Enhanced photocatalytic and photoelectrochemical properties of TiO2 nanorod arrays sensitized with CdS nanoplates

TiO2 nanorod arrays (NRAs) sensitized with CdS nanoplates (NPLs) were fabricated via a two-step method. Vertically aligned TiO2 NRAs were synthesized by a hydrothermal method, and followed by depositing CdS NPLs on TiO2 NRAs via successive ion layer absorption and reaction (SILAR) method. Their surface morphology, structure, photoelectrochemical, and photocatalytic properties were investigated. UV-via absorption spectra suggest that the absorption peaks shift from the ultraviolet region (408 nm) to the visible region (580 nm) when compared to pure TiO2 nanorod arrays. Additionally, upon irradiation of visible light, the photocurrent response of CdS NPL sensitized TiO2 NRAs after 8 SILAR cycles significantly improved, displaying an optimal photocurrent density of 168.5 μAμA/cm2, which is much higher than that of the unsensitized samples (48.1 μAμA/cm2). They also exhibited excellent photocatalytic properties where the degradation rate of methyl orange under visible light showed an enhancement of 92.4% compared to bare TiO2 NRAs. The mechanisms of the enhanced photocatalytic and photoelectrochemical properties of TiO2 nanorod arrays sensitized with CdS nanoplates are discussed in detail.