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The chemical reduction efficiencies of graphene oxide (GO) are critically important in achieving graphene-like properties in reduced graphene oxide (rGO). In this study, we assessed GO lateral size and its degree of oxidation effect on its chemical reduction efficiency in both suspension and film and the electrical conductivity of the corresponding rGO films. We show that while GO-reduction efficiency increases with the GO size of lower oxidation in suspension, the trend is opposite for film. FESEM, XRD, and Raman analyses reveal that the GO reduction efficiency in film is affected not only by GO size and degree of oxidation but also by its interlayer spacing (restacking) and the efficiency is tunable based on the use of mixed GO. Moreover, we show that the electrical conductivity of rGO films depends linearly on the C/O and Raman ID/IG ratio of rGO and not the lateral size of GO. In this study, an optimal chemical reduction was achieved using premixed large and small GO (L/SGO) at a ratio of 3:1 (w/w). Consequently, the highest electrical conductivity of 85,283 S/m was achieved out of all rGO films reported so far. We hope that our findings may help to pave the way for a simple and scalable method to fabricate tunable, electrically conductive rGO films for electronic applications. [ABSTRACT FROM AUTHOR]

This work reports on the fabrication of a novel planar reduced graphene oxide (rGO) memristor (MR) device. For the first time in the literature, the MR tunable resistive switching behavior is controlled by the GO reduction time at a constant temperature. The device is fabricated using standard microfabrication techniques on a flexible cyclic olefin copolymer substrate (COC). Thermal reduction of the GO layer at low temperatures (100 °C) avoids the drawbacks of chemical reduction methods such as toxicity and electrode metal damage during fabrication, while allowing for fine-tuning of the MR's switching behavior. The device has analog switching characteristics, with a range of different resistance states. By taking advantage of the slow nature of GO thermal annealing, the switching properties of the rGO memristors can be precisely controlled by adjusting the reduction period. At short annealing times (i.e., T < 20 h), the devices switch from high to low resistance states, while at longer annealing times the switching behavior is reversed, with the device switching from low to high resistance states (LRS to HRS). Resistive switching occurs as a result of the diffusion and removal of the oxygen functional groups in the GO film caused by Joule heating induced by the electric current. Complete electrical characterization tests are presented along with wettability and X-ray diffraction (XRD) tests. This work opens a new vision for realizing rGO-based MR devices with tunable switching properties, broadening the application horizon of the device. [ABSTRACT FROM AUTHOR]

Waste sludge disintegration and bound water reduction was investigated by comparative chemical oxidation using calcium hypochlorite, hydrogen peroxide, peroxymonusulfate and peroxydisulfate in the study. Response surface methodology (RSM) with Box-Benhken Design (BBD) was used to determine operating parameters namely initial pH (2-10), oxidant dosage (5-85 mg/g TSS), and Fe2+ to oxidant ratio (0.2-2) and disintegration time (20-100 min). According to ANOVA results, determination coefficient (R2) was found 93.2%, 76.3%, 84% and 84.8% for each oxidant, respectively. Under the optimum operating conditions, disintegration degree in terms of chemical oxygen demand (DDCOD) was calculated 11.09%, 5.23%, 10.75%, and 5.34%, respectively. Furthermore, bound water reduction (BWR) of waste sludge increased after the disintegration process, and 33.52%, 24.56%, 44.63% and 32.80% BWR values were obtained under the same operating conditions. Results show that the higher DDCOD and BWR values were achieved by calcium hypochlorite and peroxymonosulfate treatment. [ABSTRACT FROM AUTHOR]

We report an anti‐folded bowl‐shaped bisdibenzocorannulene (BDBC) featuring a new chair‐cyclohexane‐like hexagon as a bridge of two dibenzocorannulene moieties. The neutral compound showed multiple redox‐active properties and could be converted to the corresponding redox states through chemical reduction or oxidation. Chemical reduction of BDBC by stoichiometric addition of metallic potassium in the presence of [18]crown‐6 ether, provided a radical anion BDBC.− and a dianion BDBC2−, respectively; while chemical oxidation by silver hexafluoroantimonate(V), converted the neutral compound to an open‐shell singlet diradical dication (BDBC..)2+. The structural consequences of both electron‐reduction and oxidation were closely related to the release of ring‐strain of the bowl‐shaped π‐scaffold and imposed steric hindrance of the hexagonal bridge. In addition, the unusual open‐shell nature of the dication could mainly be attributed to the changing of localized antiaromaticity in the closed‐shell structure to delocalized character in the biradical, and thus the emergence of weakly bonded π‐electrons. [ABSTRACT FROM AUTHOR]

We report an anti‐folded bowl‐shaped bisdibenzocorannulene (BDBC) featuring a new chair‐cyclohexane‐like hexagon as a bridge of two dibenzocorannulene moieties. The neutral compound showed multiple redox‐active properties and could be converted to the corresponding redox states through chemical reduction or oxidation. Chemical reduction of BDBC by stoichiometric addition of metallic potassium in the presence of [18]crown‐6 ether, provided a radical anion BDBC.− and a dianion BDBC2−, respectively; while chemical oxidation by silver hexafluoroantimonate(V), converted the neutral compound to an open‐shell singlet diradical dication (BDBC..)2+. The structural consequences of both electron‐reduction and oxidation were closely related to the release of ring‐strain of the bowl‐shaped π‐scaffold and imposed steric hindrance of the hexagonal bridge. In addition, the unusual open‐shell nature of the dication could mainly be attributed to the changing of localized antiaromaticity in the closed‐shell structure to delocalized character in the biradical, and thus the emergence of weakly bonded π‐electrons. [ABSTRACT FROM AUTHOR]

Very strong difference in many properties is well documented for graphite oxides (GtO) synthesized by Brodie (BGO) and Hummers (HGO) methods. The difference is typically assigned to the type of oxidant (chlorates or KMnO 4 , respectively). However, not only oxidants but also acids used in these methods are different. It is still unclear which of the different properties of GtO are dependent on the oxidant or acid used in the synthesis. Here we synthesized a new type of graphite oxide using an oxidation agent typical for the Brodie method (KClO 3) in combination with acids so far used only in modified Hummers' method (H 2 SO 4 +H 3 PO 4). The GtO synthesized by this method (MGO) demonstrates some properties similar to BGO (higher temperature of exfoliation and less defected structure) but also similarity to some other properties of HGO (absence of sharp swelling transitions). Comparing MGO, BGO, and HGO allows us to distinguish the effects of acids and oxidants on the properties of graphite oxides. The new procedure proposed in this study allows preparation of GtO nearly free from hole/vacancy defects (similarly to BGO) but avoids dangerous HNO 3. MGO is suggested as a favorable precursor for the preparation of graphene films by thermal or chemical reduction methods. [Display omitted] • A new type of graphite oxide was synthesized. • The proposed procedure combines the most known graphite oxide preparation methods. • The prepared graphite oxide is nearly free from hole/vacancy defects. • The new synthesis route avoids using dangerous fuming nitric acid. • The new graphite oxide is a favorable precursor for the graphene films preparation. [ABSTRACT FROM AUTHOR]

