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

Abstract

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.

Exploring SnxTi1−xO2 Solid Solutions Grown onto Graphene Oxide (GO) as Selective Toluene Gas Sensors

“…Nevertheless, also in this case, the operating temperature with the highest response is 350 • C [26]. Moreover, Kim et al [34] reported exceptional toluene sensing properties of novel SnO 2 /ZnO core-shell nanowires, functionalized with Pt nanoparticles, showing an excellent R air /R analyte intensity response to 100 ppb at 300 • C. Remarkably, as sticks out, the majority of the most promising reported sensor materials achieve the best performances only at high operating temperatures, especially above 250-300 • C [26,34].…”

Highly sensitive NO2 sensors based on core‐shell array of silicon nanowires/polypyrrole and new insight into gas sensing mechanism of organic/inorganic hetero‐contact

“…Jae-Hun et al ever reported that the CuO-ZnO C-S nanowires sensor showed the highest response to CO and C 6 H 6 at a shell thickness close to Debye length (λ D ) of ZnO [32]; while according to the investigation from Park et al, the critical thickness for the shell in In 2 O 3 -ZnO C-S nanowires sensor was very close to 2λ D of ZnO [33]. The sensing mechanism of these metal oxide C-S structures has been demonstrated with several models such as the potential barrier-controlled carrier transport and the radial modulation effect in the electrondepleted shell [34][35][36][37][38]. For LNWs/PPy C-S nanowires sensors in this work, different correlation between gas response and shell thickness is revealed.…”

Atomic Layer Deposition to Materials for Gas Sensing Applications

“…Most of the structures reported in the literature are based on ALD of n‐type ZnO thin films deposited onto n‐type metal oxide nanostructures, such as NWs, NRs, and fibers. Core–shell materials have been fabricated by combining ALD with either ES,[48,56b,62,63,67] thermal evaporation,[56f,64,65,68,74,75] vapor–liquid–solid (VLS),[56a,81] or hydrothermal synthesis. An enhancement of sensitivity has been noted when a CS material was used instead of a pure material.…”

“…Metal oxides nanostructures fabricated by ALD were also decorated with metal particles, from wet impregnation processes or attachment of preformed nanoparticles. For instance, γ‐ray radiolysis was used to functionalize SnO 2 ‐core/ALD ZnO‐shell NWs with Pt NPs . The Pt‐CS NWs enabled trace detection of toluene vapor, showing unprecedented sensitivity to 100 ppb.…”