چكيده فارسي :
The photoelectrochemical (PEC) splitting of water utilizing sunlight to produce hydrogen has attracted much attention in light of its potential to store solar energy in a convenient way [1, 2]. Among materials for PEC applications, ZnO has been widely investigated as a photoanode because of its favorable band-edge position, high photocatalytic activity, high electron mobility, low cost, non-toxicity, thermal and chemical stability but, photocatalytic properties of ZnO often limited by recombination of photoexcited electron-hole pairs [3]. This paper describes the fabrication of a ZnO-Cu doped ZnO homojunction (ZnO/ZnO:Cu) photoanode by facile and cost-effective electrodeposition method at low temperature to improve the charge separation for enhanced photoelectrochemical water oxidation. ZnO/ZnO:Cu photoanode achieved a maximum photocurrent density of ~50 μA/cm2 at 1 V vs. saturated calomel electrode (SCE), which was about 2 orders of magnitudes higher than the pristine ZnO nanorods (ZnO NRs) under visible light irradiation. This study reveals that ZnO/ZnO:Cu photoanode could facilitate the separation and restrain the recombination of photo-generated electron–hole pairs. Although both Cu-doped ZnO (ZnO:Cu) and ZnO/ZnO:Cu photoanodes exhibit better PEC performances in compare with ZnO NRs photoanode, ZnO/ZnO:Cu photoanode presents an additional charge separation effect due to band bending structure. Motte-Schottky plots show that the flat band potential of ZnO/ZnO:Cu photoanode is more negative than that of pure ZnO NRs, which is beneficial for water splitting.
