No abstract

Double halide perovskites are a class of promising semiconductors applied in photocatalysis, photovoltaic devices, and emitters to replace lead halide perovskites, owing to their nontoxicity and chemical stability. However, most double perovskites always exhibit low photoluminescence quantum efficiency (PLQE) due to the indirect bandgap structure or parity‐forbidden transition problem, limiting their further applications. Herein, the self‐trapped excitons emission of Cs2NaInCl6 by Sb‐doping, showing a blue emission with high PLQE of 84%, is improved. Further, Sb/Mn codoped Cs2NaInCl6 nanocrystals are successfully synthesized by the hot‐injection method, showing a tunable dual‐emission covering the white‐light spectrum. The studies of PL properties and dynamics reveal that an energy transfer process can occur between the self‐trapped excitons and dopants (Mn2+). The work provides a new perspective to design novel lead‐free double perovskites for realizing a unique white‐light emission.

Metal-organic frameworks (MOFs), a class of microporous crystalline materials composed of organic linkers and inorganic metal ions, have attracted increasing attention in recent years. [1] Owing to their flexible tunability in composition and structure, MOFs have been applied in many areas, especially, catalysis. [2] For application of traditional MOFs in In recent years, metal-organic frameworks (MOFs) have received extensive interest because of the diversity of their composition, structure, and function. To promote the MOFs' function and performance, the construction of hollow structural metal-organic frameworks and nanoparticle-MOF composites is significantly effective but remains a considerable challenge. In this article, a transformation strategy is developed to synthesize hollow structural Co-MOF-74 by solvothermal transformation of ZIF-67. These Co-MOF-74 particles exhibit a double-layer hollow shell structure without remarkable shape change compared to original ZIF-67 particles. The formation of hollow structure stemmed from the density difference of Co between ZIF-67 and Co-MOF-74. By this strategy, hollow structural Co-MOF-74 with different sizes and shapes are obtained from corresponding ZIF-67, and metal nanoparticles@Co-MOF-74 is synthesized by corresponding nanoparticles@Co-ZIF-67. To verify the structural advantages of hollow structural Co-MOF-74 and Ag nanoparticles@Co-MOF-74, photocatalytic CO 2 reduction is used as a model reaction. Conventionally synthesized Co-MOF-74 (MOF-74-C), hollow structural Co-MOF-74 synthesized by transformation method (MOF-74-T) and Ag nanoparticles@ Co-MOF-74 (AgNPs@MOF-74) are used as cocatalysts in this reaction. As a result, the cocatalytic activity of MOF-74-T and AgNPs@MOF-74 is 1.8 times and 3.8 times that of MOF-74-C, respectively.

Transition metal sulfides hold promising potentials as Li‐free conversion‐type cathode materials for high energy density lithium metal batteries. However, the practical deployment of these materials is hampered by their poor rate capability and short cycling life. In this work, the authors take the advantage of hollow structure of CuS nanoboxes to accommodate the volume expansion and facilitate the ion diffusion during discharge–charge processes. As a result, the hollow CuS nanoboxes achieve excellent rate performance (≈371 mAh g−1 at 20 C) and ultra‐long cycle life (>1000 cycles). The structure and valence evolution of the CuS nanobox cathode are identified by scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. Furthermore, the lithium storage mechanism is revealed by galvanostatic intermittent titration technique and operando Raman spectroscopy for the initial charge–discharge process and the following reversible processes. These results suggest that the hollow CuS nanobox material is a promising candidate as a low‐cost Li‐free cathode material for high‐rate and long‐life lithium metal batteries.