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Cu 3 P with Cu vacancies is loaded on the surface of Cu nanowires by a simple vapor deposition strategy to obtain a hollow Cu@Cu 3−x P Core-shell structure, which significantly enhances the catalytic activity. [Display omitted] • Cu@Cu 3−x P hollow core–shell material with Cu vacancies was fabricated by the vapor deposition method. • The mechanism of the catalyst under different systems was elaborated. • The core–shell structure and the unique hollow structure favor the spatial separation of carriers. • Copper vacancy increases the interface area and the active sites. • The degradation pathways of 4NP and RhB were proposed depending on various analysis methods. As an important family of semiconductors, transition metal phosphides could act as effective catalysts in the treatment of organic pollutants. Herein, a novel hollow core–shell Cu@Cu 3−x P catalyst with copper vacancies, possessing excellent properties of photocatalytic and catalytic reduction for organic pollutants, was prepared by the vapor deposition method. 4-Nitrophenol (4NP) (50 μM, 3 mL) could be degraded within 2 min under the action of catalyst (0.06 mg), and the reduction rate was approached to 99.8%. Meanwhile, this catalyst displayed prominently increased Rhodamine B (RhB) photo-oxidation performance, about 1.7 and 16 times more than the bare Cu 3 P and Cu under optimal conditions (5% Cu@Cu 3−x P). Such superior catalytic performance can be ascribed to the mutual contribution of Cu vacancy (convert the band structure and supply active sites) and Cu nanowire (prevent agglomeration of Cu 3 P nanoparticles and promote the transfer of photoelectrons) and the unique hollow core–shell architecture(the rapid separation and low recombination of photoelectron-hole). The possible pathways of 4NP reduction and RhB photo-oxidation were proposed according to the results of degradation products obtained from HPLC, LC-Q-orbitrap/MS, GC-MS, and ATR-FTIR. This study can validate the extensive application of Cu@Cu 3−x P and provide a new insight for the synthesis of dual-functional catalysts containing metal defects. [ABSTRACT FROM AUTHOR]

In situ EPR spectroscopy proved to be a versatile tool to identify active sites for photocatalytic hydrogen generation in modified YTiO and CsTaWO catalysts of pyrochlore structure, in which the metal cations are located in two different positions A and B. It was found that the B-sites exclusively occupied by titanium (YTiO) and tantalum/tungsten (CsTaWO) act as electron traps on the surface. From these sites, electron transfer to the co-catalysts proceeds. Thus, the B-sites are responsible for photocatalytic water reduction. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The integration of light absorbers and catalysts for the water splitting process requires a membrane capable of both ion and electron management and product separation to realize efficient solar fuels systems. Bipolar membranes can maintain a pH gradient for optimal reaction conditions by the dissociation of water. Such membranes that contain graphene in the interfacial layer are fabricated by the chemical reduction of a uniformly deposited graphene oxide layer to convert sp3 catalyst regions to sp2 conductive regions. The resulting electrical and water dissociation properties are optimized by adjusting the exposure conditions, and treatments of less than 5 min render an interface that exceeds the conductivity requirements for integrated solar water splitting and increases the overpotential by <0.3 V. Integration with photoelectrodes is examined by characterizing the electrical interface formed between graphene and Si microwires, and we found that efficient Ohmic junctions are possible. [ABSTRACT FROM AUTHOR]

We report herein the use of the (dihydrido)iron catalyst, Fe(H)2(dmpe)2, for the selective reduction of CO2 into either bis(boryl)acetal or methoxyborane depending on the hydroborane used as a reductant. In a one-pot two-step procedure, the in situ generated bis(boryl)acetal was shown to be a reactive and versatile source of methylene to create new C-N but also C-O and C-C bonds. [ABSTRACT FROM AUTHOR]

The utilization of compounds from natural sources to prepare functional materials is of great importance. Herein, we describe for the first time the preparation of organic-inorganic hybrid catalysts by using natural phytic acid as building block. Zirconium phosphonate (Zr-PhyA) was synthesized by reaction of phytic acid and ZrCl4 and was obtained as a mesoporous material with pore sizes centered around 8.5 nm. Zr-PhyA was used to catalyze the mild and selective Meerwein-Ponndorf-Verley (MPV) reduction of various carbonyl compounds, e.g., of levulinic acid and its esters into γ-valerolactone. Further studies indicated that both Zr and phosphate groups contribute significantly to the excellent performance of Zr-PhyA. [ABSTRACT FROM AUTHOR]

Despite great achievements obtained in tandem reactions, a solution for the incompatible nature of bimetal complexes participating in a multi-step catalytic process is still an unmet challenge. Herein, we utilize a functionalized periodic mesoporous organosilica with well-defined single-site chiral organoruthenium active centers in its ordered dimensional-hexagonal mesopores as a heterogeneous catalyst, and combine it with [RuCl2(PPh3)3] to enable an efficient one-pot relay reduction–isomerization from achiral β-trifluoromethylated-α,β-unsaturated ketones to chiral β-trifluoromethylated saturated ketones in water with up to 97% ee and 100% enantiospecificity, supplying a gap in their incompatibility. Furthermore, the heterogeneous catalyst can be recovered conveniently and reused repeatedly at least eight times without loss of reactivity in the enantioselective reduction of 4,4,4-trifluoro-1,3-diphenylbut-2-enone, showing it to be particularly attractive in the practice of organic synthesis in an environmentally friendly manner. [ABSTRACT FROM AUTHOR]

