| 1. |
- Ai, Yuejie, et al.
(författare)
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Hydrophobicity and Hydrophilicity Balance Determines Shape Selectivity of Suzuki Coupling Reactions Inside Pd@meso-SiO2 Nanoreactor
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:19, s. 10244-10251
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Tidskriftsartikel (refereegranskat)abstract
- Molecular sorting and catalysis directed by shape selectivity have been extensively applied in porous extended frameworks for a low-carbon, predictable, renewable component of modern industry. A comprehensive understanding of the underlying recognition mechanism toward different shapes is unfortunately still missing, owing to the lack of structural and dynamic information under operating conditions. We demonstrate here that such difficulties can be overcome by state-of-the-art molecular dynamics simulations which provide atomistic details that are not accessible experimentally, as exemplified by our interpretation for the experimentally observed aggregation induced shape selectivity for Suzuki C-C coupling reaction catalyzed by Pd particles in mesoporous silica. It is found that both aggregation ability and aggregating pattern of the reactants play the decisive role in controlling the shape selectivity, which are in turn determined by the balance between the hydrophobicity and hydrophilicity of the reactants, or in other words, by the balance between the noncovalent hydrogen bonding interaction and van der Waals forces. A general rule that allows prediction of the shape selectivity of a reactant has been proposed and verified against experiments. We show that molecular modeling is a powerful tool for rational design of new mesoporous systems and for the control of catalytic reactions that are important for the petrochemical industry.
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| 2. |
- Cao, Xinrui, et al.
(författare)
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Dehydrogenation of Propane to Propylene by a Pd/Cu Single-Atom Catalyst : Insight from First-Principles Calculations
- 2015
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:2, s. 1016-1023
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic properties of the single-Pd-doped Cu55 nanoparticle toward propane dehydrogenation have been systemically investigated by first-principles calculations, and the possible reaction mechanisms and effects of the single and multiple Pd doping on the catalytic activity have been discussed. Calculations reveal that the low-energy catalytic conversion of propane to propylene by the Pd/Cu single-atom catalyst comprises the initial crucial C–H bond breaking at either the methyl or methylene group, the facile diffusion of detached H atoms on the Cu surface, and the subsequent C–H bond dissociation activation of the adsorbed propyl species. The single-Pd-doped Cu55 nanoparticle shows remarkable activity toward C–H bond activation, and the presence of relatively inactive Cu surface is beneficial for the coupling and desorption of detached H atoms and can reduce side reactions such as deep dehydrogenation and C–C bond breaking. The single-Pd-doped Cu55 cluster bears good balance between the maximum use of the noble metal and the activity, and it may serve as a promising single-atom catalyst toward selective dehydrogenation of propane.
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| 3. |
- Cao, Xinrui, et al.
(författare)
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Feasible Catalytic Strategy for Writing Conductive Nanoribbons on a Single-Layer Graphene Fluoride
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:39, s. 22643-22648
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Tidskriftsartikel (refereegranskat)abstract
- An accessible method for local reduction of graphene fluoride catalyzed by the Pt-coated nanotip with the assistance of a mixture of hydrogen and ethylene atmosphere is proposed and fully explored theoretically. Detailed mechanisms and roles of hydrogen and ethylene molecules in the cyclic reduction is discussed based on extensive first-principles calculations. It is demonstrated that the proposed cyclic reduction strategy is energetically favorable. This new strategy can be effectively applied in scanning probe lithography to fabricate electronic circuits at the nanoscale on graphene fluoride under mild conditions.
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| 4. |
- Chen, Zhe, et al.
(författare)
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Ruthenium/Graphene-like Layered Carbon Composite as an Efficient Hydrogen Evolution Reaction Electrocatalyst
- 2016
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:51, s. 35132-35137
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Tidskriftsartikel (refereegranskat)abstract
- Efficient water splitting through electrocatalysis has been studied extensively in modern energy devices, while the development of catalysts with activity and stability comparable to those of Pt is still a great challenge. In this work, we successfully developed a facile route to synthesize graphene-like layered carbon (GLC) from a layered silicate template. The obtained GLC has layered structure similar to that of the template and can be used as support to load ultrasmall Ru nanoparticles on it in supercritical water. The specific structure and surface properties of GLC enable Ru nanoparticles to disperse highly uniformly on it even at a large loading amount (62 wt %). When the novel Ru/GLC was used as catalyst on a glass carbon electrode for hydrogen evolution reaction (HER) in a 0.5 M H2SO4 solution, it exhibits an extremely low onset potential of only 3 mV and a small Tafel slope of 46 mV/decade. The outstanding performance proved that Ru/GLC is highly active catalyst for HER, comparable with transition-metal dichalcogenides or selenides. As the price of ruthenium is much lower than platinum, our study shows that Ru/GLC might be a promising candidate as an HER catalyst in future energy applications.
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| 5. |
- Ding, Xin, et al.
