Theoretical study of hydrogen/methyl chalcogenides (H2X and CH3XH, X = S, Se) adsorption on pristine/doped graphene quantum dots

Abstract

The adsorption of hydrogen and methyl chalcogenides on pristine and B,N-doped graphene quantum dot models was investigated using B97-3c model to understand their interactions and orientations on the considered graphene surfaces. Molecular orientation was found to significantly influence adsorption energies, surpassing the impact of adsorption position. H₂S prefers an inverse-V configuration, while H₂Se preferred an L-shape configuration, with one hydrogen parallel to the pristine surface. Both methanethiol and methaneselenol prefer the carbon-chalcogen bond nearly parallel to the surface. Doping with boron-enhanced adsorption energies compared to pristine and N-doped GQDs. Non-covalent interaction (NCI) and atoms-in-molecules (AIM) analyses revealed weak interactions, primarily involving carbon atoms. However, in certain cases, interactions with the doped boron atom were revealed as the bond path. Selenium compounds exhibit less selectivity in their adsorption orientations, as evidenced by the smaller energy difference between their two most stable configurations compared to sulfide. Charge transfer was determined to play a minor role in these systems.