Visible light-assisted formaldehyde sensor based on HoFeO3 nanoparticles with sub-ppm detection limit

In order to realize effective detection of target gas without traditional heating condition, a strategy to detect gas assisted by light illumination has attracted more and more attention. Especially, visible light illumination brings opportunities and challenges for gas detection without heating condition. Herein, the formaldehyde (HCHO) sensing properties of HoFeO3 nanoparticles assisted by various light illuminations (lambda = 365-660 nm) are systematically investigated, and red light with 660 nm is proved to be the best assisting light for HCHO detection. The detection limit of light-assisted gas sensor toward HCHO can reach sub ppm level, which is about 80 ppb. Meanwhile, it can also achieve good anti-interference performance against environmental humidity, namely, the maximum drift of response value is 9 within the humidity range of 11%-75% RH. The low detection limit and outstanding anti-interference against humidity are ascribed to the increase of the activation energy between HCHO and surface adsorbed oxygen ions and the suppression of adsorbed water molecules, which are provided by the 660 nm light illumination.