A solid oxide fuel cell (SOFC) plays
a significant role in converting
chemically stored energy to electrical energy by using clean and renewable
fuels, such as H2 and CO. The LSFCr (La0.3Sr0.7Fe0.7Cr0.3O3) perovskite
is one of the few materials that is especially efficient and stable
as a reversible SOFC (RSOFC) by performing not only the direct fuel
cell reaction to generate power but also the CO2 conversion
back to CO. Many surface chemical reactions were studied for different
perovskites, but the CO2 reduction to CO at gaseous conditions
has been reported for only a few materials. Unfortunately, for the
LSFCr perovskite the precise atomic structures during mechanism of
CO2 electrolysis is unknown. This study identifies among
many adsorption modes for CO2 on the LSFCr surface the
preferred active site and a suggested mechanism for the reaction using
density functional theory (DFT) with nudged elastic band (NEB) tools.
Surprisingly, the mechanism involves a stable, linear O–C–O
angle during adsorption of CO2 and bending of the angle
is achieved only during the transition state. The results demonstrate
the importance of oxygen vacancies in the catalytic process, as well
as the importance of a Cr dopant in the reduction despite the direct
bonding of CO2 to Fe atom. Our results on the necessity
of a particular oxygen vacancy concentration for the chemical reaction
is supported by our thermogravimetric analysis (TGA) measurement.
Introduction: The COVID-19 pandemic has cast a heavy toll in human lives and global economics. COVID-19 is caused by the SARS-CoV-2 virus, which infects cells via its spike protein binding human ACE2.Methods: To discover potential inhibitory peptidomimetic macrocycles for the spike/ACE2 complex we deployed Artificial Intelligence guided virtual screening with three distinct strategies: 1) Allosteric spike inhibitors 2) Competitive ACE2 inhibitors and 3) Competitive spike inhibitors. Screening was performed by docking macrocycles to the relevant sites, clustering and synthesizing cluster representatives. Synthesized molecules were screened for inhibition using AlphaLISA and RSV particles.Results: All three strategies yielded inhibitory peptides, but only the competitive spike inhibitors showed “hit” level activity.Discussion: These results suggest that direct inhibition of the spike RBD domain is the most attractive strategy for peptidomimetic, “head-to-tail” macrocycle drug development against the ongoing pandemic.
Sr surface segregation (SSS) in perovskite materials is a main factor causing efficiency degradation of solid oxide fuel cells (SOFC's), and therefore can affect the La0.3Sr0.7Fe0.7Cr0.3O3−δ perovskite, which is known as a compatible anode and cathode in a reversible and symmetric SOFC. As a result of segregation, the atomic rearrangements in the near‐surface environment are likely to generate additional phases to the original one such as strontium carbonate (SrCO3) at high CO2 pressure. In the current work, first principal calculations are carried out for modeling the initial formation of SrCO3 after Sr segregation in LSFCr with CO2 presence. It is found that the tendency of CO2 to participate in SrCO3 phase formation is a competing reaction to its reduction to CO on the LSFCr material, and O vacancies are needed not only to improve CO2 reduction but also to block the competing reaction of SrCO3 adsorption. Therefore, LSFCr successfully “raises the bar” of CO2 reduction catalytic efficiency by preventing unwanted Sr segregation at high concentrations of surface oxygen vacancies.
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