Improved utilization of active sites for phosphorus adsorption in FeOOH/anion exchanger nanocomposites via a glycol-solvothermal synthesis strategy

Uniform Pt76Co24 myriapods with abundant active sites were prepared by a one-pot solvothermal method, which exhibited excellent catalytic performances for ORR and HER in acid media.

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Fast Site-to-site Electron Transfer of High-entropy Alloy Nanocatalyst Driving Redox Electrocatalysis

10.21203/rs.3.rs-48124/v1 ◽

2020 ◽

Author(s):

Hongdong Li ◽

Yi Han ◽

Huan Zhao ◽

Wenjing Qi ◽

Dan Zhang ◽

...

Keyword(s):

Electron Transfer ◽

Active Sites ◽

Methanol Oxidation Reaction ◽

High Entropy Alloy ◽

Oxidation Reactions ◽

Hydrogen Electrode ◽

Efficient Catalyst ◽

High Entropy ◽

Synthesis Strategy ◽

Reduction And Oxidation

Abstract Designing electrocatalysts with high-performance for both reduction and oxidation reactions faces severe challenges. Here, the uniform and small size (~3.4 nm) high-entropy alloys (HEAs) Pt18Ni26Fe15Co14Cu27 nanoparticles (NPs) are synthesized by a simple low-temperature (<250 oC) oil phase synthesis strategy at atmospheric pressure for the first time. The Pt18Ni26Fe15Co14Cu27/C catalyst exhibits excellent electrocatalytic performance for hydrogen evolution reaction (HER) and methanol oxidation reaction (MOR). The catalyst is one of the best performance achieved by state-of-the-art alkaline HER catalysts, which shows an ultrasmall overpotential of 11 mV at the current density of 10 mA cm-2, excellent activity (10.96 A mg-1Pt at -0.07 V vs. reversible hydrogen electrode) and stability in the alkaline medium. Furthermore, it is also the most efficient catalyst (15.04 A mg-1Pt) ever reported for MOR in alkaline solution. DFT calculations confirm the multi-active sites for both HER and MOR on the HEA surface as the key factor for both proton and intermediate transformation. Meanwhile, the construction of HEA surfaces supplies the fast site-to-site electron transfer for both reduction and oxidation processes.

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Synthesis of MOFs from Zn,Cd,Ni-4-carboxyphenylboronic acid with DMF solvent

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314088706 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1129-C1129

Author(s):

Louiza Dimowa ◽

Rositsa Nikolova ◽

Ventsi Dyulgerov ◽

Vladislav Kostov-Kytin ◽

Boris Shivachev

Keyword(s):

Single Crystal ◽

Solvothermal Synthesis ◽

Chemical Properties ◽

Porous Metal ◽

X Ray Diffraction ◽

X Ray ◽

Synthesis Strategy ◽

Metal Organic ◽

New Type

Synthesis and characterization of porous metal organic frameworks (MOFs) has prompted considerable interest because of the possibility to design the pore size and physical/chemical properties by suitable selection of the organic linkers (ligands). In this work, we have chosen a classical solvothermal synthesis strategy involving 4-carboxyphenylboronic acid, a molecule that is analogic to the terephthalic acid, Zn- Cd- Ni-OAc metal salts and DMF as solvent. It is known that during solvothermal synthesis DMF decomposes to dimethylamine which is easily incorporated in MOF's [1], [2]. The obtained MOFs are characterized by single-crystal X-ray diffraction, X-ray powder diffraction, TG analyses, IR spectroscopy and BET analyses. Preliminary X-ray single crystal diffraction results showed that a new type of structure may be produced in function of the temperature. The Cd- structure crystalizes in the hexagonal Space group P6222, with respective parameters of a = 14.4113(12), c = 13.0416(7) Å (Fig. 1). The cadmium ion is tetra coordinated by the oxygens of the B(OH)2 and COO- moieties. The 4-carboxyphenylboronic acid is disorder and attempts to lower the symmetry to model the disorder resulted in unstable refinement. In the studied systems in addition to the reported new compound isotypical structures to MOF-5 containing 4-carboxyphenylboronic acid instead of 1,4-benzenedicarboxylate were also obtained.

