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Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics
Published on: April 12, 2019
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Exploring the interactions of ZDDP additive with hematite surfaces: a DFT+Ustudy
Davide Sarpa1, David D O'Regan2, Vasilios Bakolas3
1School of Chemistry and Chemical Engineering, University of Southampton, Southampton, United Kingdom.
Summary
Zinc dialkyldithiophosphates (ZDDPs) are crucial anti-wear additives. This study uses DFT+U to reveal ZDDP interactions with hematite surfaces, identifying key binding mechanisms for tribofilm formation.
Area of Science:
- Materials Science
- Tribology
- Computational Chemistry
Background:
- Zinc dialkyldithiophosphates (ZDDPs) are essential anti-wear additives in automotive lubricants.
- The mechanism of protective tribofilm formation by ZDDPs remains incompletely understood.
- Understanding ZDDP interactions with metal surfaces is critical for lubricant development.
Purpose of the Study:
- To investigate the electronic structure of hematite surfaces.
- To examine the interaction between ZDDP molecules and different hematite surface terminations.
- To elucidate the initial stages of ZDDP decomposition on metallic surfaces.
Main Methods:
- Density Functional Theory (DFT) with the DFT+U approach was employed.
- Calculations focused on bulk hematite and its (0001) surface terminations (Fe-O-Fe, O-Fe-Fe, HO-Fe-Fe).
- Electronic structure, surface states, and ZDDP adsorption energies were analyzed.
Main Results:
- The O-Fe-Fe terminated hematite surface exhibits metallic character due to oxygen dangling bonds.
- ZDDP demonstrates stronger binding affinity to the Fe-O-Fe terminated surface.
- Adsorption of ZDDP on the Fe-O-Fe surface induces significant changes in its geometry and atomic charges.
Conclusions:
- The electronic properties of hematite surfaces significantly influence ZDDP interactions.
- The Fe-O-Fe termination is identified as a preferential site for ZDDP binding.
- These findings offer new insights into ZDDP decomposition pathways on metallic surfaces, aiding in the design of advanced lubricants.
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