Pretreated bio-oil was hydroprocessed with conventional sulfided CoMo/γ-Al2O3 catalyst in a continuous packed-bed reactor. Hydroprocessing experiments were performed at a temperature of 350 to 400°C, 1500 psig hydrogen pressure, using a hydrogen flow rate of 500 mL/min at a liquid hourly space velocity of 0.2 h−1. The results from sulfided catalytic experiments were compared with our prior studies on hydroprocessing pretreated bio-oil with reduced CoMo/γ-Al2O3 catalyst. sulfided CoMo/γ-Al2O3 catalyst demonstrated higher catalytic activity and resulted in increased hydrocarbon fraction yields. Moreover, the quality of the hydrocarbon fraction, as determined by the acid value, higher heating value, and water content analysis, also improved. Sulfided CoMo/γ-Al2O3 catalyst produced a hydrocarbon fraction having a higher heating value of 44.4 MJ/kg, acid value of 0.5 mg KOH/g oil, and a total water content of 0.1%. Use of sulfided catalyst for hydroprocessing pretreated bio-oil decreased the oxygen content from 47.8 wt % in the pretreated bio-oil to nondetectable limits (∼0 wt %) in the hydrocarbon fraction. The hydrocarbon fraction was also analyzed by detailed hydrocarbon analysis and simulated distillation. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 1174-1179, 2015 [ABSTRACT FROM AUTHOR]

We report an ordered Pd3Fe intermetallic catalyst that exhibits significantly enhanced activity and durability for the oxygen reduction reaction under alkaline conditions. Ordered Pd3Fe enables a hybrid Li--air battery to exhibit the best reported full-cell cycling performance (220 cycles, 880 h). [ABSTRACT FROM AUTHOR]

Nitrophenol reduction to aminophenol with a reducing agent is conveniently carried out in aqueous medium mainly with a metal or metal oxide catalyst. This reduction is presently considered as a benchmark reaction to test a catalyst nanoparticle. Thousands of original reports have enriched this field of nanoparticle catalyzed reaction. Synthesis of different metal and metal oxide nanoparticles and their composites along with their role as catalysts for nitrophenol reduction with varying reducing agents have been elucidated here. The progress of the reaction is conveniently monitored by UV-visible spectrophotometry and hence it becomes a universally accepted model reaction. In this review we have discussed the reaction kinetics considering its elegance and importance enlightening the long known Langmuir–Hinshelwood mechanism and Eley–Rideal mechanism at length, along with a few other mechanisms recently reported. A brief description of the synthetic procedures of various nanoparticles and their respective catalytic behaviour towards nitroarene reduction has also been accounted here. [ABSTRACT FROM AUTHOR]

Fe-N-C and Co-N-C materials are promising catalysts for reducing oxygen in fuel cells. The degradation of such catalysts induced by H2O2 was investigated by contacting them ex situ with various amounts of H2O2 . The degradation increased with increasing amounts of H2O2 . The effect was most severe for Cr-N-C followed by Fe-N-C and last by Co-N-C. Treatment with H2O2 leads to diminished oxygen reduction activity at high potential and/or reduced transport properties at high current density in fuel cell. From spectroscopic characterization, it was found that 66 and 80% of the CoNxCy and FeNxCy moieties present in pristine catalysts survived the extensive H2O2 treatment, respectively. In parallel, the activity for oxygen reduction was divided by ca 6-10 for Fe-N-C and by ca 3 for Co-N-C. The results suggest that the main degradation mechanism in fuel cell for such catalysts is due to a chemical reaction with H2O2 that is generated during operation. The super-proportional decrease of the oxygen reduction activity with loss of FeNxCy and CoNxCy moieties suggests either that only a small fraction of such moieties are initially located on the top surface, or that their turnover frequency for oxygen reduction was drastically reduced due to surface oxidation by H2O2 . [ABSTRACT FROM AUTHOR]

Reaction of the diiron propanedithiolate complex [μ-(SCH2)2CHO2CC6H5]Fe2(CO)6(A) with triphenylphosphine (PPh3) orcis-1,2-bis(diphenylphosphine)ethylene (cis-dppv) in the presence of one equivalent of Me3NO·2H2O yielded a mono-substituted complex [μ-(SCH2)2CHO2CC6H5]Fe2(CO)5(PPh3) (1) or an asymmetrically substituted complex [(μ-SCH2)2CHO2CC6H5]Fe2(CO)4(κ2-dppv) (2), respectively. The structures of both complexes were characterized by spectroscopic methods and X-ray crystallography. In the solid state, the PPh3ligand in1occupies an apical position of the square pyramidal geometries of the Fe2, while thecis-dppv in2coordinates Fe2 in an apical-basal manner. The electrochemistry of both complexes was investigated. The electron-withdrawing benzoate functionality on the bridgehead carbon of the propanedithiolate bridge shifts the oxidation and reduction potentials of1or2slightly. Both complexes can catalyze the reduction of protons from CF3COOH but with a higher efficiency for2. [ABSTRACT FROM AUTHOR]

Newly designed and prepared molybdenum-nitride complexes bearing a mer-tridentate triphosphine as a ligand have been found to work as the most effective catalysts toward the catalytic reduction of dinitrogen to ammonia under ambient conditions, where up to 63 equiv of ammonia based on the Mo atom of the catalyst were produced. [ABSTRACT FROM AUTHOR]

We report the first example of a sulfinato Fe(III) complex acting as a highly active electrocatalyst for proton reduction. The sulfinate binds to the metal through oxygen, resulting in a seven-membered chelate ring that is likely hemilabile during catalysis. Proton reduction occurs at -1.57 V versus Fc/Fc+ in CH3CN with an ic/ip = 13 in CH3CN (kobs = 3300 s-1) and an overpotential of 800 mV. The catalysis is first order with respect to [catalyst] and second order with respect to [trifluoracetic acid]. An 11% increase in catalytic activity is observed in the presence of water, suggesting that sulfinate moieties are viable functional groups for aqueous proton reduction catalysts. [ABSTRACT FROM AUTHOR]

