Dual sensitization of three-dimensional ordered macroporous Co3O4 thin films with Pt/Rh for enhanced NO2 detection

• Published in: Sensors and actuators. B, Chemical Chemical, 2023-09, Vol.390, p.133876, Article 133876
• Main Authors: Pan, Hongyin, Yang, Chen, Zheng, Wei, Liu, Xianghong, Wan, Yong, Zhang, Jun
• Format: Article
• Language: English
• Subjects: Co3O4; Gas sensor; Humidity resistance; NO2; Thin films
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.133876

Metal oxide semiconductor (MOS) gas sensors currently still suffer from a challenge to achieve high response in humid environment. In this work, a gas sensor based on porous Co3O4 thin films decorated by dual Pt/Rh catalysts is demonstrated for efficient NO2 detection with high humidity-resistivity. The porous Co3O4 thin films with three-dimensional ordered microstructure are synthesized by sacrificial template method. The loading of Pt/Rh catalysts by atom layer deposition (ALD) not only improve the detection sensitivity but also improve the moisture resistance of the sensor. ALD of Pt is proved to have a crucial effect on the sensor response. The Co3O4/Pt sensor with optimized Pt loading exhibits a response of 9.74–10 ppm NO2 at 145 °C, which is nearly 5 times higher than that (2.04) of pristine Co3O4 sensor. Further ALD of Rh on Co3O4/Pt enables the sensor to have a stable response even under 90% relative humidity. With optimized ALD Pt (15 cycles) and Rh (10 cycles), the sensor can well detect 0.5–10 ppm NO2 with fast response/recovery speed, as well as a low detection limit of 49 ppb. The strategy reported herein will pave the way to the development of new sensing materials and devices. •Porous Co3O4 thin films are synthesized on interdigital electrodes by sacrificial template method.•Dual-catalysts of Pt and Rh are deposited on Co3O4 thin films by atomic layer deposition.•Pt and Rh greatly improve the gas response and humidity tolerance of Co3O4 thin film sensor towards NO2 detection.