scholarly journals Doubly-charged Negative Ions as Novel Tunable Catalysts: Graphene and Fullerene Molecules Versus Atomic Metals

2020 ◽  
Author(s):  
Kelvin Suggs ◽  
Alfred Z Msezane
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Activation Barrier ◽  
Negative Ions ◽  
Negative Ion ◽  
Functional Theory ◽  
Molecular Anions ◽  
Sanitation Systems ◽  
Doubly Charged ◽  
Energy Activation

The fundamental mechanism underlying negative-ion catalysis involves bond-strength breaking in the transition state (TS). Doubly-charged atomic/molecular anions are proposed as novel dynamic tunable catalysts and demonstrated in water oxidation to peroxide. Density Functional Theory TS calculations have found tunable energy activation barrier reduction ranging from 0.030 eV to 2.070eV, with Si2ˉ, Pu2ˉ, Pa2ˉ and Sn2ˉ the best catalysts; the radioactive elements usher in new application opportunities. C602ˉ reduces significantly the standard C60ˉ TS energy barrier while graphene increases it, behaving like cationic systems. Rank-ordered catalysts according to their reaction barrier reduction efficiency, variation across charge states and systems reveal their tunable and wide applications, ranging from water purification to biocompatible anti-viral and anti-bacterial sanitation systems.

scholarly journals Doubly-Charged Negative Ions as Novel Tunable Catalysts: Graphene and Fullerene Molecules Versus Atomic Metals

2020 ◽  
Vol 21 (18) ◽  
pp. 6714
Author(s):  
Kelvin Suggs ◽  
Alfred Z. Msezane
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Activation Barrier ◽  
Negative Ions ◽  
Negative Ion ◽  
Functional Theory ◽  
Molecular Anions ◽  
Sanitation Systems ◽  
Doubly Charged ◽  
Energy Activation

The fundamental mechanism underlying negative-ion catalysis involves bond-strength breaking in the transition state (TS). Doubly-charged atomic/molecular anions are proposed as novel dynamic tunable catalysts, as demonstrated in water oxidation into peroxide. Density Functional Theory TS calculations have found a tunable energy activation barrier reduction ranging from 0.030 eV to 2.070 eV, with Si2−, Pu2−, Pa2− and Sn2− being the best catalysts; the radioactive elements usher in new application opportunities. C602− significantly reduces the standard C60− TS energy barrier, while graphene increases it, behaving like cationic systems. According to their reaction barrier reduction efficiency, variation across charge states and systems, rank-ordered catalysts reveal their tunable and wide applications, ranging from water purification to biocompatible antiviral and antibacterial sanitation systems.

scholarly journals Fullerene Negative Ions: Formation and Catalysis

2020 ◽  
Vol 21 (9) ◽  
pp. 3159
Author(s):  
Zineb Felfli ◽  
Kelvin Suggs ◽  
Nantambu Nicholas ◽  
Alfred Z. Msezane
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Water Oxidation ◽  
Density Functional ◽  
Regge Pole ◽  
Negative Ions ◽  
State Density ◽  
Negative Ion ◽  
Functional Theory ◽  
Total Cross Sections

We first explore negative-ion formation in fullerenes C44 to C136 through low-energy electron elastic scattering total cross sections calculations using our Regge-pole methodology. Then, the formed negative ions C44ˉ to C136ˉ are used to investigate the catalysis of water oxidation to peroxide and water synthesis from H2 and O2. The exploited fundamental mechanism underlying negative-ion catalysis involves hydrogen bond strength-weakening/breaking in the transition state. Density Functional Theory transition state calculations found C60ˉ optimal for both water and peroxide synthesis, C100ˉ increases the energy barrier the most, and C136ˉ the most effective catalyst in both water synthesis and oxidation to H2O2.

scholarly journals Fullerene Negative Ions: Formation and Catalysis

2020 ◽  
Author(s):  
Zineb Felfli ◽  
Kelvin Suggs ◽  
Nantambu Nicholas ◽  
Alfred Z. Msezane
Keyword(s):  
Transition State ◽  
Cross Sections ◽  
Water Oxidation ◽  
Regge Pole ◽  
Negative Ions ◽  
Negative Ion ◽  
Total Cross Sections ◽  
Hydrogen Bond Strength ◽  
Low Energy Electron ◽  
Fundamental Mechanism

We first explore negative-ion formation in fullerenes C44, C60, C70, C98, C112, C120, C132 and C136 through low-energy electron elastic scattering total cross sections calculations using our Regge-pole methodology. Water oxidation to peroxide and water synthesis from H2 and O2 are then investigated using the anionic catalysts C44ˉ to C136ˉ. The fundamental mechanism underlying negative-ion catalysis involves hydrogen bond strength-weakening in the transition state. DFT transition state calculations found C60ˉ numerically stable for both water and peroxide synthesis, C100ˉ increases the energy barrier the most and C136ˉ the most effective catalyst in both water synthesis and oxidation to H2O2.

scholarly journals Взаимодействие alpha-частиц keV-энергий с молекулами глицил-лейцина

2021 ◽  
Vol 47 (12) ◽  
pp. 23
Author(s):  
А.А. Басалаев ◽  
А.Г. Бузыкин ◽  
В.В. Кузьмичев ◽  
М.Н. Панов ◽  
А.В. Петров ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Cross Sections ◽  
Density Functional ◽  
Molecular Ions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Singly Charged ◽  
Doubly Charged ◽  
First Time ◽  
Fragmentation Processes

Radiation damage to isolated glycyl-leucine (C8H16N2O3) molecules caused by interaction with He2+ ions was studied. For the first time, the relative cross sections of the main processes of changes in the charge state of the collision partners and the relative cross sections of the fragmentation processes of singly and doubly charged molecular ions formed during single collisions of glycyl-leucine molecules with ions have been obtained. The optimized geometry of the molecule and singly charged glycyl-leucine ion was calculated using the density functional theory (DFT).

