scholarly journals A DFT-based model to the interpretation of DC conductivity in transition metals doped zinc phosphate glass

2021 ◽  
Author(s):  
Cherif Maghni ◽  
Mohamed Kharroubi
Keyword(s):  
Activation Energy ◽  
Transition Metal ◽  
Density Functional ◽  
Phosphate Glasses ◽  
Dc Conductivity ◽  
Material Surface ◽  
Zinc Phosphate Glass ◽  
Different Temperatures ◽  
Quenching Method ◽  
Metal Doped

AbstractTernary zinc–sodium–phosphate glasses doped with transition metal of the composition Na2MxZn1−xP2O7(x = 0, 1, 2 and 5 mol %) (where M = Ni, Cu and Co) were prepared by the traditional quenching method. The ac conductivity measurements at different temperatures for the prepared glasses have been investigated, and the activation energy for dc conduction has been determined in each transition metal doped sample. The results showed that the evolution of the activation energy of the conductivity depends on the nature of the dopant ions. A model based on formal density functional theory concept in which the electrical charge exchanged between the transition-metal cations and the surrounding material surface is proposed. The outcome is a “simplified” formula which allows us to explain the evolution of the ionic dc conductivity activation energy as a function of the doped ion in interaction with the cation and the surface.

scholarly journals Theoretical Study of Direct Carbon Dioxide Conversion to Formic Acid on Transition Metal-doped Subnanometer Palladium Clusters

2021 ◽  
Vol 53 (4) ◽  
pp. 210402
Author(s):  
Adhitya Gandaryus Saputro ◽  
Arifin Luthfi Maulana ◽  
Fine Dwinita Aprilyanti ◽  
Hermawan Kresno Dipojono
Keyword(s):  
Activation Energy ◽  
Transition Metal ◽  
Formic Acid ◽  
Density Functional ◽  
Direct Conversion ◽  
Hydrogenation Reaction ◽  
Co2 Hydrogenation ◽  
Reverse Water Gas Shift ◽  
Metal Doped ◽  
Water Gas

We studied the direct conversion of CO2 to HCOOH through hydrogenation reaction without the presence of base additives on the transition metal-doped subnanometer palladium (Pd7) cluster (PdxM: M = Cu, Ni, Rh) by using a combination of density functional theory and microkinetic calculations. It was shown that the CO2 hydrogenation on Pd7 and Pd6M clusters are more selective towards the formate pathway to produce HCOOH than the reverse water gas shift pathway to produce CO. Inclusion of Ni and Rh doping in the subnanometer Pd7 cluster could successfully enhance the turnover frequency (TOF) for CO2 hydrogenation to formic acid at low temperature. The order of TOF for formic acid formation is as follows: Pd6Ni > Pd6Rh > Pd7 > Pd6Cu. This order can be explained by the trend of the activation energy of CO2 hydrogenation to formate (HCOO*). The Pd6Ni cluster has the highest TOF value because it has the lowest activation energy for the formate formation reaction. The Pd6Ni system also has a superior TOF profile for HCOOH formation compared to several metal surfaces in low and high-temperature regions. This finding suggests that the subnanometer PdxNi cluster is a promising catalyst candidate for direct CO2 hydrogenation to formic acid.

Density functional theory studies of transition metal doped Ti3N2 MXene monolayer

2021 ◽  
Vol 197 ◽  
pp. 110613
Author(s):  
Ijeoma Cynthia Onyia ◽  
Stella Ogochukwu Ezeonu ◽  
Dmitri Bessarabov ◽  
Kingsley Onyebuchi Obodo
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Density Functional ◽  
Functional Theory ◽  
Metal Doped

Spectroscopic studies of transition metal doped sodium phosphate glasses

2004 ◽  
Vol 364 (1-2) ◽  
pp. 176-179 ◽  
Author(s):  
R.V.S.S.N Ravikumar ◽  
A.V Chandrasekhar ◽  
L Ramamoorthy ◽  
B.J Reddy ◽  
Y.P Reddy ◽  
...  
Keyword(s):  
Transition Metal ◽  
Sodium Phosphate ◽  
Spectroscopic Studies ◽  
Phosphate Glasses ◽  
Metal Doped

Oxygen-evolution reactions (OER) on transition-metal-doped Fe3Co(PO4)4 iron-phosphate surfaces: a first-principles study

2021 ◽  
Author(s):  
Yogeshwaran Krishnan ◽  
Sateesh Bandaru ◽  
Niall J. English
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Oxygen Evolution ◽  
First Principles ◽  
Density Functional ◽  
Iron Phosphate ◽  
Functional Theory ◽  
First Principles Study ◽  
Metal Doped ◽  
Catalyst Surfaces

A series of transition-metal-doped Fe1−xMxCo(PO4)4(010) and Fe3Co1−xMx(PO4)4(010) electro-catalyst surfaces (with M = Mn, Os, Ru, Rh and Ir) have been modelled via density-functional theory (DFT) to gauge their oxygen-evolution reactions (OER).

scholarly journals Comprehensive Evaluation of Transition Metal Doped Ni3N to Construct High-Efficiency Hydrogen Evolution Catalyst

2021 ◽  
Author(s):  
Meng Wang ◽  
Zepeng Lv ◽  
Xuewei Lv ◽  
Qian Li ◽  
Jie Dang
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Density Functional ◽  
Rational Design ◽  
Dft Calculation ◽  
High Efficiency ◽  
Comprehensive Evaluation ◽  
Low Cost ◽  
Alkaline Electrolyte ◽  
Metal Doped

Abstract Density functional theory (DFT) calculation indicators (ΔG, densities of state, D-band and bader charge) are commonly used to predict and analyze the hydrogen evolution reaction (HER) activity of catalysts, and most studies discuss only one or few of these indicators’ impact on catalysis, but still no report has comprehensively evaluated the influence of all these indicators on catalytic performance. Herein, foreseen by comprehensive consideration first, we report transition metal doped Ni3N nanosheets combined on Ni foam for utra-efficient alkaline hydrogen evolution. For dual transition metals doped Ni3N, Co,V-Ni3N exhibits remarkable HER performance with a significantly low overpotential of only 10 mV in alkaline electrolyte and 41 mV in alkaline seawater electrolyte at 10 mA cm− 2; while for single transition metal doped Ni3N, V-Ni3N exhibits the best performance with an overpotential of 15 mV and a Tafel slope of 37 mV dec− 1. Our work highlights the importance of comprehensive evaluation of DFT calculation indexes, and opens up a new method for the rational design of efficient and low-cost catalysts.

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