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The Co-WS 2 heterostructure, loaded on nanofibers with faster electron transport rates, was designed and developed using a top-down approach to achieve high HER performance in alkaline electrolytes. Driven by the inherent electric field induced by the work function difference between Co and WS 2 , efficient electron transfer at the interface optimizes the adsorption energy of reaction intermediates and boosts catalytic activity. [Display omitted] Designing and developing cost-effective, high-performance catalysts for hydrogen evolution reaction (HER) is crucial for advancing hydrogen production technology. Tungsten-based sulfides (WS x) exhibit great potential as efficient HER catalysts, however, the activity is limited by the larger energy required for water dissociation under alkaline conditions. Herein, we adopt a top-down strategy to construct heterostructure Co-WS 2 nanofiber catalysts. The experimental results and theoretical simulations unveil that the work functions-induced built-in electric field at the interface of Co-WS 2 catalysts facilitates the electron transfer from Co to WS 2 , significantly reducing water dissociation energy and optimizing the Gibbs free energy of the entire reaction step for HER. Besides, the self-supported catalysts of Co-WS 2 nanoparticles confining 1D nanofibers exhibit an increased number of active sites. As expected, the heterostructure Co-WS 2 catalysts exhibit remarkable HER activity with an overpotential of 113 mV to reach 10 mA cm−2 and stability with 30 h catalyzing at 23 mA cm−2. This work can provide an avenue for designing highly efficient catalysts applicable to the field of energy storage and conversion. [ABSTRACT FROM AUTHOR]

Micro-nano hollow materials have become a research hotspot due to their unique structure and properties. Blast furnace gas is one of the main pollutants discharged from steelmaking, and the COS chemical property in blast furnace gas is stable, which is difficult to be effectively removed. Nano-hollow sphere composite has the advantages of large specific surface area, adjustable material size, and stable performance. It has become one of the most promising hydrolysis catalytic materials due to its good catalytic performance. In this study, the template of carbon spheres was synthesized by the glucose hydrothermal method, and activated aluminum nitrate was loaded on carbon sphere templates by the method of equal volume impregnation. Urea was used as precipitant to prepare uniform Al2O3 hollow sphere hydrolysis catalyst, and its application and removal performance in COS removal of blast furnace gas was explored. The results showed that (1) When the ratio of water to alcohol was 30 mL:90 mL and the calcination temperature was 950 ℃, the particle size of the prepared γ-Al2O3 hollow sphere hydrolysis catalyst was between 100 and 150 nm, the average pore size was 6.785 nm, the total pore volume was 0.259 cm3·g−1 and the specific surface area was 154.665 m2·g−1. (2) When the roasting temperature is 950 ℃ and the addition amount is 40 mmol, the hydrolysis catalytic efficiency of COS is the highest. After the reaction for 70 min, the hydrolysis catalytic efficiency is maintained at about 68%, and the conversion amount is 120 mg·m−3. [ABSTRACT FROM AUTHOR]

