Practical Solar Hydrogen Production Using Z-Scheme Photocathodes

Abstract

Natural processes such as photosynthesis serve as an inspiration for the vision of sustainable development. Particularly, converting water into hydrogen by using solar energy offers a practical solution to the ever-increasing global energy demand. Here, we developed a Z-scheme heterostructure photocathode for constructing photoelectrochemical cells to produce hydrogen from water. The samples were prepared by successively depositing Au particles and Cu2O nanocrystals on CuO films. For CuO-Au-Cu2O, the embedded Au can promote electron transfer from the conduction band of CuO to the valence band of Cu2O, a typical Z-scheme charge transfer scenario imitated from the natural photosynthesis. This vectorial charge transfer resulted in the situation that the photoexcited electrons accumulated at the conduction band of Cu2O (-1.83 V vs. NHE) and holes accumulated at the valence band of CuO (+0.88 V vs. NHE). With the substantially high reducing power and enhanced charge separation, CuO-Au-Cu2O photocathodes showed superior hydrogen production rates over pure CuO and CuO-Au.