto bencénico, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation photochimique, Photochemical degradation, Degradación fotoquímica, Energie, Energy, Energía, Hydroxyde double lamellaire, Layered double hydroxide, Hidróxido doble laminar, Oxyde, Oxides, Óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Phénol, Phenol, Fenol, Phénols, Phenols, Fenoles, Protection environnement, Environmental protection, Protección medio ambiente, Semiconducteur, Semiconductor materials, Semiconductor(material), Band gap energy, Layered double hydroxides, Phenol degradation, and Semiconductors

The synthesis and characterization of ZnAl and ZnGaAl layered double hydroxides and the mixed oxides derived from their calcination is presented. The semiconducting properties of the mixed oxides were analyzed by DR-UV-Vis. It was found that all mixed oxides are semiconductors with band gaps close to that of ZnO. Also, substitution of Al3+ for 5 or 10% wt. of Ga3+ decreases the band gap below that of ZnO, despite the fact that gallium oxide is a wide band gap semiconductor. Then, the photodegrading capabilities of the mixed oxides were tested using phenol, a very recalcitrant compound, as a probe. Nearly 80% of initial 40 ppm and 60% of initial 80 ppm of phenol were degraded in 6 h over ZnAl-3 and ZnGaAl-5% photocatalysts.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Défaut, Defect, Defecto, Nanotube carbone, Carbon nanotubes, Oxygène, Oxygen, Oxígeno, Pile combustible, Fuel cell, Pila combustión, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réduction chimique, Chemical reduction, Reducción química, CNTs, Defects, Fuel cells, NPMCs, and ORR

Non-precious metal catalysts for the oxygen reduction reaction (ORR) based upon the incorporation of different amounts of N into the C—C network of multiwalled carbon nanotubes (CNTs) have been prepared by using CNTs and urea as the carbon and nitrogen sources, respectively. First, and with the aim of generating different levels of defects in the carbon network, the CNTs have been subjected to ballmilling during different periods of time between 0 and 150 h. Then, urea was mixed with the treated CNTs, subjected to further ballmilling and pyrolized at 800°C. The number of defects, and as a consequence, the amount of N incorporated into the CNTs, increases with the duration of the ballmilling time. Moreover, the structure of the CNTs obtained after longer ballmilling times collapses leading to a carbon material with a high degree of microporisity. The performance of the N/CNT for the ORR, in terms of both the onset potential and mass current activity, increases with the amount of N actually incorporated into the CNT. Moreover, the H2O2 formation during ORR varies with the morphology of the catalyst. Thus, the formation of H2O2 is favored with the electrocatalysts in which the CNT structure is preserved, whereas the total reduction of O2 to H2O is favored for the electrocatalysts in which micropores are formed.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Electrochimie, Electrochemistry, Cinétique et mécanisme des réactions, Kinetics and mechanism of reactions, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Sciences appliquees, Applied sciences, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Alcanol, Alkanol, Alcool, Alcohol, Métal transition, Transition metal, Metal transición, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Electrocatalyse, Electrocatalysis, Electrocatálisis, Hydroxyde de potassium, Potassium hydroxide, Potasio hidróxido, Hyperfréquence, Microwave, Hiperfrecuencia, Irradiation hyperfréquence, Microwave irradiation, Irradiación hiperfrecuencia, Méthanol, Methanol, Metanol, Nanoparticule, Nanoparticle, Nanopartícula, Nickel, Niquel, Noir carbone, Carbon black, Carbón negro, Oxydation, Oxidation, Oxidación, Pile combustible, Fuel cell, Pila combustión, Protection environnement, Environmental protection, Protección medio ambiente, Fuel cells, KOH, and Nickel-based electrocatalyst