[Display omitted] • High active NH 2 -MIL-101(Fe)@EPS photocatalysts were facile prepared. • EPS-embedding strategy accelerated the separation of electron-hole pairs. • Photocatalysis promoted the nitrate byproduct reduction in the anammox process. • EPS accelerated the electron derived from photocatalyst transferring to bacteria. • Increased abundance of flavin and complex III accelerated electron transfer. Anaerobic ammonium oxidation (anammox) is an efficient nitrogen removal process; however, nitrate byproducts hampered its development. In this study, extracellular polymeric substances (EPS) were embedded into NH 2 -MIL-101(Fe), creating NH 2 -MIL-101(Fe)@EPS to reduce nitrate. Results revealed that chemical nitrate reduction efficiency of NH 2 -MIL-101(Fe)@EPS surpassed that of NH 2 -MIL-101(Fe) by 17.3 %. After adding 0.5 g/L NH 2 -MIL-101(Fe)@EPS within the anammox process, nitrate removal efficiency reached 63.9 %, consequently elevating the total nitrogen removal efficiency to 92.4 %. 16S rRNA sequencing results elucidated the predominant role of Candidatus Brocadia within NH 2 -MIL-101(Fe)@EPS-anammox system. Concurrently, sufficient photogenerated electrons were transferred to microorganisms, promoting the growth of Desnitratisoma and OLB17. Additionally, photogenerated electrons activated flavin and Complex III, thereby up-regulating crucial genes involved in intra/extracellular electron transfer. Subsequently, denitrification and dissimilatory nitrate reduction to ammonium were activated to reduce nitrate. In summary, this study achieved a notable rate of photocatalytic nitrate reduction within anammox process through the NH 2 -MIL-101(Fe)@EPS photocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, we investigate uniformly dispersed size-selected Pdn clusters (n = 4, 10, and 17) on alumina supports. We study the changes of clustered Pd atoms under oxidizing and reducing (O2 and CO, respectively) conditions in situ using ambient pressure XPS. The behavior of Pd in the clusters is quite different from that of Pd foil under the same conditions. For all Pd clusters, we observe only one Pd peak. The binding energy of this Pd 3d peak is ∼1-1.4 eV higher than that of metallic Pd species and changes slightly in CO and O2 environments. On the Pd foil however many different Pd species co-exist on the surface and change their oxidation states under different conditions. We find that the Pd atoms in direct contact with Al2O3 differ in oxidation state from the surface Pd atoms in a foil under reaction conditions. Compared to previous literature, we find that Pd 3d peak positions are greatly influenced by the different types of Al2O3 supports due to the combination of both initial and final state effects. [ABSTRACT FROM AUTHOR]

Cellulose-supported on Pd nanoparticles (Pd/cellulose) were successfully prepared by chemical reduction technique and characterized by various experimental tools. The Pd/cellulose catalyst was found to effectively promote the oxidation of glucose into gluconic acid under mild conditions. The base played a crucial role in the oxidation of glucose into gluconic acid. Glucose was fully converted at room temperature after 3 h by the use of stoichiometric amount of Na2CO3 to neutralize gluconic acid, and gluconic acid was obtained in a high yield of 91.2%. The catalyst was recovered from product and reused up to five times without significant loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

Lindane (γ-hexachlorocyclohexane) and its isomers (HCH) are some of the most common and most easily detected organochlorine pesticides in the environment. The widespread distribution of lindane is due to its use as an insecticide, accompanied by its persistence and bioaccumulation, whereas HCH were disposed of as waste in unmanaged landfills. Unfortunately, certain HCH (especially the most reactive ones: γ- and α-HCH) are harmful to the central nervous system and to reproductive and endocrine systems, therefore development of suitable remediation methods is needed to remove them from contaminated soil and water. This paper provides a short history of the use of lindane and a description of the properties of HCH, as well as their determination methods. The main focus of the paper, however, is a review of oxidative and reductive treatment methods. Although these methods of HCH remediation are popular, there are no review papers summarising their principles, history, advantages and disadvantages. Furthermore, recent advances in the chemical treatment of HCH are discussed and risks concerning these processes are given. Image 1 • Chemical degradation methods for HCH were critically reviewed. • Determination of HCH and related transformation products was reviewed. • First comparison of oxidative and reductive mechanism of HCH was made. • Remedial agents mainly react with HCH by dihalo-, β- and oxidative-elimination. • Discussion concerning risks related to both treatments was made. [ABSTRACT FROM AUTHOR]

First-principle generalized gradient corrected density functional calculations have been performed to study the stability of cationic and anionic Pd13+/-, and neutral Pd13O2 clusters. It is found that while cationic Pd13+ favors a Cs geometry similar to the neutral Pd13, both anionic Pd13- and neutral Pd13O2 favor a compact ∼Ih structure. A detailed analysis of the electronic structure shows that the stabilization of the delocalized 1P and 2P cluster orbitals, and the hybridization of the 1D orbitals with the oxygen atomic p orbitals play an important role in the energetic ordering of Cs and ∼Ih isomers. A structural oscillation is predicted during an oxidation/reduction cycle of Pd13 in which small energy barriers between 0.3 and 0.4 eV are involved. [ABSTRACT FROM AUTHOR]

The Ni:B2O3 nanoparticles have been synthesized by a novel two-step chemical reduction method, under ambient conditions and subsequent annealing in air. The evolution of this structure has been followed through a sequence of annealing treatments. Structural and magnetic investigations on as-prepared and annealed samples revealed that as-prepared samples are weakly magnetic and develop into spherical ferromagnetic entities with superior magnetic properties. The saturation magnetization (Ms∼42 emu/g) and coercivity (Hc∼482 Oe) at room temperature clearly suggest that the air annealed (500 °C) samples are protected from the oxidation due to formation of B2O3 protective layer. The magnetization results are consistent with the observed microstructural changes and satisfactorily explained on the basis of a core-shell model, where we consider each particle as a magnetically heterogeneous system consisting of a ferromagnetic core of Ni and nonmagnetic shell of B2O3. These results suggest that this kind of nanocomposite systems might have significant potential as a recording media. [ABSTRACT FROM AUTHOR]

