scholarly journals Molecular catalysis science: Perspective on unifying the fields of catalysis

2016 ◽  
Vol 113 (19) ◽  
pp. 5159-5166 ◽  
Author(s):  
Rong Ye ◽  
Tyler J. Hurlburt ◽  
Kairat Sabyrov ◽  
Selim Alayoglu ◽  
Gabor A. Somorjai
Keyword(s):  
Oxidation State ◽  
Photoelectron Spectroscopy ◽  
Heterogeneous Catalysts ◽  
Ambient Pressure ◽  
Catalytic Performance ◽  
Sum Frequency ◽  
Time Dynamics ◽  
Colloidal Chemistry ◽  
Surface Adsorbates ◽  
State Coordination

Colloidal chemistry is used to control the size, shape, morphology, and composition of metal nanoparticles. Model catalysts as such are applied to catalytic transformations in the three types of catalysts: heterogeneous, homogeneous, and enzymatic. Real-time dynamics of oxidation state, coordination, and bonding of nanoparticle catalysts are put under the microscope using surface techniques such as sum-frequency generation vibrational spectroscopy and ambient pressure X-ray photoelectron spectroscopy under catalytically relevant conditions. It was demonstrated that catalytic behavior and trends are strongly tied to oxidation state, the coordination number and crystallographic orientation of metal sites, and bonding and orientation of surface adsorbates. It was also found that catalytic performance can be tuned by carefully designing and fabricating catalysts from the bottom up. Homogeneous and heterogeneous catalysts, and likely enzymes, behave similarly at the molecular level. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis.

scholarly journals Operando high-pressure investigation of size-controlled CuZn catalysts for the methanol synthesis reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Núria J. Divins ◽  
David Kordus ◽  
Janis Timoshenko ◽  
Ilya Sinev ◽  
Ioannis Zegkinoglou ◽  
...  
Keyword(s):  
High Pressure ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Surface Segregation ◽  
Ambient Pressure ◽  
Catalytic Performance ◽  
Oxide Interface ◽  
X Ray ◽  
Oxide Support ◽  
Open Questions

AbstractAlthough Cu/ZnO-based catalysts have been long used for the hydrogenation of CO2 to methanol, open questions still remain regarding the role and the dynamic nature of the active sites formed at the metal-oxide interface. Here, we apply high-pressure operando spectroscopy methods to well-defined Cu and Cu0.7Zn0.3 nanoparticles supported on ZnO/Al2O3, γ-Al2O3 and SiO2 to correlate their structure, composition and catalytic performance. We obtain similar activity and methanol selectivity for Cu/ZnO/Al2O3 and CuZn/SiO2, but the methanol yield decreases with time on stream for the latter sample. Operando X-ray absorption spectroscopy data reveal the formation of reduced Zn species coexisting with ZnO on CuZn/SiO2. Near-ambient pressure X-ray photoelectron spectroscopy shows Zn surface segregation and the formation of a ZnO-rich shell on CuZn/SiO2. In this work we demonstrate the beneficial effect of Zn, even in diluted form, and highlight the influence of the oxide support and the Cu-Zn interface in the reactivity.

scholarly journals NiO-NiFe2O4-rGO Magnetic Nanomaterials for Activated Peroxymonosulfate Degradation of Rhodamine B

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 384 ◽  
Author(s):  
Xiaochen Xu ◽  
Yanfang Li ◽  
Guoquan Zhang ◽  
Fenglin Yang ◽  
Ping He
Keyword(s):  
Rhodamine B ◽  
Photoelectron Spectroscopy ◽  
Heterogeneous Catalysts ◽  
Degradation Process ◽  
Catalytic Performance ◽  
Active Species ◽  
Environmental Benefits ◽  
Magnetic Nanomaterials ◽  
Paramagnetic Resonance ◽  
X Ray

Magnetic spinel ferrites that act as heterogeneous catalysts and generate powerful radicals from peroxymono-sulfate (PMS) for the degradation of organic pollutants have received much attention in recent years due to the characteristic of environmental benefits. In this study, NiO-NiFe2O4-rGO magnetic nanomaterials were synthesized using a calcinated Ni-Fe-LDH-rGO precursor. The morphology, structure, and chemical constitution were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The catalytic performance of NiO-NiFe2O4-rGO nanoparticles was thoroughly evaluated for peroxymonosulfate (PMS) activation and its removal of rhodamine B (RhB) from water. The influence of different process parameters on the RhB degradation efficiency was examined. Further, the catalytic stability was evaluated. Under optimized conditions, the NiO-NiFe2O4-rGO/PMS system was very efficient; RhB fully degraded after 40 min at room temperature. Quenching experiments and electronic paramagnetic resonance (EPR) results suggested that SO4−· and OH· were the main active species in the degradation process. Moreover, NiO-NiFe2O4-rGO catalyst was stable without any apparent activity loss after three cycling runs.

scholarly journals Advanced Catalytic Technologies for Improved Global Security

2014 ◽  
Author(s):  
Matteo Guidotti ◽  
Chiara Bisio ◽  
Fabio Carniato ◽  
Chiara Palumbo ◽  
rinaldo psaro ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Heterogeneous Catalysts ◽  
Sulfur Mustard ◽  
Ambient Pressure ◽  
Chemical Warfare Agents ◽  
Catalytic Performance ◽  
Inorganic Materials ◽  
Aqueous Hydrogen Peroxide ◽  
Warfare Agents ◽  
Inorganic Framework

