Subsurface Oxygen Defects Electronically Interacting with Active Sites on In2O3 for Enhanced Photothermocatalytic CO2 Reduction

2021 ◽  
Author(s):  
Weiqin Wei ◽  
Zhen Wei ◽  
Ruizhe Li ◽  
zhenhua Li ◽  
Run Shi ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalyst Surface ◽  
Co2 Reduction ◽  
Catalytic Reactions ◽  
Electronic Coupling ◽  
Turnover Frequency ◽  
Structural Units ◽  
Oxygen Defects ◽  
Subsurface Oxygen ◽  
Surface Active

Abstract Oxygen defects play an important role in many catalytic reactions. Increasing surface oxygen defects can be done through reduction treatment. However, excessive reduction blocks electron channels and deactivates the catalyst surface due to electron-trapped effects by subsurface oxygen defects. How to effectively extract electrons from subsurface oxygen defects which cannot directly interact with reactants is challenging and remains elusive. Herein, we report a metallic In-embedded In2O3 nanoflake catalyst over which the turnover frequency of CO2 reduction into CO increases by a factor of 866 (7615 h-1) and 376 (2990 h-1) at same light intensity and reaction temperature, respectively, compared to In2O3. Under electron-delocalization effect of O-In-(O)Vo-In-In structural units at the interface, the electrons in the subsurface oxygen defects are extracted and gather at surface active sites. This improves the electronic coupling with CO2 and stabilizes COOH intermediate. The study opens up new insights for exquisite electronic manipulation of oxygen defects.

scholarly journals Capping experiments reveal multiple surface active sites in CeO2 and their cooperative catalysis

RSC Advances ◽  
2019 ◽  
Vol 9 (27) ◽  
pp. 15229-15237 ◽  
Author(s):  
Xiaoning Ren ◽  
Zhixin Zhang ◽  
Yehong Wang ◽  
Jianmin Lu ◽  
Jinghua An ◽  
...  
Keyword(s):  
Benzoic Acid ◽  
Active Sites ◽  
Catalytic Reactions ◽  
Cooperative Catalysis ◽  
Surface Active

Capping with pyridine, benzoic acid, and DMSO in catalytic reactions reveals the locations of surface active sites of CeO2.

Quantitative determination of the number of surface active sites and the turnover frequency for methanol oxidation over bulk metal vanadates

2003 ◽  
Vol 78 (1-4) ◽  
pp. 257-268 ◽  
Author(s):  
Laura E Briand ◽  
Jih-Mirn Jehng ◽  
Laura Cornaglia ◽  
Andrew M Hirt ◽  
Israel E Wachs
Keyword(s):  
Quantitative Determination ◽  
Methanol Oxidation ◽  
Active Sites ◽  
Turnover Frequency ◽  
Bulk Metal ◽  
Surface Active

Selectively triggering photoelectrons for CO2-to-CH4 reduction over {110} SrTiO3 with dual-metal sites

2021 ◽  
Author(s):  
Lei Lu ◽  
Xiaopeng Zhu ◽  
Shaomang Wang ◽  
Taozhu Li ◽  
Shicheng Yan ◽  
...  
Keyword(s):  
Active Sites ◽  
Co2 Reduction ◽  
Reduction Reaction ◽  
Photocatalytic Efficiency ◽  
The Poor ◽  
Strong Adsorption ◽  
Weak Adsorption ◽  
Adsorption Of Co ◽  
Surface Active ◽  
Dual Metal

Abstract In this article, the roles of surface-active sites in dominating photoelectron selectivity for CO2 reduction products are well demonstrated over photocatalyst models of {100} SrTiO3 and {110} SrTiO3. On the easily exposed {100} facets terminated with Sr-O atoms, photoelectrons are of 8 mol % for CH4 and 92 mol % for CO generation. The Sr-O-Ti configuration in the {110} facets could enrich the surface charge density due to the lower interface resistance for higher photocatalytic efficiency (1.6-fold). The dual sites of Ti and adjacent Sr atoms are active for strong adsorption and activation of the generated CO* species from primary CO2 reduction on the surface, thus kinetically favoring the activity of photoelectrons (73 mol %) in hydrogenation for CH2* species and hence CH4 product. Inversely, the poor CH4 selectivity is due to difficulty in subsequent photoelectron reduction reaction by the weak adsorption of CO* at the single-Sr site on the {100} facets, independent of the electron and proton concentration. Our results may offer some illuminating insights into the design of a highly efficient photocatalyst for selective CO2 reduction.

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

Physicochemical and Catalytic Properties of Spinels Formed by Solid-Solid Interaction Between Fe2O3and V2O5

1996 ◽  
Vol 61 (8) ◽  
pp. 1131-1140 ◽  
Author(s):  
Abd El-Aziz Ahmed Said
Keyword(s):  
Vanadium Oxide ◽  
Active Sites ◽  
Catalyst Surface ◽  
Catalytic Properties ◽  
Flow System ◽  
Oxide Catalysts ◽  
X Ray Diffraction ◽  
Selective Catalyst ◽  
X Ray ◽  
Solid Catalysts

Vanadium oxide catalysts doped or mixed with 1-50 mole % Fe3+ ions were prepared. The structure of the original samples and those calcined from 200 up to 500 °C were characterized by TG, DTA, IR and X-ray diffraction. The SBET values and texture of the solid catalysts were investigated. The catalytic dehydration-dehydrogenation of isopropanol was carried out at 200 °C using a flow system. The results obtained showed an observable decrease in the activity of V2O5 on the addition of Fe3+ ions. Moreover, Fe2V4O13 is the more active and selective catalyst than FeVO4 spinels. The results were correlated with the active sites created on the catalyst surface.

