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Integrating responsive photonic crystals (RPCs) and quantum dots (QDs) effectively to realize multimode dynamic color regulation is of great significance for promoting advances in color display science. Herein, a new type of flexible dynamic color display with multimode reversible switching between transparent and colorful states based on the combination of RPCs and CdTe QDs is designed. This unique system is fabricated by encapsulating a thin layer of ordered arrays of SiO2@CdTe@SiO2 (SQS) colloids with poly(dimethylsiloxane) (PDMS), which generates an elastic film with sandwiched structure of PDMS/SQS/PDMS. Owing to the similarity in the optical properties of PDMS and SQS, the display is highly transparent in the normal state. Moreover, the resultant flexible display exhibits obvious change in color by mechanical stimuli or UV exposure. Finally, the ability to display joints motion amplitudes of human body as well as the applications in advanced security is demonstrated. [ABSTRACT FROM AUTHOR]

The high porosity of the three-dimensional ordered macroporous structure of inverse opal photonic crystals (IOPCs) provides an ideal platform for gas sensing based on metal oxide semiconductors. Herein, Pt cluster-loaded In2O3 IOPCs were fabricated, and displayed a significantly improved response to ethanol. Various characterization techniques were used to verify the successful preparation of Pt cluster-loaded In2O3 IOPCs. In2O3 IOPCs exhibit closely arranged three-dimensional (3D) ordered macroporous structures, which contain periodic voids with an average diameter of about 150 nm and a uniform wall thickness of 20 nm. Their gas sensing performance is significantly improved at a Pt cluster loading of 2.0 wt%. Gas sensor tests showed that Pt cluster-loaded In2O3 IOPC sensors exhibited an excellent ethanol response (Ra/Rg = 103 to 50 ppm at 240 °C), which was more than 5 times higher than the response of pure In2O3 IOPCs. The sensor also demonstrated an ultra-fast response/recovery time (7/9 s), impressive selectivity, reproducibility, and long-term stability. The significantly enhanced sensing performance of Pt cluster-loaded In2O3 IOPCs is attributed to the synergistic effects of the connected 3D ordered macroporous structure, chemical and electronic sensitization of Pt nanoparticles, and p–n heterojunctions between p-type PtO, p-type PtO2 and n-type In2O3. The present findings are expected to provide enlightening insights into the design and fabrication of gas sensors with an ultra-high response and an ultra-fast response/recovery speed. [ABSTRACT FROM AUTHOR]

CH4 sensors based on metal oxide semiconductors (MOS) provide high sensitivity and fast response, but the sensitivity will be lost when they are poisoned by silicone. Therefore, there is an urgent need to address the poisoning deactivation of MOS gas sensors caused by silicone. Here, the unique strategy of coating a reactive anti-poisoning material onto the surface of the sensing material is proposed to effectively improve the anti-poisoning ability without degrading the gas sensing performance. As an experimental verification, SnO2/α-Al2O3 is designed as the anti-poisoning layer and SnO2 loaded with precious metals (Pt and Pd) as the sensing layer. Owing to the protection of the anti-poisoning layer, the response (Ra/Rg = 24.69) and the response/recovery time (1/24 s) of the sensor to CH4 remained undiminished at 364 °C after being poisoned under an air/hexamethyldisiloxane (HMDSO) (10 ppm) environment for 40 min, which meets the requirements of the Chinese National Standard (GB 15322.2-2019). The mechanism analysis shows that HMDSO can be decomposed with the adsorbed oxygen on the surface of SnO2 in the anti-poisoning layer, and CH4 can diffuse into the sensing layer to be detected. The unique anti-poisoning strategies can provide a promising insight for improving the poisoning tolerance of MOS gas sensors. [ABSTRACT FROM AUTHOR]