Fig. 3. (a) Nitrogen absorption-desorption isotherms of dice-like TiO2 nanoparticles and the corresponding pore diameter distribution (inset); (b) High-resolution XPS spectra of F 1s on the surface of ultrafine dice-like TiO2; (c) UV–vis diffuse reflectance spectra of two different anode films of dice-like TiO2 and P-18 and (d) their scattering ratio of dice-like TiO2 to P-18 films.