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Molybdenum‐ or tungsten‐dependent formate dehydrogenases have emerged as significant catalysts for the chemical reduction of CO2 to formate, with biotechnological applications envisaged in climate‐change mitigation. The role of Met405 in the active site of Desulfovibrio vulgaris formate dehydrogenase AB (DvFdhAB) has remained elusive. However, its proximity to the metal site and the conformational change that it undergoes between the resting and active forms suggests a functional role. In this work, the M405S variant was engineered, which allowed the active‐site geometry in the absence of methionine Sδ interactions with the metal site to be revealed and the role of Met405 in catalysis to be probed. This variant displayed reduced activity in both formate oxidation and CO2 reduction, together with an increased sensitivity to oxygen inactivation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen spillover induced a cooperative catalysis between Pd particles and Pd single atoms supported on carbon supports. • Few-layer graphene (FLG) support allows more extended H-spillover than multi-walled carbon nanotubes (CNT) • Pd/FLG is more active for solvent-free total hydrogenation of squalene than Pd/CNT but deactivated. • A new mechanism of thermal catalyst deactivation induced by H-spillover is proposed. General interest in solvent-free catalytic processes is driven by the development of environmentally and economically acceptable procedures. Such processes require the use of highly active and stable catalysts. This study reports on the synthesis, characterization, and kinetic evaluation of two highly active Pd catalysts supported on different carbons support, i.e., multi-walled carbon nanotubes (CNT) and few-layer graphene (FLG). These catalysts, with similar Pd loading (∼2 wt%) and containing both Pd single atoms (Pd SA) and nanoparticles (Pd NP), were systematically tested for solvent-free total hydrogenation of squalene (SQE) to obtain high-purity squalane (SQA). Thanks to the unique cooperative catalysis between Pd SA and Pd NP involving H-spillover, the activities of both catalysts were high compared to catalysts described in the literature. Solvent-free total hydrogenation of SQE could be performed under mild conditions (120 °C, 20 bar H 2 , 4 h) using ultralow Pd loading (60 ppm). However, since this reduction reaction is highly exothermic (ΔH R = − 765 kJ.mol−1), heat management during the reactor operation with these highly active catalysts is crucial to avoid deactivation and thermal runaway. Under these conditions, Pd/FLG was highly active but deactivated, unlike Pd/CNT, which still has high activity, but does not deactivate. Characterizations (ICP, XPS, Raman, TPD-MS, HAADF-STEM) of the Pd/FLG catalyst before and after reaction, supported by calculations based on density functional theory, allowed us to propose a new mechanism of catalyst deactivation involving the chemical reduction of specific surface oxygen groups of the carbon support induced by H-spillover. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, theoretical calculations have proved that alloying Pt with a suitable transition metal is likely to improve ORR mass activity when compared to Pt-alone systems. Herein, we demonstrate the preparation of bimetallic Pt–Fe nanoparticles supported on reduced graphene oxide sheets (RGOs) via a simple surfactant-free chemical reduction method. The present method produces PtFe/RGO catalyst particles with a 3.2 nm diameter without agglomeration. PtFe/RGO showed a noticeable positive half-wave potential (0.503 V vs. Ag/AgCl) compared with a commercial Pt/C catalyst (0.352 V vs. Ag/AgCl) with minimal Pt-loading on a glassy carbon electrode. Further, PtFe/RGO showed a higher ORR mass activity of 4.85 mA/cm2-geo compared to the commercial Pt/C (3.60 mA/cm2-geo). This work paves the way for designing noble−transition metal alloy electrocatalysts on RGO supports as high-performance electrocatalysts for ORR application. [ABSTRACT FROM AUTHOR]

Sodium borohydride (NaBH4) is considered a good candidate for hydrogen generation from hydrolysis because of its high hydrogen storage capacity (10.8 wt%) and environmentally friendly hydrolysis products. However, due to its sluggish hydrogen generation (HG) rate in the water, it usually needs an efficient catalyst to enhance the HG rate. In this work, graphene oxide (GO)-modified Co-B-P catalysts were obtained using a chemical in situ reduction method. The structure and composition of the as-prepared catalysts were characterized, and the catalytic performance for NaBH4 hydrolysis was measured as well. The results show that the as-prepared catalyst with a GO content of 75 mg (Co-B-P/75rGO) exhibited an optimal catalytic efficiency with an HG rate of 12087.8 mL min−1 g−1 at 25 °C, far better than majority of the findings that have been reported. The catalyst had a good stability with 88.9% of the initial catalytic efficiency following 10 cycles. In addition, Co-, B-, and P-modified graphene showed a synergistic effect improving the kinetics and thermodynamics of NaBH4 hydrolysis with a lower activation energy of 28.64 kJ mol−1. These results reveal that the GO-modified Co-B-P catalyst has good potential for borohydride hydrolysis applications. [ABSTRACT FROM AUTHOR]

The selective chemical conversion of biomass components to useful bioproducts may contribute to a renewable resource-based economy. The selective production of target bioproducts may be accomplished using heterogeneous catalysts operating under relatively moderate reaction conditions. In this work, carbohydrate biomass derived α-angelica lactone (AnL) and levulinic acid (LA) were converted to the versatile bioproduct γ-valerolactone (GVL), in the presence of nanohybrid catalysts (M-FDCA) and the microcrystalline metal-organic framework CAU-28, all of which were synthesized from bio-based 2,5-furandicarboxylic acid (FDCA) and a metal (M = Zr or Hf) precursor. The nanohybrids were prepared in a simple fast (FT) fashion, and, for comparison, via a conventional solvothermal (S) procedure. The M-FDCA catalysts stood on a higher footing than CAU-28 in the conversion of AnL and LA to GVL. The superior results for the M-FDCA catalysts may be partly due to their higher ratio S ext :S BET and nano-features, which may advantageously enhance active sites accessibility. In particular, the Hf-FDCA catalysts were stable and performed superiorly to the Zr-FDCA ones. Experimental mechanistic studies shed light on the multifunctional behavior of the hybrid catalysts in the one-pot conversion of AnL-to-GVL, which involved acid and reduction chemistry. [Display omitted] • Fast synthesis of biobased 2,5-furandicarboxylic acid (FDCA), Zr and Hf nanohybrids. • Catalyst benchmarking with microcrystalline metal-organic framework CAU-28. • Hf-FDCA best-performing in one-pot conversion of angelica lactone to γ-valerolactone. • Catalyst multifunctionality associated with -COOH of the linker and metal sites. • Hf-FDCA also best performing for levulinic acid to γ-valerolactone in 2-butanol. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, pristine and NaBH 4 etched CeO 2 nanorods supported ruthenium (Ru) catalysts were synthesized and employed to investigate the effects of chemical etching and reduction activation treatment on CO oxidation. With 1 wt% Ru loading, the CeO 2 nanorods supported catalyst samples, after 6 wt% NaBH 4 etching treatment, showed significantly promoted H 2 consumption under 100 °C and low apparent activation energy (i.e., E a ∼ 31.2 kJ/mol) for CO oxidation. In - situ CO-DRIFTS profiles revealed that, for the reduced sample, the observed CO adsorption at ∼ 2020 cm−1 at 40 °C may be related to a strong RuO x -CeO 2 interaction induced by the NaBH 4 etching treatment, which was supported by the oxygen vacancy analysis results of X-ray photoelectron spectroscopy and CO-temperature programmed desorption. The enriched surface defects on CeO 2 support due to the chemical etching and reduction treatments are believed to promote the interaction between RuO x species and CeO 2 , which is responsible for the enhanced activity of CO oxidation. [ABSTRACT FROM AUTHOR]