Imperfect stoichiometry and heterogeneity of a surface layer of SrRuO3 epitaxial thin films, grown on SrTiO3 substrates, are presented with the help of various methods. Rutherford backscattering spectroscopy, x-ray photoemission spectroscopy (XPS), and time of flight secondary ion mass spectrometry are used to obtain information about the stoichiometry and uniformity of the SrRuO3 structure. The temperature of chemical decomposition is first determined for polycrystalline samples under different conditions using thermogravimetry analysis. Then the determined values are used for thin film annealings in high and low oxygen pressure ambients, namely, air, vacuum, and hydrogen. The surface deterioration of the thin film together with changes in its electronic structure is investigated. O1s and Sr3d core lines measured by XPS for as-made samples obviously consist of multiple components indicating different chemical surroundings of atoms. Thanks to different incident beam angle measurements it is possible to distinguish between interior and surface components. Valence band spectra of the interior of the film are consistent with theoretical calculations. After annealing, the ratio of the different components changes drastically. Stoichiometry near the surface changes, mostly due to ruthenium loss (RuOX) or a segregation process. The width and position of the Ru3p line for as-made samples suggest a mixed oxidation state from metallic to fully oxidized. Long annealing in hydrogen or vacuum ambient leads to a complete reduction of ruthenium to the metallic state. Local conductivity atomic force microscopy scans reveal the presence of nonconductive adsorbates incorporated in the surface region of the film. Charge transport in these measurements shows a tunneling character. Scanning tunneling microscopy scans show some loose and mobile adsorbates on the surface, likely containing hydroxyls. These results suggest that an adequate description of a SrRuO3 thin film should take into account imperfections and high reactivity of its surface region. [ABSTRACT FROM AUTHOR]

The evolution of the structure of the adlayers and the substrate during adsorption of K and coadsorption of K and O on Rh(110) is studied by scanning tunneling microscopy and low-energy electron diffraction. The K adsorption at temperature above 450 K leads to consecutive (1×4), (1×3), and (1×2) missing-row reconstructions for coverage up to 0.12 ML, which revert back to (1×3) and (1×4) with increasing coverage up to 0.21 ML. The coadsorption of different oxygen amount at T>450 K and eventually following reduction-reoxidation cycles led to a wealth of coadsorbate structures, all involving substrate missing-row-type reconstructions, some including segmentation of Rh rows along the [110] direction. The presence of K stabilizes the (1×2) missing-row reconstruction, which facilitates the formation of a great variety of very open (10×2)-type reconstructions at high oxygen coverage, not observed in the single adsorbate systems. [ABSTRACT FROM AUTHOR]

Surface effects of electrical coronas have been studied on the low field electrodes of point-to-plane air gaps with discharges burning in negative and positive glow regimes, i.e., mainly producing chemical effects without significant sputtering or thermal effects. Most of these chemical effects are due to oxidation and reduction processes taking place in aqueous microdroplets formed by the discharge where oxides, nitrates, and cyanides, are mainly found. Generally oxidation prevails providing very high oxidation states, but using preoxidized gold samples as cathodes enabled the separate observation of reduction phenomena. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The tetrazole-functionalised calixdiquinone 5,17-di-tert-butyl-26,28-bis-(1H-tetrazole-5-ylmethoxy)-calix[4]-25,27-diquinone Q was synthesised by chemical oxidation of the bis-tetrazole calix[4]arene precursor using PbO2/HClO4. The single crystal X-ray structure determination of Q confirmed the structure and showed binding of a water molecule in the solid state. Chemical reduction of Q to the dihydroquinone QR was achieved using N,N-diethylhydroxylamine. Comparison of the solution phase photophysical properties of Q or QR in the presence of terbium ions showed significant excitation only with QR, suggesting redox switching of the photophysical response may be possible with this or similar receptor. [ABSTRACT FROM AUTHOR]

Uranium tetraboride (UB4) was successfully synthesized by boro/carbothermal reduction of UO2 with B4C and carbon as combined reduction agents under flowing argon. The effects of processing temperature and mole ratios of starting materials on phase evolution were studied. XRD results demonstrated that UB4 was obtained with 3.75 mol% B4C in excess based on the UO2/B4C/C molar ratios of 1:1:1 at 1500°C. SEM observation revealed that submicrometer‐sized quasi‐spherical UB4 particles cemented together to be an aggregate. The laser particle size analysis showed that the particle size was in the range of 1‐10 μm. The oxidation behavior of UB4 was also investigated by TG and XRD. The oxidation of UB4 started at about 500°C and it showed better oxidation resistance than other basic uranium nuclear fuels (UO2, UC, UN and U3Si2). The oxidation chemical process of UB4 was presented as a three‐step process: (a) the formation of U3O8 and B2O3 oxidation products; (b) the formation of UB2O6 intermediate product by the interaction of U3O8 and B2O3; (c) the decomposition of UB2O6 to get U3O8. [ABSTRACT FROM AUTHOR]