(författare)
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Silicon Compound Decorated Photoanode for Performance Enhanced Visible Light Driven Water Splitting
- 2016
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 215, s. 682-688
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Tidskriftsartikel (refereegranskat)abstract
- An efficient dye (1) sensitized photoelectrochemical cell (DS-PEC) has been assembled with a silicon compound (3-chloropropyl) trimethoxy-silane (Si-Cl) decorated working electrode (WE) TiO2(1 + 2). The introduction of this Si-Cl molecule on photoanode leads to better performances on efficiency than untreated ones for light driven water splitting. The firm Si-O layer formed on TiO2 increased the resistance of the TiO2/catalyst interface which is assumed to decrease charge recombination from TiO2 to the oxidized catalyst 2. The work presented here provides an effective method to improve the performances of DS-PECs.
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| 6. |
- Duan, Sai, et al.
(författare)
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Theoretical Modeling of Plasmon-Enhanced Raman Images of a Single Molecule with Subnanometer Resolution
- 2015
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 137:30, s. 9515-9518
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Tidskriftsartikel (refereegranskat)abstract
- Under local plasmonic excitation, Raman images of single molecules can now surprisingly reach subnanometer resolution. However, its physical origin has not been fully understood. Here we report a quantum-mechanical description of the interaction between a molecule and a highly confined plasmonic field. We show that When the spatial distribution of the plasmonic field is comparable to the size of the molecule, the optical transition matrix of the molecule becomes dependent on the position and distribution of the plasmonic field, resulting in a spatially resolved high-resolution Raman image of the molecule. The resonant Raman image reflects the electronic transition density of the molecule. In combination with first-principles calculations, the simulated Raman linage of a porphyrin derivative adsorbed on a silver surface nicely reproduces its experimental counterpart. The present theory provides the basic framework for describing linear and nonlinear responses of molecules under highly confined plasmonic fields.
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| 7. |
- Fan, Ke, et al.
(författare)
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Hollow Iron-Vanadium Composite Spheres : A Highly Efficient Iron-Based Water Oxidation Electrocatalyst without the Need for Nickel or Cobalt
- 2017
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 56:12, s. 3289-3293
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Tidskriftsartikel (refereegranskat)abstract
- Noble-metal-free bimetal-based electrocatalysts have shown high efficiency for water oxidation. Ni and/or Co in these electrocatalysts are essential to provide a conductive, high-surface area and a chemically stable host. However, the necessity of Ni or Co limits the scope of low-cost electrocatalysts. Herein, we report a hierarchical hollow FeV composite, which is Ni- and Co-free and highly efficient for electrocatalytic water oxidation with low overpotential 390 mV (10 mA cm(-2) catalytic current density), low Tafel slope of 36.7 mV dec(-1), and a considerable durability. This work provides a novel and efficient catalyst, and greatly expands the scope of low-cost Fe-based electrocatalysts for water splitting without need of Ni or Co.
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| 8. |
- Fan, Ke, et al.
(författare)
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Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation
- 2016
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.
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| 9. |
- Ji, Yongfei, et al.
(författare)
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A Comparative Theoretical Study of Proton-Coupled Hole Transfer for H2O and Small Organic Molecules (CH3OH, HCOOH, H2CO) on the Anatase TiO2(101) Surface
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:37, s. 21457-21462
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Tidskriftsartikel (refereegranskat)abstract
- The high oxidation power of the photogenerated hole in TiO2 has made it useful in many applications. It is of fundamental importance to understand how the hole transfers from the catalysis to adsorbates. We have performed a comparative study on the mechanism for the first proton-coupled hole transfer process in water, methanol, formic acid, and formaldehyde on the anatase TiO2(101) surface. Our results show that this process for all the molecules is concerted rather than sequential. Both the kinetic and thermodynamic effects need to be taken into account. The hole scavenging power for the four molecules under investigation is found to follow the order formaldehyde > formic acid > methanol > water, which agrees well with various experiments.
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| 10. |
- Ji, Yongfei, et al.
(författare)
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Direct Donation of Protons from H2O to CO2 in Artificial Photosynthesis on the Anatase TiO2(101) Surface
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:5, s. 3019-3023
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Tidskriftsartikel (refereegranskat)abstract
- Conversion of CO2 and H2O into value-added organic molecules via artificial photosynthesis is a promising solution to current energy and environment problems. In the reaction, it is generally believed that CO2 is converted into organic molecules by photogenerated electrons and protons that result from photo-oxidation of H2O. In this work, we investigate the possibility that H2O, without being oxidized, directly donates protons to CO2 and other intermediates adsorbed at the oxygen vacancy on the anatase TiO2(101) surface. We found that this can greatly lower the barriers (by about 0.3 eV) for the hydrogenation of CO2, CO, H2CO, and CH3O because less energy is required to displace these adsorbates to accept the proton (in H2O). The OH- group produced in these reactions can recombine with a surface-adsorbed proton to form a new H2O molecule, making H2O a shuttling center of the adsorbed protons, or it can take part in the oxygen evolution reaction with a lower barrier. The results suggest that H2O can play multiple roles in artificial photosynthesis and the reduction and oxidation parts of the reaction may have synergistic effects.
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