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  1. null (Ed.)
    Abstract In recent years, quantum-dot-like single-photon emitters in atomically thin van der Waals materials have become a promising platform for future on-chip scalable quantum light sources with unique advantages over existing technologies, notably the potential for site-specific engineering. However, the required cryogenic temperatures for the functionality of these sources has been an inhibitor of their full potential. Existing methods to create emitters in 2D materials face fundamental challenges in extending the working temperature while maintaining the emitter’s fabrication yield and purity. In this work, we demonstrate a method of creating site-controlled single-photon emitters in atomically thin WSe 2 with high yield utilizing independent and simultaneous strain engineering via nanoscale stressors and defect engineering via electron-beam irradiation. Many of the emitters exhibit biexciton cascaded emission, single-photon purities above 95%, and working temperatures up to 150 K. This methodology, coupled with possible plasmonic or optical micro-cavity integration, furthers the realization of scalable, room-temperature, and high-quality 2D single- and entangled-photon sources. 
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  2. Abstract

    As an approximation to the quantum state of solids, the band theory, developed nearly seven decades ago, fostered the advance of modern integrated solid‐state electronics, one of the most successful technologies in the history of human civilization. Nonetheless, their rapidly growing energy consumption and accompanied environmental issues call for more energy‐efficient electronics and optoelectronics, which necessitate the exploration of more advanced quantum mechanical effects, such as band‐to‐band tunneling, spin–orbit coupling, spin–valley locking, and quantum entanglement. The emerging 2D layered materials, featured by their exotic electrical, magnetic, optical, and structural properties, provide a revolutionary low‐dimensional and manufacture‐friendly platform (and many more opportunities) to implement these quantum‐engineered devices, compared to the traditional electronic materials system. Here, the progress in quantum‐engineered devices is reviewed and the opportunities/challenges of exploiting 2D materials are analyzed to highlight their unique quantum properties that enable novel energy‐efficient devices, and useful insights to quantum device engineers and 2D‐material scientists are provided.

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  3. Molybdenum sulfide (MoS2) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER) owing to its high activity and stability during the reaction. However, the efficiency of hydrogen production is limited by the number of active sites in MoS2. In this work, a simple method of fabricating polycrystalline multilayer MoS2on Mo foil for efficient hydrogen evolution is demonstrated by controlling the sulfur (S) vacancy concentration, which can introduce new bands and lower the hydrogen adsorption free energy (ΔGH). For the first time, theoretical and experimental results show that the HER performance of synthesized MoS2with S vacancy can be further enhanced by the very small amount of platinum (Pt) decoration, which can introduce new gap states and more catalytic sites in real space with suitable free energy. The fabricated hybrid electrocatalyst exhibits significantly smaller Tafel slope of 38 mV dec−1and better HER electrocatalytic activity compared to previous works. This approach provides a simple pathway to design low‐cost, efficient and sizable hydrogen‐evolving electrode by simultaneously tuning the MoS2band structure and active sites.

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