Enhanced photoanode properties of CdS nanoparticle sensitized TiO2 nanotube arrays by solvothermal synthesis

We demonstrate the synthesis of CdS-sensitized TiO2 (CdS/TiO2) nanotube arrays via the solvothermal method and describe their enhanced photoelectrochemical properties. Our new approach prevents the clogging of CdS quantum dots (QDs) at the TiO2 nanotube mouth and promotes the uniform deposition of a polycrystalline CdS on the densely aligned TiO2 nanotube arrays (TiO2 NTAs). The deposition of CdS onto the TiO2 NTA can be controlled by the deposition time and the concentration of the precursors. Photoelectrochemical measurements indicate that the electrode synthesized via the solvothermal method can achieve a stable photocurrent density of 5.7 mA/cm(2) at O-V versus Ag/AgCl under AM 1.5 G illumination, which is approximately 10% higher than that prepared using the chemical bath deposition (CBD) method. Solvothermally prepared CdS/TiO2 NTAs exhibit 125-fold enhancement in their photocurrent under visible light compared with bare TiO2 NTAs, indicating facile photogenerated electron transfer from CdS to TiO2. Solvothermally prepared CdS/TiO2 NTAs shows better photostability and longer lifetime of photoelectrons compared to those prepared by CBD method suggesting more favorable CdS TiO2 NTA interfacial contact. In general, we propose that this methodology can be useful in designing multijunction semiconductor configuration such as coating nanostructures. (C) 2013 Elsevier B.V. All rights reserved.