Unconventional ratiometric-enhanced optical sensing of oxygen by mixed-phase TiO2

TL;DR

This paper demonstrates that mixed-phase TiO2 can serve as an effective, low-cost, ratiometric optical sensor for oxygen, offering enhanced responsivity through the unique anti-correlated photoluminescence of rutile and anatase phases.

Contribution

The study introduces a novel use of mixed-phase TiO2 as a dual-emitting, ratiometric oxygen sensor with improved responsivity and practical advantages over traditional single-phase sensors.

Findings

Two-fold enhancement in optical responsivity using ratiometric approach

Effective oxygen sensing with low-cost, self-supporting TiO2

Anti-correlated PL responses enable improved measurement accuracy

Abstract

We show that mixed-phase titanium dioxide (TiO2) can be effectively employed as an unconventional, inorganic, dual-emitting and ratiometric optical sensor of O2. Simultaneous availability of rutile and anatase TiO2 PL and their peculiar anti-correlated PL responses to O2 allow using their ratio as measurement parameter associated to O2 concentration, leading to an experimental responsivity being by construction larger than the one obtainable for single-phase PL detection. A proof of this concept in given, showing a two-fold enhancement of the optical responsivity provided by the ratiometric approach. Besides the peculiar ratiometric-enhanced responsivity, other characteristics of mixed phase TiO2 can be envisaged as favorable for O2 optical probing, namely: a) low production costs, b) absence of heterogeneous components, c) self-supporting properties. These characteristics encourage experimenting its use for applications requiring high indicator quantities at competitive price, possibly also tackling the need to develop supporting matrixes that carry the luminescent probes and avoiding issues related to the use of different components for ratiometric sensing.