Low-temperature strategy for vapor phase hydrothermal synthesis of C\N\S-doped TiO2 nanorod arrays with enhanced photoelectrochemical and photocatalytic activity

In this study, a material with high photocatalytic activity was synthesized using ternary C/N/S-doped TiO2 nanorod array (TiO2); this was done using a practical and straightforward vapor-phase hydrothermal (VPH) method at a low temperature. The effect of C/N/S content on TiO2 morphology, optical, photocatalytic and photoelectrochemical (PCE) properties of the material was investigated by varying the quality of thiourea. C/N/S-TiO2 reduced the bonding rate of electron-hole pairs and enhances visible light absorption, photocatalytic, and PCE properties. The C/N/S doping could significantly adjust the absorption cut-off wavelengths (407-602 nm) and shorten the bandgap (3.04-2.18 eV) of TiO2. Under simulated sunlight, 8-C/N/S-TiO2 had the highest photocatalytic efficiency of 97.6% for methylene blue (MB) in 150 min with a rate constant of 0.0192 min(-1), which is approximately four times that of TiO2 (0.005 min(-1)). The 8-C/N/S-TiO2 photoelectrode had the lowest transfer resistance for interfacial charges and highest transient photocurrent of 33.5 mA/cm(2), which is five times higher than that of TiO2 (6.6 mA/cm(2)). The 8-C/N/S-TiO2 exhibits the most extensive PCE behavior as a photoelectrode, and has a current density of 38.2 mA/cm(2) at 2.5V(RHE), which is about two times higher than TiO2 (19.1 mA/cm(2)). The favorable sunlight-driven photocatalytic activity is probably due to the synergistic effect of C/N/S-doping, which shifts the valence band maximum of TiO2 upward. This provides new ideas for future solar cells that can use dye-sensitized TiO2 nanorod arrays as photoanodes. It is noteworthy that VPH is a very effective strategy for fabricating semiconductors doped with multiple nonmetallic elements. (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

The study synthesized a material with high photocatalytic activity using ternary C/N/S-doped TiO2 nanorod array via a vapor-phase hydrothermal method. C/N/S doping effectively adjusted the absorption cut-off wavelengths and reduced electron-hole pair recombination rate, enhancing visible light absorption, photocatalytic, and photoelectrochemical properties of the material.