For the preparation of p-type Cu2O photoanodes, we synthesized a Cu2O sheet via thermal oxidation of Cu foils, followed by an etching process with aqueous ammonia solution . Subsequently, overlayers for facile electron and hole transport were deposited on the respective sides of the Cu2O sheet using vacuum deposition methods such as atomic layer deposition (ALD), physical vapor deposition (PVD), and magnetron sputtering. First, a 15 nm Ga2O3 and a 100 nm TiO2 overlayers were sequentially deposited by ALD, followed by deposition of a 150 nm indium tin oxide (ITO) layer using PVD to form a conductive contact layer. Ag paste was painted on top of the ITO layer in a square pattern, and then Cu metal was attached to form the contact. The front layer, driving water oxidation, involved depositing a 1 nm Al2O3 layer via ALD, followed by the sequential deposition of 100 nm Au and 50 nm Ni by magnetron sputtering. Finally, the fabricated Cu2O sheet was placed on a glass slide for mechanical stability and packaged with non-conductive epoxy to create the Cu2O photoanode (Fig. ).