CdS-sensitized 1-D single-crystalline anatase TiO₂ nanowire arrays for photoelectrochemical hydrogen production

We report photoelectrochemical (PEC) properties of single crystalline anatase TiO₂ nanowire (NW) arrays which are sensitized with CdS for visible light activity. Photocurrent varies largely with increasing the growth time (from 2 to 24 h) of the TiO₂ NWs and also increasing the deposition cycles (from 7 to 13 cycles) of CdS, which are attributed to changes in morphology of the TiO₂ NWs and CdS layer. TiO₂ NW array grown for 3 h with 9-cycles of CdS deposition exhibits the maximum photocurrent of 3.6 mA/cm² at 1.23 V vs. reversible hydrogen electrode (RHE) under the 1 SUN solar light. Morphological analysis combined with photoresponse analysis show that the 3 h-grown TiO₂ NW array has the most suitable structure for PEC electrode because of large surface area for light absorption and chemical reaction, and that the 9-cycles deposited CdS layer provides the optimum light absorption and electron lifetime.