scholarly journals First-principles insight into CO hindered agglomeration of Rh and Pt single atoms on m-ZrO2

2020 ◽  
Vol 10 (17) ◽  
pp. 5847-5855
Author(s):  
Minttu M. Kauppinen ◽  
Marko M. Melander ◽  
Karoliina Honkala
Keyword(s):  
Thermodynamic Stability ◽  
First Principles ◽  
Single Atom ◽  
Reaction Conditions ◽  
Multi Scale ◽  
Single Atoms ◽  
Thermodynamic Framework ◽  
Insight Into ◽  
Non Equilibrium

Kinetic and thermodynamic stability of single-atom and nanocluster catalysts is addressed under reaction conditions within a DFT-parametrised multi-scale thermodynamic framework combining atomistic, non-equilibrium, and nanothermodynamics.

Photoinduced Synergistic Catalysis on Zn Single-Atom-Loaded Hierarchical Porous Carbon for Highly Efficient CO2 Cycloaddition Conversion

2021 ◽  
Author(s):  
Lin Gong ◽  
Ji Sun ◽  
Yousong Liu ◽  
Guangcheng Yang
Keyword(s):  
Solar Energy ◽  
Porous Carbon ◽  
Single Atom ◽  
Hierarchical Porous Carbon ◽  
Reaction Conditions ◽  
Synergistic Catalysis ◽  
Single Atoms ◽  
Significant Challenge ◽  
Highly Efficient ◽  
Hierarchical Porous

The use of solar energy to drive efficient CO2 cycloaddition conversion under mild reaction conditions is highly desired but remains a significant challenge. In this communication, a Zn single-atoms-loaded N-doped...

Screening effective single-atom ORR and OER electrocatalysts from Pt decorated MXenes by first-principles calculations

2020 ◽  
Vol 8 (33) ◽  
pp. 17065-17077
Author(s):  
Dongxiao Kan ◽  
Ruqian Lian ◽  
Dashuai Wang ◽  
Xilin Zhang ◽  
Jing Xu ◽  
...  
Keyword(s):  
First Principles ◽  
Single Atom ◽  
First Principles Calculations ◽  
Single Atoms ◽  
Catalytic Performances

Pt single atoms doped on V-, Ti-, Nb-, and Cr-based MXenes presented high catalytic performances, especially the Nb- and Cr-based ones, which were promising bifunctional ORR/OER catalysts.

First-principles insight into CO hindered agglomeration of Rh and Pt single atoms on ZrO2

2020 ◽  
Author(s):  
Minttu M. Kauppinen ◽  
Marko Melander ◽  
Karoliina Honkala
Keyword(s):  
First Principles ◽  
Density Functional ◽  
High Vacuum ◽  
Kinetic Stability ◽  
Ultra High Vacuum ◽  
Functional Theory ◽  
Single Atoms ◽  
Atomistic Thermodynamics ◽  
Using Data ◽  
Insight Into

<div><div><div><p>In this first-principles study we evaluate the thermodynamic and kinetic stability of Rh and Pt single-atoms (SAs) and subnano clusters on the monoclinic zirconia surface with and without a CO atmosphere. To address the kinetic stability and agglomeration of SAs to clusters and nanoparticles, a non-equilibrium nanothermodynamic approach is developed and parametrised using data computed with density functional theory. The bare subnano clusters are more stable than SA and become more so with increasing size, which means the agglomeration is always favoured. CO binds strongly to the single atoms and clusters, and our atomistic thermodynamics treatment indicates that some CO will be present even at ultra-high vacuum conditions. A CO atmosphere is shown to hinder cluster growth from SA, and is even capable of spontaneous cluster disintegration in the case of Pt clusters. Analysis of the CO stretching frequencies reveals that subnano clusters and single atoms should give peaks in the same region, and that using them to distinguish between surface species requires caution.</p></div></div></div>

First-principles insight into CO hindered agglomeration of Rh and Pt single atoms on ZrO2

2020 ◽  
Author(s):  
Minttu M. Kauppinen ◽  
Marko Melander ◽  
Karoliina Honkala
Keyword(s):  
First Principles ◽  
Density Functional ◽  
High Vacuum ◽  
Kinetic Stability ◽  
Ultra High Vacuum ◽  
Functional Theory ◽  
Single Atoms ◽  
Atomistic Thermodynamics ◽  
Using Data ◽  
Insight Into