Ni/C electrocatalysts were prepared by chemical deposition of nickel nanoparticles on Vulcan XC-72R carbon black using microwave irradiation technique. The time of microwave irradiation during the reduction step and nickel weight percentage were varied. This was found to affect the morphology of formed Ni/C powder as shown by TEM analysis. Increasing nickel weight percentage results in the formation of more aggregated deposits. The electrocatalytic activity of different Ni/C samples towards methanol oxidation reaction in KOH solution was studied by applying cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopic techniques. Ni/C electrocatalyst containing 30wt.% Ni [Ni/C-30] shows 5.2 times higher electrocatalytic activity than that with 10 wt.% Ni [Ni/C-10]. Heating Ni/C powder into microwave oven using the pulse mode of 30s on/10s off forms the most stable electrocatalyst for prolonged oxidation reaction. Electrochemical impedance measurements show that Ni/C-30 electrocatalyst has the lowest impedance value of 0.022 kΩ cm2, while the highest one is for Ni/C-10 [0.331 kΩ cm2] in (0.4 M methanol + 0.5 M KOH) solution at 500 mV. It confirms that Ni/C-30 has the highest electrocatalytic activity towards methanol oxidation reaction.

General chemistry, physical chemistry, Chimie générale, chimie physique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Sonochimie, Ultrasonic chemistry, Aldéhyde, Aldehyde, Aldehído, Chimie verte, Green chemistry, Química verde, Condensation Knoevenagel, Knoevenagel condensation, Condensación Knoevenage, Condensation chimique, Condensation reaction, Condensación química, Echange anion, Anion exchange, Cambio aniónico, Energie, Energy, Energía, Protection environnement, Environmental protection, Protección medio ambiente, Réaction catalytique, Catalytic reaction, Reacción catalítica, Résine, Resins, Resina, Sonochimie, Sonochemistry, Sonoquímica, Ultrason, Ultrasound, Ultrasonido, Anion-exchange resin, and Ultrasonic energy

To realize a practical and green chemistry, two important challenges need to be addressed, namely the effective process for the activation of reaction and efficient, eco-friendly and robust chemical methods for the reaction conversion to target products via highly selective catalytic and reactions. Ultrasonic energy promotes the conversion process through its special cavitational effects. Combined with anion-exchange resin as a heterogeneous, reusable and efficient catalyst, Ultrasonic energy enhances the Knoevenagel condensation and leads to reduced reaction time at lower reaction temperature with less amounts of solvent and catalyst.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Métal transition, Transition metal, Metal transición, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Croissance, Growth, Crecimiento, Dynamique moléculaire, Molecular dynamics, Dinámica molecular, Dépôt, Deposition, Depósito, Electrode, Electrodes, Electrodo, Etude expérimentale, Experimental study, Estudio experimental, Matériau poreux, Porous material, Material poroso, Pile combustible, Fuel cell, Pila combustión, Plasma, Platine, Platinum, Platino, Protection environnement, Environmental protection, Protección medio ambiente, Pulvérisation irradiation, Sputtering, Pulverización irradiación, Cluster growth, Fuel cell electrodes, Plasma sputtering deposition, and Pt catalyst

Amorphous platinum clusters supported on porous carbon have been envisaged for high-performance fuel cell electrodes. For this application, it is crucial to control the morphology of the Pt layer and the Pt-substrate interaction to maximize activity and stability. We thus investigate the morphology evolution during Pt cluster growth on a porous carbon substrate employing atomic scale molecular dynamics simulations. The simulations are based on the Pt-C interaction potential using parameters derived from density functional theory and are found to yield a Pt cluster morphology similar to that observed in low loaded fuel cell electrodes prepared by plasma sputtering. Moreover, the simulations show amorphous Pt cluster growth in agreement with X-ray diffraction and transmission electron microscopy experiments on high performance low Pt content (10 μgPt cm-2) loaded fuel cell electrodes and provide a fundamental insight in the cluster growth mechanism.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Acide carboxylique, Carboxylic acid, Acido carboxílico, Composé de métal de transition, Transition element compounds, Acide formique, Formic acid, Fórmico ácido, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Catalyseur, Catalyst, Catalizador, Matériau hybride, Hybrid material, Material híbrido, Oxyde de titane, Titanium oxide, Titanio óxido, Pile combustible, Fuel cell, Pila combustión, Protection environnement, Environmental protection, Protección medio ambiente, Support catalyseur, Catalyst support, Soporte catalizador, Fuel cells, Pd-based catalysts, and TiO2-C hybrids

