Titanium dioxide is widely used as a pigment in the paint industry due to its non-toxicity, chemical inertness and of course its optical properties. However, titanium dioxide paint film decomposes with excessive ultraviolet light and so zirconium oxide coatings are used to improve the paint stability. Chemicals such as zirconium oxychloride and zirconium sulphate are used in the coating process.
Due to its strong oxidising properties titanium dioxide is also used as a photocatalyst that oxidises and decomposes harmful organic contaminants such as algae spores, bacteria and viruses. This means it is finding applications on many surfaces including walls and surfaces of buildings, improving air quality in closed building spaces. Zirconium oxide is used as a dopant to control the photocatalytic activity of titanium oxide. The zirconium oxide gives a better phase stability, smaller particles and higher surface area, which all result in increased photocatalytic activity.