Size-dependent surface energy and Tolman length of TiO2 and SnO2 nanoparticles

In the present paper, we report the calculated results of size dependent surface energy and Tolman length of two metal oxides namely the titanium dioxide (TiO2) and tin dioxide (SnO2) nanoparticles. The methodology used here is based on simple thermodynamic model using parameters for corresponding bulk systems obtained from computer simulations using density functional theory (DFT) based data. We found that the surface energy depends on the size of particles and decreases with decreasing particle size. We also report the surface energy for different planes/facets of TiO2 and SnO2 nano-crystals and observed that the (110) plane/facet is the most stable facet as the value of the surface energy for this facet is minimum among all considered facets. Size dependence of the Tolman length shows an opposite trend than surface energy for both compounds. Tolman length is found to be decreasing with increasing size of SnO2 nanoparticles. Our calculation is found to be in agreement with the experimental results in case of TiO2 nanoparticles.