Fig. 3.

Key concepts and examples of photothermal methanation architectures. a Schematic representation of the light absorption spectra of semiconductors and plasmonic metals in comparison to the solar emission spectrum. b Light-to-heat conversion: photo-excited electrons (e⁻) interact with atomic nuclei, possibly generating phonons (ph). c Mechanisms of heat transfer within a particulate catalyst. Heat can be localized in catalyst nanoparticles by inhibiting phonon and electron transfer from the nanoparticle to its support. Structural defects, as well as phase boundaries between the catalyst and support phases, inhibit phonon and electron transfer and are hence beneficial for heat localization. Properties such as thermal and electronic conductivity, size and shape of the catalyst/support systems govern nanoscale heat transfer. d Selected potential photothermal catalyst architectures