Part 1: Increasing Contact Surface
First, there needs to be an increase in contact surface. Since spheres possess the largest surface area given a specified volume, we need to have small particles of TiO2, preferably in the shape of a sphere. But how small should we go? Our team visualizes that since modern technology permits, TiO2 particles should be nanosized to promote the greatest amount of surface area possible.
To Part 2: Reducing the Band-Gap Energy