scholarly journals Engineering single-atom dynamics with electron irradiation

2019 ◽  
Vol 5 (5) ◽  
pp. eaav2252 ◽  
Author(s):  
Cong Su ◽  
Mukesh Tripathi ◽  
Qing-Bo Yan ◽  
Zegao Wang ◽  
Zihan Zhang ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Branching Ratio ◽  
Single Step ◽  
Single Atom ◽  
Momentum Vector ◽  
The Road ◽  
Single Atoms ◽  
Atomic Engineering ◽  
Experiment And Simulation ◽  
Atom Dynamics

Atomic engineering is envisioned to involve selectively inducing the desired dynamics of single atoms and combining these steps for larger-scale assemblies. Here, we focus on the first part by surveying the single-step dynamics of graphene dopants, primarily phosphorus, caused by electron irradiation both in experiment and simulation, and develop a theory for describing the probabilities of competing configurational outcomes depending on the postcollision momentum vector of the primary knock-on atom. The predicted branching ratio of configurational transformations agrees well with our atomically resolved experiments. This suggests a way for biasing the dynamics toward desired outcomes, paving the road for designing and further upscaling atomic engineering using electron irradiation.

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>

Improving peroxymonosulfate activation by copper ion-saturated adsorbent-based single atom catalysts for the degradation of organic contaminants: electron-transfer mechanism and the key role of Cu single atoms

2021 ◽  
Author(s):  
Jingwen Pan ◽  
Baoyu Gao ◽  
Pijun Duan ◽  
Kangying Guo ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Organic Contaminants ◽  
High Salinity ◽  
Copper Ion ◽  
Single Atom ◽  
Electron Transfer Mechanism ◽  
Persulfate Oxidation ◽  
Single Atoms ◽  
Oxidation Technology

Nonradical pathway-based persulfate oxidation technology is considered to be a promising method for high-salinity organic wastewater treatment.

scholarly journals The road to fraud starts with a single step

Nature ◽  
2011 ◽  
Vol 479 (7372) ◽  
pp. 151-151 ◽  
Author(s):  
Jennifer Crocker
Keyword(s):  
Single Step ◽  
The Road

Synergy of Single Atoms Pd and Oxygen Vacancies on In2O3 for Highly Selective C1 Oxygenates Production from Methane under Visible Light

2021 ◽  
Author(s):  
Lei Luo ◽  
Lei Fu ◽  
Huifen Liu ◽  
Youxun Xu ◽  
Jialiang Xing ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Single Atom ◽  
Electron Transfer Pathway ◽  
Mild Conditions ◽  
Single Atoms ◽  
Primary Products ◽  
Critical Issues ◽  
Regulation Of Activity ◽  
Visible Irradiation ◽  
Dft Modelling

Abstract Methane (CH4) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues on both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In2O3 nanorods enabled superior photocatalytic CH4 activation by O2. The optimised catalyst reached ca. 100 µmol·h− 1 of C1 oxygenates, with a selectivity of primary products (CH3OH and CH3OOH) up to 82.5 %. Mechanism investigation elucidated that such superior photocatalysis was induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer pathway, respectively. O2 was proven to be the only oxygen source for CH3OH production, while H2O acted as the promoter for efficient CH4 activation through ·OH production and facilitated product desorption as indicated by DFT modelling. This work thus provides new understandings on simultaneous regulation of activity and selectivity by the significant synergy of single atom cocatalysts and oxygen vacancies.

scholarly journals The End of the M.E.?

2005 ◽  
Vol 127 (05) ◽  
pp. 26-29 ◽  
Author(s):  
Peter Huber ◽  
Mark P. Mills
Keyword(s):  
Fuel Cell ◽  
Mechanical Engineering ◽  
Combustion Engine ◽  
Electrical Power ◽  
Single Step ◽  
Second Century ◽  
Basic Operation ◽  
The Road ◽  
Energy Economy ◽  
On The Road

This article highlights that mechanical engineers control most of the rest of our energy economy. The engineering focus will shift inexorably toward finding the most efficient means of generating electricity on-board. Trains and monster trucks both use big diesel generators. Hybrid cars on the road today burn gasoline, but it is the fuel cell that attracts the most attention from visionaries and critics of the internal combustion engine. Remarkably elegant in its basic operation, the fuel cell transforms fuel into electricity in a single step, completely bypassing the furnace, turbine, and generator. In this scenario, mechanical engineering ultimately surrenders its last major under-the-hood citadel to chemical engineers. One might say that the age of mechanical engineering was launched by James Watt's steam engine in 1763, and propelled through its second century by Nikolaus Otto’s 1876 invention of the spark-ignited petroleum engine. We are now at the dawn of the age of electrical engineering, not because we recently learned how to generate light-speed electrical power, but because we have now finally learned how to control it.

scholarly journals Interfacial-confined coordination to single-atom nanotherapeutics

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Limei Qin ◽  
Jie Gan ◽  
Dechao Niu ◽  
Yueqiang Cao ◽  
Xuezhi Duan ◽  
...  
Keyword(s):  
Therapeutic Strategy ◽  
Single Atom ◽  
Oxygen Species ◽  
High Quality ◽  
Efficient Energy ◽  
Coordination Strategy ◽  
Single Atoms ◽  
Highly Active ◽  
Narrow Bandgap ◽  
Catalytic Sites

AbstractPursuing and developing effective methodologies to construct highly active catalytic sites to maximize the atomic and energy efficiency by material engineering are attractive. Relative to the tremendous researches of carbon-based single atom systems, the construction of bio-applicable single atom materials is still in its infancy. Herein, we propose a facile and general interfacial-confined coordination strategy to construct high-quality single-atom nanotherapeutic agent with Fe single atoms being anchored on defective carbon dots confined in a biocompatible mesoporous silica nanoreactor. Furthermore, the efficient energy conversion capability of silica-based Fe single atoms system has been demonstrated on the basis of the exogenous physical photo irradiation and endogenous biochemical reactive oxygen species stimulus in the confined mesoporous network. More importantly, the highest photothermal conversion efficiency with the mechanism of increased electron density and narrow bandgap of this single atom structure in defective carbon was proposed by the theoretical DFT calculations. The present methodology provides a scientific paradigm to design and develop versatile single atom nanotherapeutics with adjustable metal components and tune the corresponding reactions for safe and efficient tumor therapeutic strategy.

scholarly journals RTA Mathematic Simulation Principles at the Autotechnical Expertise

2021 ◽  
Vol 334 ◽  
pp. 02026
Author(s):  
Badrudin Gasanov ◽  
Artem Efimov ◽  
Jurij Grebennikov
Keyword(s):  
Mathematical Model ◽  
Road Transport ◽  
Road Accident ◽  
Momentum Vector ◽  
The Road ◽  
Solid Friction ◽  
Strain Stress ◽  
Determination Methods ◽  
Determine Step ◽  
Energy Conservation Law

The features of carrying out an autotechnical expertise (ATE) are considered in case the vehicles (V) participating in the road transport accident (RTA) don’t leave skid imprints. The examples of momentum and energy conservation law application are given at developing the road accident mathematical model. Special attention is paid to the determination methods of vehicle (V) velocity, travel directions in various RTA diagrams and archeology of deformation. For this purpose it is offered to draw a momentum vector diagram. It is reasonable that for the calculation of V deformation at RTA it is necessary to determine step by step the strain-stress state in a contact area on the basis of the theories of elasticity, plasticity, solid friction and finite-element methods. The technique of constructing an RTA mathematical model is developed. It is recommended to use at ATE of RTAs at the runs-over into the fixed obstacle (a stationary V) and collisions.

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.

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