Although Ti3C2Tx MXene is a promising material for many applications such as catalysis, energy storage, electromagnetic interference shielding due to its metallic conductivity and high processability, it’s poor resistance to oxidation at high temperatures makes its application under harsh environments challenging. Here, we report an air-stable Ti3C2Tx based composite with extracted bentonite (EB) nanosheets. In this case, oxygen molecules are shown to be preferentially adsorbed on EB. The saturated adsorption of oxygen on EB further inhibits more oxygen molecules to be adsorbed on the surface of Ti3C2Tx due to the weakened p-d orbital hybridization between adsorbed O2 and Ti3C2Tx, which is induced by the Ti3C2Tx/EB interface coupling. As a result, the composite is capable of tolerating high annealing temperatures (above 400 °C for several hours) both in air or humid environment, indicating highly improved antioxidation properties in harsh condition. The above finding is shown to be independent on the termination ratio of Ti3C2Tx obtained through different synthesis routes. Utilized as terahertz shielding materials, the composite retains its shielding ability after high-temperature treatment even up to 600 °C, while pristine Ti3C2Tx is completely oxidized with no terahertz shielding ability. Joule heating and thermal cycling performance are also demonstrated.

The trade-off between light absorption and carrier transport in semiconductor thin film photoelectrodes is a major limiting factor of their solar-to-hydrogen efficiency for photoelectrochemical water splitting. Herein, we develop a heterogeneous doping strategy that combines surface doping with bulk gradient doping to decouple light absorption and carrier transport in a thin film photoelectrode. Taking La and Mg doped Ta3N5 thin film photoanode as an example, enhanced light absorption is achieved by surface La doping through alleviating anisotropic optical absorption, while efficient carrier transport in the bulk is maintained by the gradient band structure induced by gradient Mg doping. Moreover, the homojunction formed between the La-doped layer and the gradient Mg-doped layer further promotes charge separation. As a result, the heterogeneously doped photoanode yields a half-cell solar-to-hydrogen conversion efficiency of 4.07%, which establishes Ta3N5 as a leading performer among visible‐light‐responsive photoanodes. The heterogeneous doping strategy could be extended to other semiconductor thin film light absorbers to break performance trade-offs by decoupling light absorption and carrier transport.

Fluorescence intensity ratio (FIR) thermometry, a new contactless temperature measurement, can achieve accurate measurements in a harsh environment. In this work, all-inorganic lead-free Cs 2 AgInCl 6 : Er−Yb and Cs 2 AgBiCl 6 : Er−Yb microcrystals emit bright green up-conversion emission, which are synthesized by precipitation at a low temperature (80 °C). In up-conversion emission, FIR of the 2 H 11/2 → 4 I 15/2 band to the 4 S 3/2 → 4 I 15/2 band exhibits temperature dependence, which can be used as the temperature measurement parameter, so-called FIR thermometry. Moreover, the theoretically accurate measurement range is from 100 to 600 K, achieving maximum absolute sensitivities from 0.0130 to 0.0113 K −1 , respectively. The principle of up-conversion and high sensitivity is well explained by calculating the partial density of states. Compared to the reported thermometry materials based on the FIR method, the prepared all-inorganic lead-free Cs 2 AgInCl 6 : Er−Yb and Cs 2 AgBiCl 6 : Er−Yb microcrystals show outstanding temperature measurement width and sensitivity, becoming a potential candidate for high-sensitivity optical temperature sensors.

Low-dimension perovskite materials have attracted wide attention due to their excellent optical properties and stability. Herein, Sb 3+ -doped Cs 2 ZrCl 6 crystals are synthesized by a coprecipitation method in which Sb 3+ ions partially replace Zr 4+ ions. The Cs 2 ZrCl 6 :xSb 3+ powder shows blue and orange−red emissions under a 254 and 365 nm light, respectively, due to the [ZrCl 6 ] 2− octahedron and [SbCl 6 ] 3− octahedron. The photoluminescence quantum yield (PLQY) of Cs 2 ZrCl 6 :xSb 3+ (x = 0.1) crystals is up to 52.5%. According to experimental and computational results, the emission mechanism of the Cs 2 ZrCl 6 :xSb 3+ crystals is proposed. On the one hand, a wide blue emission with a large Stokes shift is caused by the self-trapping excitons of [ZrCl 6 ] 2− octahedra under a 260 nm excitation. On the other hand, the luminescence mechanism of [SbCl 6 ] 3− octahedron is divided into two parts: 1 P 1 → 1 S 0 (490 nm) and 3 P 1 → 1 S 0 (625 nm). The broad-band emission, high PLQY, and excellent stability endow the Cs 2 ZrCl 6 :xSb 3+ powders with the potential for the fabrication of white light-emitting diodes (WLEDs). A WLED device is fabricated using a commercial 310 nm NUV chip, which shows a high color rendering index of 89.7 and a correlated color temperature of 5333 K. In addition, the synthesized Cs 2 ZrCl 6 :xSb 3+ crystals can be also successfully used for information encryption. Our work will provide a deep understanding of the photophysical properties of Sb 3+ -doped perovskites and facilitate the development of Cs 2 ZrCl 6 :xSb 3+ crystals in encrypting multilevel optical codes and WLEDs.