The electrooxidation of formic acid was performed on Pd-based catalysts supported on hybrid TiO2-C materials prepared from different carbon origins by solvothermal and slurry synthesis. It has been found that carbonized hybrid TiO2-C supports with mesopore texture and high anatase:rutile ratio in the TiO2 framework led to about three times higher activity per Pd mass unit than the catalyst prepared on a commercial Vulcan XC-72 carbon black, which will allow to reduce considerably the amount of expensive noble metal at the anode of DFAFC. The conductivities of raw TiO2/C supports are several orders of magnitude lower than that for carbon Vulcan XC-72. However, the hybrid TiO2-C supports acquire high conductivity during palladium deposition. The rate of electrooxidation of formic acid on Pd/TiO2-C catalysts, calculated per one surface Pd atom (TOF), is for TOF < 1 S-1 independent of Pd particle size and morphology of the supports. Higher activity of the Pd/TiO2-C catalysts, compared to Pd/C catalyst, results from their higher hydrophilicity which ensures good access of formic acid to the Pd crystallites in the catalyst layer, and sufficiently high conductivity providing easy electron flow from the Pd active sites to current collector. Present results indicate that hybrid inorganic/organic materials are promising supports for the direct formic acid fuel cells with Pd-based catalysts.

General chemistry, physical chemistry, Chimie générale, chimie physique, Environment, Environnement, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Electrochimie, Electrochemistry, Cinétique et mécanisme des réactions, Kinetics and mechanism of reactions, Sciences appliquees, Applied sciences, Electrotechnique. Electroenergetique, Electrical engineering. Electrical power engineering, Electroénergétique, Electrical power engineering, Conversion directe et accumulation d'énergie, Direct energy conversion and energy accumulation, Conversion électrochimique: piles et accumulateurs électrochimiques, piles à combustibles, Electrochemical conversion: primary and secondary batteries, fuel cells, Energie, Energy, Energie. Utilisation thermique des combustibles, Energy. Thermal use of fuels, Appareils de production et de conversion d'énergie: énergie thermique, énergie électrique, énergie mécanique, etc, Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc, Piles à combustible, Fuel cells, Métal transition, Transition metal, Metal transición, Carbone, Carbon, Carbono, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Electrocatalyse, Electrocatalysis, Electrocatálisis, Electrochimie, Electrochemistry, Electroquímica, Nanoparticule, Nanoparticle, Nanopartícula, Nanotube carbone, Carbon nanotubes, Nanotube multifeuillet, Multiwalled nanotube, Nanotubo pared múltiple, Oxygène, Oxygen, Oxígeno, Pile combustible, Fuel cell, Pila combustión, Platine, Platinum, Platino, Protection environnement, Environmental protection, Protección medio ambiente, Réduction chimique, Chemical reduction, Reducción química, Stabilité, Stability, Estabilidad, Electrochemical stability, Oxygen reduction reaction, and Platinum nanoparticles

A non-covalent functionalization for multi-walled carbon nanotubes has been used as an alternative to the damaging acid treatment. Platinum nanoparticles with similar particle size distribution have been deposited on the surface modified multi-walled carbon nanotubes. The interaction between platinum nanoparticles and multi-walled carbon nanotubes functionalized with 1-pyrenecarboxylic acid is studied and its electrochemical stability investigated. This study reveals the existence of a platinum-support interaction and leads to three main conclusions. First, the addition of 1-pyrenecarboxylic acid is improving the dispersion of platinum nanoparticles, leading to an improved electrochemical activity towards oxygen reduction reaction. Second, the investigations regarding the electrochemical stability showed that the platinum-support interaction plays an important role in improving the long-term stability by as much as 20%. Third, post-mortem microscopy analysis showed a surprising effect. During the electrochemical stability investigations concerned with carbon corrosion it was found that the multi-walled carbon nanotubes were undergoing severe structural change, transforming finally into carbon spheres.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Membranes, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé de métal de transition, Transition element compounds, Energie, Energy, Energía, Filtration, Filtración, Hydrophilie, Hydrophily, Hidrofilia, Membrane, Membrana, Oxyde de titane, Titanium oxide, Titanio óxido, Perméabilité, Permeability, Permeabilidad, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Technologie, Technology, Tecnología, Hydrophilicity, Membrane technology, and Modified titania

