Adsorption of glycine on the anatase (101) surface: an ab initio study

The adsorption of glycine on a clean anatase (101) surface was studied by first principles calculations. Glycine was found to bind to the surface in an undissociated form, utilizing both the carboxyl and the amino groups for the binding. The adsorption energy was found to be -23.0 kcal mol(-1). Two other configurations were found to be only slightly (by 0.6 and 1.1 kcal mol(-1)) less stable, one binding only through the lone pair of the amino group, the other adopting a dissociated binding mode. The conformational strain of glycine was found to have a significant effect on the adsorption energy. The adsorption properties of the amino and carboxyl functional groups of glycine were compared to those of ammonia and formic acid. While the amino group shows a similar binding energy to that of ammonia, the carboxyl group of glycine is able to create stronger binding to the anatase surface than formic acid.