The homogeneous electrochemical reduction of CO2 by the molecular catalyst [Ni(cyclam)]2+ is studied by electrochemistry and infrared spectroelectrochemistry. The electrochemical kinetics are probed by varying CO2 substrate and proton concentrations. Products of CO2 reduction are observed in infrared spectra obtained from spectroelectrochemical experiments. The two major species observed are a Ni(I) carbonyl, [Ni(cyclam)(CO)]+, and a Ni(II) coordinated bicarbonate, [Ni(cyclam)(CO2OH)]+. The rate-limiting step during electrocatalysis is determined to be CO loss from the deactivated species, [Ni(cyclam)(CO)]+, to produce the active catalyst, [Ni(cyclam)]+. Another macrocyclic complex, [Ni(TMC)]+, is deployed as a CO scavenger in order to inhibit the deactivation of [Ni(cyclam)]+ by CO. Addition of the CO scavenger is shown to dramatically increase the catalytic current observed for CO2 reduction. Evidence for the [Ni(TMC)]+ acting as a CO scavenger includes the observation of [Ni(TMC)(CO)]+ by IR. Density functional theory (DFT) calculations probing the optimized geometry of the [Ni(cyclam)(CO)]+ species are also presented. [ABSTRACT FROM AUTHOR]

An Ni–P–B amorphous nano-catalyst was synthesized using a facile chemical reduction method. The amorphous degree was enhanced and the transferred electron decreased with an increase of P content in Ni–P–B. In the hydrodeoxygenation (HDO) of p-cresol, the conversion using Ni–P–B was high up to 98.9% with a selectivity of 6.5% for toluene and a deoxygenation degree of 96.8% at 498 K. [ABSTRACT FROM AUTHOR]

The earlier developed flow protocol for stoichiometric reduction of an important biologically derived pharmaceutical precursor, artemisinin, to dihydroartemisinin was extended to a sequential reaction to produce one of the final APIs, artemether. A highly active heterogeneous catalyst was found for the etherification reaction. The use of QuadraSil catalyst allows to eliminate one step of reaction workup. A comparative Life Cycle Assessment of both reactions has shown advantages of the flow process over the optimized literature batch protocols. Results of LCA highlight the significance of solvents in pharmaceuticals manufacture and the advantage of flow technology, enabling small solvent inventories to be used. [ABSTRACT FROM AUTHOR]

The effect of a local proton source on the activity of a bromotricarbonyl Mn redox catalyst for CO2 reduction has been investigated. The electrochemical behaviour of the novel complex [fac-Mn(dhbpy)(CO)3Br] (dhbpy = 4-phenyl-6-(1,3-dihydroxybenzen-2-yl) 2,2'-bipyridine), containing two acidic OH groups in the proximity of the metal centre, under a CO2 atmosphere showed a sustained catalysis in homogeneous solution even in the absence of Bronsted acids. [ABSTRACT FROM AUTHOR]

The hydroxylamine oxidoreductase (HAO) from the anammox bacterium, Candidatus Kuenenia stuttgartiensis has been reported to catalyze the oxidation of hydroxylamine (NH 2 OH) to nitric oxide (NO) by using bovine cytochrome c as an oxidant. In contrast, we investigated whether the HAO from anammox bacterium strain KSU-1 could catalyze the reduction of NO with reduced benzyl viologen (BV red ) and the NO-releasing reagent, NOC 7. The reduction proceeded, resulting in the formation of NH 2 OH as a product. The oxidation rate of BV red was proportional to the concentration of BV red itself for a short period in each experiment, a situation that was termed quasi-steady state. The analyses of the states at various concentrations of HAO allowed us to determine the rate constant for the catalytic reaction, (2.85 ± 0.19) × 10 5 M −1 s −1 , governing NO reduction by BV red and HAO, which was comparable to that reported for the HAO from the ammonium oxidizer, Nitrosomonas with reduced methyl viologen. These results suggest that the anammox HAO functions to adjust anammox by inter-conversion of NO and NH 2 OH depending on the redox potential of the physiological electron transfer protein in anammox bacteria. [ABSTRACT FROM AUTHOR]

Metal nanoclusters (NCs) with diameter below 2 nm are promising catalysts in oxygen reduction reactions (ORR). However, the high surface energy of ultra-small clusters leads to structural instability, shedding doubt on practical applications. Herein, we demonstrate a self-assembly method to improve the durability of catalytic metal NCs, employing copper NCs capped by 1-dodecanethiol (DT) to form free-standing ribbons in colloidal solution. By tuning the cooperation between the dipolar attraction between Cu NCs and the van der Waals attraction between DT, the thickness of ribbons is adjusted to a single NC scale. Such free-standing ribbons exhibit excellent catalytic activity and durability in ORR. [ABSTRACT FROM AUTHOR]

The solar energy conversion efficiency of cobalt-based dye-sensitized solar cells using carbon materials as the catalyst was found similar or better than that of platinum. [ABSTRACT FROM AUTHOR]

Trimetallic PdNiAg nanoparticles supported on activated carbon were simply and reproducibly prepared by wet-impregnation followed by simultaneous reduction method without using any stabilizer at room temperature. The characterization of the resulting material was done by the combination of complimentary techniques and the sum of their results shows that the formation of well-dispersed 5.6 ± 2.2 nm PdNiAg nanoparticles in alloy form on the surface of activated carbon. These carbon supported PdNiAg nanoparticles were employed as heterogeneous catalyst in the catalytic decomposition of formic acid, which has great potential as a safe and convenient hydrogen carrier for fuel cells, under mild conditions. It was found that PdNiAg/C can catalyze the dehydrogenation of formic acid with high selectivity (~100%) and activity (TOF = 85 h-1) at 50 °C. More importantly, the exceptional stability of PdNiAg nanoparticles against to agglomeration, leaching and CO poisoning make PdNiAg/C reusable catalyst in the formic acid dehydrogenation. PdNiAg/C catalyst retains almost its inherent activity (>94%) even at 5th reuse in the dehydrogenation of formic acid with high selectivity (~100%) at complete conversion. The work reported here also includes the compilation of kinetic data for PdNiAg/C catalyzed dehydrogenation of formic acid depending on catalyst [PdNiAg], substrate [HCOOH], promoter [HCOONa] concentrations and temperature to determine the rate expression and the activation parameters (Ea, ΔH#, and ΔS#) of the catalytic reaction. [ABSTRACT FROM AUTHOR]