6-Functionalized 7-R-4,7-dihydro[1,2,4]azolo[1,5-a]pyrimidines (R = H or Me) were synthesized by Biginelli-like reaction of formaldehyde or acetaldehyde, aminoazoles, and corresponding β-dicarbonyl precursor. Alkylation of the obtained compounds proceeds smoothly at position 4, while oxidation leads to 7-R-[1,2,4]azolo[1,5-a]pyrimidines formation. 6-Ethoxycarbonyl derivatives could be reduced to the corresponding alcohols by LiAlH4 and hydrolyzed to the acids. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oxygen release from PdO due to the reverse spillover from the CeO 2 -PdO interface. • Evidence for reduction of surface ceria at low temperatures in the presence of Pd. • Adsorption calorimetry evidence for surface re-oxidation with water. Abstract The enhanced rates of reduction and re-oxidation of ceria in the presence of Pd, was investigated on both bulk ceria as well as ceria deposited over γ-Al 2 O 3. Pd addition and surface area enhancement by γ-Al 2 O 3 decreased the reduction temperature of CeO 2 as monitored by temperature programmed reduction (TPR) in H 2. Temperature programmed oxidation (TPO) and temperature programmed thermal decomposition (TPtD) measurements revealed similar results of more favorable temperatures of oxidation and thermal decomposition. Pd assisted oxygen removal from CeO 2 through a reverse spillover process as monitored by the temperature programmed thermal decomposition experiments was evident from the decomposition temperature of PdO to Pd. The adsorption microcalorimetry measurements at 323 K revealed that hydrogen adsorption initiated over Pd extends to CeO 2 by migration (or spillover). Oxygen adsorption, however, was restricted to Pd surface at 323 K. Also at the same temperature, initial H 2 O adsorption was accompanied by very high heats at low coverages indicating surface oxidation. At higher pressures, H 2 O adsorption extended to coverages representative of the monolayer over γ-Al 2 O 3 , the heats of adsorption measured at these high coverages corresponded to water condensation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The first derivative of XANES for As(III) adsorbed systems of all adsorbents are observed to have with mixed oxidation. • As(V) adsorbed samples of Ni, and Cu systems agree with that of As(V) standards. • Both reduction and oxidation behavior of arsenic is observed on to these metal oxide adsorbents. • EXAFS analysis was observed with As O bond distances in the range of 1.7–1.8 Å. • The As-M bond distances are around 2.7, 3.2 and 3.6 Å confirmed the formation of surface complexes. Abstract The present study is about surface complexation behavior of arsenic species adsorbed onto ternary metal oxide adsorbents (Ni-Al-Fe, Co-Al-Fe, Mn-Al-Fe, and Cu-Al-Fe). The analysis is carried out by X-ray absorption spectroscopy (XAS) tool. XANES (μ(E) vs. E) spectra close to the absorption edge (i.e., As K -edge) of all samples are observed along with the As(III) and As(V) standards. The first derivative of XANES for Ni-As(V), and Cu-As(V) samples agree with that of As(V) standards, respectively. Whereas, As(III) adsorbed adsorbent systems (i.e., Ni, Co, Mn, and Cu) are observed with mixed oxidation state of arsenic. A total of 65–85 % is observed with initial oxidation state (As(III) or As(V)), and remaining 15–35 % is observed with modified oxidation state (As(V) or As(III)) that explains the occurrence of possible charge transfer. EXAFS analysis shows the As-O bond distances in the range of 1.7–1.8 Å. The corresponding As-M bond distances are around 2.7, 3.2, and 3.6 Å which confirms the formation various edge sharing (2E), and corner sharing (2C, 1V) surface complexes. Surface coverage is understood as an important parameter as bidentate attachments (2E, 2C) are evident in As(III), and As(V), but monodentate attachments (1V) are only observed in As(V). [ABSTRACT FROM AUTHOR]

Highlights • Si nanowires are thermodynamically unstable during growth in gases containing even a small concentration of O 2. • Under favorable kinetic conditions Si nanowires should entirely convert into dioxide (SiO 2) • Thermal dissociation of SiO 2 in the growth conditions for nanowires is practically impossible. • Recovery is possible for any oxide through hydrogen. Abstract We have studied the thermodynamics of oxide formation, and the recovery of silicon and the metal catalysts from the dissociation of their respective oxides during the growth process of Si nanowires (NWs) under the Vapor → Liquid Droplet → Solid (VLS) mechanism. It is demonstrated that Si NWs under growth temperatures are thermodynamically unstable in any gas phase containing even a small concentration of O 2 , and under favorable kinetic conditions Si NWs should entirely convert into dioxide (SiO 2). Thermal dissociation of SiO 2 in the growth conditions for NWs is practically impossible as it would require either lowering the pressure of O 2 to an unachievable, critically low value or raising the temperature to a point which is impossible to reach in ordinary conditions. Decreasing the diameter, i.e., increasing the Si NW dispersity, leads to an increase in the interaction with O 2 and this O 2 will be held more tightly by Si. Thus, thinner NWs should oxidize stronger than thicker ones. The main metal catalysts for NW growth, as well as Si, are characterized by significant affinity with O 2 and inconvertible oxide formation reactions. The most stable Si NW growth is observed with metals (Au, Pt, Cu, Ni, etc.) whose oxides are less stable than SiO 2. Only metals with a lower affinity to O 2 than to H 2 or any other reducing agent are applicable to guarantee the recovery process when used as a catalyst for the growth of NWs. [ABSTRACT FROM AUTHOR]

A spiro-fused hexa-peri-hexabenzocoronene dimer was synthesized, and its physicochemical properties were studied by UV-Vis absorption and emission spectroscopy as well as cyclic voltammetry. Chemical oxidation of SB-HBC afforded its radical cation and dication derivatives, which could be reversibly reduced to the neutral state. [ABSTRACT FROM AUTHOR]

Abstract Various Ru nanoparticles modified porous carbon substrates were prepared as hydrogen evolution electrocatalysts via chemical reduction in this work. Before obtaining the Ru-based catalysts, different carbon substrates, including lignin, straw and shaddock peel, were selected. The carbon substrates were oxidized and nitrogen-doped under ammonia gas to further increase the physicochemical properties. Then, the nitrogen doped lignin, straw and shaddock peel were used as substrates to fabricate various Ru-based composites, which were denoted as Ru@o-NL, Ru@o-NS and Ru@o-NSP. The HER performances of Ru@o-NL, Ru@o-NS and Ru@o-NSP were fully investigated in both acidic and alkaline conditions. Experimental results indicated that all the Ru-based composites could catalyze the hydrogen evolution reaction. Ru@o-NL showed better HER activity than that of the Ru@o-NS and Ru@o-NSP. The dosage of Ru could affect the HER activity. The Ru@o-NL with 8.0 wt% Ru loading has the best HER performance. The overpotentials (@ 10 mA cm−2) of the Ru@o-NL in 0.5 M H 2 SO 4 and 1.0 M KOH were 42 and 14 mV, respectively. The corresponding Tafel slopes were 32 and 59 mV dec−1. It also had large exchange current density and good long term stability. Highlights • N-doped carbon substrates were prepared from lignin, straw and shaddock peel. • The wrinkled porous substrates were decorated with Ru nanoparticles via chemical reduction. • The materials showed superior HER performances and good long-term stability in both acidic and alkaline conditions. [ABSTRACT FROM AUTHOR]

Highlights • Honeycomb-structured Co–W–B composite was prepared by simple chemical reduction. • The Co–W–B composite was mainly composed of oxides of Co, W, and as a result of oxidation in air. • The Co–W–B composite shows high surface area, large pore volume, and good stability. • The Co–W–B composite exhibited a specific capacitance of 306.3 F g–1 at a current density of 2 A g–1. Abstract A honeycomb-structured Co–W–B composite was prepared by a simple chemical reduction process in an alcohol solution. The structure and morphology of the Co–W–B composite was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results indicate that the composite was mainly composed of oxides of Co, W, and B as a result of oxidation in air, and it was a suitable material for high-performance pseudocapacitors. Electrochemical tests indicated that the Co–W–B composite exhibited a specific capacitance of 306.3 F g–1 at a current density of 2 A g–1, which is much higher than that of a Co–B composite. Furthermore, the Co–W–B composite showed good stability, and the capacitance retained 89.2% of its initial capacitance after 2500 cycles. These results demonstrate that the honeycomb-structured Co–W–B composite is promising for use as an electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

