Fabrication and photoelectrochemical properties of CdSe quantum dot-sensitized TiO2 nanotube arrays

Abstract

CdSe quantum dot (QD) sensitized TiO2 nanotube arrays (TiO2 NTAs) were successfully prepared by successive ionic layer adsorption and reaction (SILAR) technique. Their composition, structure and photoelectrochemical property were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), UV-vis diffuse reflectance spectroscope and electrochemical workstation. The results indicate that CdSe QDs can expand the photo-response range of TiO2 NTAs from ultraviolet region to visible region up to 736 nm with increasing SILAR cycles. The photocurrent density for the CdSe QD sensitized TiO2 NTAs dramatically increases with SILAR cycles and exhibits the highest visible photocurrent density of 11.8 mA / cm2 for 6 cycles. More SILAR cycles induce a decrease of photocurrent density. The open circuit potential of CdSe QD sensitized TiO2 NTAs decrease slowly up to 0.93 eV with increasing SILAR cycles. A model is proposed to explain the influences of SILAR cycles on the visible photocurrent density of CdSe QD sensitized TiO2 NTAs.