Heterogeneous 3-D nanotubular arrays of CdS-TiO ₂: Efficient collections of reflection light for enhanced photoelectric output

This paper describes heterogeneous 3-D nanotubular arrays of CdS-TiO ₂ fabricated by sensitizing anodized 3-D arrays of TiO ₂ nanotubes with CdS nanoparticles. The radial distribution of heterogeneous arrays on the circumference of Ti wire renders them capable of collecting visible light from any direction. In surroundings where reflection visible light is artificially made by a reflector, the photocurrent output of heterogeneous 3-D arrays is enhanced by ∼69% at 0 V potential (vs. Ag/AgCl) in a standard three-electrode cell. Based on quantitative measurements of photocurrent output of 3-D arrays under known irradiation intensity from two opposite directions simultaneously, the irradiation intensity of artificial reflection light in our system was determined to be ∼58 mW cm ^-2. By optimizing the length of TiO ₂ nanotubes and deposition of CdS nanoparticles, heterogeneous 3-D arrays collect direct incident light and artificial reflection light to generate a photocurrent output (normalized to the direct irradiation area) of ∼13.2 mA at 0 V potential (vs. Ag/AgCl) under 100 mW cm ^-2 simulated full light.