CO gas-sensing properties and DFT investigation of pure and Co-modified MoO3 nanostructures: effect of solvent composition, deposition time, and cobalt concentration

• Published in: Journal of materials science. Materials in electronics 2024-04, Vol.35 (10), p.728, Article 728
• Main Authors: Ramírez, G. M., Correa, R., García, B., Olvera, Maria de la Luz, Vargas, C., Karthik, T. V. K.
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Casting; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cobalt; Cobalt oxides; Density functional theory; Deposition; Electrical properties; Functional groups; Grain size; Materials Science; Molybdenum; Molybdenum oxides; Molybdenum trioxide; Morphology; Optical and Electronic Materials; Oxide coatings; Solvents; Spray pyrolysis; Structural analysis; Thin films; X ray analysis
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-024-12501-y

In this study, thin films of pure and cobalt-modified molybdenum oxide (MoO 3 ) were deposited using nebulizing spray pyrolysis (NSP). The research delves into the influence of deposition times (30 and 60 mins), solvents (H 2 O and H 2 O/HCl), and cobalt modification (3 %wt and 6 %wt) on the structural, morphological, and electrical properties of the thin films. XRD and FTIR were employed for structural analysis, while SEM and AFM were used to examine morphology and topography. X-ray analysis revealed the predominantly amorphous state of most of the films, and FTIR allowed visualization of different functional groups of MoO 3 based on deposition time and dopant concentration. In addition, SEM revealed an increase in grain size with longer deposition times, and AFM demonstrates that the cobalt-modified films exhibited higher roughness than pure molybdenum oxide films. Pure MoO 3 films using H 2 O as a solvent showed the highest gas-sensing response to CO at 76%, followed by films modified with 6 wt% Co, which exhibited a sensing response of 66%. The cobalt-modified films exhibited a lower sensitivity response than pure films, attributed to the formation of cobalt oxide. The CO adsorption properties on multiple MoO 3 structures and Co 3 O 4 have been optimized and analyzed using density functional theory (DFT). The best absorption energy of CO onto the different phases of MoO 3 and Co 3 O 4 has been reported to contrast it with the experimental results. This study marks the first report on cobalt-modified molybdenum oxide films, combining theoretical and practical exploration for CO detection through spray pyrolysis and DFT.