Highly Responsive Pd-Decorated MoO3 Nanowall H-2 Gas Sensors Obtained from In-Situ-Controlled Thermal Oxidation of Sputtered MoS2 Films

Mobtakeri S., Habashyani S., Gur E.

ACS APPLIED MATERIALS & INTERFACES, vol.14, no.22, pp.25741-25752, 2022 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 14 Issue: 22
  • Publication Date: 2022
  • Doi Number: 10.1021/acsami.2c04804
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, EMBASE, INSPEC, MEDLINE
  • Page Numbers: pp.25741-25752
  • Keywords: thermal oxidation, RF-magnetron sputtering, MoO3, MoS2, H-2 gas sensor, gasochromism, OXIDE, TEMPERATURE, NANOSHEETS, NANOSTRUCTURES, LUBRICATION, EXFOLIATION, PERFORMANCE, DENSITY, GROWTH, WO3
  • Eskisehir Osmangazi University Affiliated: No


Among transition metal oxides, MoO3 is a promising material due to its layered structure and different oxidation states, making it suitable for different device applications. One of the methods used to grow MoO3 is radio frequency magnetron sputtering (RFMS), which is the most compatible method in industry. However, obtaining nanostructures by RFMS for metal oxides is challenging because of compact morphology film formation. In this study, alpha-MoO3 with vertical nanowalls is obtained by a two-step process; deposition of magnetron-sputtered MoS2 vertical nanowalls and postoxidation of these structures without changing the morphology. In situ transmittance and electrical measurements are performed to control the oxidation process, which shed light on understanding the oxidation of MoS2 nanowalls. The transition from MoS2 to alpha-MoO3 is investigated with partially oxidized MoS2/MoO3 samples with different thicknesses. It is also concluded that oxidation starts from nanowalls perpendicular to the substrate and lasts with oxidation of basal planes. Four different thicknesses of alpha-MoO3 nanowall samples are fabricated for H-2 gas sensors. Also, the effect of Pd deposition on the H-2-sensing properties of sensors is deeply investigated. An outstanding response of 3.3 x 10(5) as well as the response and recovery times of 379 and 304 s, respectively, are achieved from the thinnest Pd-loaded sample. Also, the gas-sensing mechanism is explored by gasochromic measurements to investigate the sensor behaviors under the conditions of dry air and N-2 gas as the carrier gas.