scholarly journals Investigation of Gas Diffusion Electrode Systems for the Electrochemical CO2 Conversion

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 482
Author(s):  
Hilmar Guzmán ◽  
Federica Zammillo ◽  
Daniela Roldán ◽  
Camilla Galletti ◽  
Nunzio Russo ◽  
...  
Keyword(s):  
Carbon Capture ◽  
Active Sites ◽  
Co2 Reduction ◽  
Gas Diffusion ◽  
Gas Diffusion Electrode ◽  
Catalyst Loading ◽  
Co2 Conversion ◽  
Atmospheric Conditions ◽  
Electrochemical Co2 Reduction ◽  
Liquid Products

Electrochemical CO2 reduction is a promising carbon capture and utilisation technology. Herein, a continuous flow gas diffusion electrode (GDE)-cell configuration has been studied to convert CO2 via electrochemical reduction under atmospheric conditions. To this purpose, Cu-based electrocatalysts immobilised on a porous and conductive GDE have been tested. Many system variables have been evaluated to find the most promising conditions able to lead to increased production of CO2 reduction liquid products, specifically: applied potentials, catalyst loading, Nafion content, KHCO3 electrolyte concentration, and the presence of metal oxides, like ZnO or/and Al2O3. In particular, the CO productivity increased at the lowest Nafion content of 15%, leading to syngas with an H2/CO ratio of ~1. Meanwhile, at the highest Nafion content (45%), C2+ products formation has been increased, and the CO selectivity has been decreased by 80%. The reported results revealed that the liquid crossover through the GDE highly impacts CO2 diffusion to the catalyst active sites, thus reducing the CO2 conversion efficiency. Through mathematical modelling, it has been confirmed that the increase of the local pH, coupled to the electrode-wetting, promotes the formation of bicarbonate species that deactivate the catalysts surface, hindering the mechanisms for the C2+ liquid products generation. These results want to shine the spotlight on kinetics and transport limitations, shifting the focus from catalytic activity of materials to other involved factors.

Cathodic Corrosion Activated Fe-based Nanoglass as Highly-Active and -Stable Oxygen Evolution Catalyst for Water Splitting

2021 ◽  
Author(s):  
Kaiyao Wu ◽  
Fei Chu ◽  
Yuying Meng ◽  
Kaveh Edalati ◽  
Qingsheng Gao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Amorphous Alloys ◽  
Precious Metal ◽  
Active Sites ◽  
Metal Free ◽  
Highly Active ◽  
Stable Oxygen ◽  
Surface Active

Transition metal-based amorphous alloys have attracted increasing attention as precious-metal-free electrocatalysts for oxygen evolution reaction (OER) of water splitting due to their high macro-conductivity and abundant surface active sites. However,...

scholarly journals Facet-dependent active sites of a single Cu2O particle photocatalyst for CO2 reduction to methanol

Nature Energy ◽  
2019 ◽  
Vol 4 (11) ◽  
pp. 957-968 ◽  
Author(s):  
Yimin A. Wu ◽  
Ian McNulty ◽  
Cong Liu ◽  
Kah Chun Lau ◽  
Qi Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
Co2 Reduction ◽  
Cu2o Particle

Valence variation of phase-pure M1 MoVNbTe oxide by plasma treatment for improved catalytic performance in oxidative dehydrogenation of ethane

RSC Advances ◽  
2015 ◽  
Vol 5 (111) ◽  
pp. 91295-91301 ◽  
Author(s):  
Xin Chen ◽  
Qianli Yang ◽  
Bozhao Chu ◽  
Hang An ◽  
Yi Cheng
Keyword(s):  
Surface Modification ◽  
Metal Oxide ◽  
Plasma Treatment ◽  
Oxidative Dehydrogenation ◽  
Oxidation State ◽  
Active Sites ◽  
Oxygen Plasma ◽  
Catalyst Surface ◽  
Catalytic Performance ◽  
Phase Pure

This work presents a new method of catalyst surface modification by using oxygen plasma to change the oxidation state of active sites in metal oxide catalysts.

scholarly journals Prepare a catalyst consist of rare earth minerals to denitrate via NH3-SCR

2020 ◽  
Vol 9 (1) ◽  
pp. 191-202
Author(s):  
Jian Wang ◽  
Chao Zhu ◽  
Baowei Li ◽  
Zhijun Gong ◽  
Zhaolei Meng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Active Sites ◽  
Nh3 Scr ◽  
Composite Oxides ◽  
Rare Earth Minerals ◽  
Denitrification Activity ◽  
Denitrification Reactor ◽  
Surface Active ◽  
Rare Earth Tailings ◽  
Treatment Step

AbstractTo research the roles of rare earth minerals in denitrification via the NH3-SCR, a mixture was made by certain ratio of rare earth concentrates and rare earth tailings, then treated by microwave roasting, and acids and bases to form a denitrification catalyst. The mineral phase structure and surface morphology of the catalyst were characterized by XRD, BET, SEM and EDS. The surface properties of the catalyst were tested by TPD and XPS methods, and the denitrification activity of the catalyst was evaluated in a denitrification reactor. The results showed that the denitrification efficiency increased up to 82% with complete processing. XRD, BET, SEM, and EDS spectrum analysis stated that the treated minerals contained cerium oxides and Fe−Ce composite oxides. The surface of the modified minerals became rough and porous, the surface area increased, and the surface-active sites were exposed. The results of NH3-TPD and NO-TPD showed that the catalyst surface could gradually adsorb more NH3 and NO after each step. XPS analysis indicated that there were more Ce3+, Fe2+, and lattice oxygen in rare earth minerals catalyst after each treatment step.

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