Stability of Oxygenated Groups on Pristine and Defective Diamond Surfaces

TL;DR

This study uses atomistic simulations to analyze the stability of various oxygenated groups on different diamond surfaces, revealing how surface type and defects influence the dominant oxygen groups formed during oxidation.

Contribution

It provides new insights into the stability of oxygenated groups on diamond surfaces using reactive molecular mechanics simulations, considering both pristine and defective surfaces.

Findings

COH is most stable on perfect (110) surfaces.

COC is favored on defective (110) and both pristine and defective (111) surfaces.

COC stability depends on surface defects and type.

Abstract

The surface functionalization of diamond has been extensively studied through a variety of techniques, such as oxidation. Several oxygen groups have been correspondingly detected on the oxidized diamond, such as COC (ester), CO (ketonic), and COH (hydroxyl). However, the composition and relative concentration of these groups on diamond surfaces can be affected by the type of oxygenation treatment and the diamond surface quality. To investigate the stability of the oxygenated groups at specific diamond surfaces, we evaluated through fully atomistic reactive molecular mechanics (FARMM) simulations, using the ReaxFF force field, the formation energies of CO, COC, and COH groups on pristine and defective diamond surfaces (110), (111), and (311). According to our findings, the COH group has the lowest formation energy on a perfect (110) surface, while the COC is favored on a defective surface. As for the (111) surface, the COC group is the most stable for both pristine and defective surfaces. Similarly, COC group is also the most stable one on the defective/perfect (311) surface. In this way, our results suggest that if in a diamond film the (110) surface is the major exposed facet, the most adsorbed oxygen group could be either COH or COC, in which the COC would depend on the level of surface defects.