Colorimetric oxygen sensor based on nano-sized black TiO2 catalysts: DFT modeling and experiments

초록

There are the imperious demands for novel oxygen (O-2) sensors in cutting-edge biochemical technologies and industrial hygiene. Here, we develop a colorimetric O-2 sensor based on a spherical nano-sized reduced TiO2 (TiO2 - x) catalyst, which resolves the critical bottlenecks of conventional systems. The sensing mechanism of our O-2 sensors relies on two characteristics which are proven by simulations based on density functional theory (DFT) calculations. First, nano-TiO2-x, in the partially reduced form, shows a rapid, reversible O-2 uptake at room temperature. Second, the partially reduced form of nano-TiO2-x called black TiO2, shows a change in the lightness of color. Owing to these characteristics, the developed sensor it is well-suited for use at ambient temperature/pressure in the absence of a reference gas, in contrast with the conventional system. Also, it allows long-term operations and it can withstand degradation because the former comprises solid-state inorganic compounds.

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