For the fabrication of floating photocatalyst sheets for vapour-phase water splitting, carbon paper was cut into 1.4 cm  1.4 cm sheets and a thin layer of optical glue was applied on the perimeter of the sheets. The optical glue mask acts as a second layer of protection to prevent the photocatalyst layer from being exposed to the liquid feedstock. The sheets were then placed in a UV ozone cleaner for 20 min to cure the glue and remove possible organic material from the surface of the sheets. A hydrophobic coating was applied on the sheets following a modified procedure. . In brief, dichlorodimethylsilane and heptane were mixed at a volume ratio of 2 : 1. The sheets were immersed in this solution for 1 h. After rinsing in heptane, the sheets were heat-treated at 423 K for 30 min.