Nanoscale Bimetallic AuPt-Functionalized Metal Oxide Chemiresistors: Ppb-Level and Selective Detection for Ozone and Acetone

As the most widely used gas sensors, metal oxide semiconductor (MOS)-based chemiresistors have been facing great challenges in achieving ppb-level and selective detection of the target gas. The rational design and employment of bimetallic nanocatalysts (NCs) are expected to address this issue. In this work, the well-shaped and monodispersed AuPt NCs (diameter ≈ 9 nm) were functionalized on one-dimensional (1D) In2O3 nanofibers (NFs) to construct efficient gas sensors. The sensor demonstrated dual-selective and ppb-level detection for ozone (O3) and acetone (C3H6O) at different optimal working temperatures. For the possible application exploitation, a circuit was designed to monitor O3 concentration and provide warnings when the concentration safety limit (50 ppb) was exceeded. Moreover, simulated exhaled breath measurements were also carried out to diagnose diabetes through C3H6O concentration. The selective detection for O3 and C3H6O was further analyzed by principal component analysis (PCA). The drastically enhanced sensing performances were attributed to the synergistic catalytic effect of AuPt NCs. Both the "spillover effect" and the Schottky barrier at the interfaces of AuPt NCs and In2O3 NFs promoted the sensing processes of O3 and C3H6O.