Fast-responding ethanol sensor with extremely low detection limit: Influence of Pt film thickness on gas sensing properties
Jae Han Chung, Eunsol Lee, Junho Hwang, Junha Park, Seungjong Hwang, Dongwook Youm, Dohyeon Shin, Ki Chang Kwon, Soonmin Yim, Wooyoung Lee, Donghwi Cho, Kwangjae Lee, Young-Seok Shim
Abstract
• Fabrication of uniform, scalable In 2 O 3 nanorods decorated with Pt nanoparticles via glancing angle deposition (GLAD). • Optimizing Pt NP size and distribution for ethanol sensing by tuning In 2 O 3 NR form factors and Pt NP thickness ~2 nm. • Demonstrating ethanol detection limits of 0.42 ppb (dry air) and 6.1 ppb (80% RH at 450 °C) with mechanism studies. To facilitate alcohol detection in exhaled breath, high-performance gas sensors capable of rapidly responding to low-concentration target gases in highly humid environments are required. In this study, we developed In 2 O 3 nanorods (NRs) decorated with Pt nanoparticles (NPs) to improve selective C 2 H 5 OH detection under dry and 80 % relative humidity (RH) conditions. Using glancing angle deposition (GLAD), we fabricated In 2 O 3 NRs with Pt film of varying film thicknesses (0.5, 1, and 2 nm), which transformed to NPs after the subsequent annealing process, to systematically identify the optimal Pt NPs size and distribution. Optimized In 2 O 3 NRs with an initial Pt thickness of 1 nm exhibited the highest ethanol response at 450 °C, with a theoretical detection limit (DL) calculated to be 0.42 parts per billion (ppb) in dry air and 6.1 ppb under 80 % RH. This enhanced performance is attributed to the expansion of the electron depletion layer (EDL) due to Schottky barrier formation at the Pt- In 2 O 3 interface, alongside a spillover effect that enhances gas adsorption and reaction on the In 2 O 3 surface, where Pt NPs contribute both electronic and chemical sensitization effects. These findings indicate that In 2 O 3 NRs with Pt NPs are promising candidates for next-generation ignition interlock devices (IIDs), offering high selectivity, rapid response times, and stability in high-humidity environments.