High-Active Anatase TiO2 Nanosheets Exposed with 95% {100} Facets Toward Efficient H2 Evolution and CO2 Photoreduction

We succeed in preparation of anatase TiO2 single crystals with marked photocatalytic activity via a facile and effective method. This TiO2 is composed of TiO2 ultrathin nanosheets (2 nm in thickness) with 95% of exposed {100} facet, which is considered to be the active facet for photocatalytic reaction. This percentage (95%) is the highest among previously reported {100} facet exposed anatase TiO2. More importantly, due to this high ratio, our developed TiO2 nanosheets showed marked photocatalytic activity, about 5 times higher activity in both H-2 evolution and CO2 reduction than the reference sample, TiO2 cuboids with 53% of exposed {100} facet. For the TiO2 nanosheets, both the higher percentage of exposed {100} facets and larger surface area can offer more surface active sites in the photocatalytic reaction. On the other hand, the superior electronic band structure which results from the higher percentage of {100) facet is also beneficial for the higher activity. This study exemplifies that the facet engineering of semiconductors is one of the most effective strategies to achieve advanced properties over photofunctional materials for solar energy conversion.