A novel superparamagnetic gold/halloysite nanotubes/FeO (Au/HNTs/FeO) nanocomposite with coaxial structure was designed and fabricated by selective decoration of the inner lumen and the external wall of halloysite nanotubes (HNTs) based on the difference inside/outside surface charges. The structure and composition of Au/HNTs/FeO were characterized by transmission electron microscope, powder X-ray diffraction, and X-ray fluorescence. The results indicated that Au nanorods selectively generated within the lumen of HNTs, while FeO nanoparticles uniformly deposited on the external wall. It was particularly worth mentioning that the structure of HNTs was not destroyed in the preparation process of Au/HNTs/FeO nanocomposites. The catalytic activity of the as-prepared Au/HNTs/FeO was investigated for the reduction of 4-nitrophenol in the presence of NaBH. The Au/HNTs/FeO nanocomposites exhibited excellent catalytic activity and cycling stability according to the kinetic data of the catalytic reduction reaction. In addition, the Au/HNTs/FeO catalysts can be easily manipulated by an external magnetic field for recycling. [ABSTRACT FROM AUTHOR]

The application of anthraquinone (AQ) as a pulping catalyst has been well documented in scientific studies and mill applications. AQ is known to increase the rate of delignification, enabling a reduction in pulping time, temperature, or chemical charge and an increase in pulp yield. This review does not focus extensively on specific details of AQ use but rather on critical milestones in the AQ process lifecycle, including its initial introduction, investigation of the reaction mechanism, and evaluation of best use by the pulping industry. The importance and difficulty of an economic justification for use of AQ are discussed, including their complication by modest improvement in yield obtained using AQ and low cost of the displaced chemicals. In many mills, documenting increased net mill revenue resulting from the use of AQ has been impossible. Recent health and safety studies and regulatory decisions have put the continuing use of AQ by industry in jeopardy. Given the unknown health risks, international regulatory environment, modest improvements available using AQ, and difficulty in economically accounting for the benefits, this likely represents the final chapter in the AQ life cycle. [ABSTRACT FROM AUTHOR]

Keywords: Redox; Iron Sulfide; Electron transfer; Electrocatalysis EN Redox Iron Sulfide Electron transfer Electrocatalysis 1 1 1 06/24/22 20220622 NES 220622 B The Cover Feature b shows two different natural sceneries where iron sulfides play a key role in mediating chemical reductions. Redox, Iron Sulfide, Electron transfer, Electrocatalysis. [Extracted from the article]

[Display omitted] • Discovery of electrocatalytic materials for CO 2 reduction is essential to mitigate greenhouse effect. • Chemical reduction of CO 2 by reverse water-gas shift reaction on the Ru(0001) surface has illustrated. • We explore the role of water solvation on the CO 2 conversion path by assessing the H-shuttled (O-H bond formation) and water solvated (C-H bond formation). In this work, we systematically illustrate CO 2 reduction by H 2 on the Ru(0001) surface using periodic DFT calculations with micro-kinetic modeling to explore adsorbate-substrate, adsorbate-solvent, solvent-substrate interactions as well as reaction mechanisms. The effects of adsorbate-substrate interactions, water-mediated protonation kinetics, thermodynamics, and transient potential sweeps on reaction rate and selectivity are also studied. We propose three simple thermodynamic descriptors (CO + O, HCOO, and COOH) that represent the effectiveness of CO selectivity on Ru catalysts. More importantly, we explore the role of water solvation on the CO 2 conversion by assessing the H-shuttled (O-H bond formation) and water solvated (C-H bond formation) with various solvation models. To examine the solvation effect, a 6H 2 O/Ru(0001) water bilayer model is constructed by optimizing six H 2 O molecules close to the Ru surface, and multiple H-bonds are observed as local-minimum solvation structures among water molecules. Finally, the efficiency of the ruthenium catalyst is expressed by turnover frequencies (TOFs). We hope that these insights will deliver useful guidelines for designing more efficient, earth-abundant electrocatalysts in the future. [ABSTRACT FROM AUTHOR]

CO 2 electroreduction to value-added chemicals and fuels has gained increasing attention; however, there are only a few catalysts with high performance under mild conditions that can be used in this technique. In this study, single metal Pb, In and bimetallic PbIn catalysts for aqueous CO 2 electroreduction were prepared using a facile 3-step process including PbIn granulation by reducing Pb(NO 3) 2 /In(NO 3) 3 aqueous solution with NaBH 4 , calcination in air, and in situ electroreduction. The bimetallic PbIn catalysts had better catalytic performance on CO 2 electroreduction than single metal catalysts. The bimetallic Pb 7 In 3 catalyst (atomic ratios of Pb and In is 7:3) presented the highest formic acid faradaic efficiency of 91.6% at −1.26 V vs reversible hydrogen electrode in a 0.5 M CO 2 -saturated KHCO 3 aqueous solution, which was 13% and 9.7% higher than that of single Pb and In catalysts, respectively. Moreover, the catalyst remained active after 10 h of continuous CO 2 electrolysis with a stale current density of −17 mA cm−2. The experimental results showed that the excellent catalytic performance of Pb 7 In 3 catalyst may stem from its higher electrochemical active surface area, lower charge-transfer resistance and the synergistic effect of Pb and In in the catalyst. The presented bimetallic PbIn catalysts may have a wide of application prospect, and they may be synthesized from heavy metals in industrial wastewaters. [Display omitted] • Bimetallic PbIn catalysts were prepared for selective carbon dioxide electroreduction into formic acid. • The catalysts were obtained via a three-step process: chemical reduction, annealing, and electroreduction. • The Pb 7 In 3 catalyst showed a high electrocatalytic activity. • A high faradic efficiency of formic acid formation (>90%) was achieved at −1.26 V vs reversible hydrogen electrode. • A stable current density (−17 mA cm−2) was kept for 10 h. [ABSTRACT FROM AUTHOR]