Diesel oxidation catalysts Pt-Pd-(y)ZrO2-(z)WO3/CeZrOx-Al2O3 with total Pt & Pd loading of only 0.68 wt.% were prepared and investigated for oxidation activity and stability of CO, C3H6, and NO. Introduction of ZrO2 greatly improved low-temperature activities and retained stability especially for CO and C3H6 oxidation after treated at 800 °C. With the optimal loading amount of 6 wt% ZrO2, 2 wt% WO3 was introduced to the system and showed higher activity. Reaction temperature for 50% CO and C3H6 conversion declined to 160 and 181 °C, and the maximal NO conversion increased to 50%. By using XRD, TEM, CO chemisorption, XPS, and H2-TPR analysis, it was found that ZrO2 could inhibit aggregation of Pt and Pd, improve metal dispersion, and increase surface-chemisorbed oxygen after high-temperature treatment, accounting for promoted performance. Also, there were more reducible oxide species in ZrO2-doped catalysts. ZrO2 could induce reduction of noble metal oxides and surface ceria by weakening Pt-O-Ce interaction, which increased the ability to dissociate H2 and spillover effect of dissociated hydrogen to ceria. Doping WO3 increased metal dispersion of fresh samples and brought more Pt0 species that were active sites for oxidation reactions. Thus, ZrO2 and WO3 could be effective additives for oxidation catalysts to synergistically improve their activities and thermal stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchically devised NiFeO x H y catalyst showed high OER activity under alkaline condition. • NiFeO x H y /Ni heterostructure was in-situ formed via a surface reconstruction process. • Charge transfer at the catalyst-electrolyte interface was improved with Fe incorporation into Ni (oxy)hydroxide. • Fe species located at the outer surface of NiOOH structure served as the OER active site. Nickel iron (oxy)hydroxide (NiFeO x H y) is among the most active electrocatalysts for oxygen evolution reaction (OER) in the alkaline media. Development of new design strategy for NiFeO x H y electrode with respect to intrinsic activity and number of active species is highly attractive. Here we report a hierarchical fabrication for NiFeO x H y electrode towards efficient oxygen evolution. Three-dimensional mesoporous NiO was initially prepared and reduced to a polycrystalline Ni metal framework. Despite the poor OER activity for Ni-based catalyst, the incorporation of surface Fe species induced a notably high current density for the oxygen evolution. The results indicated that the Fe species, located at outer surface region, played a key role as the OER active sites. It is also found that the surface of metallic Ni was reconstructed to (oxy)hydroxide phase with ease compared to NiO. As a result, a heterostructure composed of an OER-active NiFe (oxy)hydroxide shell and an electron-conductive Ni core was formed. In this fabricated NiFeO x H y /Ni catalyst, the promoted intrinsic activity, number of active sites and charge-transfer ability all taken into account contribute to an efficient OER process. [ABSTRACT FROM AUTHOR]

An organobase assisted approach is adopted to synthesize a series of β-ketoenamine-linked covalent organic frameworks (COFs), exhibiting superior crystallinity and porosity in comparison with those using an acidic catalyst. The quality promotion arises from the organobase-modulated transimination that favors the reaction kinetics for self-improvement of ordered structures. [ABSTRACT FROM AUTHOR]

• MNi/CNTs with controlled metal distribution was successfully synthesized. • The secondary metal M had profound effects on reducibility and surface property. • CoNi/CNTs showed the best abilities in anti-sintering and coke resistance. • Hydrogen was more selective over CoNi/CNTs by promoting water gas shift reaction. The bimetallic MNi/CNTs (M Co, Cu and Fe) catalysts with controlled metal distribution were prepared by a two-step impregnation method. The catalysts were characterized by N 2 adsorption/desorption, XRD, XPS, TPR, HAADF-STEM, TEM and TG to study the porous structure, changes in crystalline phases during the reaction, surface chemical state, reducibility, the element distribution, sintering of metal particles and the deposited coke for the calcined and/or spent catalysts. The results showed that the Ni oxide was successfully introduced into the cave and the other one was dispersed on the external wall of CNTs. The addition of the secondary metals had significant influences on the reducibility, resulting in the quite different surface properties which was directly linked to the products distribution in glycerol reforming reaction. The sample CoNi/CNTs performed better in both anti-sintering and coke resistance, and over which the product was more selective to hydrogen by enhancing the water gas shift reaction. [ABSTRACT FROM AUTHOR]

