Hollow and substrate-supported Prussian blue, its analogs, and their derivatives for green water splitting

To meet the current energy needs of society, the highly efficient and continuous production of clean energy is required. One of the key issues facing the green hydrogen evolution is the construction of efficient, low-cost electrocatalysts. Prussian blue (PB), Prussian blue analogs (PBAs), and their derivatives have tunable metal centers and have attracted significant interest as novel photo- and electrochemical catalysts. In this review, recent research progress into PB/PBA-based hollow structures, substrate-supported nanostructures, and their derivatives for green water splitting is discussed and summarized. First, several remarkable examples of nanostructured PB/PBAs supported on substrates (copper foil, carbon cloth, and nickel foam) and hollow structures (such as single-shelled hollow boxes, open hollow cages, and intricate hollow structures (multi–shell and yolk–shell)) are discussed in detail, including their synthesis and formation mechanisms. Subsequently, the applications of PB/PBA derivatives ((hydr)oxides, phosphides, chalcogenides, and carbides) for water splitting are discussed. Finally, the limitations in this research area and the most urgent challenges are summarized. We hope that this review will stimulate more researchers to develop technologies based on these intricate PB/PBA structures and their derivatives for highly efficient, green water splitting.