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

Abstract

Au/Ga2O3 photocatalysts were prepared by three different methods (pre-formed Au nanoparticles, borohydride reduction, and impregnation-H2 reduction) and tested as photocatalysts for methane conversion coupled with hydrogen production from water. The photocatalysts were characterized by Xray 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 H2, 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 mmol g−1 h−1 for C2H6 and 15 000 mmol g−1 h−1 for H2 was obtained. The Au content, nanoparticle sizes and interactions with Ga2O3 strongly influenced the photocatalytic activity.