Ag‐Doped Free‐Standing 2D TiO₂ Sheets: Electronic, Optical, Magnetic, and Self‐Healing Behaviour

Abstract

Beyond a critical doping level, Ag ‐ 2D TiO2 sheets (ATO) are deemed to be a flexible transparent conductor, useful for visible‐range functional photonic/optoelectronic devices/sensors, sunlight‐sensitive catalysis, and light‐activated resistive switching. Due to the lack of control of surface energy which often leads to the formation of structural defects and even dimensionality crossover (2D to 0D) of materials during doping reaction, it is challenging to obtain ATO with a controlled doping level. Gauging the urgency, therefore we report the surface energy‐controlled synthesis of ATO employing liquid phase exfoliation of TiO2 and subsequent hydrothermal Ag‐doping in the presence of Hexamethylenetetramine (HMTA). Electron microscopy and atomic force microscopy reveal ATO sheets with large lateral dimensions. 6‐fold, 4‐fold, and strain‐mediated crystallographic phases of 2D ATO have been revealed by high‐resolution electron imaging. Successful tuning of the band gap down to ~ 2 eV with Ag doping up to ~ 10% is obtained. Synthesized 2D ATO have been investigated for their electrical, optical, optoelectronic, photoluminescence, and ferromagnetic behaviour. Visible light‐sensitive thermally/structurally robust semiconductor/conductor via tuneable doping will pave the way for their flexible as well as wearable device applications. Self‐healing effect of AFM tip‐generated mechanical stress has also been demonstrated.

Synergistic effects of oxygen vacancies and mesoporous structures in amorphous C@TiO2 for photocatalytic CO2 reduction

“…Various methods are employed in TiO 2 defect engineering, including element doping, 6 intrinsic oxygen vacancies, 7 and stress manipulation. 8 Common dopants, such as Au, Pt, and Ag, significantly increase costs while enhancing light absorption. 9 , 10 Introducing oxygen vacancies on the TiO 2 surface can provide additional active sites and surface reaction centers, promoting the separation of photogenerated electron-hole pairs and improving photocatalytic activity.…”