Visible Light Assisted Gas Sensing with TiO2 Nanowires

TL;DR

This study demonstrates that TiO2 nanowire chemiresistors can detect gases under visible light illumination due to doping-induced photoactivity, combining light harvesting and sensing in a single nanostructure.

Contribution

It introduces visible light-assisted gas sensing using doped TiO2 nanowires, highlighting their photoactivity and potential for integrated sensing and light harvesting.

Findings

Gas sensing response is enhanced under visible light illumination.

Doping with C/N creates states enabling visible light photoactivity.

TiO2 nanowires show promise for combined light harvesting and gas sensing.

Abstract

Sensing response of individual single-crystal titania nanowires configured as chemiresistors for detecting reducing (CO, H2) and oxidizing (O2) gases is shown to be sensitive to visible light illumination. It is assumed that doping of the TiO2 nanowires with C and/or N during carbon assisted vapor-solid growth creates extrinsic states in the band gap close to the valence band maximum, which enables photoactivity at the photon energies of visible light. The inherently large surface-to-volume ratio of nanowires, along with facile transport of the photo-generated carriers to/from the nanowires surface promote the adsorption/desorption of donor/acceptor molecules, and therefore open the possibility for visible light assisted gas sensing. The photo-catalytic performance of TiO2 nanowire chemiresistors demonstrates the prospect of combining light harvesting and sensing action in a single nanostructure.