Development of molecular cluster models to probe pyrite surface reactivity

Area of Science:

• Biogeochemistry
• Computational Mineralogy
• Microbial Metabolism

Background:

• Anaerobic methanogens can reductively dissolve pyrite (FeS2).
• Microbes utilize dissolution products for iron and sulfur biosynthesis.
• Understanding mineral-surface redox reactions is crucial for microbial processes.

Purpose of the Study:

• To develop atomic-scale nanoparticle models of pyrite.
• To describe fundamental redox steps at the mineral surface during microbial reduction.
• To model microbial extracellular electron-transfer reactions on pyrite.

Main Methods:

• Computational modeling of n(FeS2) nanoparticles derived from bulk pyrite structure.
• Development of maquettes representing reactive surface sites with Fe(II) and persulfide (S22-) ligation.
• Guidelines for obtaining low-energy structures by analyzing inter-site interactions.

Main Results:

• Created atomic-scale models (maquettes) of pyrite nanoparticles (n=8, 18, 32).
• Identified coordinatively unsaturated Fe(II) sites and persulfide ligation.
• Established principles for constructing stable, low-energy nanoparticle models.

Conclusions:

• Developed computational nano-reactors for studying pyrite reductive dissolution.
• Enhanced understanding of reactive sites for microbial extracellular electron transfer.
• Provides a framework for modeling microbe-mineral interactions at the atomic scale.