Rutile TiO2 nanowire arrays interconnected with ZnO nanosheets for high performance electrochemical UV sensors

Abstract

One-dimensional nanostructured materials, which have a high aspect ratio and large interface area, provide a promising scheme to fabricate fast-response and super-sensitive electrochemical ultraviolet (UV) sensors. In this work, we demonstrate a UV sensor based on vertically aligned TiO₂ nanowire arrays interconnected with ZnO nanosheets. The UV light sensing performance was investigated by integrating the nanostructure into a photoelectrochemical (PEC) cell. Benefiting from the fast transport paths of photoelectrons provided by the ZnO nanosheets, the PEC cell exhibits a super sensitivity and a fast responsivity. The on/off ratio is about 997 under a periodic UV irradiation of 25 mW cm⁻², and the short-circuit photocurrent density reaches 44.63 μA cm⁻², which is 70% and 59% higher than that of the bare TiO₂ nanowire arrays and TiO₂ nanoparticle films. The response and recovery times are also improved from 32.5 and 8.0 ms to 13.5 and 4.0 ms, respectively. This work provides an efficient strategy to improve the performance of electrochemical devices by building external electron transport paths in the working electrode.