Deep exploration of factors affecting the selectivity of gas sensors

The gas sensing performance of Au@In₂O₃ under thermal and optical excitation conditions was systematically studied. • It reveals that the Fermi level follows different regulation rules under heating and illumination conditions. • Explains the physical essence of selective changes. Innovatively, the “selective dynamic regulation” model was proposed. Improving the selectivity of semiconductor based sensitive materials is a widely concerned topic in the field of gas sensors. However, due to the complexity of sensitive processes, there are still diverse opinions on the factors that affect selectivity. In this work, a series of experiments based on Au@In 2 O 3 nanospheres is designed to explore the important factors that affect selectivity. It is proposed that Fermi level is an important role in affecting sensor selectivity. Innovatively explained the essence of Fermi level changes under light driven and thermal driven conditions. A core-shell Au@In 2 O 3 nanosphere gas sensor with dual selectivity under different condition is reported. Under heating conditions, Au@In 2 O 3 nanosphere shows a super selectivity for 1-butanol and its sensitivity up to 170.7 towards 100 ppm 1-butanol at 190 °C. Under lighting conditions, Au@In 2 O 3 displays ultra-high selectivity to formaldehyde, and its sensitivity towards 100 ppm formaldehyde as high as 232.5 under 480 nm illumination. Under heating and lighting conditions, the variation of Fermi level follows different rules, leading to changes in selectivity. This work not only provides new ideas for the design of highly selective gas sensors, but also opens up new paths for the multi scenario application of sensors. Download: Download high-res image (120KB) Download: Download full-size image