By using spatially resolved photoelectron spectromicroscopy, we have investigated the formation of Cu(I) oxide phases when a bulk Cu foil is exposed to a near ambient pressure of molecular oxygen. The experiment was performed by using a novel cell for in operando measurements capable to overcome the so called ‘pressure gap’. We have found that the oxidation of Cu proceeds through the formation of Cu(I) oxide domains in the micron and submicron range size, the evolution of which affects the overall morphology of the Cu surface as well. Chemical and morphological changes have been simultaneously detected. It was, surprisingly, found that during the oxidation process in many areas domains having +1 valence state do not spread on the metallic regions which homogenously oxidize; no chemical oxidizing wave was detected by the available lateral resolution and time frame. [ABSTRACT FROM AUTHOR]

• CTAB capped Ag0, Re0, and Ag@Re as persulfate heterogeneous activators. • Ag@Re exhibits excellent activation activity to generate reactive radical species. • Activation energy was found to be lower (32.6 kJ/mol) to the degradation of xylenol orange. • SO 4 -• is the major radical reactive species. Silver-rhenium bi-metallic nanoparticles (Ag-Re) were prepared by the combination of colloidal sols of silver and rhenium at room temperature. The silver and rhenium sols were synthesized by using the chemical reduction of silver nitrate and ammonium perrhenate with sodium borohydride in presence of cetyltrimethylammonium bromide (CTAB). The morphology (shape, size, elemental composition, oxidation states, and crystalline nature) and textural properties (pore size, pore volume, and surface area) of Ag0-Re0 were determined with EDX, SEM, TEM, XPS, XRD, and nitrogen adsorption-desorption isotherm. The Ag0-Re0 was used as heterogeneous persulfate (S 2 O 8 2−) activator to generate reactive radical species (SO 4 −• and HO•) for the degradation of xylenol orange (XO) at 434 nm. The Ag-Re exhibits higher XO degradation efficiency than that of mono-metallic Ag0 and Re0 nanoparticles, respectively. The degradation efficiency strongly depends on the concentrations of S 2 O 8 2−, XO, pH, temperature, and amount of Ag0-Re0. The role of SO 4 −• and HO• were established by using ethanol, and tertiary butanol as radical scavengers. The activation energy was found to be 85.2, 63.5, and 32.6 kJ/mol, respectively, to the degradation of XO by activated S 2 O 8 2− with Re0, Ag0, and Ag0-Re0. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work investigated the effect of reduction-oxidation(R-O) pretreatment on the CO oxidation activity of Co 3 O 4 /Al 2 O 3 catalyst. After the reduction-oxidation treatment, the crystalline size of Co 3 O 4 supported on the Al 2 O 3 decreased and it exposed more Co 3+ , resulting in the improvement of CO oxidation activity. Compared with the as-prepared conventional Co 3 O 4 /Al 2 O 3 catalyst, the Co 3 O 4 /Al 2 O 3 -R-O catalyst is easy to be reduced at lower temperature. The surface reconstruction occurred during the reduction-oxidation pretreatment accounting for the improvement of the catalytic activity. This study reveals the importance of R-O pretreatment as a strategy for the improvement of supported metal oxide catalyst with advanced catalytic performance. [ABSTRACT FROM AUTHOR]

Highly-dispersed copper nanoparticles (Cu NPs) were fabricated on the surface of reduced graphene oxide via direct hydrazine hydrate reduction of Cu2+ in aqueous solution. Scanning electron microscope and transmission electron microscope images show that the Cu NPs are distributed on the surface of graphene nanosheets, and the average particle size was about 40 nm. The Cu NPs supported on graphene have high reaction activity for the oxidation of toluene to corresponding benzaldehyde. It was found that the selectivity reached 66.5% and the conversion of toluene reached 11.5%. [ABSTRACT FROM AUTHOR]

A new four-step synthesis of 3,4- and 3,6-dihydro-2H-thiopran-1,1-dioxides from dihydro-2H-thiopyran-3(4H)-one is reported. The title compounds are synthesized starting with oxidation of the ketone with a 30% aqueous solution of hydrogen peroxide in a mixture of AcOH-Ac2O. The keto group is then reduced by sodium borohydride followed by mesylation and elimination of methanesulfonic acid under basic conditions (pyridine for 3,4-isomer and aqueous NaOH for 3,6-isomer). This sequence is simpler, than previously known methods, uses cheaper and more readily available reagents, and leads to 2H-thiopran-1,1-dioxides on multigram scale with 64% and 74% total yields, respectively. The structure and purity of the compounds were confirmed by 2D NMR and GCMS methods. The proposed method expands the means to access functionalized cyclic sulfones as building blocks in the synthesis of combinatorial libraries of new biologically active compounds. [ABSTRACT FROM AUTHOR]

Laccases (EC 1.10.3.2) catalyze oxidation of phenolic groups in lignin to phenoxyl radicals during reduction of O 2 to H 2 O. Here, we examine the influence on this radical formation of mediators which are presumed to act by shuttling electrons between the laccase and the subunits in lignin that the enzyme cannot approach directly. Treatments of three different lignins with laccase-mediator-systems (LMS) including laccases derived from Trametes versicolor and Myceliophthora thermophila , respectively, and four individual mediators, 1-hydroxybenzotriazole (HBT), N-hydroxyphthalimide (HPI), 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) were assessed by real time electron paramagnetic resonance measurements. Radical steady state concentrations and radical formation rates were quantified. LMS treatments with 500 μM N-OH type mediators (HPI or HBT) did not affect the lignin radical formation, but increased doses of those mediators (5 mM) surprisingly led to significantly decreased radical formation rates and lowered steady state radical concentrations. Laccase-TEMPO treatment at a 5 mM mediator dose was the only system that significantly increased steady state radical concentration and rate of radical formation in beech organosolv lignin. The data suggest that electron shuttling by mediators is not a significant general mechanism for enhancing laccase catalyzed oxidation of biorefinery lignin substrates, and the results thus provide a new view on laccase catalyzed lignin modification. [ABSTRACT FROM AUTHOR]

