Methoxy radical adsorption on gold nanoparticles: a comparison with methanethiol and methylamine radicals

Abstract

The adsorption of a methoxy radical ($$\hbox {OCH}_3$$) on the low-energy flat gold surfaces Au(111), Au(100) and Au(110) and on surface defects (adatoms) was compared with those of methanethiol ($$\hbox {SCH}_3$$) and methylamine ($$\hbox {NHCH}_3$$) radicals. Using dispersion-corrected DFT, we showed that the adsorption energy of $$\hbox {OCH}_3$$ on gold is significantly lower than that of $$\hbox {SCH}_3$$ but not very far from that of $$\hbox {NHCH}_3$$. Whatever the molecule, we found that the adsorption energy is of the same order on Au(110) and Au(100), and smaller on Au(111) and that the charge transfer goes from the surface to the molecule. The charge transferred to $$\hbox {SCH}_3$$ is very small, while that transferred to $$\hbox {NHCH}_3$$ is slightly larger, but still three times smaller than in the case of $$\hbox {OCH}_3$$. Concerning the competition between adsorption sites, we observed that undercoordinated atoms are not systematically more favoured than flat surfaces.