Visible light active ultrafiltration (UF) membranes coated with modified nanostructured titania (m-TiO2) were for the first time developed using a sol-gel preparation technique combined with a dip-coating deposition procedure. It has been confirmed that the structural, morphological and physicochemical properties of the modified titania membranes strongly depend on the dip-coating and calcination rates. The modified membranes were incorporated in a water purification photocatalytic reactor in continuous flow filtration conditions and tested for the photocatalytic degradation of azo-dye model compounds (namely methyl orange - MO and methylene blue - MB) with very promising results. The photocatalytic experiments took place under ambient operating temperature and low pressure without any compromise on the efficiency of the membrane's permeate flux. Without irradiation, the permeability drops with increasing flow rates of the solution that is forced to penetrate through their pore structure. The photocatalytic efficiency depends on the effluent flow rate however, under both UV and visible light, the permeability was continuously increasing due to the photoinduced hydrophilicity effect. Compared to MO, the MB pollutant was degraded at much higher rate due to its better adsorption, independently of the type of the membrane. The permeability of the membranes increases with the volume treated due to the wettability of the m-TiO2 treated membrane, rendering the need for regeneration or anti-fouling procedures unnecessary and making the process more energy efficient. Due to the low temperature function and the photoinduced hydrophilic effect of the modified TiO2 photocatalytic UF membranes, the photocatalytic reactor can efficiently work without any extra device, fact that leads to low installation and operating costs and provides an energy efficient procedure of cleaning polluted aqueous solutions.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Chauffage, Heating, Calefacción, Défaut, Defect, Defecto, Lacune, Vacancy, Cavidad, Nanocristal, Nanocrystal, Oxyde de titane, Titanium oxide, Titanio óxido, Oxygène, Oxygen, Oxígeno, Photocatalyse, Photocatalysis, Fotocatálisis, Propriété optique, Optical properties, Propiedad óptica, Oxygen vacancy, Ti3+ defects, Titanium dioxide, and Vacuum heating

In this study, we investigated vacuum-treated TiO2 nanocrystals. They displayed long-wavelength optical absorption due to the existence of oxygen vacancy and Ti3+ defects, and also possibly the surface structural disorder. Both oxygen vacancy and Ti3+ defects influenced the photocatalytic activities in methylene blue decomposition and hydrogen generation. Oxygen vacancy benefited photocatalytic methylene blue (MB) decomposition, but harmed the photocatalytic hydrogen generation. Ti3+ defects displayed a more complicated effect.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Bleu méthylène, Methylene blue, Azul metileno, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Dégradation, Degradation, Degradación, Mécanisme, Mechanism, Mecanismo, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Précipitation, Precipitation, Precipitación, Degradation mechanism, Fe(II)Fe(III)-LDHs, Heterogeneous-Fenton, and Methylene Blue

The present study focused on the degradation of Methylene Blue in a heterogeneous Fenton-like process catalyzed by a type of new heterogeneous catalyst named Fe(II)Fe(III)-LDHs. The three Fe(II)Fe(III)-LDHs catalysts were prepared by co-precipitation of FeSO4.7H2O and Fe2(SO4)3. The results indicated that all three Fe(II)Fe(III)-LDHs synthesized showed good catalytic activity, and the most active catalyst toward Methylene Blue decomposition was prepared at the ratio [Fe2+ ]/[Fe3+] = 1:0 at air atmosphere. The degradation of MB performed well at acidic and neutral conditions, 100% color removal of Methylene Blue (10mg/L) was achieved in 1 h, and the fastest reaction rate obtained at pH 3 according to the pseudo-second order reaction kinetic was 6.185. During the degradation process of Methylene Blue, the solution pH was found to be decreased, and Cl-, SO42-, NO3- were determined. Pleiocarpamine, DL-Norleucine and benzothiazole that have rarely been detected in previous reports about the other heterogeneous-Fenton processes were observed. Methylene Blue degraded in two different pathways simultaneously, and finally the intermediates were mineralized to water and dioxide. In term of the distinctive characteristics of Fe(II)Fe(III)-LDHs, the heterogeneous Fenton process catalyzed by Fe(II)Fe(III)-LDHs was promising in wastewater treatment.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Composé de métal de transition, Transition element compounds, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Composé modèle, Model compound, Compuesto modelo, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Uracile, Uracil, Uracilo, 6-Hydroxymethyl uracil (6-HOMU), Cylindrospermopsin (CYN), NF-TiO2, and Visible light