The main objective of this work is to study the influence of thermal oxidation on the chemical composition and magnetic properties of iron nanoparticles which were manufactured in a simple chemical reduction of Fe 3+ ions coming from iron salt with sodium borohydride. The annealing processing was performed in an argon atmosphere containing the traces of oxygen to avoid spontaneous oxidation of iron at temperatures ranging from 200 °C to 800 °C. The chemical composition and magnetic properties of as-prepared and thermally-treated nanoparticles were determined by means of X-ray diffractometry, Raman spectroscopy, Mössbauer spectroscopy and vibrating sample magnetometry. Due to the magnetic interactions, the investigated iron nanoparticles tended to create the dense aggregates which were difficult to split even at low temperatures. This caused that there was no empty space between them, which led to their partial sintering at elevated temperatures. These features hindered their precise morphological observations using the electron microscopy techniques. The obtained results show that the annealing process up to 800 °C resulted in a progressive change in the chemical composition of as-prepared iron nanoparticles which was associated with their oxidation. As a consequence, their magnetic properties also depended on the annealing temperature. For instance, considering the values of saturation magnetization, its highest value was recorded for the as-prepared nanoparticles at 1 T and it equals 149 emu/g, while the saturation point for nanoparticles treated at 600 °C and higher temperatures was not reached even at the magnetic field of about 5 T. Moreover, a significant enhancement of coercivity was observed for the iron nanoparticles annealed over 600 °C. [ABSTRACT FROM AUTHOR]

A high‐yielding and high‐rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi‐jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure. [ABSTRACT FROM AUTHOR]

Impregnation catalysts based on CuO, MnOx, and CuO-MnOx with different Cu/Mn ratios supported on ceramic monoliths of alumina and silica are studied by BET, mercury porosimetry, X-ray diffraction analysis, transmission and scanning electron microscopy, temperature-programmed reduction with H2, diffuse reflectance electron spectroscopy, and differential dissolution. It is found that, in the butane oxidation reaction, CuO-MnOx catalysts exert a synergistic effect, which is attributed to the formation of highly defective phases of complex oxides of the nonstoichiometric spinel type with a large number of interparticle boundaries in the near-surface layers of the support. [ABSTRACT FROM AUTHOR]

New materials based on electric arc furnace (EAF) dust have been produced via temperature-programmed reduction using hydrogen gas at different temperatures. Scanning electron microscopy, thermal analysis, X-ray diffraction, and Mössbauer spectroscopy suggested that the EAF dust is reduced by hydrogen at 600 and 700 °C producing reduced iron, e.g., iron (II) and iron metallic, magnetics and more active catalytic phases. The new materials show magnetic behavior as well as EAF starting material. Electron paramagnetic resonance studies using N-t-butyl-α-phenylnitrone as a trapped radical agent were performed showing characteristic signals related to paramagnetic species produced exclusively by the interaction of catalysts with hydrogen peroxide (H2O2). The new magnetic materials were successfully used for pollutant removal by adsorption followed by oxidation of model dyes such as methylene blue and indigo carmine. In addition, the great advantage of these materials is that they may be easily recovered magnetically and reused. [ABSTRACT FROM AUTHOR]

Abstract: A dinuclear CoII complex, [Co2(tphz)(tpy)2]n+ (n=4, 3 or 2; tphz: tetrapyridophenazine; tpy: terpyridine), has been assembled using the redox‐active and strongly complexing tphz bridging ligand. The magnetic properties of this complex can be tuned from spin‐crossover with T1/2≈470 K for the pristine compound (n=4) to single‐molecule magnet with an ST=5/2 spin ground state when once reduced (n=3) to finally a diamagnetic species when twice reduced (n=2). The two successive and reversible reductions are concomitant with an increase of the spin delocalization within the complex, promoting remarkably large magnetic exchange couplings and high‐spin species even at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: Density functional theory (DFT) was utilized to explore the reduction of gold(III) complexes by the amino acid glycine (Gly). Interestingly, when the nitrogen atom of Gly coordinates to the gold(III) center, its Cα‐hydrogen atom becomes so acidic that it can be easily deprotonated by a mild base like water. The deprotonation converts the amino acid into a potent reductant by which gold(III) is reduced to gold(I) with a moderate activation energy. To our knowledge, this is the first contribution suggesting that primary amines are oxidized to imines via direct α‐carbon deprotonation. This finding may provide new insights into the mechanistic interpretation of amine oxidations catalyzed/mediated by a center with high cathodic reduction potential. This work also provides a rationalization behind why gold(III) complexes with amine‐based polydentate ligands are reluctant to undergo a redox process. Gold(III) reduction occurs most efficiently if the Cα proton leaves in the plane of the Cα, N and Au atoms. Chelation prevents this alignment, resulting in the gold(III) complex being unreactive toward reduction. It has been experimentally found that gold(III) is capable of oxidizing Gly to glyoxylic acid (GA) as the initial product. The latter, in the presence of another gold(III) complex, has been reported to undergo oxidative decarboxylation to afford CO2 and HCOOH. This process is found to be mediated by formation of a geminal diol intermediate produced by reaction of water with the aldehyde functional group of the coordinated GA. [ABSTRACT FROM AUTHOR]

The Al-Fe pillared interlayered clay catalyst (PILC) was synthesized by pillaring bentonite clay with Al and Fe metal cations. 4-Nitrophenol (4-NP) was oxidized over Al-Fe PILC using catalytic wet peroxide oxidation process. The catalyst was characterized using X-ray diffraction, BET, wavelength-dispersive X-ray fluorescence, FTIR, and thermogravimetric analysis/derivative thermogravimetric techniques. The Al-Fe PILC was thermally stable as compared to bentonite clay. Reaction kinetics for the catalytic oxidation of 4-NP onto Al-Fe PILC was described using Fermi’s equation. Fermi’s model was fitted well to the experimental data for the degradation of 4-NP and total organic carbon (TOC) removal histories and followed pseudo-first-order rate equation. The apparent activation energies for 4-NP degradation and TOC removal histories were 21.17 and 14.12 kJ/mol, respectively. In the present study, the mechanistic pathways for the catalytic oxidation of 4-NP based upon TOC reduction have been proposed. The toxicity of 4-NP after oxidation decreased as the zone of inhibition decreased to 5 mm from 12 mm. [ABSTRACT FROM AUTHOR]

Nowadays, clean-up of waters with coexisting heavy metal ions and organic pollutants is of great environmental importance. In this study, a novel sewage sludge-derived char-based catalyst was firstly synthesized, and coupled with hydrogen peroxide for the simultaneous removal of copper (II) and norfloxacin in aqueous solutions. The most relevant findings revealed that zero-valent iron and zero-valent aluminum particles were successfully formed on the catalyst surface when the leaching of the sludge-derived char was reduced by the green tea extract. Nearly 100% of both copper (II) and norfloxacin were simultaneously removed due to a synergistic effect between the reduction of copper (II) and the oxidation of norfloxacin over the catalyst. The gradual addition mode of hydrogen peroxide exhibited a better performance on the simultaneous removal of copper (II) and norfloxacin. The coexisting anions like nitrate and phosphate had significant negative effects on the copper (II) removal, whereas carbonate, fluoride and phosphate had significant negative effects on the norfloxacin removal. Different copper species like zero-valent copper, copper oxide and copper hydroxide were identified in copper (II) reduction process, whereas a total of eight oxidative products were identified in norfloxacin oxidation process. A possible reaction mechanism for the simultaneous removal of copper (II) and norfloxacin by the sewage sludge-derived char-based catalyst/hydrogen peroxide system was proposed. The adsorption of both copper (II) and norfloxacin over the catalyst were firstly occurred, and then the reduction of copper (II) over both zero-valent iron and zero-valent aluminum particles on the catalyst surface as well as the Fenton oxidation of norfloxacin were followed. [ABSTRACT FROM AUTHOR]

