Polymer-coating of photocatalytic particles to prevent sintering in their calcination process

A method to prevent sintering of photocatalytic particles in a calcination process is developed to allow their crystallization without a significant decrease in their specific surface area. A sacrificial layer of polymer to prevent the particle from sintering was employed for the crystallization of amorphous titania particles in the heat treatment at 500 °C. The heat treatment simultaneously removed the polymer layer by pyrolysis. The heat treatment using a sacrificial layer of polymer could suppress a decrease in the specific surface area of titania particles and also maintain colloidal stability in water, attaining a photocatalytic activity higher than that without using a sacrificial layer. These results indicate that the polymer-coating technique is effective for crystallization of photocatalytic particles without a loss of both colloidal stability and photocatalytic activity of the particles.