Tuning the area percentage of reactive surface of TiO2 by strain engineering.

Surfaces with high reactivity usually have a low area percentage, which greatly limits the efficiency of surface reactivity. In this Letter we demonstrate a generic way of increasing the percentage of the highly reactive surface by using external strain. Bulk and surface elastic properties of TiO2 are studied via density functional theory calculations. The equilibrium shape of anatase TiO2 under applied strain is discussed based on the elastic properties. We find that when 5% compressive strain is applied biaxially along [100] and [010]; directions, the area percentage of the anatase (001) surface can be increased by ~5 times in comparison with the case when no strain is applied. Since the moderate strain does not introduce extrinsic defects into the material, we propose that it is an ideal way to increase the reactivity of titanium dioxide crystallites by applying biaxial compressive external strain along the a axis.