Abstract: We report on a headspace gas chromatographic method for determining the content of 3‐chloro‐1,2‐propanediol in polyamideamine epichlorohydrin resin solution. It was based on quantitatively converting 3‐chloro‐1,2‐propanediol to formaldehyde by periodate oxidation in a closed headspace sample vial at a room temperature for 10 min, and then to methanol by borohydride reduction at 90°C for 40 min followed by the headspace gas chromatographic measurement. The results showed that the present method has an excellent measurement precision (relative standard deviation < 2.60%) and accuracy (recoveries from 96.4–102%) in 3‐chloro‐1,2‐propanediol analysis. The limit of quantitation was 0.031 mg/mL. It is simple and suitable for determining the 3‐chloro‐1,2‐propanediol content in polyamideamine epichlorohydrin resin solution. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the oxidation degree of multiwalled carbon nanotubes (MWCNTs) for the detection of NADH was evaluated in this paper. MWCNTs were oxidized by microwave‐assisted sulfonitic treatment at different times (5, 10, 15, and 30 min) and deposited onto a graphite screen printed electrodes. Oxidized MWCNTs were characterized and the electrochemical performance evaluated. The best sensor in terms of sensitivity and stability was obtained after 15 minutes of oxidation (SPE/CNT15). A significant reduction of the NADH oxidation potential was recorded for oxidized MWCNTs compared with unmodified MWCNTs (0.270 V and 0.500 V, respectively vs. Ag/AgCl pseudo reference electrode), increasing the selectivity of the system. Chronoamperometric calibration curves carried out applying a potential of 0.3 V for 1 min were linear in the 4–35 μM range of NADH. A limit of detection of 1 μM was achieved with negligible surface fouling (three consecutive calibration curves, 30 total measurements: slope decrease 5.9 %). Inter electrode reproducibility (n=13) was good resulting in RSD of 15.2 % and 5.0 % for the peak intensity and the oxidation potential, respectively. Quantification of glucose in white wine samples was carried out to demonstrate the ability of the NADH sensor to work in real samples. A good correlation with a spectrophotometric kit for the glucose quantification was achieved. [ABSTRACT FROM AUTHOR]

Surface-fluorinated TiO materials with high {001} facet exposure were prepared by a simple and high-yield preparation procedure. Faceted/fluorinated samples showed a high photocatalytic performance not only in oxidation processes, tested in phenol and methyl orange degradation, but also in a reduction process as Cr(VI) photoreduction. Reaction rates for these materials greatly exceeded the ones obtained for materials prepared without fluorine addition and for commercial TiO Degussa (Evonik) P25 used as reference photocatalyst. A broad characterisation of the samples allowed us to estimate the percentages of different facets and the amount and form in which the fluorine is found on the surfaces. Good photocatalytic behaviour can be ascribed to both high {001} facet exposure and adsorbed fluorine on the photocatalysts surfaces. [ABSTRACT FROM AUTHOR]

The development of a hydrometallurgical process to recover manganese and silver from manganese–silver ores is reported. Insoluble manganese(IV) was reduced to soluble manganese(II) in an aqueous medium with calcium sulfide (CaS) as the reductant, and the resultant residue was then leached by a sulfuric acid solution. Thiosulfate (S 2 O 3 2 − ) was produced in situ in the reduction stage. The S 2 O 3 2 − by-product was reserved and used as the lixiviant for the subsequent silver leaching step with copper(II) and ammonia additives. The production of S 2 O 3 2 − was 0.168 mol/L in the reduction stage and the recovery of manganese reached 98.0% in the acid leaching stage under the optimum conditions. Notably, 57.5% of silver was recovered when only the S 2 O 3 2 − -containing liquor from the reduction stage was used, and 92.0% of silver was recovered when a small amount of supplementary S 2 O 3 2 − was used. [ABSTRACT FROM AUTHOR]

Vanadium (V) is widely used industrially, and plays an important role in the biosphere. Sensitive and reliable analytical methods to determine V in various kinds of samples are of extensive interest. Mainly two spectrophotometric methods developed in the last decade are discussed, namely complex formation methods and catalytic methods. The former is based on either oxidation or reduction of V leading to coloured complexes with proper reagents; they are applicable to determination of V at the mg L−1 level. Catalytic methods are based on the ability of V to catalyse the oxidation of various organic dyes and are applicable to determination at the μg L−1 level. Both methods are used for determination of V in environmental and biological samples. [ABSTRACT FROM AUTHOR]

Effects of trace BaCO 3 addition were investigated on microstructure and electrical properties of La-doped BaTiO 3 ceramics prepared via reduction-reoxidation method. The addition of BaCO 3 could effectively facilitate the densification and grain growth of ceramics. SEM images suggested that numerous pores presented in ceramics due to the decomposition of BaCO 3 to expel generated CO 2 gas. The presence of pores promoted reoxidation of the reduced ceramics. As a result, lowering room-temperature (RT) resistivity and improving PTCR jump were simultaneously achieved as suitable amount of BaCO 3 was added. An optimal addition of 0.3 mol% BaCO 3 led to a low RT resistivity of about 28 Ω cm and a PTCR jump up to 10 3.7 after ceramics were fired at 1100 °C in high-purity N 2 and reoxidized at 800 °C in air. [ABSTRACT FROM AUTHOR]

A series of ceria modified CuO/γ-Al 2 O 3 (CuO-CeO 2 /γ-Al 2 O 3 ) catalysts were prepared via stepwise impregnation (CuCeAl-SI) and co-impregnation (CuCeAl-CI) method and tested in the model reaction of NO reduction by CO. It was found that the influence of impregnation modes on the catalytic properties of CuCeAl samples mainly lies on the control of ceria particle sizes and modulation of the distribution of various copper species. In both impregnation modes, ceria was mainly spread on γ-Al 2 O 3 as small particles while copper species were highly dispersed. A quantitative estimation of copper species was tentatively provided via a combined surface acid leaching experiment and H 2 -TPR characterization for the first time. The results showed that for CuCeAl-CI catalyst, about 55% and 25% copper species were dispersed on γ-Al 2 O 3 and nanosized ceria, respectively, while about 20% was migrated into ceria lattice during the calcination process. In contrast, in CuCeAl-SI sample, the corresponding values changed to about 25%, 70% and 5%, respectively. The synergistic effect between copper species and ceria can promote the improvement of catalytic performance, which results in higher activity of CuCeAl-SI than that of CuCeAl-CI catalyst. [ABSTRACT FROM AUTHOR]

