Fast-Response Colorimetric UVC Sensor Made of a Ga2O3 Photocatalyst with a Hole Scavenger

Abstract

A fast-response colorimetric ultraviolet-C (UVC) sensor was demonstrated using a gallium oxide (Ga2O3) photocatalyst with small amounts of triethanolamine (TEOA) in methylene blue (MB) solutions and a conventional RGB photodetector. The color of the MB solution changed upon UVC exposure, which was observed using an in situ RGB photodetector. Thereby, the UVC exposure was numerically quantified as an MB reduction rate with the R value of the photodetector, which was linearly correlated with the measured spectral absorbance using a UV-Vis spectrophotometer. Small amount of TEOA in the MB solution served as a hole scavenger, which resulted in fast MB color changes due to the enhanced charge separation. However, excessive TEOA over 5 wt.% started to block the catalytical active site on the surface of Ga2O3, prohibiting the chemical reaction between the MB molecules and catalytic sites. The proposed colorimetric UVC sensor could monitor the detrimental UVC radiation with high responsivity at a low cost.

Impact of Al doping on a hydrothermally synthesized β-Ga2O3 nanostructure for photocatalysis applications

“…It is noted that this degradation of MB solution was not affected by the pH value in the range of 8.0 to 10.5. 50 Fig. 6(b) also shows the Al dopant effect on the redox potential, surface area, crystallographic defects, oxygen defects, and GB-induced defects, and their correlation with the photocatalytic activity.…”

Sunlight-Responsive Titania–Hydrated Tungsten Oxide Heteronanoparticles/Paper-Based Color-Switching Film for Solar Ultraviolet Radiation Monitors

“…Although ultraviolet (UV) radiation is essential for the production of vitamin D and beneficial for human health, excessive exposure to solar UV radiation has many associated risk factors, such as skin cancer and photoaging. , Since sunlight exposure is the major source of UV radiation in our daily life for humans, a smart UV sensor that can monitor real-time solar UV radiation in daily life is highly desired for warning people about harmful levels of solar UV radiation. − Tremendous efforts have been devoted to the development of UV sensors to monitor solar UV radiation in recent years. − For example, Zheng et al fabricated a UV sensor based on electrospun polycaprolactone fibers by doping with photochromic dyes or embroidering the photochromic core–sheath yarns . Xu et al developed a self-powered UV photodetector based on a p-CuZnS/n-TiO 2 nanotube array heterojunction equipped with a smartphone to detect ambient UV power density .…”