RESUMO
The shuttling and sluggish conversion kinetics of lithium polysulfides (LiPSs) lead to poor cycling performance and low energy efficiency in lithium-sulfur batteries (LSBs). In this work, a hierarchically structured nanocomposite, synthesized through a surfactant-directed hydrothermal growth following dopamine-protected pyrolysis, serves as a bidirectional catalyst for LSBs. This nanocomposite comprises N-doped reduced graphene oxide (rGO) nanosheets anchored with uniformly distributed TiO2-x nanoparticles via interfacial N-Ti and C-Ti bonding, resulting in the formation of abundant 2D/0D Schottky heterojunctions (rGO/TiO2-x). Density functional theory (DFT) calculations and in situ Raman characterizations demonstrate that rGO/TiO2-x effectively inhibits the shuttling of LiPSs with enhanced redox kinetics, achieving high utilization of the sulfur cathode and improving the overall reversibility. A high areal capacity is attained at a high sulfur loading and a low electrolyte/sulfur ratio. The initial specific capacity reaches 1010 mA h g-1 at a current density of 0.2C (1C = 1675 mA g-1), and a retention of 86.4 % is attained over 100 cycles. A light-emitting diode (LED) screen using two LSBs with rGO/TiO2-x demonstrates their high potential for practical applications.
RESUMO
All-inorganic perovskites have garnered significant attention in optoelectronics. Herein, square CsPb2Br5 nanosheets, with lateral dimensions of up to 200 µm and a thickness of less than 50 nm, were successfully synthesized via a straightforward aqueous method using HBr as a morphology-tailoring agent. A photodetector composed of a single nanosheet was subsequently fabricated and exhibited remarkable photodetection capabilities, demonstrating a detectivity of 5.98 × 109 Jones. These findings offer new perspectives on the synthesis and utilization of CsPb2Br5 and other perovskite nanostructures in optoelectronic devices.
RESUMO
The successful synthesis of a 1T'/2H MoS2 heterophase bilayer offers potential building blocks for constructing novel nanoelectronic and optoelectronic devices. Here, first principles calculations are applied to explore and modulate its contact nature. The calculated results show a finite Schottky barrier of â¼0.56 eV, and a dominant tunneling barrier of â¼2 eV exists at the contact interface of the 1T'/2H MoS2 heterophase bilayer. The Schottky barrier can be eliminated by adatoms and strains. Although the two strategies have an insignificant effect on the dominant tunneling barrier, they alter the regions with local potentials lower than that of the inter-layer gap related barrier.