A Facile and Controllable Vapor-Phase Hydrothermal Approach to Anionic S(2−)-doped TiO(2) Nanorod Arrays with Enhanced Photoelectrochemical and Photocatalytic Activity

Anionic S(2−)-doped TiO(2) nanorod arrays (S(2−)-TiO(2)) were synthesized by a facile and controllable vapor-phase hydrothermal (VPH) approach based on the sulfur source of H(2)S gas. After the VPH treatment of TiO(2) nanorod arrays (TNA), the isolated O(2−) species replaces the S(2−) ion in TiO(2) (TiO(2−x)S(x)). The structural, morphological, optical, compositional, photocatalytic and photoelectrochemical (PEC) properties of the obtained samples were investigated in detail. It was found that S(2−)-TiO(2) can enhance the separation rate of electron–hole pairs, improve the absorption of visible light, and augment the photocatalytic and photoelectrochemical properties. Anionic S(2−) doping can significantly adjust the absorption cut-off wavelength (409.5–542.5 nm) and shorten the bandgap (3.05-2.29 eV) of TNA. For the degradation of methylene orange (MO) under mercury lamp light, the 0.24 At%S(2−)-TiO(2) (0.24S(2−)-TiO(2)) sample exhibited the best photogradation efficiency of 73% in 180 min compared to bare TiO(2) (46%). The 0.24S(2−)-TiO(2) showed the highest photocurrent of 10.6 μA/cm(2), which was 1.73 times higher than that of bare TiO(2) (6.1μA/cm(2)). The results confirmed that the visible light absorption, photocurrent and photocatalytic activity optimization of TNA are closely related not only to anionic S(2−)-doped but also different ratios of anionic S(2−)-doped. It is noteworthy that the VPH approach is very promising for applications in low cost and highly efficient ion doping into nanomaterials for energy devices.