In this work, via the method of wet impregnation and chemical reduction, low-cost and available bentonite modified by cetyltrimethylammonium bromide (CTAB) was utilized as support to synthesize a novel organobentonite-supported Pd composite catalyst used for the catalytic transfer hydrogenation (CTH) of polyunsaturated fatty acid methyl ester (FAME). According to the results of characterization analysis, the organic modifier of CTAB was intercalated into the interlayer of bentonite, and the active metal Pd was immobilized and uniformly dispersed in the prepared composite catalyst. The possible formation mechanism of composite catalyst was proposed. The synthesized composite catalyst presented higher hydrogenation activity and selectivity compared with the pure nano-Pd catalyst. Moreover, the excellent stability remained for the composite catalyst after five catalytic runs in FAMEs hydrogenation. Hence, bentonite, as an economical and promising feedstock, could be used to synthesize a high-efficient and stable supported Pd composite catalyst successfully for the CTH of FAME. Low-cost bentonite, used as raw material, was modified by cetyltrimethylammonium bromide (CTAB) through the cation exchange process, forming organobentonite (OB) with an increased interlayer spacing. The cations of CTAB might be absorbed into the interlayers and on the surface of bentonite. The Pd ions were introduced through the impregnation of precursor solution of Pd (H2PdCl4) and bound to the cations of CTAB via electrostatic interactions. After the chemical reduction process by using NaBH4, the anionic PdCl42− could be reduced to metal Pd, which was immobilized and dispersed in the interlayers and on the surface of organobentonite, and then a novel Pd/OB composite catalyst formed. According to the result of TEM measurement, Pd particles showed the spheroidal shapes and dispersed uniformly in the synthesized composite catalyst. [ABSTRACT FROM AUTHOR]

The preparation of Ru nanoparticles supported on γ-Al2O3 followed by chemical reduction using RuCl3 as a precursor is demonstrated, and their properties are compared to Ru nanoparticles supported on γ-Al2O3 prepared by impregnation of γ-Al2O3 with Ru3(CO)12 and subsequent thermal decomposition. The Ru nanoparticles resulting from chemical reduction of RuCl3 are slightly larger (1.2 vs. 0.8 nm). In addition, Ru nanoparticles were deposited on Stöber SiO2 using both deposition techniques. These particles were larger than the ones deposited on γ-Al2O3 (2.5 and 3.4 nm for chemical reduction and thermal decomposition, respectively). Taking into account the size differences between the Ru nanoparticles, all catalysts display similar activity (0.14–0.63 mol·gRu−1·h−1) and selectivity (≥99%) in the sunlight-powered Sabatier reaction. Ergo, the use of toxic and volatile Ru3(CO)12 can be avoided, since catalysts prepared by chemical reduction of RuCl3 display similar catalytic performance. [ABSTRACT FROM AUTHOR]

For effective CO2 methanation, monometallic Co(10)/SiO2 and Ni(10)/SiO2 and bimetallic Ni(5)Co(5)/SiO2 and Ni(2)Co(8)/SiO2 nanocomposite (NC) catalysts, where numbers between brackets indicate the metal content (wt%), have been prepared with solvate-stimulated modification, thermal decomposition, and chemical reduction stages using nanosilica A-300 as a carrier. The catalysts were characterized using SEM–EDX, nitrogen physisorption, and X-ray powder diffraction. The samples before and after the reduction with hydrogen have a similar mesoporous texture. The bimetallic Ni–Co/SiO2 NC catalysts showed improved catalytic activity compared to Ni/SiO2. The formers are characterized by the smallest bimetallic crystallites of ca. 12 nm in size. Activity in the methanation of the Ni–Co/SiO2 NC catalysts depends on the cobalt content resulting in a prominent increase in CO2 conversion and methane yield at 250–350 °C. The SEM–EDX analysis showed unusual flower-like nanostructures and proved the random distribution of Ni/Co bimetallic aggregates in the nanosilica matrix at the nanoscale level. Both Ni(2)Co(8)/SiO2 and Ni(5)Co(5)/SiO2 exhibited high activity in the CO2 methanation with 81–88% CH4 yield at 450 °C. The results of thermo-programmed desorption mass spectroscopy revealed that the catalytic reaction is passed through the formation of O-containing intermediates bound to the active Ni–Co and nanosilica sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • OMNs Pt-Ru-Ir catalyst shows improved oxygen bifunctional electrocatalysis. • Superior ORR activity (0.21 mA/µg & 0.33 mA/cm2) with extended durability was found. • Excellent OER activity with low Tafel slope and enhanced durability obtained for Pt 70 Ru 25 Ir 5. • Synergistic and mesoporous morphology with trace Ir boosting the bifunctional oxygen kinetics. An efficient oxygen bifunctional catalyst Pt-Ru-Ir with ordered mesoporous nanostructures (OMNs) was successfully synthesized by chemical reduction using KIT-6 mesoporous silica as a template. The crystallographic behavior, electronic effects, and microstructure of the catalysts were investigated by XRD, XPS, SEM, and TEM analysis. The influence of OMNs and the effect of Ir content in Pt-Ru-Ir catalyst on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were investigated. The synergistic and electronic effects play an important role in electrocatalytic performance through the electronic coupling between Pt, Ru and Ir followed by the alloy formation with different lattice strain percentages. Amongst, the OMNs Pt 70 Ru 25 Ir 5 catalyst exhibits the highest mass activity of 0.21 mA µg−1 and specific activity of 0.33 mA cm−2 for ORR, which are nearly 5-fold greater than those for benchmark Pt/C catalyst. Furthermore, the Pt 70 Ru 25 Ir 5 demonstrated enhanced OER activity with an overpotential of 470 mV at 10 mA cm−2, an onset potential of 1.70 V, and a Tafel slope of 118 mV dec-1, outperforming commercial IrO 2. In addition, the durability of the Pt 70 Ru 25 Ir 5 catalyst for ORR and OER are found to be extended in comparison with that of other catalysts reported in this work after 6000 cycles. These results demonstrate that the ordered OMNs Pt-Ru-Ir with low Ir content (∼5 wt%) could be a promising oxygen bifunctional catalyst for electrochemical energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction to value‐added chemicals/fuels provides a promising way to mitigate CO2 emission and alleviate energy shortage. CO2‐to‐CO conversion involves only two‐electron/proton transfer and thus is kinetically fast. Among the various developed CO2‐to‐CO reduction electrocatalysts, transition metal/N‐doped carbon (M‐N‐C) catalysts are attractive due to their low cost and high activity. In this work, recent progress on the development of M‐N‐C catalysts for electrochemical CO2‐to‐CO conversion is reviewed in detail. The regulation of the active sites in M‐N‐C catalysts and their related adjustable electrocatalytic CO2 reduction performance is discussed. A visual performance comparison of M‐N‐C catalysts for CO2 reduction reaction (CO2RR) reported over the recent years is given, which suggests that Ni and Fe‐N‐C catalysts are the most promising candidates for large‐scale reduction of CO2 to produce CO. Finally, outlooks and challenges are proposed for future research of CO2‐to‐CO conversion. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction to high-value-added chemicals is one of the most promising and challenging research in the energy conversion field. An efficient ECR catalyst based on a Cu-based conductive metal-organic framework (Cu-DBC) is dedicated to producing CH4 with superior activity and selectivity, showing a Faradaic efficiency of CH4 as high as ~80% and a large current density of −203 mA cm−2 at −0.9 V vs. RHE. The further investigation based on theoretical calculations and experimental results indicates the Cu-DBC with oxygen-coordinated Cu sites exhibits higher selectivity and activity over the other two crystalline ECR catalysts with nitrogen-coordinated Cu sites due to the lower energy barriers of Cu-O4 sites during ECR process. This work unravels the strong dependence of ECR selectivity on the Cu site coordination environment in crystalline porous catalysts, and provides a platform for constructing highly selective ECR catalysts. Crystalline porous catalysts with single Cu sites are dedicated to exploring the dependence of CO2 electroreduction selectivity on the coordination environment of catalytic sites. The conductive MOF Cu-DBC with oxygen-coordinated Cu sites shows a high Faradaic efficiency ~80% of CO2-to-CH4. [ABSTRACT FROM AUTHOR]