The carbothermic reduction behavior of original ilmenite and pre-oxidized ilmenite concentrates were investigated by a non-isothermal method using a thermogravimetry facility. The reaction degree was calculated using the tail gas composition and the Starink method to analyze the activation energy of the reduction. The results demonstrated that trends of different reaction degree curves are similar under the same conditions. The average activation energy of the pre-oxidized ilmenite concentrate was less than that of the original form by approximately 25%, and the starting reduction temperature was lower by 67 K than that of the original ilmenite concentrate. However, the reduction time of the pre-oxidized ilmenite concentrate was longer than that of the original ilmenite concentrate for the same reaction degree; therefore, a slow reduction rate for the oxidization sample was observed. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS) were used to characterize the phase and micro-morphology of the two raw materials and compare the reduction products. [ABSTRACT FROM AUTHOR]

This paper presents an attempt to build a very reduced kinetics mechanism of n-heptane to simulate the two stage ignition process in terms of ignition delay time and in-cylinder pressure profiles over the whole range of engine operations. Starting from the previous 26 reactions and 25 species mechanism, two reduced schemes have been developed, one with 18 reactions and 19 species and the other with 13 reactions and 14 species. The reduction step shows that when the reactions describing the first stage are reduced as in the 18-step model, the accuracy is poor. The second 13-step model, where the reaction path describing the low temperature period has been kept, is more reliable when the window of engine operations is restricted. From this reduction step, a two-part reaction mechanism linked with a temperature criterion has been developed, while maintaining a wide range of engine operating conditions. This mechanism includes a low temperature reaction group and a high temperature reaction group, linked with a transition temperature correlation. Ignition delay times calculated with the two-part model are compared to those from the detailed mechanism. In addition, the comparison of the Indicated Mean Effective Pressure (IMEP) with the results of the previous 26-step mechanism has been done. The results obtained with the present model are in good agreement with the 26-step one. Moreover, this model has a very short computational time and thus could be used in CFD simulations as well as single zone or multi-zone engine models, and also model-based design. [ABSTRACT FROM AUTHOR]

Syngas production in micro-scale reactors could enhance heat and mass transfer with suitable dynamic behavior. Seeking environmentally friendly and energy efficient, chemical looping reforming could be employed for not only syngas production, but also lower CO 2 emission. In this process, while the reduction part has a role of indirect clean combustion of fossil fuels such as methane with an oxygen carrier such as NiO without NO x emission, oxygen is transferred to the depleted NiO in the oxidation part. In the present work, a microreactor assembly is proposed to thermally couple the reduction and oxidation reactors. The proposed geometry is mathematically modeled and analyzed. The configuration not only uses the heat of oxidation, but also mitigates temperature fluctuations inside the channels which is harmful for all oxygen carriers. After the performance study of two separate reduction and oxidation reactors in adiabatic mode, coupling of two reactors is analyzed for syngas production in the reduction reactor. The results show that in contrast to the separate adiabatic reactors, lower temperature changes with a maximum of 125 K is attained in the thermally coupled mode. Effective parameters such as thermal conductivity, reaction rates, H 2 and CO production rates and solid conversions are investigated. The produced syngas has a H 2 :CO ratio of about 6 which is reduced by adding CO 2 gas into the feed. The results also show that a 38% decrease in H 2 :CO ratio is resulted from a 100% increase of CO 2 :CH 4 ratio. Analysis of the channel dimension shows that the syngas production is dropped with increasing channel width due to decrease in effective surface to volume of the reactor. The results demonstrate feasibility of an intensified micro system for small scale syngas production using chemical looping reforming technology. [ABSTRACT FROM AUTHOR]

Although the water resource is not exhaustible, the water quality must be preserved. It does represent a major challenge for the coming decades. Since water is used for many different industrial, agricultural and domestic applications, a wide variety of waste effluents is being produced. Since conventional wastewater treatment plants, mainly based on biological processes, are poorly efficient for the treatment of toxic and/or non-biodegradable and/or highly concentrated effluents, new solutions are being looked for. Many different approaches have been investigated and catalytic processes may play a crucial role. Both oxidation and reduction processes for the treatment of chlorophenols have been reviewed. The principle of each of those processes is being described, the key parameters are identified and subsequently the major challenges to be overcome both in terms of material science and/or catalytic efficiency (activity and selectivity) are highlighted to offer a general but homogenized overview of the state-of-the-art in the different fields. Finally, the most recent developments in each field are shortly discussed. [ABSTRACT FROM AUTHOR]

The activation of readily prepared, air-stable cobalt(II) bis(carboxylate) pre-catalysts for the functionalization of C( sp2)−H bonds has been systematically studied. With the pyridine bis(phosphine) chelate, iPrPNP, treatment of 1- (O2CtBu)2 with either B2Pin2 or HBPin generated cobalt boryl products. With the former, reduction to (iPrPNP)CoIBPin was observed while with the latter, oxidation to the cobalt(III) dihydride boryl, trans-(iPrPNP)Co(H)2BPin occurred. The catalytically inactive cobalt complex, Co[PinB(O2CtBu)2]2, accompanied formation of the cobalt-boryl products in both cases. These results demonstrate that the pre-catalyst activation from cobalt(II) bis(carboxylates), although effective and utilizes an air-stable precursor, is less efficient than activation of cobalt(I) alkyl or cobalt(III) dihydride boryl complexes, which are quantitatively converted to the catalytically relevant cobalt(I) boryl. Related cobalt(III) dihydride silyl and cobalt(I) silyl complexes were also synthesized from treatment of trans-(iPrPNP)Co(H)2BPin and (iPrPNP)CoPh with HSi(OEt)3, respectively. No catalytic silylation of arenes was observed with either complex likely due to the kinetic preference for reversible C−H reductive elimination rather than product- forming C−Si bond formation from cobalt(III). Syntheses of the cobalt(II) bis(carboxylate) and cobalt(I) alkyl of iPrPONOP, a pincer where the methylene spacers have been replaced by oxygen atoms, were unsuccessful due to deleterious P−O bond cleavage of the pincer. Despite their structural similarity, the rich catalytic chemistry of iPrPNP was not translated to iPrPONOP due to the inability to access stable cobalt precursors as a result of ligand decomposition via P−O bond cleavage. [ABSTRACT FROM AUTHOR]