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

Theoretical study on the reaction mechanism of reverse water–gas shift reaction using a Rh–Mo6S8 cluster

RSC Advances ◽  
2016 ◽  
Vol 6 (110) ◽  
pp. 108270-108279 ◽  
Author(s):  
Zhaoru Cao ◽  
Ling Guo ◽  
Naying Liu ◽  
Xiaoli Zheng ◽  
Wenli Li ◽  
...  
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Density Functional Theory Calculations ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Functional Theory ◽  
Reverse Water Gas Shift ◽  
Rwgs Reaction ◽  
Shift Reaction ◽  
Water Gas

The reverse water gas shift (RWGS) reaction catalyzed by a Rh–Mo6S8 cluster is investigated using density functional theory calculations.

scholarly journals Elucidating the Influence of Electric Fields toward CO2 Activation on YSZ (111)

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 271
Author(s):  
Nisa Ulumuddin ◽  
Fanglin Che ◽  
Jung-Il Yang ◽  
Su Ha ◽  
Jean-Sabin McEwen
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Heterogeneous Catalysts ◽  
Co2 Reduction ◽  
Total Density ◽  
Reverse Water Gas Shift ◽  
High Thermodynamic Stability ◽  
Shift Reaction ◽  
Water Gas

Despite its high thermodynamic stability, the presence of a negative electric field is known to facilitate the activation of CO2 through electrostatic effects. To utilize electric fields for a reverse water gas shift reaction, it is critical to elucidate the role of an electric field on a catalyst surface toward activating a CO2 molecule. We conduct a first-principles study to gain an atomic and electronic description of adsorbed CO2 on YSZ (111) surfaces when external electric fields of +1 V/Å, 0 V/Å, and −1 V/Å are applied. We find that the application of an external electric field generally destabilizes oxide bonds, where the direction of the field affects the location of the most favorable oxygen vacancy. The direction of the field also drastically impacts how CO2 adsorbs on the surface. CO2 is bound by physisorption when a +1 V/Å field is applied, a similar interaction as to how it is adsorbed in the absence of a field. This interaction changes to chemisorption when the surface is exposed to a −1 V/Å field value, resulting in the formation of a CO3− complex. The strong interaction is reflected through a direct charge transfer and an orbital splitting within the Olatticep-states. While CO2 remains physisorbed when a +1 V/Å field value is applied, our total density of states analysis indicates that a positive field pulls the charge away from the adsorbate, resulting in a shift of its bonding and antibonding peaks to higher energies, allowing a stronger interaction with YSZ (111). Ultimately, the effect of an electric field toward CO2 adsorption is not negligible, and there is potential in utilizing electric fields to favor the thermodynamics of CO2 reduction on heterogeneous catalysts.

First-Principles DFT Insights into the Mechanisms of CO2 Reduction to CO on Fe (100)-Ni Bimetals

2021 ◽  
Author(s):  
Caroline Kwawu ◽  
Albert Aniagyei ◽  
Destiny Konadu ◽  
Elliot Menkah ◽  
Richard Tia
Keyword(s):  
Carbon Monoxide ◽  
Binding Site ◽  
Active Sites ◽  
Density Functional ◽  
Co2 Reduction ◽  
Density Functional Theory Calculations ◽  
Hydrocarbon Fuel ◽  
Generalized Gradient ◽  
Efficient Catalyst ◽  
Stepped Surface

Abstract Iron and nickel are known active sites in the enzyme carbon monoxide dehydrogenases (CODH) which catalyzes CO2 to CO reversibly. The presence of nickel impurities in the earth abundant iron surface could provide a more efficient catalyst for CO2 degradation into CO, which is a feedstock for hydrocarbon fuel production. In the present study, we have employed spin-polarized dispersion-corrected density functional theory calculations within the generalized gradient approximation to elucidate the active sites on Fe (100)-Ni bimetals. We sort to ascertain the mechanism of CO2 dissociation to carbon monoxide on Ni deposited and alloyed surfaces at 0.25, 0.50 and 1 monolayer (ML) impurity concentrations. CO2 and (CO + O) bind exothermically i.e., -0.87 eV and − 1.51 eV respectively to the bare Fe (100) surface with a decomposition barrier of 0.53 eV. The presence of nickel generally lowers the amount of charge transferred to CO2 moiety. Generally, the binding strengths of CO2 were reduced on the modified surfaces and the extent of its activation was lowered. The barriers for CO2 dissociation increased mainly upon introduction of Ni impurities which is undesired. However, the 0.5 ML deposited (FeNi0.5(A)) surface is promising for CO2 decomposition, providing a lower energy barrier (of 0.32 eV) than the pristine Fe (100) surface. This active 1-dimensional defective FeNi0.5(A) surface provides a stepped surface and Ni-Ni bridge binding site for CO2 on Fe (100). Ni-Ni bridge site on Fe (100) is more effective for both CO2 binding or sequestration and dissociation compared to the stepped surface providing the Fe-Ni bridge binding site.

Elucidation of the high CO2 reduction selectivity of isolated Rh supported on TiO2: a DFT study

2016 ◽  
Vol 6 (15) ◽  
pp. 6128-6136 ◽  
Author(s):  
Sicong Ma ◽  
Weiyu Song ◽  
Bing Liu ◽  
Huiling Zheng ◽  
Jianlin Deng ◽  
...  
Keyword(s):  
Co2 Reduction ◽  
Water Gas Shift ◽  
Dft Study ◽  
Water Gas Shift Reaction ◽  
High Co2 ◽  
Reverse Water Gas Shift ◽  
Shift Reaction ◽  
Water Gas

Methanation and reverse water-gas shift reaction are two important reactions that could happen simultaneously during the process of CO2 reduction.

Synergy between Pd and Au in a Pd–Au(100) bimetallic surface for the water gas shift reaction: a DFT study

RSC Advances ◽  
2015 ◽  
Vol 5 (58) ◽  
pp. 47066-47073 ◽  
Author(s):  
Muhammad Adnan Saqlain ◽  
Akhtar Hussain ◽  
Muhammad Siddiq ◽  
Alexandre A. Leitão
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Water Gas Shift ◽  
Dft Study ◽  
Water Gas Shift Reaction ◽  
Functional Theory ◽  
Bimetallic Surface ◽  
Shift Reaction ◽  
Water Gas

Density functional theory calculations were performed to model a reaction relevant bimetallic surface and study the water gas shift reaction.

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.

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