The purpose of this work is activity evaluation of optimized Pd–Cu/rGO as an anode catalyst for electrooxidation of low ethanol concentrations (5–50 mM) in order to use in fuel cell-based breath alcohol analyzer. Accordingly, a simple and one-step synthesis of Pd/rGO and Pd–Cu/rGO with an optimized Pd/Cu ratio was performed via the chemical reduction method and evaluated for ethanol oxidation reaction (EOR). According to the transmission electron microscopy (TEM) and cyclic voltammetry (CV), the particle size and electrochemical active surface area (ECSA) of Pd0.9–Cu0.1/rGO were 4.5 nm and 181.5 m2 g−1, respectively. The ratio of If/Ib was measured to be 0.7 and 2.6 for Pd/rGO and Pd0.9–Cu0.1/rGO in the 0.5 M KOH solution containing 50 mM ethanol, thus indicating that the presence of Cu in the alloyed catalyst structure improved the catalytic activity by removing carbonaceous intermediates from the catalyst surface. Obtained results revealed that the onset potential (Eonset) of Pd0.9–Cu0.1/rGO was negatively shifted to 240 mV, as compared to Pd/rGO and no carbonate blockage of Pd–Cu/rGO sites happened in the presence of K2CO3. Therefore, Pd0.9–Cu0.1/rGO could be regarded as a superior anode catalyst for use in the anion exchange membrane fuel cell-based breath alcohol analyzer. [ABSTRACT FROM AUTHOR]

Solar-light driven CO2 reduction into value-added chemicals and fuels emerges as a significant approach for CO2 conversion. However, inefficient electron-hole separation and the complex multi-electrons transfer processes hamper the efficiency of CO2 photoreduction. Herein, we prepare ferroelectric Bi3TiNbO9 nanosheets and employ corona poling to strengthen their ferroelectric polarization to facilitate the bulk charge separation within Bi3TiNbO9 nanosheets. Furthermore, surface oxygen vacancies are introduced to extend the photo-absorption of the synthesized materials and also to promote the adsorption and activation of CO2 molecules on the catalysts' surface. More importantly, the oxygen vacancies exert a pinning effect on ferroelectric domains that enables Bi3TiNbO9 nanosheets to maintain superb ferroelectric polarization, tackling above-mentioned key challenges in photocatalytic CO2 reduction. This work highlights the importance of ferroelectric properties and controlled surface defect engineering, and emphasizes the key roles of tuning bulk and surface properties in enhancing the CO2 photoreduction performance. Solar-driven CO2 reduction into value-added chemicals and fuels is attracting worldwide attention. Here, substantially enhanced photocatalytic CO2 reduction activity is achieved via the synergy of surface oxygen vacancies and ferroelectric polarization over Bi3TiNbO9 photocatalyst. [ABSTRACT FROM AUTHOR]

In this study, Ag–Ni@MWCNTs nanocomposites with different Ag/Ni ratios have been prepared through a simple and effective chemical reduction strategy. Morphological, structural and elemental composition of the as-prepared nanocomposites has been examined by using SEM, TEM, EDS and XRD, respectively. Electrochemical study of all the samples was carried out via cyclic voltammetry. Successful synthesis, desired surface morphology and expected elemental composition of the obtained nanocomposites have been confirmed from the above mentioned analytical techniques. The Ag–Ni@MWCNTs nanocomposites show better electrocatalytic activity toward glucose oxidation owing to a greater number of active sites provided by support material (MWCNTs) and synergistic effect present among the atoms of Ag and Ni. The optimized Ag1–Ni9@MWCNTs catalyst displayed high sensitivity (1485 µA mM−1 cm−2), wide linear range (4 mM) and low limit of detection (7 µM) toward glucose sensing. [ABSTRACT FROM AUTHOR]

The production of tetrahydrofurfuryl alcohol (THFAL) from biomass-derived furfural (FF) via one-pot hydrogenation is challenging owing to the high hydrogen pressure and temperature requirements of the system. In this study, a hydrothermal method is used to synthesize a series of wrinkled silica (KCC-1) supports having different morphologies and textural properties by modulating the cetylpyridinium bromide hydrate (CPB)/tetraethyl orthosilicate (TEOS) ratio. Subsequently, Pd-supported KCC-1 catalysts are fabricated along with a Pd/SiO 2 catalyst (for comparative studies) via a chemical reduction method. Interestingly, the morphological features of the supports, such as the specific surface area, pore size, and Pd anchoring sites, differed significantly for different CPB/TEOS ratios. Among the synthesized catalysts, Pd/KCC 0.3, with the lowest proportion of Pd nanoparticles deposited on the external porous surface, exhibits the highest catalytic activity, owing to its large specific surface area and moderate pore size. Moreover, it shows the highest FF conversion of 100% and THFAL selectivity of 85% in 6 h at 50 °C under 20 bar H 2. • KCC-1 supports with different morphologies are prepared by tuning CPB/TEOS ratios. • The correlation between the morphological features and the catalytic activity of Pd-based catalysts have been investigated. • Pd/KCC-1 catalsyts show higher selectivity for one-pot hydrogenation of furfural compared to Pd/SiO 2. • Pd/KCC 0.3 catalyst with a large surface area and low fiber density showed the highest selectivity to THFAL. [ABSTRACT FROM AUTHOR]

