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.
Keywords: absorption of visible light; anionic S2−-TiO2 nanorod arrays; photocatalytic activity; vapor-phase hydrothermal.