The challenge of breaking the C–C bond in ethylene glycol oxidation requires an efficient electrocatalyst. A porous oxide as the promoter boosts the dispersion of noble metal onto the electrocatalyst surface. Porous Li 2 TiO 3 (LT) was synthesized, characterized, and applied as a promoter for palladium nanoparticles. The nano-Pd as a stable and efficient catalyst was stabilized on spinel LT promoter via two different reduction approaches including chemical (NaBH 4) and electrochemical (Zn sheet/HCl) systems. Different techniques such X-ray diffraction, Fourier Transform Infrared Spectroscopy, Energy-Dispersive X-Ray Spectroscopy, Differential scanning calorimetry, thermogravimetric analysis, Barrett-Joyner-Halenda test, scanning electron microscopy, and transition electron microscopy were characterization of LT and LT/Pd. The size of the mesopores is between 2 and 19 nm. In comparison with non-promoted Pd, Pd/LT electrocatalyst was shown an excellent efficiency in parameters like electrochemical active surface area and anti-CO poisoning behaviour. The LT increases the removal of intermediates created in the oxidation of ethylene glycol that can poison the surface of Pd catalyst. This is due to the presence of the lattice oxygens in LT structure and Ti switching between its high and low valances. The morphology of as-synthesized electrocatalysts that was probed by FESEM micrographs demonstrates the embedment of nano-Pd onto the surface and into LT cavities. The results showed that the nano-Pd manufactured with the chemical reduction has a smaller size with high dispersion than the electrochemical reduction system. In this study, for the first time, the adsorption isotherms of fuel on the catalyst's surface were determined through the calculations of adsorption and desorption of hydrogen in the different concentrations of ethylene glycol. [Display omitted] • Fabrication and characterization of porous Li 2 TiO 3 • Incorporation of Pd on Li 2 TiO 3 via chemical and electrochemical reductions • Effect comparison of Pd reduction method on its electrocatalytic activity • Study of Pd activity with and without oxide support for ethylene glycol oxidation [ABSTRACT FROM AUTHOR]

• The Cu/20NPAC catalyst is prepared by a simple impregnation calcination method. • There is a synergistic effect between Cu and N, P co-doped support. • N, P co-doped support can effectively improve the dispersion of Cu. • N, P co-doped support can effectively inhibit the reduction of Cu. • Cu-based catalysts show excellent catalytic performance in acetylene hydration. N, P co-doped Cu-based catalyst was synthesized by calcining activated carbon impregnated with diammonium hydrogen phosphate and impregnating active component copper. When the contents of N and P were 0.40% and 2.61% and the reaction temperature was 225 ℃, Cu/20NPAC catalyst had 90.4% acetylene conversion and 88.8% acetaldehyde selectivity, and notably, the catalytic performance remained basically unchanged within 20 h of reaction, which was superior than the Cu-based and Zn-based catalysts reported. The characterization results confirmed the excellent catalytic performance depended on the synergistic effect between N, P doped activated carbon and active component copper. TEM showed that the doped support could effectively improve the dispersion of active component copper and inhibit metal agglomeration. H 2 -TPR and XPS illustrated reduction of high valence copper were effectively inhibited in catalyst preparation and reaction. In addition, TPD showed an increased adsorption to acetylene. The high activity and stability of the catalyst showed that N, P co-doped support was an effective way to improve the catalytic performance of acetylene hydration. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the catalytic reduction of 4-nitrophenol by heterostructured Au–Fe 3 O 4 nanocatalysts using NaBH 4 as the reducing agent was investigated under various environmental conditions. The electron behaviors at the interface of Au and Fe 3 O 4 nanoparticles were examined to elucidate the reaction mechanisms for 4-nitrophenol reduction. The transmission electron microscopic images show that the average particle size of Au–Fe 3 O 4 heterostructures increases slightly from 14 to 18 nm after phase transfer from oil phase to aqueous solution. The X-ray photoelectron and X-ray absorption near edge spectroscopic results show the electron flow from Au seeds to Fe 3 O 4 , resulting in the formation of positively charged Au surface to accelerate the catalytic reduction efficiency and rate of 4-nitrophenol. In addition, the reduction of 4-nitrophenol is a surface-mediated reaction and the catalytic efficiency and rate of 4-nitrophenol is highly dependent on the initial 4-nitrophenol concentration, pH, and reaction temperature. The increase in pH lowers the reduction efficiency and rate of 4-nitrophenol and a 2.4-fold decrease in the pseudo-first-order rate constant is observed when pH increases from 5 to 9. In addition, the Au–Fe 3 O 4 nanocatalysts show a good separation ability and reusability which can be repeatedly applied for complete reduction of 4-nitrophenol for at least six successive cycles without the loss of morphology and saturation magnetization. Results obtained in this study clearly demonstrate that the Au–Fe 3 O 4 heterostructures are excellent nanocatalysts which can be applied in heterogeneous catalysis, water treatment, and green chemistry. [ABSTRACT FROM AUTHOR]

Two-electron mixed-valence compounds promote the rearrangement of the two-electron bond photochemically. Such complexes are especially effective at managing the activation of hydrohalic adds (HX). Closed HX-splitting cydes require proton reduction to H2 and halide oxidation to X2 to be both accomplished, the latter of which is thermodynamically and ldnetically demanding. Phosphazane-bridged Rh2 catalysts have been especially effective at activating HX via photogenerated ligandbridged intermediates; such intermediates are analogues of the dassical ligand-bridged intermediates proposed in binuclear elimination reactions. Herein, a new family of phosphazane-bridged Rh2 photocatalysts has been developed where the halide-bridged geometry is designed into the ground state. The targeted geometries were accessed by replacing previously used alkyl isocyanides with aryl isocyanide ligands, which provided access to families of Rh2L, complexes. H2 evolution with Rh2 catalysts typically proceeds via two-electron photoreduction, protonation to afford Rh hydrides, and photochemical H2 evolution. Herein, we have directly observed each of these steps in stoichiometric reactions. Reactivity differences between Rh2 chloride and bromide complexes have been delineated. H2 evolution from both HCI and HBr proceeds with a halide-bridged Rh2 hydride photoresting state. The H2-evolution efficiency of the new family of halide-bridged catalysts is compared to a related catalyst in which ligand-bridged geometries are not stabilized in the molecular ground state, and the new complexes are found to more efficiendy facilitate H2 evolution. [ABSTRACT FROM AUTHOR]