• A value-added and efficient technology for recycling spent Ag-Al 2 O 3 catalyst is proposed. • High-value-added spherical silver powder is synthesized by a simple chemical reduction method. • A fitted mathematical model of particle size for silver powder is obtained. • The interactions between the factors are investigated. The spent Ag-Al 2 O 3 catalyst is an important silver secondary resource due to its high content of Ag. However, the most commonly used nitric acid leaching method produces toxic and harmful NO x gases. Herein, a novel clean method was proposed to treat the spent Ag-Al 2 O 3 catalyst using the green leaching agent cerium ammonium nitrate instead of nitric acid to effectively avoid the generation of toxic NO x gases. More importantly, value-added monodisperse micro-sized uniform spherical particles were synthesized directly from the leaching solution by a simple chemical reduction method. The influence of leaching conditions on the leaching ratio of Ag and leaching kinetics were discussed in detail. The response surface methodology was applied to optimize the synthesis parameters of silver powder and explore the interactions between the synthesis process parameters. Under the optimal leaching parameters, the leaching ratio of Ag reached 99.69 %. The leaching kinetic analysis of leaching indicated that the leaching reaction of spent Ag-Al 2 O 3 catalyst was controlled by chemical reaction. By the response surface methodology design, a fitted mathematical model of the particle size for silver powder and the optimum synthesis parameters of silver powder were obtained. The optimum synthesis parameters of silver powder were as follows: [Fe2+] = 1.08 mol/L, [Ag+] = 1.01 mol/L, and dispersant dosage of 2.05 wt%. The average experimental particle size of 1.337 μm was very close to the predicted value of 1.343 μm obtained from the fitted model, indicating that the fitted model of particle size for silver powders was very good. This process not only provides a clean and value-added method for recycling the spent Ag-Al 2 O 3 catalyst, but also helps to promote the balanced and high-value utilization of high-abundance cerium. [ABSTRACT FROM AUTHOR]

• Ni@Pd/C and Ni@PdRh/C core–shell nanoparticles were synthesized. • Catalytic activity toward ethanol oxidation depends on structure and composition. • The addition of Rh improves the catalytic activity and stability of Ni@Pd/C. • Ni@PdRh/C exhibited the highest catalytic activity for ethanol electro-oxidation. • The catalytic activity for Ni@PdRh/C was three times higher, compared to Pd/C. This paper describes the synthesis and catalytic activity of carbon-supported Pd/C, PdNi/C, and PdNiRh/C catalysts with core–shell morphologies towards the oxidation of ethanol in alkaline media. The catalysts are synthesised by a chemical reduction method using sodium borohydride as the reducing agent. Electrochemical characterisations show that the addition of Ni and Rh enhances remarkably the electrocatalytic activity of the materials due to the bifunctional and electronic effects in PdNi/C and PdNiRh/C catalysts, and the synergetic effect of the bifunctional and core–shell morphology on the Ni@Pd/C and Ni@PdRh/C catalysts. Electrochemical impedance spectra reveal lower values of charge transfer resistance for Pd 60 Ni 20 Rh 20 /C and Ni 20 @Pd 60 Rh 20 /C. Chronoamperometric tests also reveal the Ni 20 @Pd 60 Rh 20 /C catalyst displays current densities 9.3 times higher than the Pd/C catalyst. The superior catalytic performance of the trimetallic core–shell Ni 20 @Pd 60 Rh 20 /C catalyst can result from the synergy between the metals and the presence of core–shell morphology. [ABSTRACT FROM AUTHOR]

This work narrates the synthesis of poly (acrylic acid) hydrogel microparticles (PAAHMPs), fabrication of silver nanoparticles (AgNPs) inside the structure of the prepared PAAHMPs and catalytic applications of PAAHMPs fabricated with AgNPs (PAAHMPs/AgNPs). The PAAHMPs were prepared by inverse suspension polymerization technique while fabrication of AgNPs was carried out by chemical reduction method using sodium borohydride (NaBH4) as reducing agent. The identification of functional groups in bare PAAHMPs and in the PAAHMPs/AgNPs composite system was carried out by the Fourier transform infrared spectroscopy. The size and morphology of the prepared hydrogel and its composite was studied by scanning electron microscopy and transmission electron microscopy. X‐ray diffraction and thermal gravimetric analyzer was also used to characterize the bare PAAHMPs and PAAHMPs/AgNPs composite. The prepared PAAHMPs/AgNPs composite was used as catalyst for the reduction of nitro aromatic pollutants and an industrial dye, that is, 4‐Nitrophenol (4‐NP), 2‐Nitrophenol (2‐NP) and methyl orange. No loss in catalytic activity was noted in seven consecutive cycles of recycling process while only 37.5% loss in catalytic activity was observed upon storing the catalyst for 90 days. [ABSTRACT FROM AUTHOR]

High-throughput (HT) methodology was applied for the synthesis, characterization and catalytic testing of Cu- and Ni-based catalysts for glucose hydrogenation. Design of Experiment (DoE) was used in all steps. The deposition and reduction of both metals was performed using chemical reduction with hydrazine method. In total 36 catalysts were synthetized, characterized and tested in 5 days. The amount of metal deposited on the support was chosen as the discriminative and determining parameter. The catalysts were tested at low temperature in the hydrogenation of glucose to sorbitol. • High-throughput methods allow shortening the time of development of a new catalytic process. • Ni and Cu-supported catalysts can be easily obtained by reduction-precipitation method. • The activity strongly depends on preparation conditions. • The use of Design of Experiments (DoE) permits to minimize the number of experiments and to optimize their interpretation. • Good performances in hydrogenation of glucose to sorbitol were obtained for Cu/SiO 2 and Ni/Al 2 O 3 catalysts. A high-throughput (HT) methodology was applied for the synthesis, characterization and catalytic testing of silica and alumina supported Cu- and Ni-based catalysts for glucose hydrogenation. A design of Experiment (DoE) approach was also used in all steps. The deposition and reduction of both metals was performed using the chemical reduction with hydrazine method. In total, 36 catalysts were synthetized, characterized and tested in 5 days. The amount of metal deposited on the support was chosen as the discriminative and determining parameter. The catalysts were tested at low temperature (130 °C) in the hydrogenation of glucose to sorbitol. The results showed that the chemical reduction-precipitation method could be performed using fully automatized robots. The deposition of the metals strongly depended on the nature of the support, the temperature of the reduction and hydrazine/H 2 O ratio. The maximum metal precipitation occurred at higher temperature (70 °C) and lower N 2 H 4 /H 2 O ratio (0.04 mol/mol) in both cases. The results clearly showed that glucose conversion is higher for the catalysts synthesized at 70 °C compared to the catalysts synthesized at 50 °C, irrespective of the metal precursors, supports and hydrazine/water ratios employed during catalysts syntheses. With a total timespan of around 5 days we showed that HT methods applied to all the steps (synthesis, characterization and testing) can significantly reduce the time needed to develop a new catalytic process. [ABSTRACT FROM AUTHOR]

