Building adsorption-segregated sites of gas molecules for sensitive xylene detection

Reasonably engineering the adsorption and excitation sites of oxygen and target gas molecules for expected sensing properties of semiconductor metal oxides (SMO) is still challenging. Here, we proposed a gas-segregated strategy involving spatially-separated Ir and W5+-Vo sites to respectively provide specific adsorption and excitation zones of oxygen and target gas molecules for sensitive xylene detection. We find that the introduced Ir sites can induce O2 adsorption and enhance the reactive oxygen species formation through spillover effects, while W5+-Vo sites tend to drive the target xylene molecules aggregation along the supported WO3 surface, and thus synergistically promote the sensing property. This process can be experimentally confirmed by NAP-XPS, ex situ XPS, in situ Raman and theoretical calculations results. The final Ir-c-WO3 sensor exhibits high response ability towards xylene (1-100 ppm) at 180 °C operating temperature, fast response/recovery speed (2.9s/18s @ 15 ppm) and excellent selectivity. Our study thus provides a valid method for xylene detection and opens up a new perspective for the construction of macromolecular active gas sensing materials.