Highlights: [•] Evaluated 4 TWC formulations for the production of NH3 for passive SCR. [•] All produced NH3 over range of rich conditions; Pd-only had highest NH3 selectivity. [•] At high temperatures, NH3 production requires richer conditions. [•] Under cycling conditions richer conditions required to achieve NH3 yield. [•] Optimal TWC temperature is in the 400–450°C range. [ABSTRACT FROM AUTHOR]

Efficient catalytic two-electron reduction of dioxygen (O2) by octamethylferrocene (Me8Fc) produced hydrogen peroxide (H2O2) using a high-valent chromium(V)-- oxo corroie complex, [(tpfc)Crv(O)] (tpfc = tris- (pentafluorophenyl)corrole) as a catalyst precursor in the presence of trifiuoroacetic acid (TFA) in acetonitrile (MeCN). The facile two-electron reduction of [(tpfc)Crv(O)] by 2 equiv of Me8Fc in the presence of excess TFA produced the & corresponding chromium(III) corrole [(tpfc)CrIII(OH2)] via fast electron transfer from Me8Fc to [(tpfc)Crv(O)] followed by double protonation of [(tpfc)CrIV(O)]- and facile secondelectron transfer from Me8Fc. The rate-detennining step in the catalytic two-electron reduction of O2 by Me8Fc in the presence of excess TFA is inner-sphere electron transfer from [(tpfc)CrIII(OH2)] to O2 to produce the chromium(IV) superoxo species [(tpfc)CrIV(O2)], followed by fast proton-coupled electron transfer reduction of [(tpfc)CrIII(O2* )] by Me8Fc to yield H2O2 accompanied by regeneration of [(tpfc)CrIII(OH2]. Thus, although the catalytic two-electron reduction of O2 by MegFc was started by [(tpfc)Crv(O)], no regeneration of [(tpfc)Crv(O)] was observed in the presence of excess TFA, regardless of the tetragonal chromium complex being to the left of the oxo wall. In the presence of a stoichiometric amount of TFA, however, disproportionation of [(dpc)CrIV(O)]- occurred via the protonated species [(tpfc)CrIV(OH)] to produce [(tpfc)CrIII(OH2)] and [(tpfc)Crv(0)]. [ABSTRACT FROM AUTHOR]

Abstract: The novel and efficient selenium-catalyzed reductive N-heterocyclization of γ-nitro substituted carbonyl compounds with carbon monoxide has been developed. Various multisubstituted 1H-pyrroles can be easily prepared by this protocol. The one-pot synthesis of ethyl 1H-pyrrole-3-carboxylate derivatives was also successfully attained by the selenium-catalyzed reaction of β-ketoester, vinyl nitro compounds and carbon monoxide. [Copyright &y& Elsevier]

Highlights: [•] Highly efficient Pd/CNF catalyst for bromates reduction in water is presented. [•] Production of carbon nanofibre support scaled to 10g. [•] LCA study of carbon nanofibrous catalyst was developed. [ABSTRACT FROM AUTHOR]

Novel reactive materials for catalytic degradation of chlorinated organic compounds in water at ambient conditions have been prepared on the basis of silica-supported Pd-Fe nanoparticles. Nanoscale Fe-Pd particles were synthesized inside porous silica supports using (NH4)3[Fe(C2O4)3] and [Pd(NH3)4]Cl2 or Pd acetate as reaction precursors. According to temperature programmed reduction (TPR) studies, Pd introduction decreased the reduction temperature of the supported Fe n+ species and nearly complete reduction with H2 was observed at 400 °C. The successful surface loading with Pd was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Characterization of the samples by X-ray diffraction (XRD) and X-ray absorption near-edge structure + extended X-ray absorption fine structure (XANES + EXAFS) verified the presence of highly dispersed Pd0, Pd x Fe1- x and Fe0 phases. Reduction of the supported precursors in hydrogen resulted in materials that were highly active in perchloroethene (PCE) degradation and 2-chlorobiphenyl (2-ClBP) dechlorination. It was found that highly dispersed amorphous Fe-Pd bimetallic nanoparticles on silica support showed superior catalytic activity against PCE dechlorination in comparison to the free-standing Fe-Pd nanoparticles. For the samples with the same Fe content, the conversion of chlorinated organics as well as the stability increased with the Pd loading, e.g., the most effective degradation of PCEs and 2-ClBP was achieved at a Pd loading of 2.3-3.2 wt. %. [ABSTRACT FROM AUTHOR]

Rising atmospheric CO2 is expected to have negative effects on the global environment from its role in climate change and ocean acidification. Utilizing CO2 as a feedstock to make valuable chemicals is potentially more desirable than sequestration. A substantial reduction of CO2 levels requires a large-scale CO2 catalytic conversion process, which in turn requires the discovery of low-cost catalysts. Results from the current study demonstrate the feasibility of using the non-precious metal material molybdenum carbide (Mo2C) as an active and selective catalyst for CO2 conversion by H2. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ni-MOR, Co-MOR and Fe-MOR are active for SCR of N2O with CH4 in the presence of O2. [•] Despite relative H+ and Na+ amount, the activity order is Fe-MOR>Ni-MOR>Co-MOR. [•] The CO2 selectivity is 100% on Ni-MOR and lower on Fe-MOR and Co-MOR. [•] Ni-MOR are promising catalysts for the simultaneous SCR of N2O and NO x using CH4. [•] On all catalysts FTIR showed isolated tmi with at least two coordinative vacancies. [Copyright &y& Elsevier]

