Highly selective detection of ppb-level formaldehyde realized by regulating the surface chemisorbed oxygen of Ga-doped In2O3 microspheres

• Published in: Journal of alloys and compounds 2025-01, Vol.1010, p.177201, Article 177201
• Main Authors: Liang, Qihua, Lin, Guotao, Gao, Junting, Li, Zequan, Feng, Qingge
• Format: Article
• Language: English
• Subjects: Fermi level regulation; Formaldehyde; Gas sensor; Surface chemisorbed oxygen
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.177201

Formaldehyde is a ubiquitous indoor pollutant. Developing metal oxide semiconductors gas sensors for selective ppb-level formaldehyde detection is challenging. Therefore, developing gas sensors that can selectively detect indoor formaldehyde at ppb levels is important. In this study, outer-walled thin sheet-like microspheres of Ga-doped In2O3 (GaxIn2-xO3, x = 0, 0.1, 0.2, 0.3, and 0.4) were fabricated using a facile two-step synthetic method. The Ga0.3In1.7O3 based sensor shows the response (556 ± 25) to 100 ppm formaldehyde at 80 °C, which is around 6.5 times that of the pure In2O3 based sensor at 90 °C. Furthermore, it has fast response time (< 3 s), excellent selectivity (SFormaldehyde/SEthanol = 160, SFormaldehyde/SAcetone = 267), good stability (at least 60 days), and ultra-low limit of detection (10 ppb) for formaldehyde at 80 °C. The improved formaldehyde sensing performance of Ga0.3In1.7O3 microspheres is attributed to the optimization of surface chemisorbed oxygen, which is caused by Ga doping regulating the Fermi level of In2O3 as well as an increase in the specific surface area. [Display omitted] •Ga-doped In2O3 microspheres with outer-walled thin sheet-like were fabricated by a facile two-step synthetic method.•The Ga0.3In1.7O3 based sensor demonstrates excellent selectivity and a low detection limit of 10 ppb for formaldehyde.•The enhanced response of Ga0.3In1.7O3 to formaldehyde can be attributed to the increase of surface chemisorbed oxygen.•The excellent selectivity can be primarily attributed to the regulation of the Fermi level in Ga-doped In2O3 microspheres.