Density Functional Theory Study of Monoethanolamine Adsorption on Hydroxylated Cr2O3 Surfaces

International audienceThe adsorption of monoethanolamine (MEA), a well-known CO2 capture amine, on the hydroxylated (0001)-Cr2O3 surface was investigated by periodic density functional theory calculations and complementary ab initio molecular dynamics. Two different adsorption modes were investigated: adsorption of MEA above the hydroxylated surface and substitution of a surface water molecule by MEA. Several MEA coverages were studied from 0.25 to 1 monolayer. An atomistic thermodynamic approach was used to take into account the effects of temperature and solvation on the MEA adsorption process in aqueous solution. MEA can adsorb on the surface in a parallel orientation, and H-bonds are formed between amine and alcohol groups and different (H)OH groups at the surface. In the gas phase at 0 K, the formation of a monolayer (ML) of MEA above the surface is the most favorable adsorption mode. In aqueous solution at 298.15K, calculations have suggested that MEA adsorbs above the hydroxylated Cr2O3 surface with a density of 2.37 MEA/nm2 (0.5 ML). However, the substitution process was found to be endothermic at temperatures above 298.15 K

Stress Concentration in the Bulk Cr2O3: Effects of Temperature and Point Defects

Modeling the growth and failure of passive oxide films formed on stainless steels is of general interest for the use of stainless steel as structural material and of special interest in the context of life time extension of light water reactors in nuclear power plants. Using the DFT+U approach, a theoretical investigation on the resistance to failure of the chromium-rich inner oxide layer formed at the surface of chromium-containing austenitic alloys (stainless steel and nickel based alloys) has been performed. The investigations were done for periodic bulk models. The data at the atomic scale were extrapolated by using the Universal Binding Energy Relationships (UBERs) model in order to estimate the mechanical behavior of a 10 μm thick oxide scale. The calculated stress values are in good agreement with experiments. Tensile stress for the bulk chromia was observed. The effects of temperature and structural defects on cracking were investigated. The possibility of cracking intensifies at high temperature compared to 0 K investigations. Higher susceptibility to cracking was observed in presence of defects compared to nondefective oxide, in agreement with experimental observation

First-principles investigation of the structural and electronic properties of self-assemblies of functional molecules on graphene

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