As a novel type of promising materials, metal halide perovskites are a rising star in the field of optoelectronics. On this basis, a new frontier of zero-dimensional perovskite-related Cs4PbBr6 with bright green emission and high stability has attracted an enormous amount of attention, even though its photoluminescence still requires to clarification. Herein, the controllable phase transformation between three-dimensional CsPbBr3 and zero-dimensional Cs4PbBr6 is easily achieved in a facile ligand-assisted supersaturated recrystallization synthesis procedure via tuning the amount of surfactants, and their unique optical properties are investigated and compared in detail. Both Cs4PbBr6 and CsPbBr3 produce remarkably intense green luminescence with quantum yields up to 45% and 80%, respectively; however, significantly different emitting behaviors are observed. The fluorescence lifetime of Cs4PbBr6 is much longer than that of CsPbBr3, and photo-blinking is easily detected in the Cs4PbBr6 product, proving that the zero-dimensional Cs4PbBr6 is indeed a highly luminescent perovskite-related material. Additionally, for the first time, tunable emissions over the visible-light spectral region are demonstrated to be achievable via halogen composition modulations in the Cs4PbX6 (X = Cl, Br, I) samples. Our study brings a simple method for the phase control of CsPbBr3/Cs4PbBr6 and demonstrates the intrinsic luminescence nature of the zero-dimensional perovskite-related Cs4PbX6 products.

Lithium–sulfur batteries are regarded as a promising energy storage system.

Carbon fiber composites composed of carbon fiber and pyrolytic carbon (PyC) matrix have great potential application in the brakes of aircrafts, where the combination of high mechanical strength and excellent frictional properties are required. In this work, two-component silicon-based interlocking enhancements were designed and constructed into carbon fiber composites for boosting the mechanical and frictional properties. Specially, silicon carbide nanowires (SiCnws) and silicon nitride nanobelts (Si3N4nbs) could form interlocking architectures, where SiCnws are rooted firmly on the carbon fiber surface in the radial direction and Si3N4nbs integrate the PyC matrix with carbon fibers together via a networked shape. SiCnws–Si3N4nbs not only refine the PyC matrix but also promote the bonding of the fiber/matrix interface and the cohesion strength of the PyC matrix, thus enhancing the mechanical and frictional properties. Benefiting from the SiCnws–Si3N4nbs synergistic effect and interlocking enhancement mechanism, the interlaminar shear strength and compressive strength of carbon fiber composites increased by 88.41% and 73.40%, respectively. In addition, the friction coefficient and wear rate of carbon fiber composites decreased by 39.50% and 69.88%, respectively. This work could open up an interlocking enhancement strategy for efficiently fabricating carbon fiber composites and promoting mechanical and frictional properties that could be used in the brakes of aircrafts.

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