• OFGs, PFRs and redox properties of BC facilitate the generation of ROS. • BC and BC-based catalysts could effectively activate H 2 O 2 and persulfate. • BC-based photocatalysts could effectively degrade pollutants. • BC-based catalysts could effectively degrade pollutants in sonocatalytic systems. • BC-based catalysts may be a good alternative for the degradation of pollutants. Biochar (BC) is one of the most remarkable materials for environmental remediation. An increasing number of researchers have attempted to utilize BC as a catalyst to generate reactive oxygen species (ROS) and sulfate radicals. This work focuses on the development and progress of BC-based catalysts in different systems, including redox systems, Fenton-like systems, sonocatalytic systems and photocatalytic systems. Most importantly, the catalytic performance and mechanism of different types of BC-based catalysts are thoroughly investigated. Furthermore, the applications of BC-based catalysts in wastewater, sediments, soil and gas are presented. Special attention is paid to the factors involved in the generation of ROS and sulfate radicals, such as oxygen-containing functional groups (OFGs), persistent free radicals (PFRs) and redox properties. The generation processes of ROS and sulfate radicals are presented in detail. And the removal pathways of three mechanisms are elaborated. Furthermore, research in this field is still at an early stage, and many improvements are required before the technology can be efficiently scaled up and put into practice. This review enriches the knowledge about the generation processes of ROS and sulfate radicals by BC-based catalysts and improves the understanding of the catalytic performance and catalytic mechanism of BC-based catalysts for pollutants. [ABSTRACT FROM AUTHOR]

Photocatalytic reduction of nitrate ( NO 3 − ) is a green and potentially inexpensive technique for reducing NO 3 − pollution in ground water. TiO 2 -based photocatalysts have been studied extensively for this purpose. In the present study, the semiconducting catalyst CuFe 0.7 Cr 0.3 S 2 was applied to NO 3 − reduction. Loading this catalyst with metal co-catalysts (Ru, Au, Cu, Ag, Pt, and Pd) greatly increased the rate of NO 3 − reduction and the N 2 selectivity. In addition, there was a synergistic enhancement of the photocatalytic performance when the catalyst was loaded two co-catalysts. For example, the catalyst loaded with Pd and Au at mass fractions of 0.75% and 3%, respectively, could photocatalyze the complete reduction of NO 3 − in a 100 ppm N aqueous solution with 100% N 2 selectivity in less than 5 h with UV irradiation. However, with an inner irradiation from a full-arc Xe lamp, the NO 3 − conversion rate reduced to 0.065 mg N/h, probably because of the low density of the photoexcited electrons. The results show the potential of metal sulfides for photocatalytic reduction of NO 3 − , and the possibility of use of visible light. [ABSTRACT FROM AUTHOR]

The theoretical calculation about the catalytic mechanism of MCM-41 supported phosphoric acid (SPAM) in the alkylation desulfurization of fluid catalytic cracking (FCC) gasoline demonstrated that properly reducing the amount of effective acid on the surface was beneficial to further enhancing the catalyst performance. Based on the previously optimized preparation of SPAM (weight ratio of total acid/MCM-41 6:1, calcination temperature 773 K and weigh ratio of H 3 PO 4 /H 4 P 2 O 7 1:2.5), an improvement by diluting the concentration of mixed phosphoric acids in the impregnating solution was carried out in this work. The surface structure and catalytic behavior of improved SPAM were investigated by structural characterization and experimental verification, respectively. The results proved that decreasing the concentration of mixed phosphoric acids in the impregnating solution in the preparation of SPAM could effectively reduce the existing acid amount on the catalyst surface by increasing the catalyst crystallinity, and both the surface acid strength and the total acids amount of SPAM were reduced. Moreover, the catalytic activity and selectivity of improved SPAM for thiophenic sulfurs alkylation in the alkylation desulfurization were enhanced and the olefins polymerization reactions were suppressed to a lower extent. Besides, the theoretical calculation was verified by this study, which opened a particularly appealing opportunity for the application of SPAM in the industrial alkylation desulfurization of gasoline. [ABSTRACT FROM AUTHOR]

