Our atmosphere on earth is based on the photodissociation of water, a fundamental process used by nature in oxygenic photosynthesis to convert solar energy into storable and chemical energy. It is based on the so-called Z scheme, where photons of different energies are absorbed in a staggered energy level system.
Currently, artificial photosynthesis systems are being developed intensively based on the analog of the Z scheme, for example in tandem solar cells. Here, the oxidation of water carried by light to oxygen at the anode is accompanied by the production of so-called solar fuels at the cathode: hydrogen, a storable fuel that can be used as raw material for fuel cells, generating energy for the transport or carbon dioxide reduction products, keeping the promise of converting emissions to fuels that use renewable energy. Inorganic systems have produced the highest efficiencies and stabilities by combining tandem absorbers with high activity electrocatalysts.