TiO2 photocatalyses of 6-hydroxymethyl uracil (6-HOMU) a model compound for the potent cyanotoxin, cylindrospermopsin (CYN), were carried out employing visible and UV irradiation using different non-metal doped TiO2 materials, nitrogen and fluorine-TiO2 (NF-TiO2), phosphorus and fluorine-TiO2 (PF-TiO2) and sulfur-TiO2 (S-TiO2). The model compound was readily degraded under UV TiO2 photocatalysis with pseudo-first-order rate constants (k) of 2.1, 1.0, and 0.44h-1 for NF-TiO2, PF-TiO2 and S-TiO2, respectively. Under visible light activated (VLA), NF-TiO2 was the most active photocatalyst, PF-TiO2 was marginally active and S-TiO2 inactive. VLA NF-TiO2 was effective and increased the k with increasing pH from 3 to 9. The presence of humic acid (HA), Fe3+ and Cu2+ can enhance the degradation. However, at 20ppm HA significant inhibition was observed, likely due to shadowing of the catalyst, quenching of ROS or blocking active sites of TiO2. We probed the roles of different reactive oxygen species (ROS) using specific scavengers and the results indicate that O2•- plays an important role in VLA TiO2 photocatalysis. Our results demonstrate that NF-TiO2 photocatalysis is effective under UV and visible irradiation and over a range of water qualities. VLA NF-TiO2 photocatalysis is an attractive alternative technology for the CYN contaminated water treatment.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Electrochimie, Electrochemistry, Photoélectrochimie. Electrochimiluminescence, Photoelectrochemistry. Electrochemiluminescence, Composé de métal de transition, Transition element compounds, Bactéricidie, Bactericidal effect, Bactericidia, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Oxyde de titane, Titanium oxide, Titanio óxido, Photocatalyse, Photocatalysis, Fotocatálisis, Protection environnement, Environmental protection, Protección medio ambiente, Rutile, Rutilo, Photoélectrocatalyse, Photoelectrocatalysis, (111} facets, Inactivation, and Rutile TiO2

This work reported the use of a UV and visible light active rutile TiO2 photoanode with 100% exposed {111} faceted surface for photocatalytic and photoelectrocatalytic bactericidal applications. The bactericidal performances of the photoanode with UV and visible light driven photocatalysis and photoelectrocatalysis processes were evaluated using Escherichia coli as the test bacteria. Under the UV irradiation, 99.97% inactivation of 45 mL of 1.0 × 107 CFU/mL E. coli cells can be achieved within 10min for photoelectrocatalysis treatment, while only 96.40% inactivation can be obtained within 30min for photocatalysis treatment. Under the visible light irritation, 88.46% inactivation can be achieved with 180 min photocatalytic treatment, while 100% inactivation by photoelectrocatalytic treatment can be achieved over the same period. The bactericidal performance of the rutile TiO2 film was also evaluated for sunlight driven photocatalysis treatment. 1.0 mL of 1.0 × 107 CFU/mL E. coli cells can be completely inactivated within 2.0 min. The rutile TiO2 film photocatalyst can be used for 20 consecutive bactericidal experiments without the noticeable change in bactericidal performance.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie des réactions induites par rayonnements, particules et ultrasons, Physical chemistry of induced reactions (with radiations, particles and ultrasonics), Photochimie, Photochemistry, Physicochimie de surface, Surface physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Composé de métal de transition, Transition element compounds, Anatase, Anatasa, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Diffusion, Difusión, Interface, Interfase, Ion, Ions, Ión, Nanoparticule, Nanoparticle, Nanopartícula, Oxydation, Oxidation, Oxidación, Oxyde de titane, Titanium oxide, Titanio óxido, Peroxyde d'hydrogène, Hydrogen peroxide, Peróxido de hydrogeno, Photocatalyse, Photocatalysis, Fotocatálisis, Interface ion diffusion-redox reaction, Ti3+ self-doped TiO2, TiH2, and Visible light photocatalytic

