Anionic S2−-doped TiO2 nanorod arrays (S2−-TiO2) were synthesized by a facile and controllable vapor-phase hydrothermal (VPH) approach based on the sulfur source of H2S gas. After the VPH treatment of TiO2 nanorod arrays (TNA), the isolated O2− species replaces the S2− ion in TiO2 (TiO2−xSx). The structural, morphological, optical, compositional, photocatalytic and photoelectrochemical (PEC) properties of the obtained samples were investigated in detail. It was found that S2−-TiO2 can enhance the separation rate of electron–hole pairs, improve the absorption of visible light, and augment the photocatalytic and photoelectrochemical properties. Anionic S2− 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%S2−-TiO2 (0.24S2−-TiO2) sample exhibited the best photogradation efficiency of 73% in 180 min compared to bare TiO2 (46%). The 0.24S2−-TiO2 showed the highest photocurrent of 10.6 μA/cm2, which was 1.73 times higher than that of bare TiO2 (6.1μA/cm2). The results confirmed that the visible light absorption, photocurrent and photocatalytic activity optimization of TNA are closely related not only to anionic S2−-doped but also different ratios of anionic S2−-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.
Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays
