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

Abstract

Excessive exposure to ultraviolet (UV) rays in sunlight is harmful to human skin. The development of an intelligent UV monitor that can detect the solar UV intensity in real time is highly desirable for human health and safety. In this work, a sunlight-responsive paper-based color-switching film (PCSF) is developed by combining color-switchable titania/hydrated tungsten oxide (THTO) heteronanoparticles with a sticker paper substrate. The THTO heteronanoparticles with an average size of 10 nm are distributed tightly on the surface of the paper substrate. Owing to the advantages of the excellent sensitivity and selectivity to solar UV radiation of THTO heteronanoparticles and the high flexibility of the paper substrate, the PCSF shows great potential for solar UV radiation monitors. With the solar UV intensity increasing from 0.75 to 3.25 mW•cm −2 , the color of PCSF changes from colorless to blue and even dark blue. Moreover, the color change of the PCSF under solar UV irradiation featuring 40 s is calibrated to indicate the solar UV radiation intensity. Taking the advantage of the excellent sensitivity and selectivity to solar UV radiation, high reversibility, flexibility, and low cost, we further demonstrate the application of the PCSF as a reusable wristband for smart solar UV radiation monitors. This work provides a way for solar UV radiation monitors that could provide naked-eye monitoring of real-time personal solar UV radiation.

Bismuth Oxychloride Nanoflakes Enabled High Sensitivity Colorimetric UV Dosimetry

“…However, it requires other instruments such as a mobile app to quantify the dosage and that are expensive at $30 for a single sensor. Two paper-based colorimetric UV sensors were fabricated using phosphomolybdic acid (PMA)/citric acid and titania–hydrated tungsten oxide (THTO) . These colorimetric UV sensors provide a great UV response to UVA and UVB; however, their largest pitfall is their maximum exposure.…”

“…Two paper-based colorimetric UV sensors were fabricated using phosphomolybdic acid (PMA)/ citric acid 52 and titania−hydrated tungsten oxide (THTO). 53 These colorimetric UV sensors provide a great UV response to UVA and UVB; however, their largest pitfall is their maximum exposure. The PMA/citric acid sensor reported a maximum exposure time of 120 s, while the THTO sensor reported a maximum exposure of 60 s. These short maximum exposure times severely limit the applications of these sensors.…”

Chelating Coordination Regulated Photochromic Electrospun Nanofibers for Waterproof and Long-Color-Retention Rewritable Wearables

“…1−5 Compared with organic materials, TMOs are preferable for photochromic wearables because of their higher thermal stability, strength, and chemical resistance. 6,7 Thus, various TMOs, such as molybdenum oxide (MoO 3 ), 8−10 vanadium oxide (V 2 O 5 ), 11,12 zinc oxide (ZnO), 13,14 and cobalt oxide (CoO), 15,16 have been employed in constructing photochromic materials. Despite its super stability, the color-switching of MoO 3 needs the assistance of strong oxidizing agents.…”

“…Photochromic wearables, generally consisting of fibrous materials incorporated with organic materials, inorganic transition metal oxides (TMOs), or their hybrid, have attracted tremendous attention for future rewritable ink-free media owing to their fast color-switching rates, superior reversibility, and high fatigue resistance. − Compared with organic materials, TMOs are preferable for photochromic wearables because of their higher thermal stability, strength, and chemical resistance. , Thus, various TMOs, such as molybdenum oxide (MoO 3 ), − vanadium oxide (V 2 O 5 ), , zinc oxide (ZnO), , and cobalt oxide (CoO), , have been employed in constructing photochromic materials. Despite its super stability, the color-switching of MoO 3 needs the assistance of strong oxidizing agents .…”

Kinetic Studies of WO3-Based Photochromism in Polyvinyl Alcohol Film

“…Especially, the electrochromism of WO 3 has been widely studied for smart windows to modulate the near infrared (NIR) solar radiation, which is considered as a promising technology to save energy in buildings. − Transparent indium tin oxide electrodes coated with amorphous WO 3 or hexagonal sodium tungsten bronze nanorods turned blue when cathodic potentials were applied. Transmittance of those electrodes was high at 400–520 nm, and their absorption was extended to the NIR range. , On the other hand, photochromic behaviors of WO 3 have been extensively studied for applications as information storage media, color sensor, nanoinks, and UV monitors. ,− Various forms of WO 3 such as colloidal nanoparticles, powders, small disks prepared by pressing powders, thin films on glasses or fibers and nanosheets have been investigated for various applications. In the case of opaque solid samples, the color change to blue under light irradiation has been studied by measuring diffuse reflectance spectra using an integrating sphere.…”