Semiconductors-based Z-scheme materials for photoelectrochemical water splitting: A review

Photoelectrochemical (PEC) water splitting is among the most promising approaches for a potentially clean and renewable source for hydrogen fuel from the splitting of water into hydrogen and oxygen using light source and energy conversion due to its practical efficiency. The innovative approach is the construction of a two-step photoexcitation system, often called a Z-scheme photocatalysis system, which mimics natural photosynthesis. The PEC splitting of water using various Z-scheme materials is initiated by the direct absorption of a photon, which creates separated electrons and holes in the energy band gap of the material. A Z-scheme system employs two photocatalysts, one producing H2 and the other O2, usually with the aid of an electron shuttle. This review focuses on the current state of research on nanoscale-enhanced Z-scheme photocatalyst materials for the water splitting reaction. Additionally, the recent advances achieved in especially metal oxides, metal sulfides, g-C3N4, and semiconductors-based Z-scheme materials as photocatalyst systems for water-splitting, are also covered.