Highly sensitive formaldehyde gas sensor based on SnO2/Zn2SnO4 hybrid structures

Formaldehyde, a common indoor air pollutant emitted from building decoration materials, poses a significant health hazard, potentially leading to cancer. Therefore, developing a gas sensor capable of real-time monitoring of indoor formaldehyde concentration is essential. Herein, a metal oxide semiconductor gas sensor with SnO2/Zn2SnO4 hybrid structure as the sensitive material has been successfully fabricated. The sensor exhibits the ability to detect formaldehyde down to 50 ppb, meeting the safety concentration limit proposed by the World Health Organization (WHO). Additionally, it displays rapid response characteristics, with a response time of 84 seconds and a recovery time of 46 seconds for 50 ppb of formaldehyde at 200 °C, respectively. Moreover, the sensor demonstrates good selectivity and long-term stability, making it promising for real-time monitoring of indoor air pollutants. Furthermore, the evolution process of intermediates in the sensing reaction was investigated by in-situ diffuse reflaxions infrared fourier transformations spectroscopy, providing a comprehensive understanding of the surface chemistry. This in-depth comprehension offers valuable insights into the mechanisms underlying formaldehyde sensing.