二維氮化鎢(W5N6)的合成方法、表徵分析與潛在應用

Abstract

二維過渡金屬氮化物因其獨特且可調節的鍵合性質，展現出創新電子和機械能力的光明前景，使其有別於其他二維材料。然而，在相關規模上實現均勻合成是一項相當大的挑戰。本研究展示了受限生長技術在調控和提升二維金屬氮化物形貌方面的潛力。通過在氣-液-固過程中限制反應體積，我們獲得了更高的前驅物濃度，從而降低了成核密度、增大了晶粒尺寸並抑制了多層生長。我們說明了強鍵合如何提升二維氮化鎢的形貌和功能。我們的自下而上合成揭示了一種獨特的基板穩定效應，超越了范德華外延，促進了W5N6的形成，而非較低的金屬氮化物。通過全面的結構和電子特性表徵，我們展示了使用銅受限的VLS外延技術進行大規模合成單層W5N6。這種材料表現出具有有趣的間接能帶結構的半金屬行為。此外，它在抗機械損傷和化學反應方面表現出卓越的韌性。利用這些電子性質和穩健特性，我們證明了W5N6作為原子尺度乾蝕刻阻擋層的實用性，促進了高性能二維材料接觸的集成。我們通過石墨受限的VLS過程創新形貌控制技術，生成邊緣富集的二維氮化鎢，顯著提升了氫演化能力，證據是前所未有的55 mV/dec的Tafel斜率。W5N6 卓越的化學穩定性可實現有效的選擇區域硫化製程，從而形成二維橫向結構 W5N6/WS2。半金屬W5N6和半導體WS2之間的界面表現出高品質的相互作用，使得WS2的電氣性能比傳統金屬電極提高十倍以上。二維過渡金屬氮化物在推進電子設備和功能界面方面的潛力

Two-dimensional transition metal nitrides offer promising prospects for innovative electronic and mechanical capabilities owing to their distinct and adjustable bonding properties, distinguishing them from other 2D materials. However, achieving uniform synthesis at a relevant scale poses a considerable challenge. This research showcases the potential of confined growth techniques in regulating and enhancing the morphology of 2D metal nitrides. By confining the reaction volume in vapor-liquid-solid processes, we attained a higher precursor concentration, resulting in reduced nucleation density, larger grain sizes, and suppressed multilayer growth. We illustrate how robust bonding elevates the morphology and functionality of 2D tungsten nitrides. Our bottom-up synthesis reveals a unique substrate stabilization effect, surpassing van der Waals epitaxy and promoting the formation of W5N6 over lower metal nitrides. Through thorough structural and electronic characterization, we demonstrate the large-scale synthesis of monolayer W5N6 using copper confined VLS epitaxy. This material exhibits semimetallic behavior characterized by an intriguing indirect band structure. Moreover, it displays remarkable resilience against both mechanical damage and chemical reactions. Leveraging these electronic properties and robust characteristics, we demonstrate the practicality of W5N6 as atomic-scale dry etch stops, facilitating the integration of high-performance 2D material contacts. Our innovation in morphology control through the graphite confined VLS process has been utilized to generate edge-enriched 2D tungsten nitrides, resulting in significantly enhanced hydrogen evolution ability, as evidenced by an unprecedented Tafel slope of 55 mV/dec. The exceptional chemical stability of W5N6 allows for effective selective sulfurization, resulting in the formation of a 2D lateral structure W5N6/WS2. The interface between the semimetal W5N6 and semiconductor WS2 demonstrates a high-quality interaction, leading to a more than tenfold enhancement in the electrical performance of WS2 compared to conventional metal electrodes.