TiO2-decorated graphenes as efficient photoswitches with high oxygen sensitivity

Abstract

We detail a facile fabrication and testing method of functionalizing single-layer graphenes (SLGs) by photoactive TiO₂ thin films as test-beds for building efficient multifunctional optoelectronic devices. Interestingly, tuning the photoactivity of TiO₂ enables us to realize fast and significant photoswitching effects in TiO₂-graphene devices. More importantly, using the hybrid devices as solid-state gas sensors, we have demonstrated a reversible and linear electrical sensitivity towards oxygen gas in the full concentration range (5–100%) at room temperature and ambient pressure, with a calculated minimum detection limit (MDL) of 0.01% oxygen. The unique oxygen sensitivity of the devices is attributed to the synergetic effect of the photoactivity of TiO₂ and the environmental ultrasensitivity of SLGs. These results form the basis for new types of future ultrasensitive multifunctional integrated devices for a variety of possible detection and/or sensing applications.