Anatase phase Ti3+ self-doped TiO2-x nanoparticles (NPs) has been successfully synthesized by a simple interface ion diffusion-redox reaction using TiH2 and H2O2 as precursors. The structure, crystallinity, morphology and other properties of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The chemical states of Ti in the samples were confirmed by X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) spectra confirm the presence of high concentration of Ti3+ in the bulk and surface of the as-prepared substoichiometric TiO2-x NPs. Composition of the samples was also analyzed by energy dispersive X-ray spectra (EDX) and the results indicate the exist of oxygen vacancies. UV-vis diffuse reflectance spectroscopy (UV-vis DRS) showed that Ti3+ self-doped TiO2-x NPs have a strong absorption between 400 and 800 nm. The formation mechanism of the Ti3+ self-doped TiO2-x NPs was also discussed. Methylene blue (MB) solutions were used as model wastewater to evaluate the visible-light photocatalytic activity of the samples. Under visible light radiation, the samples exhibit excellent ability in the photocatalytic degradation of MB and splitting of water to produce H2. The most active Ti3+ self-doped TiO2-x NPs obtained at 500 C exhibits 68-fold enhancement for the visible light decomposition of MB in comparison to commercial P25 TiO2. The samples also show an excellent cyclic stability of the photocatalytic activity of degrading MB.

General chemistry, physical chemistry, Chimie générale, chimie physique, Energy, Énergie, Chemical engineering, Génie chimique, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Théorie des réactions, cinétique générale. Catalyse. Nomenclature, documentation chimique, informatique chimique, Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry, Catalyse, Catalysis, Physicochimie de surface, Surface physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Matériaux poreux, Porous materials, Matériau poreux, Porous material, Material poroso, Adsorbant, Adsorbent, Adsorbente, Adsorption, Adsorción, Catalyse hétérogène, Heterogeneous catalysis, Catálisis heterogénea, Mésoporosité, Mesoporosity, Mesoporosidad, Protection environnement, Environmental protection, Protección medio ambiente, Sorption, Sorción, Structure pores, Pore structure, Estructura poros, Support, Soporte, Tamis moléculaire, Molecular sieve, Tamiz molecular, Technologie bas carbone, 3-D support, CO2 capture, Mesoporous molecular sieve, Molecular basket sorbent, and Polyethylenimine

Three-dimensional (3-D) mesoporous materials including mesocellular siliceous foam (MCF), MSU-J and hexagonal mesoporous silica (HMS) were examined as supports of molecular basket sorbents (3-D MBS) by loading CO2-philic polyethylenimine (PEI). The CO2 sorption performance of the 3-D MBS was evaluated in comparison with the MBS by using MCM-41, SBA-15 and carbon black (CB) as the supports. The effect of PEI loading on the sorption capacity is associated with the sorption temperature and pore structure of the support. At 30 wt% PEI loading, the increase in temperature from 30 to 75 C has a slight and even negative effect on the sorption capacity; while at 65 wt% PEI loading, it has a significant, positive effect. Superior CO2 sorption capacity and sorption rate of 3-D MBS over 2-D and 1-D MBS were observed. MCF-based MBS with 65 wt% PEI loading (PEI(65)/MCF) gave the highest CO2 sorption capacity of 201 mg-CP2/g-sorb. The maximum PEI loading for MCF was up to 80 wt%, which is the largest among the support materials studied in this work, and is related to its largest pore volume. The highest sorption capacity and sorption rate of PEI(65)/MCF are ascribed to its largest pore size and unique 3-D pore structure, which facilitate the CO2 diffusion, promote mass transfer and offer more accessible sorption sites. The present work demonstrates that the 3-D mesoporous solid amine sorbents are more effective for CO2 capture in comparison with 1-D and 2-D materials in terms of higher sorption capacity and faster sorption rate. The pore structure (pore dimension, pore size, pore volume) of the support, PEI loading and temperature are the three key factors that determine the sorption capacity and sorption rate.