Ultraviolet (UV) irradiation is dangerous and can cause serious skin diseases if skin is excessively exposed to it. Thus, it is highly desirable for human health to monitor the UV radiation intensity. In this report, a flexible and stretchable dual-response UV radiation detector is reported by integrating UV-responsive color-switchable WO3 quantum dots (QDs) with an electrical hydrogel. With the radiation intensity of UV increasing from 0.5 to 10 mW/cm2, the color of the hydrogel switched to dark blue gradually due to the excellent photochromic property of WO3 QDs to UV radiation. Furthermore, a linear relationship can be established between color difference and UV radiation intensity. Hence, the color difference of the hydrogel under solar UV irradiation can be used to estimate the solar UV radiation intensity in daily life. In addition, when the UV radiation intensity is greater than 10 mW/cm2, the photochromic hydrogel converts the colorimetric response into the electrical resistance change. Thus, due to its excellent photochromic and electrical resistance response properties for UV irradiation, the prepared hydrogel provides an idea for developing novel detection instruments.
A solid-state Z-scheme system, with the synergistic integration of the advantages of various narrow-band semiconductors, is considered to be a potential strategy to develop efficient photocatalysts for operation under visible light illumination. However, the charge separation efficiency of these systems has always been reduced by disordered electron transfer between coupling semiconductors. In this work, we constructed a direct Z-scheme system WO3-MoS2-Pt through the loading of WO3 quantum dots onto MoS2 nanosheets and the selective depositing of a Pt co-catalyst onto MoS2. X-ray diffraction, transmission electron microscopy, atomic electron microscopy and x-ray photoelectron spectroscopy, etc were used to confirm the successful preparation of the targeted photocatalyst. This photocatalytic system showed high visible-light-driven H2 evolution activity (802.2 μmol · h−1 · g−1) and good photostability. Control experiment and mechanism analysis suggested that the remarkable performance can be attributed to the heterojunction formed WO3 and MoS2 and the vectorial electron transfer (WO3 → MoS2 → Pt) achieved by selectively loading the Pt co-catalyst.
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