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 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 H₂, C₂H₆, CO, and CO₂ with minor quantities of C₂H₄, C₃H_8, 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 μmol g⁻¹ h⁻¹ for C₂H₆ and 15 000 μmol g⁻¹ h⁻¹ for H₂ was obtained. The Au content, nanoparticle sizes and interactions with Ga₂O₃ strongly influenced the photocatalytic activity.