scholarly journals Switchable Structure Promoted Leaching Free Atomically Dispersed Pt Catalyst for Low Carbon Biomass Polyol Oxidation

2021 ◽  
Author(s):  
Hao Yan ◽  
Mingyue Zhao ◽  
Xin Zhou ◽  
Siming Zhao ◽  
Shangfeng Li ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Pt Catalyst ◽  
Catalyst Stability ◽  
Grand Challenge ◽  
Low Carbon ◽  
Hydroxy Acids ◽  
Carbon Biomass ◽  
Coordination Effect

Abstract Achieving efficient catalytic conversion over heterogeneous catalyst with excellent resistance against leaching is still a grand challenge for sustainable chemical synthesis in aqueous solution. Herein, we devised a leaching free atomically dispersed Pt1/hydroxyapatite (HAP) catalyst with unique switchable structure via a simple and green in-situ anchoring strategy. Gratifyingly, this robust Pt1/HAP catalyst exhibits remarkable catalytic selectivity and catalyst stability for the selective oxidation of C2-C4 bio-polyols (e.g., ethylene glycol, propanediol, glycerol and butanediol) to corresponding primary hydroxy acids. X-ray absorption spectroscopy, in-situ Fourier Transform infrared spectroscopy, density functional theory calculation and kinetics study elucidated that the switchable Pt-(O-P) linkages with strong electronic-withdrawing function of PO43− (Pt1-OPO43− active site) not only realize the activation of C-H bond, but also destabilize the transition state from adsorbed hydroxy acids toward the C-C cleavage, resulting in the sharply increased selectivity of hydroxy acids. Moreover, the strong PO43−-coordination effect, originating from the enhanced interaction between positively charged Pt1 and negatively charged OPO43−, provides electrostatic stabilization for the atomically dispersed Pt, ensuring the highly efficient catalysis of Pt1/HAP for over 160 hours without metal leaching. This finding opens up new opportunities for efficient upgrading of bio-polyols over atomically dispersed catalysts.

The catalytic mechanism of the Au@TiO2−x/ZnO catalyst towards a low-temperature water-gas shift reaction

2020 ◽  
Vol 10 (3) ◽  
pp. 768-775
Author(s):  
Ning Liu ◽  
Pan Yin ◽  
Ming Xu ◽  
Yusen Yang ◽  
Shaomin Zhang ◽  
...  
Keyword(s):  
Density Functional ◽  
Catalytic Mechanism ◽  
Density Functional Theory Calculation ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Functional Theory ◽  
Shift Reaction ◽  
Water Gas ◽  
Theory Calculation

A redox mechanism towards the water-gas shift reaction was certified based on in situ/operando experiments and density functional theory calculation studies.

scholarly journals In Situ Exfoliation and Pt Deposition of Antimonene for Formic Acid Oxidation via a Predominant Dehydrogenation Pathway

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Yiqiong Zhang ◽  
Man Qiao ◽  
Yucheng Huang ◽  
Yuqin Zou ◽  
Zhijuan Liu ◽  
...  
Keyword(s):  
Formic Acid ◽  
Density Functional ◽  
Specific Activity ◽  
Pt Nanoparticles ◽  
Formic Acid Oxidation ◽  
Pt Catalyst ◽  
Acid Oxidation ◽  
Electronic Interaction ◽  
Pt Electrocatalysts

Direct formic acid fuel cell (DFAFC) has been considered as a promising energy conversion device for stationary and mobile applications. Advanced platinum (Pt) electrocatalysts for formic acid oxidation reaction (FAOR) are critical for DFAFC. However, the oxidation of formic acid on Pt catalysts often occurs via a dual pathway mechanism, which hinders the catalytic activity owing to the CO poisoning. Herein, we directly exfoliate bulk antimony to 2D antimonene (Sb) and in situ load Pt nanoparticles onto antimonene sheets with the assistance of ethylenediamine. According to the Bader charge analysis, the charge transfer from antimonene to Pt occurs, confirming the electronic interaction between Pt and Sb. Interestingly, antimonene, as a cocatalyst, alters the oxidation pathway for FAOR over Pt catalyst and makes FAOR follow the more efficient dehydrogenation pathway. The density functional theory (DFT) calculation demonstrates that antimonene can activate Pt to be a lower oxidative state and facilitate the oxidation of HCOOH into CO2 via a direct pathway, resulting in a weakened intermediate binding strength and better CO tolerance for FAOR. The specific activity of FAOR on Pt/Sb is 4.5 times, and the mass activity is 2.6 times higher than the conventional Pt/C.

scholarly journals Unique S-scheme heterojunctions in self-assembled TiO2/CsPbBr3 hybrids for CO2 photoreduction

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Feiyan Xu ◽  
Kai Meng ◽  
Bei Cheng ◽  
Shengyao Wang ◽  
Jingsan Xu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Experimental Studies ◽  
Reduction Rate ◽  
Internal Electric Field ◽  
Functional Theory ◽  
Self Assembling ◽  
Theory Calculation