A series of Ru/AlO catalysts were prepared to study the effect of the amount and the origin of residual chlorine on chemisorptive property and the ammonia synthesis activity. The catalysts were characterized by X-ray fluorescence, CO chemisorption, transmission Electron Microscopy, X-ray photoelectron spectroscopy, hydrogen temperature-programmed desorption, hydrogen temperature-programmed reduction. It is found that the presence of chlorine had a limited impact on Ru particle size. Residual chlorine originated from RuCl would not influence on Ru 3d binding energy, but chlorine from HCl solution significantly increased Ru 3d binding energy. Regardless of their source, the presence of chlorine severely reduced the amount of hydrogen species corresponding to the desorption peak at medium temperature. The inhibition effect of chlorine on hydrogen adsorption was more strong for Ru catalyst with residual chlorine from the RuCl precursor. With a similar amount of residual chlorine, the catalysts with chlorine originated from the RuCl precursor showed much lower catalytic activity than those prepared by impregnation of HCl. These results suggest that chlorine mainly affects the catalytic properties of alumina supported Ru catalysts for ammonia synthesis by selective site blocking. Graphical Abstract: Chlorine affects on the sites at the metal/support interface for Ru/AlO catalysts, and then hydrogen adsorption and ammonia synthesis both are suppressed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353–413K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds. [Copyright &y& Elsevier]

Citric acid (CA) was used to modify graphited activated carbon (AC) for improving size distribution of Ru particles and catalytic activity of the Ru/AC catalyst. The influence of CA on the texture of AC and Ru/AC, Ru distribution and catalytic activity were investigated. TEM, TGA, TPD-MS, CO pulse chemisorption and N2 physisorption indicate that CA modified AC creates more functional groups and thus more homogeneous dispersion of Ru nanoparticles. TEM images show most of the Ru particles were ca. 2–2.5 nm for the CA4 + Ru4/AC catalyst. The increase of ammonia synthesis activity for Ru–Ba–K/AC catalyst is more than 16% when the content of CA in AC is 4 wt.% at 673 K and 10,000 h−1. [ABSTRACT FROM AUTHOR]

Cerium-modified Cu-SSZ-13 catalysts were prepared by an aqueous ion-exchange method, and Ce and Cu were incorporated through different ion-exchange sequences. The results of NH3-SCR activity evaluations displayed that Cu1(CeCu)2 catalyst presented excellent catalytic activity, and over 90% NOx conversion was obtained across the temperature range of 200–500 °C. The characterization results showed that the ion-exchange sequence of Cu and Ce species influenced the crystallinity of the zeolites and the coordination of Al. A small amount of Ce could participate in the reduction process and change the location and coordination environment of copper ions. Furthermore, Ce-modified Cu-SSZ-13 catalysts possessed more acidic sites due to their containing replacement of Ce and movement of Cu in the preparation process. The cooperation of strong redox abilities and NH3 storage capacity led to the increase of active adsorbed species adsorption and resulted in better activity of Cu1(CeCu)2. [ABSTRACT FROM AUTHOR]

An efficient and reusable heterogeneous catalyst with oxime‐derived palladacycle immobilized in an ionic liquid brush has been synthesized and an environmentally‐friendly procedure have been developed for coupling aryl iodides and bromides with acrylic acid. These reactions were conducted in neat water under aerobic conditions with water‐insoluble or even solid aryl halides and they proceeded smoothly and cleanly without any organic co‐solvent or other additives. The ionic liquid brush could be easily recovered and reused at least five times without significant loss of activity. The protocol has the advantages of excellent yields, environmental friendliness, and catalyst recyclability. [ABSTRACT FROM AUTHOR]

Cu-SSZ-13 has been generally considered as the predominant commercial selective catalytic reduction (SCR) catalyst in the NH3-SCR reaction because of its superior activity and durability. However, in real applications, SCR catalysts readily undergo hydrothermal aging and sulfur poisoning. In this work, the deactivation and regeneration of a commercial Cu-SSZ-13 catalyst was investigated for SO2 exposures during hydrothermal aging and the effect of different regeneration temperatures was compared. By using XRD, SEM, H2-temperature programmed reduction (TPR), X–ray photoelectron spectra (XPS) and NH3-temperature programmed desorption (TPD) analysis, it was found that SO2 poisoning influenced the chabazite (CHA) structure even if regeneration cannot restore its original structure, the redox ability and ammonia storage performance also influenced by sulfation and the regeneration process. Moreover, the extent of a decrease in redox ability was more severe than acidity, suggesting that the amount of isolated Cu2+ and Cu+ reduction was responsible for irreversible deactivation over the Cu-SSZ-13 catalyst. Combined with the analysis of Ea values and pre-exponential factor of the SCR reaction, a more likely explanation for the irreversible deactivation was that active sites were lost mostly in sulfated and regenerated process sites. [ABSTRACT FROM AUTHOR]

