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.

Enhanced selectivity of CO2 reverse water-gas reaction over Ni2P/CeO2 catalyst

2021 ◽  
Author(s):  
Sha Cui ◽  
Xiaosheng Wang ◽  
Luhui Wang ◽  
Xianmin Zheng
Keyword(s):  
High Temperature ◽  
Transition Metal ◽  
Hydrogenation Reaction ◽  
Co2 Hydrogenation ◽  
Ni Catalyst ◽  
Metal Phosphide ◽  
Transition Metal Phosphide ◽  
Water Gas ◽  
Metal Sintering ◽  
Enhanced Selectivity

Ni catalyst tended to methanation and easily metal sintering at high temperature in CO2 hydrogenation reaction. Herein, Ni2P, typical kind of transition metal phosphide, had been demonstrated to be efficient...

scholarly journals Mechanisms of CO2 reduction into CO and formic acid on Fe (100): a DFT study

2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Caroline R. Kwawu ◽  
Albert Aniagyei ◽  
Destiny Konadu ◽  
Boniface Yeboah Antwi
Keyword(s):  
Formic Acid ◽  
Density Functional ◽  
Co2 Reduction ◽  
Density Functional Theory Calculations ◽  
The Other ◽  
Acid Formation ◽  
Generalized Gradient ◽  
Reverse Water Gas Shift ◽  
Shift Reaction ◽  
Water Gas

AbstractUnderstanding the mechanism of CO2 reduction on iron is crucial for the design of more efficient and cheaper iron electrocatalyst for CO2 conversion. In the present study, we have employed spin-polarized density functional theory calculations within the generalized gradient approximation (DFT-GGA) to elucidate the mechanism of CO2 reduction into carbon monoxide and formic acid on the Fe (100) facet. We also sort to understand the transformations of the other isomers of adsorbed CO2 on iron as earlier mechanistic studies are centred on the transformations of the C2v geometry alone and not the other possible conformations i.e., flip-C2v and Cs modes. Two alternative reduction routes were considered i.e., the direct CO2 dissociation against the hydrogen-assisted CO2 transformation through formate and carboxylate into CO and formic acid. Our results show that CO2 in the C2v mode is the precursor to the formation of both products i.e., CO and formic acid. Both the formation and transformation of CO2 in the Cs and flip-C2v is challenging kinetically and thermodynamically compared to the C2v mode. The formic acid formation is favoured over CO via the reverse water gas shift reaction mechanism on Fe (100). Both formic acid formation and CO formation will proceed via the carboxylate intermediate since formate is a stable intermediate whose transformation into formic acid is challenging both kinetically and thermodynamically. Graphic abstract

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 Production of Fuels and Chemicals from a CO2/H2 Mixture

Reactions ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 130-146
Author(s):  
Yali Yao ◽  
Baraka Celestin Sempuga ◽  
Xinying Liu ◽  
Diane Hildebrandt
Keyword(s):  
Co2 Hydrogenation ◽  
Water Gas Shift ◽  
Liquid Fuels ◽  
Saturated Hydrocarbons ◽  
Reverse Water Gas Shift ◽  
Cu Catalyst ◽  
In Series ◽  
Fuels And Chemicals ◽  
Water Gas ◽  
Aspen Simulation

In order to explore co-production alternatives, a once-through process for CO2 hydrogenation to chemicals and liquid fuels was investigated experimentally. In this approach, two different catalysts were considered; the first was a Cu-based catalyst that hydrogenates CO2 to methanol and CO and the second a Fisher–Tropsch (FT) Co-based catalyst. The two catalysts were loaded into different reactors and were initially operated separately. The experimental results show that: (1) the Cu catalyst was very active in both the methanol synthesis and reverse-water gas shift (R-WGS) reactions and these two reactions were restricted by thermodynamic equilibrium; this was also supported by an Aspen plus simulation of an (equilibrium) Gibbs reactor. The Aspen simulation results also indicated that the reactor can be operated adiabatically under certain conditions, given that the methanol reaction is exothermic and R-WGS is endothermic. (2) the FT catalyst produced mainly CH4 and short chain saturated hydrocarbons when the feed was CO2/H2. When the two reactors were coupled in series and the presence of CO in the tail gas from the first reactor (loaded with Cu catalyst) significantly improves the FT product selectivity toward higher carbon hydrocarbons in the second reactor compared to the standalone FT reactor with only CO2/H2 in the feed.

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

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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