<div><div><div><p>In this first-principles study we evaluate the thermodynamic and kinetic stability of Rh and Pt single-atoms (SAs) and subnano clusters on the monoclinic zirconia surface with and without a CO atmosphere. To address the kinetic stability and agglomeration of SAs to clusters and nanoparticles, a non-equilibrium nanothermodynamic approach is developed and parametrised using data computed with density functional theory. The bare subnano clusters are more stable than SA and become more so with increasing size, which means the agglomeration is always favoured. CO binds strongly to the single atoms and clusters, and our atomistic thermodynamics treatment indicates that some CO will be present even at ultra-high vacuum conditions. A CO atmosphere is shown to hinder cluster growth from SA, and is even capable of spontaneous cluster disintegration in the case of Pt clusters. Analysis of the CO stretching frequencies reveals that subnano clusters and single atoms should give peaks in the same region, and that using them to distinguish between surface species requires caution.</p></div></div></div>

scholarly journals Rh single atoms on TiO2 dynamically respond to reaction conditions by adapting their site

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yan Tang ◽  
Chithra Asokan ◽  
Mingjie Xu ◽  
George W. Graham ◽  
Xiaoqing Pan ◽  
...  
Keyword(s):  
Active Site ◽  
Co Adsorption ◽  
Water Gas Shift ◽  
Single Atom ◽  
Reaction Conditions ◽  
Local Coordination ◽  
Single Atoms ◽  
Reverse Water Gas Shift ◽  
Catalytic Active Site ◽  
Water Gas

Abstract Single-atom catalysts are widely investigated heterogeneous catalysts; however, the identification of the local environment of single atoms under experimental conditions, as well as operando characterization of their structural changes during catalytic reactions are still challenging. Here, the preferred local coordination of Rh single atoms is investigated on TiO2 during calcination in O2, reduction in H2, CO adsorption, and reverse water gas shift (RWGS) reaction conditions. Theoretical and experimental studies clearly demonstrate that Rh single atoms adapt their local coordination and reactivity in response to various redox conditions. Single-atom catalysts hence do not have static local coordinations, but can switch from inactive to active structure under reaction conditions, hence explaining some conflicting literature accounts. The combination of approaches also elucidates the structure of the catalytic active site during reverse water gas shift. This insight on the real nature of the active site is key for the design of high-performance catalysts.

Tunable Carbon Surface from Mono- to Multi-Metallic Single Atoms

2020 ◽  
Author(s):  
Weihong Lai ◽  
Heng Wang ◽  
Quan jiang ◽  
Zichao Yan ◽  
Hanwen Liu ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Structural Evolution ◽  
Charge Compensation ◽  
Catalytic Reactions ◽  
Single Atom ◽  
Carbon Surface ◽  
Hydrogen Electrode ◽  
Single Atoms ◽  
Mass Activity ◽  
Co Doped

<p>Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe<sup>3+</sup>), cobalt (Co<sup>3+</sup>), ruthenium (Ru<sup>3+</sup>), palladium (Pd<sup>2+</sup>), indium (In<sup>3+</sup>), iridium (Ir<sup>2+</sup>), and platinum (Pt<sup>2+</sup>) . As illustrated in Figure 1, the carbon surface can be tuned with different level of compositional complexities, including unary Pt<sub>1</sub>@NC, binary (MSAC-2, (PtFe)<sub>1</sub>@NC), ternary (MSAC-3, (PtFeIr)<sub>1</sub>@NC), quaternary (MSAC-4, (PtFeIrRu)<sub>1</sub>@NC), quinary (MSAC-5, (PtFeIrRuCo)<sub>1</sub>@NC), senary (MSAC-6, (PtFeIrRuCoPd)<sub>1</sub>@NC), and septenary (MSAC-7, (PtFeIrRuCoPdIn)<sub>1</sub>@NC) samples. The structural evolution of carbon surface dictates the activities of both ORR and HER. The senary MSAC-6 achieves the ORR mass activity of 18.1 A·mg<sub>metal</sub><sup>-1</sup> at 0.9 V (Vs reversible hydrogen electrode (RHE)) over 30K cycles, which is 164 times higher than that of commercial Pt/C. The quaternary MSAC-4 presented a comparable HER catalytic capability with that of Pt/C. These results indicate that the highly complexed carbon surface can enhance its ability over general electrochemical catalytic reactions. The mechanisms regarding of the ORR and HER activities of the alternated carbon surface are also theoretically and experimentally investigated in this work, showing that the synergistic effects amongst the co-doped atoms can activate or inactivate certain single-atom sites.</p>

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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