A series of NiCe x Al (x = 0.1, 0.3, 0.5, 0.7 and 0.9) mixed metal oxides catalysts was synthesized through decomposing the corresponding layered double hydroxides (LDH) precursors, and then characterized by TG, XRD, N 2 adsorption/desorption, XPS, H 2 -TPR, H 2 -TPD etc. techniques. The results showed that the introduction of Ce could efficiently restrict the agglomeration of Ni species. The generated Ni–Ce–O solid solution could create the oxygen vacancies and enhance the oxygen mobility which further improved the properties of active sites including Ni dispersion and surface area, and suppressed coke deposition. The Ni2+ species was reduced by Ce3+ under the reaction conditions to give the metallic Ni as active sites in catalyzing steam reforming of glycerol for the production of hydrogen. The best catalytic performance was obtained over the sample NiCe 0.7 Al which exhibited the better Ni dispersion and larger surface, and lower quantity of deposited coke by establishing the correlations. The reaction was more selective to hydrogen thanks to the enhancement of water gas shift reaction and suppression of CO methanation reaction. Image 1 • Impurity co-existed in Ce contained NiAl layered double hydroxides precursors. • Ce could stabilize the Ni species but restrict the reduction of Ni2+ by hydrogen. • Ce3+ reduced the Ni2+ into the active metallic Ni under the reaction conditions. • Ce/Al ratio had important influences on Ni properties. • Coke deposition was suppressed by introducing Ce into the catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Through-focus exit-wavefunction reconstruction in high-resolution transmission electron microscopy has been applied to process the image series obtained from both the simple ZSM-5 catalyst and an iron-loaded one prepared by impregnation. In conventional high-resolution transmission electron microscopic observations, artificial patches due to electron optical effects always appear in the centers of the ten-member ring channels of the ZSM-5 structures, preventing the atomic details in the channels to be revealed, which are crucial information for understanding the catalytic properties of this type of catalysts. Our study shows that such artificial patches can be removed in the retrieved exit-wavefunctions, allowing the projected structures of the ZSM-5 zeolites to be imaged. Together with X-ray energy dispersive spectroscopy, through-focus exit-wavefunction reconstruction confirmed the existence of iron atoms in the ten-member ring channels of the iron-loaded ZSM-5 catalyst. [Copyright &y& Elsevier]

• Microwave assisted direct arylation of 1-benzyl-1,2,3-triazoles into corresponding 1-benzyl-5-aryl-1,2,3-triazoles. • Pd(OAc) 2 as the catalyst and P(t Bu) 3 -HBF 4 as the ligand. • Good to excellent yields can be obtained. • Good chemoselectivity and group tolerance. A new efficient pathway for synthesis of 1-benzyl-5-aryl-1,2,3-triazoles by regioselective direct arylation between 1-benzyl-1,2,3-triazole and Ar-Br is developed. The microwave assisted reaction proceeded smoothly with good yield with high C5 position selectivity and a possible pathway of direct arylation is discussed. This methodology provides a simple way to construct 1,5-disubstituted 1,2,3-triazoles moiety. [ABSTRACT FROM AUTHOR]

