Structure-dependent biomorphology Co3O4-In2O3 nanorods for expired acetone gas sensor

Currently, the detection of acetone in exhaled breath is extensively utilized for the preliminary diagnosis of diabetes and for tracking fat oxidation in exercise. However, semiconductor gas sensors often require enhancement in breath analysis because of their inherent limitations in selectivity and sensitivity to humidity. In this research, we have synthesized an effective and humidity-unaffected acetone sensing material. This was achieved by utilizing the surface induction effect of porous biomass carbon derived from hemp stems to promote the dispersion of Co3O4-In2O3 heterostructure composites, thereby increasing the availability of active sites. This unique structure is achieved by precisely integrating the p-n heterostructure formed by Co3O4-In2O3 nanorods with the hierarchical porous carbon skeleton obtained via the calcination of templates. The p-n heterostructure enhances charge carrier concentration at the interface, thereby augmenting the activation of surface-active oxygen. The composite material's interface barrier improves sensor selectivity, reducing operating temperature (200 degrees C) and enhancing response rate. In this work, our best sample Coln-3/BC gas sensor exhibits excellent response towards acetone gas (S=Rair/Rgas=56.8 at 100 ppm), low detection limit of 10 ppb, a linear relationship between sensing response and humidity that strikes a balance between irrelevance as well as exceptional selectivity and stability. Therefore, constructing hierarchical structures and gas-sensing materials based on p-n heterojunctions holds promising prospects.