scholarly journals Unraveling the mechanism of biomimetic hydrogen fuel production – a first principles molecular dynamics study

2020 ◽  
Vol 22 (19) ◽  
pp. 10447-10454 ◽  
Author(s):  
Rakesh C. Puthenkalathil ◽  
Mihajlo Etinski ◽  
Bernd Ensing
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
First Principles ◽  
Molecular Hydrogen ◽  
Energy Landscape ◽  
Free Energy Landscape ◽  
Hydrogen Fuel ◽  
Fuel Production ◽  
Hydrogenase Enzyme ◽  
First Principles Molecular Dynamics

The Fe2(bdt)(CO)6 [bdt = benzenedithiolato] complex, a synthetic mimic of the [FeFe] hydrogenase enzyme can electrochemically convert protons into molecular hydrogen. The free energy landscape reveals a different mechanism for the biomimetic cycle.

Li deposition and desolvation with electron transfer at a silicon/propylene-carbonate interface: transition-state and free-energy profiles by large-scale first-principles molecular dynamics

2018 ◽  
Vol 20 (17) ◽  
pp. 11586-11591 ◽  
Author(s):  
Tsukuru Ohwaki ◽  
Taisuke Ozaki ◽  
Yukihiro Okuno ◽  
Tamio Ikeshoji ◽  
Hideto Imai ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
First Principles ◽  
Large Scale ◽  
Dynamics Simulation ◽  
Charge Transfer Process ◽  
Energy Profiles ◽  
Process Coupling ◽  
Free Energy Profiles ◽  
First Principles Molecular Dynamics

We report the result of a large-scale first-principles molecular dynamics simulation under different electric biases performed to understand the charge transfer process coupling with lithium deposition and desolvation processes.

scholarly journals First-principles-informed energetic span and microkinetic analysis of ethanol catalytic conversion to 1,3-butadiene on MgO

2020 ◽  
Author(s):  
Astrid Boje ◽  
William E. Taifan ◽  
Henrik Ström ◽  
Tomas Bucko ◽  
Jonas Baltrusaitis ◽  
...  
Keyword(s):  
Free Energy ◽  
Gas Phase ◽  
First Principles ◽  
Surface Coverage ◽  
Energy Landscape ◽  
High Surface ◽  
Catalytic Conversion ◽  
Free Energy Landscape ◽  
Catalyst Composition ◽  
The Impact

Kinetic modeling of single-step catalytic conversion of ethanol to 1,3-butadiene is necessary to inform accurate process design. This paper considers the synthesis of 1,3-butadiene on an MgO (100) step-edge using first-principles-informed energetic span and microkinetic analysis to explore the reaction free energy landscapes and kinetic limitations of competing reaction pathways. Previous studies have observed mechanisms proceeding via both dehydrogenation and dehydration of ethanol, and highlighted sensitivity to conditions and catalyst composition. Here, we use the energetic span concept to characterize the theoretical maximum turnover and degree of rate control for states in each reaction pathway, finding dehydrogenation to be more active than dehydration for producing 1,3-butadiene, and suggesting states in the dehydrogenation, dehydration, and condensation steps to be rate-determining. The influence of temperature on the relative rate contribution of each state is quantified and explained through the varying temperature sensitivity of the free energy landscape. A microkinetic model is developed to explore the impact of competition between pathways, interaction with gas-phase species, and high surface coverage of stable reaction intermediates. This suggests that the turnover obtained may be significantly lower than predicted from the free energy landscape alone. The theoretical rate-determining states were found to contribute to high surface coverage of adsorbed ethanol and longer, oxygenated hydrocarbons. The combined energetic span and microkinetic analysis permits investigation of a complex system from two perspectives, each with inherent advantages, and helps elucidate conflicting observations of rate determining steps and product distribution by considering the interplay between the different pathways and the equilibrium with gas-phase products.

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