Photocatalytic nitrogen (N 2) fixation provides a green avenue for the production of ammonia (NH 3), which is extremely significant for global biogeochemical cycle. However, there is still lack of highly efficient catalyst to improve the N 2 photofixation efficiency. In this work, oxygen vacancy engineered perovskite SrTiO 3 materials have been prepared by post reduction using lithium alkylamine solution and served as effective catalysts for visible-light-driven N 2 -to-NH 3 conversion. The formation and concentration of oxygen vacancies were confirmed by electron paramagnetic resonance, X-ray photoelectron spectroscopy and thermogravimetric analyses. The SrTiO 3 catalyst with optimized oxygen vacancies concentration exhibited improved photocatalytic N 2 reduction rate of 306.87 μmol·g−1·h−1, which is approach ten-fold higher than that of pristine SrTiO 3. Electrochemical impedance spectroscopy and photoluminescence measurements reveal that optimum amount of oxygen vacancies can promote the effective adsorption of N 2 molecules and improve the photocatalytic performance by facilitating the fast separation of photo-generated charge carriers. Moreover, the as-fabricated defective SrTiO 3 exhibited outstanding stability, which makes it emerge the promising potential for further practical applications. This work offers a feasible method for the design of high performance photocatalysts through defect engineering. • Synthesized defective SrTiO 3 catalysts by lithium alkylamine solution reduction. • Oxygen vacancies regulation to improve the photocatalytic NRR activity for SrTiO 3. • About ten-fold NH 3 formation rate (873.48 μmol·g−1·h−1) to original SrTiO 3. • Defective SrTiO 3 suppressed the recombination of the photogenerated carriers. [ABSTRACT FROM AUTHOR]

• The (Fe x , Co y)-NG/mpg-C 3 N 4 materials exhibited excellent activity due to the synergistic effect of well-defined dual sites. The photocatalytic hydrogen evolution reaction is a promising and powerful approach to replace traditional fossil fuels. Herein, we have fabricated Fe, Co dual single atoms dispersed on nitrogen-doped graphene ((Fe x , Co y)-NG) by freeze-drying method, which can as a highly efficient co-catalyst. The (Fe x , Co y)-NG loaded mesoporous graphitic carbon nitride (mpg-C 3 N 4) exhibits an excellently high performance for photocatalytic hydrogen evolution. The high activity can belong to two ways: (i) the ultrathin mpg-C 3 N 4 not only increases the absorption and active sites but also shortens the charge migration distance; (ii) The nitrogen functional groups from NG can provide abundant coordination sites to evenly bind Fe and Co atoms. The photocatalytic hydrogen evolution performances (Fe x , Co y)-NG co-catalyst with different content ratios of Fe atoms and Co atoms were also investigated. The optimized hydrogen production rate (1958 μmol g−1) of 5 wt% (Fe 0.2 , Co 0.8)-NG/mpg-C 3 N 4 is obviously higher compared to the monometallic counterparts (5 wt% Fe-NG/mpg-C 3 N 4 or 5 wt% Co-NG/mpg-C 3 N 4). The higher photoactivities are due to the synergistic effect between Fe and Co. [ABSTRACT FROM AUTHOR]

Abstract: A series of Ru/Sm2O3–CeO2 catalysts were prepared by using a co-precipitation (CP) method and characterized by XRD, BET, SEM, H2-TPD-MS, H2-TPR and CO chemisorption. The activity test shows that ammonia concentration of the catalyst with 7% Sm is 13.4% at 10MPa, 10,000h−1, 425°C, which is 21% higher than that of Ru/CeO2. Such high catalytic activity was due to three effects: the morphology changes of catalyst, electrodonating property of partially reduced CeO2−x to Ru metal and the property of easily hydrogen desorption derived from the presence of Sm3+ in ceria. [Copyright &y& Elsevier]

Abstract: Ru/MgO–CeO2 catalysts were prepared by using co-precipitation (CP), deposition precipitation (DP) and modified deposition precipitation (MDP) methods. These samples were characterized by XRD, N2 physisorption, H2-TPD, N2-TPD, H2-TPR and CO chemisorption. It is found that the catalytic activity of Ru/MgO–CeO2 prepared by MDP method was 2.5 times higher than that of the catalyst prepared with the DP route under the same reaction conditions. The activity of the catalyst with MDP method was also higher than that of Ru/MgO–CeO2 synthesized by CP method. The possible influence factors of preparation methods on the catalytic performance were proposed based on the experimental results. [ABSTRACT FROM AUTHOR]