Abstract Exploring photocatalysts to promote CO2 photoreduction into solar fuels is of great significance. We develop TiO2/perovskite (CsPbBr3) S-scheme heterojunctions synthesized by a facile electrostatic-driven self-assembling approach. Density functional theory calculation combined with experimental studies proves the electron transfer from CsPbBr3 quantum dots (QDs) to TiO2, resulting in the construction of internal electric field (IEF) directing from CsPbBr3 to TiO2 upon hybridization. The IEF drives the photoexcited electrons in TiO2 to CsPbBr3 upon light irradiation as revealed by in-situ X-ray photoelectron spectroscopy analysis, suggesting the formation of an S-scheme heterojunction in the TiO2/CsPbBr3 nanohybrids which greatly promotes the separation of electron-hole pairs to foster efficient CO2 photoreduction. The hybrid nanofibers unveil a higher CO2-reduction rate (9.02 μmol g–1 h–1) comparing with pristine TiO2 nanofibers (4.68 μmol g–1 h–1). Isotope (13CO2) tracer results confirm that the reduction products originate from CO2 source.

scholarly journals Measuring the structure and equation of state of polyethylene terephthalate at megabar pressures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Lütgert ◽  
J. Vorberger ◽  
N. J. Hartley ◽  
K. Voigt ◽  
M. Rödel ◽  
...  
Keyword(s):  
Equation Of State ◽  
Polyethylene Terephthalate ◽  
Density Functional ◽  
Equations Of State ◽  
Md Simulations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Shock Hugoniot ◽  
Highly Correlated

AbstractWe present structure and equation of state (EOS) measurements of biaxially orientated polyethylene terephthalate (PET, $$({\hbox {C}}_{10} {\hbox {H}}_8 {\hbox {O}}_4)_n$$ ( C 10 H 8 O 4 ) n , also called mylar) shock-compressed to ($$155 \pm 20$$ 155 ± 20 ) GPa and ($$6000 \pm 1000$$ 6000 ± 1000 ) K using in situ X-ray diffraction, Doppler velocimetry, and optical pyrometry. Comparing to density functional theory molecular dynamics (DFT-MD) simulations, we find a highly correlated liquid at conditions differing from predictions by some equations of state tables, which underlines the influence of complex chemical interactions in this regime. EOS calculations from ab initio DFT-MD simulations and shock Hugoniot measurements of density, pressure and temperature confirm the discrepancy to these tables and present an experimentally benchmarked correction to the description of PET as an exemplary material to represent the mixture of light elements at planetary interior conditions.

Ordered boron phosphorus codoped graphene realizing widely tunable quasi Dirac-cone gap

2021 ◽  
Vol 9 (12) ◽  
pp. 4316-4321
Author(s):  
L.-B. Meng ◽  
S. Ni ◽  
Z. M. Zhang ◽  
S. K. He ◽  
W. M. Zhou
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Dirac Cone ◽  
Functional Theory ◽  
Theory Calculation

Density functional theory calculation predicts a novel ordered boron phosphorus codoped graphene realizing a widely tunable Dirac-cone gap.

scholarly journals Regulating coordination number in atomically dispersed Pt species on defect-rich graphene for n-butane dehydrogenation reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaowen Chen ◽  
Mi Peng ◽  
Xiangbin Cai ◽  
Yunlei Chen ◽  
Zhimin Jia ◽  
...  
Keyword(s):  
Coordination Number ◽  
Density Functional ◽  
Activation Barrier ◽  
Density Functional Theory Calculation ◽  
Catalytic Performance ◽  
Atomic Level ◽  
Metal Nanoparticle ◽  
Single Atom ◽  
Nano Structure ◽  
Theory Calculation

AbstractMetal nanoparticle (NP), cluster and isolated metal atom (or single atom, SA) exhibit different catalytic performance in heterogeneous catalysis originating from their distinct nanostructures. To maximize atom efficiency and boost activity for catalysis, the construction of structure–performance relationship provides an effective way at the atomic level. Here, we successfully fabricate fully exposed Pt3 clusters on the defective nanodiamond@graphene (ND@G) by the assistance of atomically dispersed Sn promoters, and correlated the n-butane direct dehydrogenation (DDH) activity with the average coordination number (CN) of Pt-Pt bond in Pt NP, Pt3 cluster and Pt SA for fundamentally understanding structure (especially the sub-nano structure) effects on n-butane DDH reaction at the atomic level. The as-prepared fully exposed Pt3 cluster catalyst shows higher conversion (35.4%) and remarkable alkene selectivity (99.0%) for n-butane direct DDH reaction at 450 °C, compared to typical Pt NP and Pt SA catalysts supported on ND@G. Density functional theory calculation (DFT) reveal that the fully exposed Pt3 clusters possess favorable dehydrogenation activation barrier of n-butane and reasonable desorption barrier of butene in the DDH reaction.

In Situ Exsolved Au Nanoparticles from Perovskite Oxide for Efficient Epoxidation of Styrene

2021 ◽  
Author(s):  
Yang Gao ◽  
Xing Chen ◽  
Shuqi Hu ◽  
Shiguo Zhang
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Analysis ◽  
Density Functional ◽  
Au Nanoparticles ◽  
Oxide Catalyst ◽  
Density Functional Theory Calculations ◽  
Average Diameter ◽  
Perovskite Oxide ◽  
Functional Theory

Au-doped SrTiO3 perovskite oxide catalyst (Sr0.995Au0.005TiO3-δ) has been designed and synthesized based on thermodynamic analysis and density functional theory calculations. During reduction, Au nanoparticles with an average diameter of 2...

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