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[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]

• 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]

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]

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]