Can Defective Schreibersite Deliver Prebiotic Phosphorus?

The origin of bioavailable phosphorus remains one of the major unresolved questions in prebiotic chemistry. The most widely accepted hypotheses invoke an exogenous delivery of phosphorus during the Archean Eon (ca. 4 billion years ago), associated with the Late Heavy Bombardment and involving the iron-nickel phosphide mineral schreibersite ((Fe,Ni)3P). Over the past decades, these hypotheses have been supported by aqueous corrosion experiments, showing that schreibersite releases a variety of oxygenated phosphorus species, including phosphates. In this work, we investigate the wetting and corrosion of the reactive schreibersite (001) surface (Fe2NiP) by means of periodic DFT simulations up to the formation of phosphate species. Unlike previous studies, which considered only the pristine (001) surface, here we investigate defective surface models to assess structural defects that facilitate phosphate formation. The results reveal significant changes in the thermodynamics of the corrosion process, whereas the kinetic barriers remain remarkably similar to those calculated for the pristine (001) surface, differing by less than 5 kJ mol-1, well within the intrinsic chemical accuracy of DFT calculations. These findings indicate that the pristine (001) surface provides a reliable and robust structural model for investigating phosphate formation and, potentially, more complex prebiotic processes, such as phosphorylation of organic molecules. Consequently, increasingly complex structural models representing advanced stages of corrosion are not required, despite the substantial morphological and compositional changes expected to occur during surface degradation.