Highlights: [•] Nickel nanoparticles/reduced graphene oxide (Ni/rGO) composite has been synthesized. [•] Ni/rGO can be used as a magnetic recoverable catalyst. [•] Ni/rGO exhibits good catalytic activity for the reduction of 4-nitrophenol. [•] The use of rGO as the catalyst support leads to a synergistic effect. [•] NIR irradiation can enhance the activity of Ni/rGO via photothermal conversion. [ABSTRACT FROM AUTHOR]

With the goal of improving previously reported Mn bipyridine electrocatalysts in terms of increased activity and reduced overpotential, a bulky bipyridine ligand, 6,6'-dimesityl-2,2'-bipyridine (mesbpy), was utilized to eliminate dimerization in the catalytic cycle. Synthesis, electrocatalytic properties, X-ray diffraction (XRD) studies, and infrared spectroelectrochemistry (IR-SEC) of Mn(mesbpy)(CO)3Br and [Mn(mesbpy)(CO)3(MeCN)](OTf) are reported. Unlike previously reported Mn bipyridine catalysts, these Mn complexes exhibit a single, two-electron reduction wave under nitrogen, with no evidence of dimerization. The anionic complex, [Mn(mesbpy)(CO)3]-, is formed at 300 mV more positive potential than the corresponding state is formed in typical Mn bipyridine catalysts. IR-SEC experiments and chemical reductions with KC8 provide insights into the species leading up to the anionic state, specifically that both the singly reduced and doubly reduced Mn complexes form at the same potential. When formed, the anionic complex binds CO2 with H+, but catalytic activity does not occur until a ∼400 mV more negative potential is present. The Mn complexes show high activity and Faradaic efficiency for CO2 reduction to CO with the addition of weak Bronsted acids. IR-SEC experiments under CO2/H+ indicate that reduction of a Mn(I)-CO2H catalytic intermediate may be the cause of this unusual "over-reduction" required to initiate catalysis. [ABSTRACT FROM AUTHOR]

Several NOx reduction technologies under development in recent years have now been commercialized, including selective catalytic reduction (SCR) with NH or hydrocarbons, and Lean NOx Trap. The aim of the present study is to investigate characteristics on NOx adsorption according to the oxygen concentration, de-NOx performance according to lean/rich injection cycle and toxic intermediates at LNT downstram for lean-burn gasoline engine. Under oxygen of 6%, NOx storage capacity was the highest, showed the highest NOx conversion of 98%. The reason for this phenomena is because the excited oxygen atoms at high oxygen concentration increased oxidizing power of NO. Under low temperature of 205°C, LNT catalyst showed the least NOx conversion of 14% because its activity became lower, while the generation rate of toxic HNCO was highest as CO which is generated during the rich condition, reacts with NOx stored on Ba site. [ABSTRACT FROM AUTHOR]

We have reported a LaMnO-based, Pt free lean NO trap (LNT) catalyst shows promising NO reduction activities, but the mechanism of NO reduction or the role of the perovskite over this catalyst has not been addressed. This paper presented our investigation on the mechanistic aspects of NO adsorption and reduction over several LaMnO-based LNT catalysts. NO can be effectively oxidized to NO on LaMnO at 350 °C, while little NO (NO + NO) can be stored verified by the following temperature programmed desorption experiment; under the same conditions, a significant amount of NO (41 μmol NO/g washcoat) were stored over BaO/AlO/LaMnO indicating NO are adsorbed mainly on the BaO/AlO. The temperature programmed surface reaction with CO demonstrated that although it can store NO during the lean period, failed to reduce NO by CO over the BaO/AlO/LaMnO catalyst. After adding Pd into BaO/AlO/LaMnO, NO can not only be stored during the lean conditions but also reduced. It could be concluded that the Pd catalyst, not perovskite, is responsible for NO reduction during the rich conditions. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: La0.8Sr0.2Cr0.95Ru0.05O3−x (LSCR) and Sm0.8Ba0.2Cr0.95Ru0.05O3−x (SBCR), Ru-substituted perovskite catalysts, are investigated for the partial oxidation (POX) of diesel to produce hydrogen-rich gases for fuel cell applications. Metal-substituted perovskite materials have been investigated as reforming catalysts because the metal atoms are well-dispersed in the perovskite structure. However, Ru de-mixing and a secondary phase of LSCR and SBCR are observed after reduction at high temperature. The thermal stability, sulfur tolerance and aromatic decomposition over LSCR and SBCR are compared to those over Ru on Ce0.9Gd0.1O2−x (CGO). During the thermal stability test, the catalytic activities of LSCR and SBCR improve after operating at 1000 °C. The sulfur tolerance and aromatic decomposition activity of LSCR and SBCR improve when the temperature increases to 950 °C. The improvements are attributed to the de-mixed Ru from the perovskite structure at high temperatures under a reductive atmosphere. [Copyright &y& Elsevier]

Highlights: [•] Furfural residues conversion into reducing sugars was researched. [•] Potential commercial physicochemical pretreatment methods are developed. [•] Carbon-based sulfonated solid acid catalysts were applied. [•] The catalysts are green, efficient, and low cost. [ABSTRACT FROM AUTHOR]