A density functional theory study on the performance of graphene and N-doped graphene supported Au3 cluster catalyst for acetylene hydrochlorination

2016 ◽  
Vol 94 (10) ◽  
pp. 842-847 ◽  
Author(s):  
Fei Zhao ◽  
Yang Wang ◽  
Lihua Kang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Gap ◽  
Activation Barrier ◽  
Similar Reaction ◽  
Functional Theory ◽  
Acetylene Hydrochlorination ◽  
Doped Graphene ◽  
Calculated Activation ◽  
Calculated Activation Barrier

Density functional theory (DFT) calculation was used to investigate the mechanism of Au3 clusters, separately supported on pure graphene (Au3/graphene) and one graphitic N-doped graphene (Au3/N-graphene). These supported Au3 clusters were used to catalyze acetylene hydrochlorination. Results show that the graphene supporter could obviously enhance the adsorption of reactants. Also, N-atom doping could broaden the energy gap between the HOMO of graphene and the LUMO of Au3, leading to the significantly attenuated interaction between the Au3 cluster and graphene by more than 19 kcal/mol (1 cal = 4.184 J). The two catalysts possessed extremely similar reaction mechanisms with activation energy values of 23.26 and 23.89 kcal/mol, respectively. The calculated activation barrier declined in the order of Au3 < Au3/N-graphene < Au3/graphene, suggesting that Au3/N-graphene could be a potential catalyst for acetylene hydrochlorination.

scholarly journals Sn-Doped Hematite for Photoelectrochemical Water Splitting: The Effect of Sn Concentration

2020 ◽  
Vol 234 (4) ◽  
pp. 683-698 ◽  
Author(s):  
Siyuan Zhang ◽  
Hamidreza Hajiyani ◽  
Alexander G. Hufnagel ◽  
Jonathan Kampmann ◽  
Benjamin Breitbach ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Atomic Layer ◽  
Solubility Limit ◽  
Metallic State ◽  
Equilibrium Solubility ◽  
Functional Theory ◽  
Sn Doping ◽  
Layer Deposition

AbstractHematite-based photoanodes have been intensively studied for photoelectrochemical water oxidation. The n-type dopant Sn has been shown to benefit the activity of hematite anodes. We demonstrate in this study that Sn-doped hematite thin films grown by atomic layer deposition can achieve uniform doping across the film thickness up to at least 32 mol%, far exceeding the equilibrium solubility limit of less than 1 mol%. On the other hand, with the introduction of Sn doping, the hematite crystallite size decreases and many twin boundaries form in the film, which may contribute to the low photocurrent observed in these films. Density functional theory calculations with a Hubbard U term show that Sn doping has multiple effects on the hematite properties. With increasing Sn4+ content, the Fe2+ concentration increases, leading to a reduction of the band gap and finally to a metallic state. This goes hand in hand with an increase of the lattice constant.

Theoretical Study of Ethylene Addition to O=W(=CH2)(CH3)2

2007 ◽  
Vol 62 (3) ◽  
pp. 367-372 ◽  
Author(s):  
Robin Haunschild ◽  
Gernot Frenking
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Activation Barrier ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Stable Isomer ◽  
Functional Theory ◽  
B3lyp Level ◽  
Rhenium Compound ◽  
Favorable Reaction

Quantum chemical calculations using density functional theory at the B3LYP level of theory were carried out to investigate the reaction pathways for the addition of ethylene to WO(CH3)2(CH2) (W1). The results are compared to those of previous theoretical studies of the ethylene addition to OsO3(CH2) (Os1) and ReO2(CH3)(CH2) (Re1). The theoretically predicted reactions pathways exhibit significant differences. The energetically most favourable reaction of the tungsten system W1 is the [2+2]W,C addition across theW=C double bond yielding the metallacyclobutane W3a which then rearranges to the slightly more stable isomer W3b. The [2+2]Re,C addition of the rhenium compound yielding the metallacyclobutane Re3a has the lowest activation barrier for the ethylene addition to the rhenium system, but the reaction is endothermic while the exothermic formation of the more stable isomer Re3b has a much higher activation barrier. The [3+2]C,O addition Os1+C2H4→Os2 is the thermodynamically most favorable reaction of the osmium compound.

Ruthenium-based catalysts for water oxidation: the key role of carboxyl groups as proton acceptors

2020 ◽  
Vol 22 (9) ◽  
pp. 5249-5254 ◽  
Author(s):  
Yuting Liu ◽  
Xiaofang Su ◽  
Wei Guan ◽  
Likai Yan
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Water Oxidation ◽  
Density Functional ◽  
Carboxyl Groups ◽  
Functional Theory

In this work, the mechanism of water oxidation catalyzed by an Ru-based complex [Ru(L)]+ (L = 5,5-chelated 2-carboxy-phen, 2,2′;6′,2′′-terpyridine) was studied by density functional theory (DFT) calculations.

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