Methane conversion coupled with hydrogen production from water using Au/Ga₂O₃ photocatalysts prepared by different methods

Au/Ga2O3 photocatalysts were prepared by three different methods (pre-formed Au nanoparticles, borohydride reduction, and impregnation-H-2 reduction) and tested as photocatalysts for methane conversion coupled with hydrogen production from water. The photocatalysts were characterized by X-ray fluorescence, X-ray diffraction, UV-vis, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and PL spectroscopy. The reactions were performed with the photocatalysts dispersed in water in a bubbling methane stream under UV-light illumination. The products were identified and quantified by gas chromatography (GC-FID/TCD/MSD). The main products formed were H-2, C2H6, CO, and CO2 with minor quantities of C2H4, C3H8, and C4H10. The best performances were observed for the photocatalysts prepared with the nominal Au content of 0.1 wt% regardless of the method used. A production rate of about 100 & mu;mol g(-1) h(-1) for C2H6 and 15 000 & mu;mol g(-1) h(-1) for H-2 was obtained. The Au content, nanoparticle sizes and interactions with Ga2O3 strongly influenced the photocatalytic activity.