Optimal engineering of CdS/PbS co-sensitized TiO2 nanotube arrays for enhanced photoelectrochemical performance

Abstract

TiO2 nanotube arrays (NTAs) are decorated with CdS/PbS nano-sensitizers by successive ionic layer adsorption and reaction (SILAR) method. The uniform growth of the CdS and PbS nanoparticles on the surface and inner side of TiO2 Nanotube Arrays (NTAs) has been confirmed by Transmission Electron microscopy measurements. The impact of the CdS and PbS semiconductor quantum dots (SQDs) on the photoelectrochemical performance (PEC) of TiO2 NTAs was systematically investigated, and the optimal decoration of the CdS and PbS SQDs on the TiO2 NTAs was obtained. CdS/PbS co-sensitized TiO2 NTA photoanode films show excellent response to visible light (with absorption extended to 825 nm) and enhanced PEC performance. The best performing device showed an enhanced photocurrent density under the 0.62V vs SCE up to 8.2 mA/cm2, and high photoconversion efficiency up to 5.35%, which is 16.7 times higher than the pure TiO2 NTAs. The enhanced PEC performance of TiO2 NTAs is attributed to the co-sensitization, heterojunction formation and electron “pool” effect imparted on the NTAs by the coupling of CdS and PbS SQDs.