Abstract In recent years, heteroatom-doped biomass-derived carbon has attracted intensive attention in vast fields due to their inexpensive precursors and abundant resources, especially in oxygen reduction reaction and supercapacitors. This research demonstrates a simple strategy to prepare mulberry leaves-derived nitrogen, sulfur dual-doped ladder-like porous carbon material, which possesses high content of nitrogen (8.17 at %), sulfur (1.97 at %), large surface area (1689 m2 g−1) and porous structure with a mass of micropores and mesopores. With respect to electrode material of supercapacitor, the nitrogen, sulfur dual-doped ladder-like carbon exhibits large specific capacitance of 243.4 F g−1 at 0.1 A g−1 and outstanding durability (94% retention after 5000 cycles at 3 A g−1). Moreover, in comparison to Pt/C catalyst, nitrogen, sulfur dual-doped ladder-like porous carbon presents excellent electrochemical performances of long term stability (90.2% retention after 20000 s) and resistance to methanol crossover for oxygen reduction reaction. This work successfully may provide a new case to take advantage of nature materials to fabricate heteroatom-doped carbon for energy conversion and storage. Highlights • Mulberry leaves are used to prepare bifunctional carbon materials. • A unique ladder-like porous carbon is obtained for the first time. • The N,S doped porous carbon exhibits outstanding durability for SC. • The N,S doped porous carbon presents excellent long stability for ORR. [ABSTRACT FROM AUTHOR]

We have synthesized catalysts for the hydrogen reduction of germanium tetrachloride: a catalyst based on multiwalled carbon nanotubes and a hybrid catalyst based on multiwalled carbon nanotubes whose surface was decorated with copper-containing nanoparticles. The hybrid catalyst has been characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results demonstrate that it consists of multiwalled carbon nanotubes whose surface is decorated with copper nanoparticles in a cuprous oxide shell (Cu2O/Cu/MWCNTs). The catalytic activity of the hybrid catalyst exceeds that of the as-prepared MWCNTs. The use of the Cu2O/Cu/MWCNT hybrid catalyst as a catalyst for the hydrogen reduction of germanium tetrachloride allows the reaction temperature to be lowered and ensures 95.7% germanium tetrachloride conversion at 873 K. [ABSTRACT FROM AUTHOR]

Constructing an efficient and reusable catalyst for catalyzing NaBH 4 hydrolysis for H 2 production is of vital significance. Herein, the Ru particles decorated Co 3 B-CoP heterostructures are obtained by chemical reduction and gas-phase phosphating treatment. The strong electronic interaction and abundant heterojunctions between the Co 3 B-CoP substrate and Ru particles have been elucidated. The optimal Ru 0.063 /Co 3 B-CoP catalyst exhibits a fast hydrogen generation rate (8875.8 mL min−1 g cat −1) and a high turnover frequency (636.0 min−1) at 25 °C, superior to most ever reported catalysts. The excellent NaBH 4 hydrolysis performance can be attributed to the lower activation energy (47.6 kJ mol−1) and the synergy between Co 3 B-CoP substrate and Ru particles. Density functional theory calculations show that electrons penetrate into Ru particles from Co 3 B-CoP substrate, in which the electron-rich Ru particles can selectively adsorb BH 4 − ions, while the electron-deficient Co 3 B-CoP facilitates the capture of H 2 O molecules, thereby synergistically promote the catalyzing NaBH 4 hydrolysis to produce H 2. [Display omitted] • Ru particles decorated Co 3 B-CoP are constructed by three controllable steps. • The heterostructure and electronic interaction of the catalyst have been confirmed. • The catalyst exhibits high HGR and TOF, superior to most ever reported catalysts. • The synergy between Ru and Co 3 B-CoP is the key reason for good performance. [ABSTRACT FROM AUTHOR]

The use of red mud as a support material was evaluated in this study to develop a novel bimetallic catalyst for highly reactive and selective nitrate removal from water and wastewater. The catalyst was optimized for the selection of promoter metal (i.e., Sn, Cu, In, and Zn) and then for noble metal (i.e., Pd, Pt, and Au). Sn-Pd-red mud and In-Pd-red mud catalysts achieved a complete nitrate removal. Sn-Pd-red mud showed 5.1 times higher removal kinetics (k = 11.57 × 10 −2  min −1 ) than that of In-Pd-red mud (k = 2.27 × 10 −2  min −1 ). The results from characterization study confirmed that the enhanced nitrate removal kinetics of Sn-Pd-red mud was mainly attributed to 1) its high affinity towards nitrate, 2) low alloying effect of Sn on Pd, 3) high reduction potential of Sn, and 4) high H 2 activation by Pd, as compared to those of other red mud supported bimetallic catalysts. We also found that the interaction between CaO and Fe 2 O 3 was the driving force for the enhanced nitrate reduction and high N 2 selectivity in this study. A complete nitrate removal with high N 2 selectivity (>88%) was preserved during the 11 times of recycling tests with consistent reduction kinetics (k = 10.87 ± 0.48 × 10 −2  min −1 ), indicating that red mud could be an excellent support material for efficient and durable bimetallic catalyst for the enhanced selective nitrate reduction. [ABSTRACT FROM AUTHOR]

Uniform mesoporous iron titanium (CT-FeTi) catalysts were synthesized by a CTAB-assisted process and exhibited good catalytic activity and H 2 O resistance when tested in the selective catalytic reduction (SCR) of NO with NH 3 at low temperature. BET, TPD, TPSR and in situ DRIFTS were carried out to reveal the inhibition mechanism of H 2 O on SCR reaction and determine the role of CTAB in the improved H 2 O resistance during low-temperature SCR processes. Results showed that H 2 O inhibited the adsorption of NO on the surface of CT-FeTi catalysts, as well as the formation of the intermediate species (–NH 2 ), which was produced by the reaction Fe 3+ + NH 3 → Fe 2+ - NH 2 + H + . CTAB acted as a “structural” and “chemical” promoter, not only optimizing the pore size to avoid being excessively enlarged in the presence of H 2 O, but also enhancing the adsorption of bridging nitrate and NH 3 species on Lewis acid sites, thus improving the catalytic activity and H 2 O resistance. [ABSTRACT FROM AUTHOR]

Phosphorus were employed to investigate the influences on the acid sites and reaction mechanism of FeTiO x SCR catalyst. The introduction of phosphorus inhibited the SCR activity by suppressing the redox property, decreasing the surface acidity and reducing the surface area. In particular, phosphorus preferentially bonded to the electron-deficient Ti 4+ and Fe 3+ cations on the surface as P-O-Fe and P-O-Ti, thereby blocking the Lewis acid sites (Fe-NH 3 or Ti-NH 3 ). Although phosphate provided additional Brønsted acid sites (P-O-NH 4 + ), the larger decrease of Lewis acid sites results in the decrease of total surface acidity. The newly formed Brønsted acid sites showed less SCR active at low temperature and exhibited high thermal stability and reactivity at high temperature, which leads to a new pathway following the L-H mechanism and an enhancement of high temperature performance. [ABSTRACT FROM AUTHOR]

Co-Mo bimetallic nanoparticles (NPs) with various compositions were prepared on a CeO 2 support (Co-Mo/CeO 2 ) by sodium naphthalenide driven reduction. The Co-Mo/CeO 2 catalyst exhibits much higher activity for ammonia synthesis than monometallic catalysts such as Co/CeO 2 and Mo/CeO 2 , and the optimum activity is obtained at Co:Mo = 4:6. X-ray absorption fine structure (XAFS) analyses reveal that Co 3 Mo 3 N NPs are formed after ammonia synthesis reaction. Nitrogen temperature programmed desorption (N 2 -TPD) measurements indicate that the Co-Mo/CeO 2 catalyst possesses a large number of nitrogen adsorption sites with an intermediate nitrogen adsorption energy between that of Co and Mo. Furthermore, nitrogen vacancy sites, which are active sites for N 2 dissociation, are more easily formed on the Co-Mo/CeO 2 catalyst than on bulk-type Co 3 Mo 3 N. As a consequence, the turnover frequency of the Co-Mo/CeO 2 catalyst is much higher than that of bulk-type Co 3 Mo 3 N and is comparable to that of the efficient Ru/CeO 2 catalyst. [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]

