On the True Photoreactivity Order of {001}, {010}, and {101} Facets of Anatase TiO₂ Crystals

Contrary to conventional understanding, clean anatase {001} facets exhibit lower photoreactivity than {101} facets. Furthermore, the {010} facets showed the highest photocatalytic reactivity in generating OH radicals and hydrogen evolution. This behavior was revealed by studies on crystals grown hydrothermally to have a predominance of {001}, {101}, or {010} facets (left to right in picture (a) and (b)–(d), respectively).