Catalytic materials are complex systems that contain different units, typically a carrier and an active phase. For many reactions, redox-active materials constitute the active phase. Active catalytic phases based on metal oxides include, but are not limited to, silver, copper, vanadium, molybdenum, iron, cobalt, and titanium oxides, and most notably ceria.(1, 2) This results in variable occupations of the d or f states of the cations. Therefore, the proper energy alignment of these states is mandatory for the adequate description of the chemistry responsible for the catalytic processes. In particular, all the challenges related to energy-harvesting and storage technologies are intrinsically linked to the small energy difference between the different spin configurations, the easy transfer between them, and the correct alignment of the energy states.