The Role of Cu(I) Species for Photocatalytic Hydrogen Generation Over CuOx/TiO2

The fabrication of different CuO (x) species (Cu(0), Cu(I) and Cu(II) species) over TiO2 has been accomplished and their roles in photoinduced hydrogen generation have been investigated. The results indicate that the positive charge in CuO (x) center affect photo-induced charge transfer significantly. Cu(I) species seems promote photocurrent generation while the Cu(II) species inhibits the photocurrent generation. Photoactivity order follows the similar sequence. Lower temperature calcination helps the formation of Cu(I) species and higher temperature treatment leads to the formation of Cu(II) species. At the lower loading level, the Cu content increase leads to the activity increase, but over loading of copper resulted in the decrease of activities for hydrogen generation. Detail analysis indicates that too much copper loading induces more Cu(II) center formation, as a results, the activity for hydrogen generation decreases. The species of Cu(0) does no affect the activity obviously at low loading level and shows detrimental effect at high loading level. The optimal loading amount of copper is 1.0Cu (wt%).