This review focuses on the importance of coupling of catalytic reactions which involves dehydrogenation and hydrogenation simultaneously and the study of catalytic materials that are designed, adopted and/or modified for these reactions. The special features of these reactions are minimization of H utilization and reduction in production cost. Structural and textural properties also play a decisive role in this kind of coupled reactions. This particular review although not comprehensive discusses the significant progress made in the area of coupled reactions and also helps future researchers or engineers to find out the improvements required in areas such as advancements in catalytic material preparation, design of the new reactors and the application of new technologies. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this study, the effects of operation variables on catalytic performance of CeO2–MnOx(0.25)–Ba mixed oxide in catalytic reduction of NO with ammonia are investigated by using design of experiments. A response surface methodology (RSM) combined with the central composite design (CCD) is used to model and optimize the process variables, including concentration of O2(vol.%), NH3/NO ratio in the gas feed, gas hourly space velocity (GHSV) and reaction temperature (°C) on the NO conversion and N2selectivity as responses. TheR2values for both generated models were greater than 0.9, confirming the capability of quadratic RSM model in fitting the obtained experimental data. According to the results, GHSV had the largest and negative effect on the NO conversion, while it was an insignificant parameter on the N2selectivity in the design space. Also, NH3/NO ratio was the most effective parameter on the N2selectivity. Under the optimum conditions: 4.75 vol.% O2, NH3/NO ratio of 0.9, GHSV of 12,000 h−1and 197.5°C, the predicted values for NO conversion and N2selectivity were 96.47% and 93.96%, respectively. The obtained experimental values in optimum condition agreed with those predicted, indicating suitability of the RSM model to estimate the values of the responses. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we attempted to synthesize a hybrid nanostructure by the incorporation of Au nanoparticles (NPs) with polymer-coated Fe3O4 microspheres. Also, Au NPs on 3-aminopropyl triethylsilane (APTS)-modified Fe3O4@SiO2 and Fe3O4@polymer microspheres were synthesized to assess the catalytic activity of Au NPs on Fe3O4@polymer microspheres for the reduction of 4-nitrophenol. It was found that Au NPs on Fe3O4@polymer catalysts showed higher catalytic activity and recyclability than other APTS-modified catalysts. [Copyright &y& Elsevier]

The present work reports up-to-date information regarding the reaction mechanism of the catalytic hydrogenation of nitrates in water media. In the present mechanistic study, an attempt is made, for the first time, to elucidate the crucial role of several catalysts and reaction parameters in the mechanism of the NO-3/H2 reaction. Steady-state isotopic transient kinetic analysis (SSITKA) experiments coupled with ex situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were performed on supported Pd-Cu catalysts for the NO-3/H2 and NO-3/H2/O2 reactions. The latter experiments revealed that the formation and surface coverage of various adsorbed active intermediate N-species on the support or Pd/Cu metal surface is significantly favored in the presence of TiO2 in the support mixture and in the presence of oxygen in the reaction's gaseous feed stream. The differences in the reactivity of these adsorbed N-species, found in the present work, adequately explain the large effect of the chemical composition of the support and the gas feed composition on catalyst behaviour (activity and selectivity). The present study leads to solid mechanistic evidence concerning the presence of a hydrogen spillover process from the metal to the support. Moreover, this study shows that Cu clusters are active sites for the reduction of nitrates to nitrites. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the effect of various Co–B catalyst synthesis conditions on the catalyst surface morphology and kinetic parameters. The Co–B catalyst was synthesized on IR-120/TP-207 resin surface by using ion exchange and chemical reduction method using NaBH4 as a reduction agent. The reduction conditions which were investigated here were: reduction temperature, NaBH4 concentration, pH value, NaBH4 adding flowrate and different types of resins. The result shows reduction temperature gives the most dramatic effect on surface morphology which is caused by competing reactions of reduction and hydrolysis. Low reduction temperature resulted in a slower Co–B reduction rate and made the catalyst surface denser with a branched structure. This created more surface area than higher reduction temperatures. Low reduction temperature catalyst had the better performance on NaBH4 hydrolysis reaction for hydrogen generation rate. The optimal reduction temperature of the Co–B/IR-120 is 25 °C. The L-H model was used to regress kinetic parameters from the experiment data. The frequency factor, activation energy and adsorption constant are 1.17 × 109 mol gcat−1 min−1, 70.65 kJ mol−1, and 6.8 L mol−1 at 40 °C, respectively. Finally, the TP-207 resin was used instead of IR-120. After scanning for all catalyst synthesis conditions, the Co–B/TP-207 had the higher catalyst loading, faster hydrogen generation rate and more stable than Co–B/IR-120. [ABSTRACT FROM AUTHOR]

Bifunctional EH activation offers a promising approach for the design of two-electron-reduction catalysts with late first-row metals, such as Ni. To this end, we have been pursuing H2 activation reactions at late-metal boratranes and herein describe a diphosphine-borane-supported Ni-(H2) complex, [(PhDPB iPr)Ni(H2)], which has been characterized in solution. 1H NMR spectroscopy confirms the presence of an intact H2 ligand. A range of data, including electronic-structure calculations, suggests a d10 configuration for [(PhDPB iPr)Ni(H2)] as most appropriate. Such a configuration is highly unusual among transition-metal H2 adducts. The nonclassical H2 adduct is an intermediate in the complete activation of H2 across the NiB interaction. Reaction-coordinate analysis suggests synergistic activation of the H2 ligand by both the Ni and B centers of the nickel boratrane subunit, thus highlighting an important role of the borane ligand both in stabilizing the d10 Ni-(H2) interaction and in the H-H cleavage step. [ABSTRACT FROM AUTHOR]

Abstract: A facile solution-phase process was developed for the selective preparation of single-crystalline copper (Cu) nanohexagons, nanospindles, and microflowers by the reduction of cuprous iodide with sodium ascorbate in the presence of surfactants such as cetyltrimethylammonium chloride and Pluronic F-127 or cetyltrimethylammonium bromide. The Cu nanoparticle samples obtained at different stages of growth were studied by X-ray diffraction (XRD). The final products were characterized by XRD, scanning electron microscopy, and UV–vis spectroscopy. The UV–vis spectra of the as-synthesized Cu nanostructures exhibited morphology-dependant optical property. The Cu microflowers showed significant catalytic activity in click chemistry. [Copyright &y& Elsevier]