The uniform nanoporous CeO 2 catalysts with different content of Ag were prepared by etching the CuO/CeO 2 /Ag 2 O mixed oxides in a HCl aqueous solution. The removal of CuO resulted in the formation of ultrafine nanoporous CeO 2 , inside which Ag nanoparticles were formed in situ by combining a chemical reduction. The sizes of pore channel and ligament were less than 20 nm. The test results revealed that the nanoporous CeO 2 -Ag catalysts exhibited an enhanced catalytic activity toward the oxidation of CO. The catalytic activity was attributed to the enhancement of interfacial interaction between CeO 2 ligament and Ag particle. [ABSTRACT FROM AUTHOR]

Metal-free electrocatalyst is an emerging energy material to replace precious metal for effective oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a working electrochemical energy conversion device. Developing an effective bifunctional catalyst with abundant highly active sites and full exposure to reactants is strongly considered. Herein a nitrogen-doped mesoporous graphene framework (NMGF) was proposed with intrinsic N/O heteroatoms and abundant topological defects for metal-free ORR/OER. The NMGF was fabricated by direct chemical vapor deposition on MgO template. The as-obtained NMGF exhibited high porosity with a large specific surface area of 1440 m 2 g −1 as well as a high electrical conductivity of 57.0 S cm −1 . This unique structure is demonstrated to possess several advantages, including plentiful active centers due to defects and heteroatoms, improved utilization efficiency by very high electrochemically active surface area and hydrophilic surface, facilitated ion diffusion through interconnected pores and smooth electron transportation in the highly conductive 3D framework, thereby leading to superior ORR and OER bifunctional activity. The ORR half-wave potential was 0.714 V, and the potential to reach 10.0 mA cm −2 OER current density was 1.664 V with the potential gap of 0.95 V. This bifunctional performance was better than routine precious metal-based catalysts ( e.g. Pt/C and IrO 2 ) for oxygen redox reaction. [ABSTRACT FROM AUTHOR]

Low-cost metallic nanoparticles as catalysts with good performance are highly desired for the development of hydrogen storage materials. In this work, ceria-doped CuNi nanoparticles were successfully immobilized on the surfaces of reduced graphene oxide (rGO) by a simple co-reduction approach in aqueous solution at room temperature, characterized by ICP-OES, XRD, TEM, SEM-EDS and XPS techniques. The as-synthesized CuNi-CeO 2 /rGO nanocomposites with various metal contents had been employed as heterogeneous catalysts for the hydrolytic dehydrogenation of ammonia borane (NH 3 BH 3 , AB) under mild conditions. The optimal catalyst of Cu 0.8 Ni 0.2 -CeO 2 /rGO with CeO 2 content of 13.9 mol% exhibited an excellent catalytic activity with the exceedingly high TOF value of 34.4·mol H2 ·mol catalyst −1 ·min −1 at 298 K. The apparent activation energy was calculated to be 19.1 kJ mol −1 , even lower than most of noble-metal-based catalysts for AB dehydrogenation. The detailed kinetics of AB hydrolysis catalyzed by Cu 0.8 Ni 0.2 -CeO 2 /rGO had been investigated on different concentrations of catalyst, substrate and temperatures. Moreover, the obtained in situ hydrogen from AB hydrolysis can be further applied to reduce 4-nitrophenol with a high TOF value of 8.1 min −1 at room temperature. The high catalytic activity of Cu 0.8 Ni 0.2 -CeO 2 /rGO would be contributed to the small size of CuNi-CeO 2 NPs, metal-metal synergy, and the metal-support interaction. [ABSTRACT FROM AUTHOR]

The storage and reduction of NO x was examined over a series of mechanically mixed LaMn 0.9 Fe 0.1 O 3 (LMF) + Ba/Al 2 O 3 (BA), Pt-LMF + BA and LMF + BA + Pt/Al 2 O 3 (PA) catalysts in order to investigate the function of Pt in plasma-assisted NSR reaction. Efforts were also made to optimize the location of Pt to give the best H 2 reduction ability. [ABSTRACT FROM AUTHOR]

The stability of MnO x based low temperature SCR catalysts remained to be a serious issue. This report explored use of multi-walled carbon nanotubes (MWCNTs) network with uniform structure as a “rigid” pore template for synthesis of mesoporous MnO x -TiO 2 SCR catalyst with high surface area and high stability. The results showed that MWCNT network imposed MnO x -TiO 2 catalyst a mesoporous porosity with a narrow pore size distribution centered on ∼13.2 nm and a surface area of 131.6 m 2 g −1 stabilized at 500 °C. The mesoporous structure was formed by interconnected nanoparticles, comprised of crystallized rutile TiO 2 core surrounded by amorphous MnOx, with an average diameter of ∼8 nm. The catalyst exhibited an excellent low temperature SCR activity and selectivity as well as high resistance to deactivation and poison by H 2 O and SO 2 . SnO 2 modification led to degradation of catalytic performance in low temperature (60–180 °C) side, but improvement at high temperature side (240–360 °C), especially at high gas velocity, which can be attributed to change in structure, reactivity of MnO x and surface acidity induced by SnO 2 addition. [ABSTRACT FROM AUTHOR]

Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH3COO)2) and ((NH4)2HPO4) as a precursor. The NixPy/SiO2 catalysts were characterized using chemical analysis N2 physisorption, XRD, TEM, 31P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO) was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h-1. The Ni/P ratio was found to affect the nickel phosphide phase composition, POx groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of POx groups' content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis), we proposed that the enhancement of acid POx groups' content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis. [ABSTRACT FROM AUTHOR]

A strategy for tuning the surface property of Single Walled Carbon Nanotubes (SWNTs) for enhanced methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) along with methanol tolerance is presented. The surface functionality is tailored using controlled acid and base treatment. Acid treatment leads to the attachment of carboxylic carbon (CC) fragments to SWNT making it hydrophilic (P3-SWNT). Base treatment of P3-SWNT with 0.05 M NaOH reduces the CCs and makes it hydrophobic (P33-SWNT). Pt catalyst supported on the P3-SWNT possesses enhanced MOR whereas that supported on P33-SWNT not only enhances ORR kinetics but also possess good tolerance towards methanol oxidation as verified by the electrochemical technique. [ABSTRACT FROM AUTHOR]

