RESUMO
The application of X-ray imaging in military, industrial flaw detection, and medical examination is inseparable from the wide application of scintillator materials. In order to substitute for lead, lower costs, and reduce self-absorption, organic-inorganic hybrid lead-free perovskite scintillators are emerging as a new option. In this work, novel (TEA)2Zr1-xTexCl6 perovskite microcrystals (MCs) were successfully synthesized by a hydrothermal method, with Te4+ doping, which leads to yellow triplet-state self-trapped excitons emission. The emission peak of (TEA)2Zr1-xTexCl6 located at 605 nm under X-ray excitation, which was applied to X-ray imaging, shows a clear wiring structure inside the USB connector. The detection limit (DL) of 820 nGyair/s for (TEA)2Zr0.9Te0.1Cl6 is well below the dose rate corresponding to a standard medical X-ray diagnosis is 5.5 µGyair/s. This work opens up a new path for organic-inorganic hybrid lead-free scintillators.
RESUMO
Lead halide perovskites are prospective candidates for CO2 photoconversion. Herein, we report copper-doped lead-free Cs2AgSbCl6 double perovskite microcrystals (MCs) for gas-solid phase photocatalytic CO2 reduction. The 0.2Cu@Cs2AgSbCl6 double perovskite MCs display unprecedented CO2 photoreduction capability with CO and CH4 yields of 412 and 128 µmol g-1, respectively. The ultrafast transient absorption spectroscopy reveals the enhanced separation of photoexcited carriers in copper-doped Cs2AgSbCl6 MCs. The active sites and reaction intermediates on the surface of the doped Cs2AgSbCl6 are dynamically monitored and precisely unraveled based on the in-situ Fourier transform infrared spectroscopy investigation. In combination with density functional theory calculations, it is revealed that the copper-doped Cs2AgSbCl6 MCs facilitate sturdy CO2 adsorption and activation and strikingly enhance the photocatalytic performance. This work offers an in-depth interpretation of the photocatalytic mechanism of Cs2AgSbCl6 doped with copper, which may provide guidance for future design of high-performance photocatalysts for solar fuel production.
RESUMO
Organic-inorganic hybrid perovskites have attracted extensive attention for potential memory applications because of their excellent properties, such as high charge carrier mobility and fast ion migration. Herein, the two-dimensional HAPbI4 perovskite with an octahedral structure and high stability was prepared by a facile solution method. Moreover, the resistive random access memory (RRAM) with the Ag/PMMA/HAPbI4/ITO structure has been successfully fabricated by spin coating and vacuum thermal evaporation. The as-prepared RRAM device based on HAPbI4 demonstrated superior resistive switching performance. The on/off ratio is as high as 105, and the corresponding retention of the device exceeds 10â¯000 s; furthermore, the RRAM device could be kept stable after being kept in the air for 24 weeks.
RESUMO
In response to calling for a sustainable and carbon-neutral economy, the conversion of CO2 to useful chemicals using the solar energy is a potential tactic to relieve the global energy dilemma and environmental issues, which has been a hot topic so far. Recently, the lead halide perovskites as novel photocatalysts have attracted researchers' interests. However, they generally encounter poor stability and lead toxicity, restricting their large-scale practical applications. Here, the lead-free Cs2TeX6 (X = Cl, Cl0.5Br0.5, Br, Br0.5I0.5, and I) perovskite microcrystals with strong stability were prepared and used to realize the CO2 photocatalytic reduction efficiently. The prepared Cs2TeBr6 microcrystals delivered stronger photocatalytic ability than many previously reported photocatalysts, with the CO and CH4 yields of 308.63 and 60.42 µmolg-1, respectively, under 3 h of illumination. The presented strategy in our work provides new ideas of designing and preparing efficient and practical CO2 reduction photocatalysts based on nonleaded and high-stability halide perovskites.
RESUMO
Latent fingerprints (LFPs) are important evidence in crime scenes and forensic investigations, but they are invisible to the naked eye. In this work, a novel fluorescent probe was developed by integrating a narrow-band-emitting green afterglow phosphor, SrGa12O19:Mn2+ (SGO:Mn), and ethyl cellulose (EC) for the efficient visualization of LFPs. The hydrophobic interactions between the powder and lipid-rich LFPs made the ridge structures more defined and easily identifiable. The background fluorescence of the substrates was completely avoided because of the time-gated fluorescence of the afterglow phosphor. All the three levels of LFP degrees were clearly imaged due to the high sensitivity. Moreover, the SGO:Mn-EC powder was highly stable in neutral, acidic, and alkaline environments. In addition, 60 day-aged LFPs were successfully visualized by the powder. All performances showed that this strategy for LFP recognition has merits such as low cost, non-destructive nature, reliability, superior universality, and legible details. Together, these results show the great application prospects of this powder in forensic identification and criminal investigation.
