“…Photoelectrochemical (PEC) water splitting over semiconductor metal oxides has attracted numerous interests [2][3][4][5][6][7][8], because it is a promising and environmentally friendly method to produce hydrogen [9][10][11][12][13][14][15]. Among various metal oxides, transition metal oxides, such as TiO 2 [13,16], ZnO [17][18][19], Fe 2 O 3 [20], In 2 O 3 [21], have been extensively investigated as photoelectrodes for PEC water splitting, and remarkable progresses have been achieved [22,23]. On the other hand, it is still important to develop new high-efficient photoanodes.…”