First-Principles Surface Characterization and Water Adsorption of Fe₃P Schreibersite

Abstract

The meteoritic mineral schreibersite, e.g., Fe3P, is a proposed abiotic source of phosphorus for phosphate ion (PO4 –) production, needed for nucleobases, phospholipids, and other life building materials. Schreibersite could have acted as both a source of elemental phosphorus and as a catalyst, and the hostile conditions on early Earth could have accelerated its degradation in different environments. Here, we present results from quantum calculations of bulk schreibersite and of its low Miller index surfaces. We also investigate water surface adsorption and identify possible dissociation pathways on the most stable facet. Our calculations provide useful chemical insights into schreibersite interactions in aqueous environments, paving the way for further detailed investigation on more reactive surfaces. Our results help provide a “bottom-up” understanding for phosphorylated organic synthesis on the primitive planet and its role in producing life building molecules.

Elucidating the Initial Steps in α-Uranium Hydriding Using First-Principles Calculations

“…Surface energies and adsorptions have been shown to be relatively insensitive to the value of the Hubbard U correction in actinides . Similar results have been seen with materials containing lower-Z metals, where inclusion of GGA + U had a minimal effect on surface energy ordering . In addition, uranium phases are known to exhibit magnetic moments at their surface, − which can affect surface adsorption energies.…”

“…38 Similar results have been seen with materials containing lower-Z metals, where inclusion of GGA + U had a minimal effect on surface energy ordering. 39 In addition, uranium phases are known to exhibit magnetic moments at their surface, 40−42 which can affect surface adsorption energies. In order to assess these effects on α-U surface properties and hydrogen adsorption, we have chosen to perform a bounding study using PBE on the faceted (012) and (102) surfaces, which are the two highest energy/most reactive surfaces studied in our work (see Section 3.3 for further discussion).…”

Computational Study on the Water Corrosion Process at Schreibersite (Fe2NiP) Surfaces: from Phosphide to Phosphates

“…Very few computational works are available on this kind of material; on Fe 3 P, i.e., the forerunner of bulk schreibersite, periodic quantum mechanical simulations were performed dedicated to predict its phase stability under the extreme conditions of temperature and pressure that can be found in meteorites and comets. − In a recent work published by us, we studied and characterized bulk and surfaces of Fe 2 NiP, calibrating the methodology by comparing our simulation with experimental Raman spectra . In the last year, two papers studying single water adsorption and deprotonation on the most stable (110) surface of Fe 3 P and Fe 2 NiP were published, , elucidating some features not clear from the experiments, i.e., on which sites water adsorbs (only on metals if it is in the molecular form), and the fact that water deprotonation is not thermodynamically favorable (at least on the most stable surface). A comparison with previous corrosion experiments , followed by IR spectroscopy is also available showing a very good agreement between computed and experimental results …”