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A general strategy for preparing pyrrolic-N4 type single-atom catalysts via pre-located isolated atoms

Nature Communications ◽

10.1038/s41467-021-27143-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Junjie Li ◽

Ya-fei Jiang ◽

Qi Wang ◽

Cong-Qiao Xu ◽

Duojie Wu ◽

...

Keyword(s):

Active Sites ◽

Density Functional ◽

Rational Design ◽

Catalytic Performance ◽

Single Atom ◽

General Strategy ◽

New Findings ◽

Synthesis Strategy ◽

Structure Density ◽

Application Fields

AbstractSingle-atom catalysts (SACs) have been applied in many fields due to their superior catalytic performance. Because of the unique properties of the single-atom-site, using the single atoms as catalysts to synthesize SACs is promising. In this work, we have successfully achieved Co1 SAC using Pt1 atoms as catalysts. More importantly, this synthesis strategy can be extended to achieve Fe and Ni SACs as well. X-ray absorption spectroscopy (XAS) results demonstrate that the achieved Fe, Co, and Ni SACs are in a M1-pyrrolic N4 (M= Fe, Co, and Ni) structure. Density functional theory (DFT) studies show that the Co(Cp)2 dissociation is enhanced by Pt1 atoms, thus leading to the formation of Co1 atoms instead of nanoparticles. These SACs are also evaluated under hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and the nature of active sites under HER are unveiled by the operando XAS studies. These new findings extend the application fields of SACs to catalytic fabrication methodology, which is promising for the rational design of advanced SACs.

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One-step solvothermal synthesis of Al-promoted Fe3O4 magnetic catalysts for the selective oxidation of benzyl alcohol to benzaldehyde with H2O2 in water

RSC Advances ◽

10.1039/c6ra23019a ◽

2016 ◽

Vol 6 (103) ◽

pp. 101048-101060 ◽

Cited By ~ 20

Author(s):

Leisha Xiong ◽

Rong Chen ◽

Fengxi Chen

Keyword(s):

Catalytic Activity ◽

Synergistic Effect ◽

Benzyl Alcohol ◽

Selective Oxidation ◽

Solvothermal Synthesis ◽

Active Sites ◽

Title Reaction ◽

Oxidation Of Benzyl Alcohol ◽

One Step

The in situ modification of Fe3O4 by aluminium introduced new active sites besides the primary iron sites. Their synergistic effect contributes to much better catalytic activity of Al-promoted Fe3O4 in the title reaction.

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Ni-Based Composites from Chitosan Biopolymer a One-Step Synthesis for Oxygen Evolution Reaction

Catalysts ◽

10.3390/catal9050471 ◽

2019 ◽

Vol 9 (5) ◽

pp. 471 ◽

Cited By ~ 1

Author(s):

Behzad Aghabarari ◽

José Manuel Luque-Centeno ◽

Maricarmen Capel-Sánchez ◽

Maria Jesús Lázaro Elorri ◽

Maria Victoria Martínez-Huerta

Keyword(s):

Oxygen Evolution ◽

Oxygen Evolution Reaction ◽

Active Sites ◽

Renewable Energy Sources ◽

O2 Evolution ◽

Onset Potential ◽

Synthesis Strategy ◽

One Step ◽

Cost Efficient ◽

Chitosan Biopolymer

Cost-efficient and sustainable electrocatalysts for oxygen evolution reaction (OER) is highly desired in the search for clean and renewable energy sources. In this study, we develop a new one-step synthesis strategy of novel composites based on Ni and molybdenum carbide embedded in N- and P-dual doped carbon matrices using mainly chitosan biopolymer as the carbon and nitrogen source, and molybdophosphoric acid (HMoP) as the P and Mo precursor. Two composites have been investigated through annealing a mixture of Ni/chitosan and HMoP with two unlike carbon matrices, melamine and graphene oxide, at a high temperature. Both composites exhibit similar multi-active sites with high electrocatalytic activity for OER in an alkaline medium, which is comparable to the IrO2 catalyst. For this study, an accurate measurement of the onset potential for O2 evolution has been used by means of a rotating ring-disk electrode (RRDE). The use of this method allows confirming a better stability in the chitosan/graphene composite. This work serves as a promising approach for the conversion of feedstock and renewable chitosan into desired OER catalysts.

