Thin-walled $SnO_2$ nanotubes functionalized by nanocatalysts-based exhaled breath sensors

Abstract

The nanostructuring of metal oxide, which is one of the promising sensing materials, has been studied for in-creasing surface area, porosity, and productivity. With such nanostructuring as a sensing materials in mind, me-so-porous and hollow nanostructure is ideal design due to its high surface area and gas accessibility. On top of nanostructuring, consistent functionalization of nanocatalysts on sensing layers is also important issue. To achieve these key points, we here report synthesis of thin-walled $SnO_2$ nanotubes (NTs), and meso (2-50 nm) and macro (>50 nm) size pores loaded thin-walled $SnO_2$ NTs functionalized by bio-inspired Pt nanocatalysts (Pt-PS_$SnO_2$ NTs). Due to its high gas accessibility and optimized catalytic effect, they exhibited high sensitivity ($R_{air}/R_{gas$} = 192 @ 5 ppm acetone), excellent selectivity, and great limit of detection (10 ppb acetone). Very im-portantly, sensor arrays assembled with PS_$SnO_2$ NTs, Pt-PS_$SnO_2$ NTs and Pt-$SnO_2$ NTs enable the directly discrimination between the simulated diabetic patients and healthy people in their breath.