The abatement of toxic chemical warfare agents (CWA) is conventionally achieved via stoichiometric reactions using strong oxidants with high environmental impact and/or via thermal degradation. The international Project “NanoContraChem”, in the framework of NATO Science for Peace and Security Programme, aims at obtaining innovative nanostructured inorganic materials for the catalytic decontamination of CWA. In the first year of activity, a class of heterogeneous catalysts has been designed to transform selectively and under mild conditions toxic organosulfur chemical agents in non-noxious products with reduced environmental impact. Nb(V)-containing saponite clay was identified as an optimal catalyst for the CWA oxidative abatement. The conventional synthetic protocol used to obtain saponite materials was modified to allow the insertion of Nb(V) ions within the inorganic framework of the clay, thus obtaining a bi-functional catalyst with strong oxidizing and acid properties. The catalytic performance of these clays was evaluated in the oxidation reaction of (2-chloroethyl)ethylsulfide (CEES), simulant of sulfur mustard (blistering CWA), with aqueous hydrogen peroxide. Remarkable activity and outstanding selectivity to the related sulfoxide were obtained, at room temperature and ambient pressure. The new class of Nb(V)-containing clays have been tested for acute and chronic toxicity with bioluminescent bacteria, Photobacterium leiognathii Sh1. A study of biocidal properties of saponite materials (both containing and non-containing Nb sites) has been carried out by means of bioluminescence inhibition tests. None of the solids have shown significant detrimental effects on the bacteria. These results suggest thus the possibility to use these Nb-saponite catalysts as environmentally-safe tools for the decontamination and abatement of CWA.

scholarly journals Water adsorption, dissociation and oxidation on SrTiO3 and ferroelectric surfaces revealed by ambient pressure X-ray photoelectron spectroscopy

2019 ◽  
Vol 21 (9) ◽  
pp. 4920-4930 ◽  
Author(s):  
Neus Domingo ◽  
Elzbieta Pach ◽  
Kumara Cordero-Edwards ◽  
Virginia Pérez-Dieste ◽  
Carlos Escudero ◽  
...  
Keyword(s):  
Surface Water ◽  
Photoelectron Spectroscopy ◽  
Redox Reactions ◽  
Water Adsorption ◽  
Ambient Pressure ◽  
Atmospheric Conditions ◽  
X Ray ◽  
Surface Adsorbates ◽  
Ferroelectric Surfaces ◽  
Ferroelectric Oxides

Unveiling surface adsorbates under atmospheric conditions and in surface water redox reactions on TiO2 terminated surfaces and ferroelectric oxides, as studied by AP-XPS.

scholarly journals Sum frequency generation spectroscopy in heterogeneous model catalysis: a minireview of CO-related processes

2021 ◽  
Author(s):  
Xia Li ◽  
Günther Rupprechter
Keyword(s):  
Surface Science ◽  
Science Studies ◽  
Ambient Pressure ◽  
Sum Frequency Generation ◽  
Heterogeneous Model ◽  
Model Catalysis ◽  
Sum Frequency ◽  
Pressure Surface ◽  
Sum Frequency Generation Spectroscopy ◽  
Frequency Generation

Sum frequency generation (SFG) vibrational spectroscopy is applied to ambient pressure surface science studies of adsorption and catalytic reactions at solid/gas interfaces.

scholarly journals Mechanochemically Synthetized PAN-Based Co-N-Doped Carbon Materials as Electrocatalyst for Oxygen Evolution Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 290
Author(s):  
Paulette Gómez-López ◽  
José Ángel Salatti-Dorado ◽  
Daily Rodríguez-Padrón ◽  
Manuel Cano ◽  
Clemente G. Alvarado-Beltrán ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Carbon Nanomaterials ◽  
Carbon Materials ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
New Class ◽  
Electrocatalytic Performance ◽  
Alkaline Environments ◽  
Metal Doped

We report a new class of polyacrylonitrile (PAN)-based Co-N-doped carbon materials that can act as suitable catalyst for oxygen evolution reactions (OER). Different Co loadings were mechanochemically added into post-consumed PAN fibers. Subsequently, the samples were treated at 300 °C under air (PAN-A) or nitrogen (PAN-N) atmosphere to promote simultaneously the Co3O4 species and PAN cyclization. The resulting electrocatalysts were fully characterized and analyzed by X-ray diffraction (XRD) and photoelectron spectroscopy (XPS), transmission (TEM) and scanning electron (SEM) microscopies, as well as nitrogen porosimetry. The catalytic performance of the Co-N-doped carbon nanomaterials were tested for OER in alkaline environments. Cobalt-doped PAN-A samples showed worse OER electrocatalytic performance than their homologous PAN-N ones. The PAN-N/3% Co catalyst exhibited the lowest OER overpotential (460 mV) among all the Co-N-doped carbon nanocomposites, reaching 10 mA/cm2. This work provides in-depth insights on the electrocatalytic performance of metal-doped carbon nanomaterials for OER.

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