Effect of TiO 2 nanoshape on the photoproduction of hydrogen from water-ethanol mixtures over Au 3 Cu/TiO 2 prepared with preformed Au-Cu alloy nanoparticles

Abstract

A series of TiO2 nanoshapes (microurchins, nanobelts, nanowires, microrods and nanotubes) were prepared and decorated with preformed nanoparticles of Au-Cu alloy (Au:Cu¿=¿3:1 molar, 1¿wt.% metal content). The resulting photocatalysts were tested for the photogeneration of hydrogen using water-ethanol gaseous mixtures (H2O:EtOH¿=¿1:9 molar basis) under dynamic conditions (26,000 h-1) and compared with a conventional sample prepared using P25. The use of preformed nanoparticles of Au-Cu alloy with the same geometric and electronic characteristics ensured a proper assessment of the influence of the different TiO2 supports on the photoproduction of hydrogen by providing a similar number and quality of metal-support contact points. The yield of hydrogen produced on a weight basis over the Au3Cu/TiO2 samples followed the trend microrods ~P25¿>¿>nanotubes¿>¿nanowires¿>¿nanobelts¿>¿microurchins. A stable hydrogen photogeneration rate of ca. 270¿µmol H2¿g-1¿min-1 was obtained over titania microrods decorated with Au3Cu whereas the photogeneration of hydrogen over P25 decorated with Au3Cu decreased progressively over time on stream.