Batch experiments were conducted to study the photocatalytic oxidation of aqueous ammonia (NH3/NH4+) over platinized titanate nanotubes (platinized TNTs). The reaction kinetics of NH3/NH4+ oxidation is considerably enhanced by the platinization of TNTs. The observed rate constant (k(obs)) for NH3/NH4+ oxidation over platinized TNTs was 1.69 x 10(-2) min(-1), while the unamended TNTs gave a k(obs) = 1.23 x 10(-3) min(-1). The selectivity of nitrogen gas (N-2) from degraded NH3/NH4+ increased with platinum loading to 87.8% after 1 h photocatalysis. In contrast, NH3/NH4+ to nitrate (NO3-) conversion was low due to a large NH3/NH4+ to nitrite (NO2-) energy barrier. High-resolution transmission electron microscopy shows that platinum deposits are formed primarily on the internal surface of the hollow structure of TNTs instead of being deposited on the external surface of TNTs. Based on the analysis of Xray photoelectron spectroscopy, a mechanism is proposed in which N-2 is produced from the NH3/NH4+ adsorbed on platinum deposits while NO2-/NO3- is formed from the NH3/NH4+ adsorbed on titanate sites. (C) 2010 Elsevier B.V. All rights reserved.