Graphical Lead halide perovskite has triggered a lot of research due to its superior optical properties. However, halide perovskite materials have poor environmental stabilities and are easily affected by external factors such as water and heat, resulting in structural decomposition and performance failure. Contrary to this commonplace concept, CsPbBr 3 can convert to CsPb 2 Br 5 partially when meeting a small amount of water, and the CsPbBr 3 @CsPb 2 Br 5 composite is synthesized by an in situ method accordingly. The CsPbBr 3 @CsPb 2 Br 5 composite shows an enhanced catalytic performance compared with pure CsPbBr 3 , as well as a dramatically synergistic effect of photo and thermal for catalytic CO 2 hydrogenation. Lead halide perovskite has triggered a lot of research due to its superior optical properties. However, halide perovskite materials have poor environmental stabilities and are easily affected by external factors such as water and heat, resulting in structural decomposition and performance failure. Contrary to this commonplace concept, it is found that CsPbBr 3 (CPB) can convert to CsPb 2 Br 5 (CP2B5) partially when meeting a small amount of water, and the CsPbBr 3 @CsPb 2 Br 5 (CPB@CP2B5) composite is synthesized by an in situ method accordingly. The CPB@CP2B5 composite shows an enhanced catalytic performance compared with pure CPB, as well as a dramatically synergistic effect of photo and thermal for catalytic CO 2 hydrogenation. The CO production rate of CPB@CP2B5 is determined as 69 μmol g −1 h −1 under light irradiation at 200 °C, which is 156.8 and 43.4 times higher than that under pure photo (0.44 μmol g −1 h −1 ) and pure thermal (1.59 μmol g −1 h −1 ) condition, respectively. Meanwhile, the CPB@CP2B5 sample is also stable, which shows no significant decline in the catalytic activity during 8 cycles of repeated experiments. The probable mechanism is explored by utilizing a series of in situ characterizations.
All-inorganic cesium lead halide perovskite CsPb2Br5 nanocrystals (NCs) have attracted tremendous attention owing to their unique optoelectronic properties. However, their tolerance to atmospheric moisture is limited by their corresponding poor stability, which has drastically prevented the broad application of the materials in lasers, light-emitting diodes (LED) and, most recently, photocatalysis. To address this issue, we have successfully demonstrated the design and synthesis of a nanocomposite material, CsPb2Br5 NCs coated in mesoporous silica (NCs-MS), with high photoluminescence (PL) intensity, bright emission and enhanced water stability, thermal stability and photostability versus naked CsPb2Br5 NCs. The components and structure of the prepared CsPb2Br5 NCs-MS nanocomposite were investigated in detail by PL, XRD, TEM and HAADF-STEM studies. Furthermore, the mechanism behind the outstanding stability and optical properties of the prepared NCs-MS nanocomposite is discussed. Owing to the ultrahigh stability of the NCs-MS nanocomposite, the white LED (WLED) assembled by coating the CsPb2Br5 NCs-MS nanocomposite and commercial red CaAlSiN3:Eu2+ phosphor powder on an InGaN blue chip showed CIE chromaticity coordinates of (0.3377, 0.3309) and presented excellent optical parameters with a CRI of 82.9, a CCT of 5035 K and an LE of 64.9 lm W−1. This work provides a new pathway for the synthesis and application of all-inorganic cesium lead halide perovskite materials in WLEDs and display devices.
Mian Zhang,Hongbo Li,Qiang Jing,Zhenda Lu,Peng Wang
Recent microstructural studies on lead halide perovskite nanocrystals have consistently reported the coexistence of byproduct nanoparticles (NPs). However, the nature of these NPs and their formation mechanism are still a matter of debate. Herein, we have investigated the structure and compositions of the NPs located on colloidal cesium lead bromide nanocrystals (CsPbBr3NCs), mainly through aberration-corrected transmission electron microscopy and spectroscopy. Our results show that these NPs can be assigned to PbBr2and CsPb2Br5. The new CsPb2Br5species are formed by reacting CsPbBr3NCs with the remaining PbBr2during the drying process. In addition, observation of the metallic Pb NPs are ascribed to the electron damage effect on CsPbBr3NCs during transmission electron microscopy imaging.Keywords:lead halide perovskite materials;colloidal cesium lead halide nanocrystals;scanning transmission electron microscopy and spectroscopy
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