Realization of ppb-Scale Toluene-Sensing Abilities with Pt-Functionalized SnO2-ZnO Core-Shell Nanowires.

In this paper, we report the exceptional toluene-sensing properties of SnO2-ZnO core-shell nanowires (C-S NWs) functionalized with Pt nanoparticles (NPs). A response of 279 was obtained for 100 ppb of toluene, and to the best of our knowledge, this is the highest toluene response to be reported in the literature. The SnO2-ZnO C-S NWs were synthesized via a two-step process: First, a networked core of SnO2 nanowires was prepared via vapor-liquid-solid growth on the patterned electrode layer. Second, the ZnO shell layers were created with atomic layer deposition. The electron-depleted region of the shell layer was further expanded by attaching Pt NPs, which were synthesized using γ-ray radiolysis, to the shell layer. In addition to the expansion of the electron-depleted region, the catalytic effect of Pt on toluene greatly improved the toluene-sensing performance of the C-S NWs. The extraordinary toluene-sensing ability of the Pt-functionalized C-S NWs means they have great potential as the sensing platform in exhaled breath sensors to detect ppb-scale toluene.