Sonochemical Hydrogen Production Efficiently Catalyzed by Au/TiO2

Abstract

Au/TiO2 was used as a highly efficient sonocatalyst to produce H2 from water or aqueous solutions. Au/TiO2 significantly increased the yields of H• and •OH radicals in the sonolysis of water. Product analysis and isotope evidence indicated that hydrogen molecules derived from methanol/water solutions were formed by three pathways: (1) recombination of two H• atoms from the cleavage of water molecules, (2) H-abstraction from methanol by H• generated by water cleavage, and (3) thermal reforming of methanol. The relative importance of each pathway was assessed by carefully analyzing the hydrogen-isotope composition of the evolved hydrogen gas using a modified gas chromatograph. The source of hydrogen in the H2 evolved from methanol/water solutions during sonolysis was also addressed. Data showed that, although the addition of methanol in the presence of Au/TiO2 resulted in a 12-fold increase in the rate of H2 evolution, nearly half of the hydrogen atoms were nevertheless derived from water molecules. Control...