Low working temperature and high sensitivity of gas sensors are critical in their practical applications; however, these properties are usually contradictory and cannot be realized simultaneously. Here, ZnO porous nanowires (PNWs) are prepared by a modified electrospinning method, and Pt nanoparticles (NPs) are doped on their surface by chemical reduction. The effects on morphology, specific surface area, and oxygen vacancy are discussed for the acetone gas-sensing performance. Results showed that Pt-ZnO PNWs responded optimally to acetone gas at 160 °C at 16.7–1.8 ppm, which was three-fold greater than that of pristine ZnO PNWs. In addition, the lowest detection limit is 50 ppb, a ten-fold lower level than pristine ZnO PNWs. The sensor exhibits superior acetone selectivity, humidity resistance, repeatability, long-time stability, noble metals, and a porous design with a large surface area, providing synergistic effects that increase the number of surface adsorption sites. Thus, the approach provided a new comprehension for loading a high-dispersibility catalyst onto the porous structure surface as a potential breath analyzer. [Display omitted] • Pt-ZnO with porous 1D nanowires morphology prepared by modified electrospinning. • The novel porous structure provided abundant active sites and diffusion channels. • Pt NPs doping induced more oxygen vacancy due to the catalytic action. • The Pt-ZnO PNWs sensor exhibited superior acetone sensing at low temperature. • The gas-sensing mechanism was expounded in detail. [ABSTRACT FROM AUTHOR]

By using in situ X-ray diffraction, we were able to demonstrate the effect of H 2 O on the reduction of cobalt oxide particles for Fischer-Tropsch Synthesis. Reduction of Co 3 O 4 to Co via CoO in H 2 produces large quantities of water, which was thought to have an impact upon the reduction of the catalyst down a reactor bed. Bed profiles are produced from saturation of the bottom of the catalyst bed from the H 2 O produced from the top of the bed. This contribution clearly shows the impact of H 2 O on the cobalt crystallites to hinder reduction and facilitate sintering of the cobalt particles. In situ X-ray diffraction was used to follow the reduction of the cobalt phase throughout the evolution of the reduction process, while controlled water production and cofeed was used to study the effect across different water levels (from 0 up to 1% H 2 O). Each study in turn produced clear transitions to CoO and Co metal, while H 2 O shifted the peaks to higher transition temperatures and slowed the reduction process to cobalt metal. [ABSTRACT FROM AUTHOR]

In this work, the regeneration of rich CO 2 -loaded monoethanolamine (MEA) solvent with two catalysts (e.g. SAPO-34 and SO 4 2− /TiO 2 ) was investigated in order to reduce the energy requirement for solvent regeneration. The regeneration behavior with and without catalyst of a 5M MEA solution with an initial CO 2 loading of 0.5 mol CO 2 /mol amine at 96 °C was studied to compare their CO 2 desorption rate and heat duties. The results show that the two solid acid catalysts can reduce the heat duty for solvent regeneration and increase the CO 2 desorption rate in comparison with blank test. The mechanism of CO 2 desorption with catalyst in 5M MEA was proposed based on the result of catalyst characterization (e.g. N 2 absorption/desorption experiment, Py-IR, NH 3 -TPD, FT-IR and XRD) to better understand the desorption process. The results indicate that SAPO-34 with the higher joint value of Brϕnsted/Lewis acid sites ratio (B/L) and mesopore surface area (MSA) shows the faster CO 2 desorption rate and lower heat duty than SO 4 2− /TiO 2 . Based on the experimental results, the addition of solid acid catalysts into amine solution could be considered as one of choices to reduce the heat duty for CO 2 desorption from CO 2 -loaded amine solvent. [ABSTRACT FROM AUTHOR]

N-doped microporous carbon as an exceptional metal-free catalyst from waste biomass ( banana peel as representative ) was obtained via fast catalysis carbonization, followed by N-doping modification. The method achieves a relatively high C conversion efficiency of ∼41.9%. The final carbon materials are doped by N (∼3 at.%) and possess high surface area (∼1097 m 2 g −1 ) and abundant micropores. Compared to commercial Pt/C materials, the as-prepared carbon catalyst exhibits a comparable electrocatalytic activity and much better stability. Furthermore, the metal-free catalyst loaded Zn-air battery possesses higher discharge voltage and power density as compared with that of commercial Pt/C. This novel technique can also be readily applied to produce metal-free carbon catalysts from other typical waste biomass (e.g., orange peel, leaves) as the carbon sources. The method can be developed as a potentially general and effective industrial route to transform waste biomass into high value-added microporous carbon with superior functionalities. [ABSTRACT FROM AUTHOR]

CuO-CeO 2 -ZrO 2 /cordierite catalysts have been successfully prepared by the impregnation reduction method. The effects of processing parameters such as the condition of reduction process, calcination temperature, the addition of surfactant on the size and shape of catalyst particles were studied by X-ray diffraction (XRD), BET surface area measurements, and scanning electron microscopy (SEM). The catalytic performance of the as-prepared catalysts for CO oxidation were evaluated by using a microreactor-GC system. The results indicate that the processing parameters influence greatly the size and shape of catalyst particles. Fragmental shape catalysts were formed when the impregnated samples were reduced in the thermostat water bath. However, spherical-like particles were obtained by ultrasonic-assisted in the reduction process. Tiny flower-like catalyst particles were found when the surfactant were used. When the calcination temperature decreased, the grain size of catalysts has reduced, and the catalytic activity for CO oxidation has been improved. The introduction of ultrasonic and surfactant resulted in larger specific surface area and better catalytic performance. [ABSTRACT FROM AUTHOR]

A magnetically separable core-shell-like catalyst Ni-Pd/CB is designed and synthesized via a facile sequential reduction strategy. It is found that the Pd nanocrystals with a thickness of ∼1.67 nm and a length of ∼7.92 nm are intimately coupled with the Ni cores and the formed core-shell-like Ni-Pd nanoparticles are well dispersed on the CB surface with much smaller particle size and narrower size distribution as compared with that of unsupported ones. The ligand-free Ni-Pd/CB nanocatalyst is evaluated for Suzuki-Miyaura coupling reaction and exhibits excellent catalytic activity under mild aerobic conditions without using toxic solvents and inert protective atmosphere, achieving green catalysis. The high catalytic performance of Ni-Pd/CB catalyst can be attributed to its unique core-shell-like nanostructure and the concerted effects between the individual components. The introduction of Ni not only makes the catalyst magnetically separable in a suspension system, but also significantly lowers the cost. [ABSTRACT FROM AUTHOR]

Cobalt nanoparticles have been prepared by reduction of cobalt chloride by sodium borohydride. They are very active catalysts for ethanol steam reforming at moderate temperature. The best catalytic materials show full ethanol conversion and hydrogen yields of the order of 83% and stable activity for 8 h when tested at 773 K, GHSV 324,000 h −1 with diluted 1:6 ethanol:water feed in He 41.6%. The amount of coproduced methane is very low (yield <0.05%). Experiments performed at different space velocities provide evidence of the intermediate formation of acetaldehyde in the ethanol steam reforming path. The fresh Co nanopowders are amorphous and are actually contaminated mainly by Boron species and traces of Na, Cl and C. During reaction, Cobalt nanoparticles are transformed into cubic metallic Co crystallites. The surface properties of these materials are very sensitive to: (I) the separation procedure from the reaction medium at the end of the preparation step, and (II) the conditions of ageing and storage in the laboratory. An increasing time of ageing seems to favor the formation of borates species and the observed oxidation of metallic cobalt to cobalt oxides. These phenomena could be associated to the loss in the catalytic activity that results in a lower ethanol conversion, lower hydrogen yield and sometimes, higher selectivity to acetaldehyde. [ABSTRACT FROM AUTHOR]

