The term photocatalyst is a combination of two words: photo, attributed to photon, and catalyst, which is a substance that alters the reaction rate in its presence [1–3]. As far as is known, since the discovery of photocatalytic water splitting on TiO2-based metal oxide by Fujishima and Honda in 1972, photocatalysis is widely utilized as a strategy that uses light to activate photocatalytic feedstocks to produce reactive oxy- gen species (i.e., •OH, •O2−/HO2•, 1O2, and H2O2), which are the main oxidants that drive chemical reactions. Besides, the photocatalysis process can be divided into two categories based on the appearance of the physical state of the utilized reactants
