Tailoring More Active Titania Photocatalysts

By customizing the surface structure of titanium dioxide particles, researchers at Dalian Institute of Chemical Physics, in China, have significantly boosted the semiconductor's catalytic activity in photochemical water-splitting reactions (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200704788). Titanium dioxide is a relatively inexpensive, nontoxic photocatalyst that, in addition to splitting water to make hydrogen, can decompose organic materials and is used for its sterilizing and antifouling properties in coatings, windows, and other products. To probe the relationship between TiO₂'s catalytic activity and its anatase and rutile crystalline forms, Can Li and coworkers used wet chemical methods and heat treatments to prepare a series of samples in which they varied the relative amounts of the two forms. Judging by the quantity of hydrogen produced via the water-splitting reaction, they found that the best samples, which were four times more active than the pure rutile form, were composed of large rutile particles (500 nm) covered with tiny anatase crystallites (<30 nm). The team proposes that the interfaces between the two crystalline forms serve as catalytic hot spots that boost activity.