B-doped, B–N co-doped and B–N–F tri-doped TiO 2 catalysts were prepared via a sol–gel method using H 3 BO 3 , NH 4 Cl and NH 4 F as B, N and N–F dopant precursors, respectively. N-doped, N–F co-doped and a pure TiO 2 (undoped) samples were also prepared by the same method as blank samples, for comparison. The catalysts were evaluated for the simultaneous photocatalytic reduction of Cr(VI) and oxidation of benzoic acid (BA). XRD analysis shows the formation of pure TiO 2 anatase phase in all cases, with crystallite size varying from 10.1 nm to 14.6 nm for all doped samples. UV–vis DRS spectra show narrowing of the band gap ( E g ) for all doped samples, compared to the undoped TiO 2 . Concomitant presence of N and F ions i.e. in N–F co-doped and B–N–F tri-doped TiO 2 catalysts, causes the most pronounced decrease of E g while B–N co-doped and B–N–F tri-doped TiO 2 have lower E g values than mono B-doped but higher than N-doped and N–F co-doped TiO 2 . B and N doping also causes an increase of specific surface area and a decrease in mean pore diameter. Electron Paramagnetic Resonance (EPR) spectroscopy was employed for a detailed investigation of the structure and photoexcited species formed in these catalysts. The EPR data show that N-doping forms N b photoexcited species which react as holes, Ti 4+ –O − oxygen vacancies (OVs) and Ti 3+ lattice and surface defects. B-doping enhances the formation of Ti 4+ –O − oxygen vacancies and the quantities of O 2 H and OH radicals. In B-doped and B–N co-doped samples, boron causes the most prominent induction of Ti 3+ lattice centers. Boron in interstitial sites, with oxygen atoms [BO 3 ] behaves as a three-electron donor leading to the formation of B 3+ and reduction of Ti 4+ to Ti 3+ . Under UV–vis irradiation, Cr(VI) reduction followed the trend: TB1 > TBN1 > TBNF1 > TNF1 > TN1 > undoped TiO 2 ; while benzoic acid (BA) oxidation trend was: TB1 > TBNF1 > TBN1 > TNF1 > TN1 > undoped TiO 2 . Cr(VI) reduction and BA oxidation rates are in agreement with EPR-detected Ti 4+ –O − oxygen vacancies and O 2 H, OH photoexcited radicals, respectively. [ABSTRACT FROM AUTHOR]

Nanostructure cerium–titanium catalysts including fluoride (F − ) doped ones were prepared by impregnation (Ce/TiO 2 and Ce/F–TiO 2 ) and co-precipitation (CeTi and CeTiF) method, and tested as ozonation catalysts for low-temperature NO X removal ranging from 40 to 180 °C. Interestingly, the doping of F − promotes the NO X removal for CeTi whereas inhibits the removal for Ce/TiO 2 . The NO X removal presents linear relationship with the concentration of hydroxyl radicals ( OH). The surface –OH linked to Ce atoms as well as the H 2 O adsorption over Ce atoms play the important role in the generation of ·OH radicals. The doping of F − into CeTi improves the activation of Ce–OH linkage bonds and the adsorption of H 2 O over Ce atoms, thus increasing the concentration of OH radicals and catalytic activities. Although the doping of F − into Ce/TiO 2 enhances the density of surface –OH, the ones linked to Ce atoms remain constant and the H 2 O adsorption over Ce atoms are declined, finally declining the catalytic activities. [ABSTRACT FROM AUTHOR]

We describe herein the synthesis of solid Au@Pd and hollow AgPd nanoflowers displaying controlled sizes and compositions in order to investigate how their size, composition, and the presence of Au in the core of the nanoparticles influence their catalytic performance toward both liquid and gas-phase transformations. While the size and composition of Au@Pd and AgPd the nanoflowers could be controlled as function of growth time, their structure (solid or hollow) was dependent on the nature of the seeds employed for the synthesis, i.e., Au or Ag nanoparticles. Moreover, Au@Pd and AgPd nanoflowers were successfully supported onto commercial silica displaying truly uniform dispersion. The catalytic activities of Au@Pd and AgPd nanoflowers were investigated toward the 4-nitrophenol reduction and the benzene, toluene, and o-xylene (BTX) oxidation. The catalytic activities for the reduction of 4-nitrophenol decreased as follows: Au@Pd > Au@Pd > AgPd and AgPd > Au@Pd > AgPd, suggesting that the Au core enhanced the catalytic activity relative to the hollow material when for Pd at.% was up to 80. Regarding the BTX oxidation, supported Au@Pd displayed higher catalytic activities than AgPd nanoflowers, also illustrating the role of the Au cores in the nanoflowers for improving catalytic performance. We believe these results may serve as a platform for the synthesis of Pd-based bimetallic nanomaterials that enable the correlation between these physical/chemical parameters and properties and thus optimized catalytic activities. [ABSTRACT FROM AUTHOR]

A series of WO 3 -doped Mn–Zr mixed oxide catalysts were investigated for the selective catalytic reduction of NO x by NH 3 (NH 3 –SCR). It was found that the added WO 3 significantly enhanced the catalytic performance of Mn–Zr mixed oxide catalyst for NH 3 –SCR of NO x . In situ diffuse reflectance infrared transform spectroscopy (DRIFTS) studies revealed that the highly dispersed WO 3 not only resulted in more acid sites formed on the catalyst surface, but also inhibited the adsorption of the inactive nitrate specie, leaving more active sites available for the adsorption of NH 3 . In addition, the synergetic effect between W and Mn contributes to improving the redox property of the catalyst. Therefore, the high catalytic deNO x performance was obtained over WO 3 -promoted Mn–Zr mixed oxide catalyst. [ABSTRACT FROM AUTHOR]

Total oxidation of toluene over a CuO–CeO 2 /Al 2 O 3 catalyst was studied by means of Temporal Analysis of Products (TAP) at temperatures of 723–873 K in the absence and presence of oxygen (molar toluene:oxygen ratio = 1:9) at degrees of reduction of the catalyst up to 0.42. A single set of kinetic parameters corresponding to the steps of the detailed mechanism can describe the experimental data. A detailed mechanism with oxidation occurring on Ce 3+ sites and reduction on Cu 2+ sites formed the basis of a microkinetic model. The interaction of reactants and products with the catalyst support was taken into account. A distinction was made between O atoms at the surface of the catalytically active phase and those in the bulk. Transport of the latter to the surface was explicitly accounted for in the model. The abstraction of hydrogen atoms leading to the formation of water is the fastest process. The formation of carbon dioxide occurs through three kinetically significant steps. The potentially slowest step in the whole process was found to be the destruction of the aromatic ring. A linear dependency of the activation energies of the processes which include transport of oxygen from the bulk to the catalyst surface, on the degree of reduction of the catalyst was found. Analysis of the dependency of the catalytic behavior on the catalyst descriptors provided information about the optimum catalyst composition and fraction of the active component exposed, which can be used for catalyst optimization. [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 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]

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]