Search

Portable sensors with high selectivity and sensitivity are essential for ammonia detection. In this work, a colorimetric sensor based on non-close-packed photonic crystals (NPCs) was developed for visual monitoring of ammonia, which had great selectivity, stability, and durability. The initial structural color of the NPCs was customized in the entire color range by tuning the PMMA concentration and acrylamide (AM) content. Ethylene glycol-NPCs (EG-NPCs) with a softer texture were obtained by swelling of the NPCs in 5% glycerol & 30% ethylene glycol solution, and the reflective peak of the EG-NPCs with 50 mg mL−1 AM shifted from 459 nm to 626 nm. Besides, the abundant hydroxyl groups in the EG-NPCs can form hydrogen bonds with ammonia, resulting in a greater decrease in the lattice distance. The reflective peak of the EG-NPCs blue shifted from 626 nm to 482 nm when the ammonia concentration increased from 0 μL cm−3 to 0.12 μL cm−3, and the δλ = 144 nm, which realized colorimetric sensing in the entire visible color range. The excellent selectivity, stability, and durability of the colorimetric sensors make it possible to sense ammonia in the air, which is critical for the safe production of chemical plants, farms, and other key sites. [ABSTRACT FROM AUTHOR]

Theoretical calculations and numerical simulations play a crucial role in analyzing material properties and devising effective research strategies. In this study, the photonic band gap (PBG) of polymethyl methacrylate (PMMA) and polystyrene (PS) photonic crystals was successfully predicted using theoretical calculations and numerical simulations. The agreement between the predicted results and the actual reflection peaks reached an impressive level of 99%. Utilizing SEM images, the prediction of reflection peaks in acrylamide (AM)—based photonic hydrogels was conducted using theoretical formulas and Rsoft 2019–Bandsolve software v2019.09. The relationship between the actual reflection peaks and compressive strains in AM-based photonic hydrogels featuring 251 nm PMMA PCs exhibited a remarkable similarity of over 96% with the theoretical and simulated results. In conclusion, an exploration was conducted into the relationship between reflection peaks and compressive strains for AM-based 270 nm PMMA photonic hydrogels, allowing the prediction of the actual reflection peaks under compression. The consistency observed between theoretical/simulated reflection peaks and actual reflection peaks validates the efficacy of this approach in evaluating the optical properties of photonic materials and predicting their responsive effects. This method offers a straightforward and expeditious solution for the design and fabrication of photonic materials. [ABSTRACT FROM AUTHOR]

In response to growing concerns about public safety and environmental conservation, it is essential to develop a precise identification method for trace explosives. To improve the stability and detection sensitivity of perovskite quantum dots (PQDs) and address the issue of low porosity in traditional polymer-based photonic crystals (PhCs), this study proposed a PQD photoluminescence (PL) enhancement strategy based on the slow light effect of ZIF-8 PhCs for highly sensitive, selective, and convenient detection of 2,4,6-trinitrophenol (TNP). The slow light effect at the photonic band gap edge is the basis of amplifying the PL signal. PhCs were fabricated by the evaporation-induced self-assembly method. The diffraction wavelength overlapping the whole visible region was designed to match the emission wavelength of PQDs. Results showed that PhCs matching the PBG edge with PQDs' emission peak amplified the PL signal 11.3 times, significantly improving sensitivity for trace TNP detection with a limit as low as 2.52 nM. Moreover, there was a 13.3-fold enhancement of PQDs' fluorescence lifetime when the emission wavelength fell in the PBG range. The hydrophobic surface of ZIF-8 PhCs enhanced the PQDs' stability and moisture resistance. Furthermore, the selective quenching mechanism of TNP by the sensor was photoinduced electron transfer (PET) verified by DFT calculations and time-resolved PL decay dynamics measurements. This study demonstrated great potential for manipulating light emission enhancement by PhCs in developing efficient fluorescent sensors for trace environmental pollutant detection.