Between photocatalysis and photosynthesis: Synchrotron spectroscopy methods on molecules and materials for solar hydrogen generation

► We provide a series of soft X-ray and nuclear resonant vibration spectroscopy experiments relevant for solar hydrogen production. ► Metal oxide photoelectrodes and photosynthesis protein motifs are investigated. ► Ex situ and photoelectrochemical in situ studies are presented. ► The relevant role of defect states on surfaces, in sub-surfaces and in the bulk is elucidated.