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Early fire warning represents an active and effective way to avoid potential fire hazards. The hydrogel-based temperature sensor shows high temperature sensitivity, flexibility, and flame retardancy, etc., which makes it an ideal candidate for early fire warning. Herein, we prepared double network (DN) SA-PAM-Fe hydrogels with sodium alginate (SA), acrylamide (AM) and FeCl 3 , and studied the influence of different water content and Fe3+ concentration on their sensing properties. The ion-conductive DN hydrogels are highly sensitive to temperatures, and the temperature sensitivity of SA-PAM-Fe hydrogels can reach a maximum of 1.28%/°C in the temperature range of 25–90 °C. This means that the SA-PAM-Fe hydrogel temperature sensor can be applied to monitor temperature changes with high resolution. The hydrogel sensor showed enhanced water retention performance with glycerol in SA-PAM-Fe hydrogel via solution replacement, because evaporation and crystallization of free water molecules in the hydrogel system could be suppressed by forming strong hydrogen bonds between glycerol and water molecules. Its maximum fluctuation of temperature sensitivity does not exceed 5.4% and 10% after 72 h preservation at room temperature and 24 h at 90 °C, respectively. The hydrogel sensor also exhibits excellent flame retardancy and flexibility due to the high water content. It is self-extinguished immediately as well as can be twisted, bent and lifted 500 g weight after being subjected to the flame. This work sheds light on the fabrication of self-extinguished and flexible temperature sensors for early fire warning. [ABSTRACT FROM AUTHOR]

Enhancement of light harvesting has been a persistent objective for elevating dye excitation and therefore power conversion efficiency of dye-sensitized solar cells (DSSCs). Here we launch a strategy of markedly enhancing light harvesting by caging TiO 2 nanoparticles with curved silica microsheets. The results show that the strategy is versatile in suppressing the recombination reaction of electrons with I 3 − species in liquid electrolyte. Due to the superior reflective behaviors of curved silica microsheets, an optimal efficiency of 9.22% is recorded under simulated air mass 1.5 global sunlight on the DSSC in comparison with 6.51% and 7.51% from pristine TiO 2 and planar silicate microsheet incorporated TiO 2 photoanode based solar cells, respectively. This strategy is also believed to be applicable to other solar cells such as perovskite solar cells and quantum dot-sensitized solar cells. [ABSTRACT FROM AUTHOR]