Fig. 1. The designed wood/photocatalyst biphase photothermal–photocatalytic system.

a Schematic of the fabrication process of the wood/photocatalyst structure that generates the water steam and catalyzes its splitting for hydrogen evolution. b Raman spectra taken at different depths along the cross-section of wood/CoO microchannels with an interval of 500 µm. c The photo of the wood/CoO system floating on water. d Reflection spectra of the wood and wood/CoO systems. e Infrared radiation thermal image from the wood/CoO system under light illumination. f The potential of wood/CoO under 100 mW cm⁻² light illumination. g The estimated local temperature of CoO NPs through the measured potential.