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Enhancing hydrogenation activity of Ni-Mo sulfide hydrodesulfurization catalysts

Science Advances ◽

10.1126/sciadv.aax5331 ◽

2020 ◽

Vol 6 (19) ◽

pp. eaax5331 ◽

Cited By ~ 3

Author(s):

Manuel F. Wagenhofer ◽

Hui Shi ◽

Oliver Y. Gutiérrez ◽

Andreas Jentys ◽

Johannes A. Lercher

Keyword(s):

Catalytic Activity ◽

Active Sites ◽

Supported Catalysts ◽

Alumina Support ◽

Site Specific ◽

Hydrodesulfurization Catalysts ◽

Synthesis Strategy ◽

Order Of Magnitude ◽

Base Strength ◽

Mo Sulfide

Unsupported Ni-Mo sulfides have been hydrothermally synthesized and purified by HCl leaching to remove Ni sulfides. Unblocking of active sites by leaching significantly increases the catalytic activity for dibenzothiophene hydrodesulfurization. The site-specific rates of both direct (hydrogenolytic) and hydrogenative desulfurization routes on these active sites that consist of coordinatively unsaturated Ni and sulfhydryl groups were identical for all unsupported sulfides. The hydrogenative desulfurization rates were more than an order of magnitude higher on unsupported Ni-Mo sulfides than on Al2O3-supported catalysts, while they were similar for the direct (hydrogenolytic) desulfurization. The higher activity is concluded to be caused by the lower average electronegativity, i.e., higher base strength and polarity, of Ni-Mo sulfides in the absence of the alumina support and the modified adsorption of reactants enabled by multilayer stacking. Beyond the specific catalytic reaction, the synthesis strategy points to promising scalable routes to sulfide materials broadly applied in hydrogenation and hydrotreating.

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Recognizing soft templates as stimulators in multivariate modulation of tin phosphate and its application in catalysis for alkyl levulinate synthesis

Catalysis Science & Technology ◽

10.1039/d0cy01637c ◽

2021 ◽

Author(s):

Pandian Manjunathan ◽

Dhanush Y. Shanbhag ◽

Ajayan Vinu ◽

Ganapati V. Shanbhag

Keyword(s):

Furfuryl Alcohol ◽

Active Sites ◽

Soft Template ◽

One Pot ◽

Synthesis Strategy ◽

Alkyl Levulinate ◽

High Yields ◽

Soft Templates

Soft template tunes and controls explicitly both morphology and nature of active sites during the synthesis of tin phosphate catalyst. This synthesis strategy helped in producing alkyl levulinate in high yields from one-pot alcoholysis of furfuryl alcohol.

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What catalysis needs from the electron microscopist

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105539 ◽

1988 ◽

Vol 46 ◽

pp. 694-695

Author(s):

Alexis T. Bell

Keyword(s):

Active Sites ◽

Heterogeneous Catalysts ◽

Catalyst Deactivation ◽

Surface Composition ◽

Internal Surface ◽

Active Phase ◽

Atomic Scale ◽

Metal Catalyst ◽

Internal Surface Area ◽

Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

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Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168104 ◽

1994 ◽

Vol 52 ◽

pp. 74-75

Author(s):

C. Jacobsen ◽

J. Fu ◽

S. Mayer ◽

Y. Wang ◽

S. Williams

Keyword(s):

Visible Light ◽

Active Sites ◽

Light Emission ◽

Chinese Hamster ◽

Polystyrene Spheres ◽

Good Resistance ◽

X Ray ◽

Selective Staining ◽

Visible Light Emission ◽

Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

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