I've had studies that show that titanium oxide has a lot to do with it, and because of its unique structure, it has many catalytic applications, including photocatalytic. The following articles describe the uses of this substance as well as its alloys.
Article Strong pyro-electro-chemical coupling of Ba 0.7 Sr 0.3 TiO 3...
Article Enhancement of pyroelectric catalysis of ferroelectric BaTiO...
Article High pyrocatalytic properties of pyroelectric BaTiO3 nanofib...