The TMDC layers can be grown and crystallized with the c-axis of the crystallites parallel or perpendicular to the substrate normal, depending on the application. For photoelectrocatalytic applications, the perpendicular orientation of the c-axis is favorable, since this configuration ensures exposure of the edge sites to the contacting electrolyte, allowing an efficient charge transfer to the electrolyte. However, the recombination of the photogenerated electron-hole pairs happens at the prismatic sites of hexagonal crystallites (edge sites), i.e. at -planes.