Since their discovery in 2004, beginning with graphene, the field of two-dimensional (2D) materials has expanded tremendously as additional families of materials are discovered. These families include MXenes, transition metal dichalcogenides (TMDs), 2D metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), 2D polymers, perovskites, oxides, and many others. 2D materials experience quantum confinement, have ultrahigh surface area to volume ratios, and have anisotropic properties, which result in unique material properties. Moreover, when coupled with the specific family based properties, 2D materials again broaden and diversify their properties; for example, they can have metallic-like conductivity or be semiconductors or insulators. The same diversity occurs in every physiochemical property. Due to this broad range of properties, 2D materials have been widely studied and demonstrated to solve problems that no other class of materials can. Benefiting from their unique properties, 2D materials receive significant attention worldwide, and thousands of research groups strive to understand every aspect of these materials. One major opportunity in 2D materials is the controllable synthesis and discovery science. Within the 2D material space, the synthesis approach plays an outsized role in the key materials attributes such as defect densities, surface functionalization, flake sizes, and much more. Moreover, many of the families of 2D materials contain a broad set of chemistries; there remain significant gaps in knowledge on how the chemistry of 2D materials affects their properties. Within many of the more recent families of 2D materials, there is still ample fundamental science being conducted related to which chemistries can be incorporated. Following synthesis, postsynthetic modifications, including single-atom doping and grafting reactions, further refine their properties. Finally, understanding the scalability of 2D materials synthesis enabling their use beyond the laboratory is key. Another major opportunity is a fundamental understanding as to why they have the properties that they do. 2D materials have demonstrated a variety of interesting quantum effects, such as superconductivity, weak localization, topological insulation, and others. In many cases, these quantum effects can lead to novel applications, such as valleytronics or twistronics. Beyond quantum effects, fundamental questions remain about the origin of the electronic, chemical, mechanical, biological, and physical properties. For many 2D material systems, fundamental studies related to their properties are overlooked by groups wanting to delve directly into applications. However, a rational understanding of the structure of 2D materials and their resultant properties is key to exceeding the state-of-the-art. In many cases, theoretical studies related to 2D materials rely on simplified systems that ignore defects, inclusions, and other detrimental effects; but these are often pivotal to understanding 2D systems. Bridging the gap between experimental and theoretical work will benefit scientists across every discipline of 2D materials. In terms of applications, it is nearly impossible to overstate how important 2D materials will be for shaping our future. It is vital to consider which applications best utilize the novel properties that 2D materials bring, specifically within each class of materials. Validation of these experiments and applications is necessary; demonstrations of a single device with exceptional performance are not sufficient, instead focus should be placed on reproducibility of these devices, especially within the context of how they will be used in the real world. Moreover, when exceptional performance is demonstrated, understanding why this performance occurs is necessary; simple demonstrations are important but only provide a surface-level understanding of the phenomena that occur. Finally, understanding and considering the end-stage use of 2D materials is of paramount importance. As reports surface about the detrimental effects of different chemicals and materials that have been commercialized for decades; the 2D materials community has a responsibility to avoid these same issues. This necessitates studies dedicated to full life cycle analysis; determining truly green synthesis pathways that maintain the properties of interest, while minimizing negative effects on the environment. The end-of-life degradation or recycling of 2D materials is important; while 2D materials have exciting properties, it is a moral obligation to ensure that their use-cases have an overall positive effect on the world. In many cases, it is almost certain that these materials will be discharged into the environment, thus it is necessary to understand whether they are ecologically damaging prior to their widespread use. Novel technologies and approaches that can reclaim or reuse 2D materials present an opportunity that can have outsized effects on the future world. In this special issue of Accounts of Chemical Research, leading scientists spanning different classes of 2D materials have been invited to give updates related to the state-of-the-art in their field. Through this collection, we aim to foster cross-disciplinary dialogue and reveal new opportunities that may emerge at the intersections of these rapidly advancing fields. This article has not yet been cited by other publications.

中文翻译：

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2D 材料的挑战和机遇


自 2004 年发现石墨烯以来，随着其他材料家族的发现，二维 （2D） 材料领域得到了极大的扩展。这些系列包括 MXenes、过渡金属二硫化物 （TMD）、2D 金属有机框架 （MOF） 和共价有机框架 （COF）、2D 聚合物、钙钛矿、氧化物等。2D 材料经历量子限制，具有超高的表面积体积比，并具有各向异性特性，从而产生独特的材料特性。此外，当与基于特定系列的属性相结合时，2D 材料再次拓宽和多样化了它们的性能;例如，它们可以具有类似金属的导电性，或者是半导体或绝缘体。相同的多样性发生在每种理化性质中。由于这种广泛的特性，2D 材料已被广泛研究和证明可以解决其他类别材料无法解决的问题。得益于其独特的特性，2D 材料在世界范围内受到广泛关注，数以千计的研究小组努力了解这些材料的各个方面。2D 材料的一个主要机会是可控合成和发现科学。在 2D 材料空间中，合成方法在关键材料属性（如缺陷密度、表面功能化、薄片尺寸等）中发挥着巨大作用。此外，许多 2D 材料系列包含广泛的化学成分;关于 2D 材料的化学性质如何影响其特性，仍然存在重大知识差距。在许多较新的二维材料家族中，仍然有大量的基础科学与哪些化学成分可以结合有关。 合成后，合成后修饰，包括单原子掺杂和接枝反应，进一步细化了它们的性质。最后，了解 2D 材料合成的可扩展性，使其能够在实验室之外使用是关键。另一个重大机会是基本理解它们为什么具有这些特性。二维材料已经展示了各种有趣的量子效应，例如超导性、弱定位、拓扑绝缘等。在许多情况下，这些量子效应可以带来新的应用，例如 valleytronics 或 twistronics。除了量子效应之外，关于电子、化学、机械、生物和物理特性的起源仍然存在基本问题。对于许多 2D 材料系统，与其特性相关的基础研究被想要直接深入研究应用的团队所忽视。然而，对 2D 材料的结构及其结果特性的理性理解是超越最先进技术的关键。在许多情况下，与 2D 材料相关的理论研究依赖于简化的系统，这些系统忽略了缺陷、夹杂物和其他有害影响;但这些通常是理解 2D 系统的关键。弥合实验和理论工作之间的差距将使 2D 材料各个学科的科学家受益。在应用方面，2D 材料对于塑造我们的未来的重要性几乎不为过。考虑哪些应用最能利用 2D 材料带来的新颖特性至关重要，特别是在每类材料中。 这些实验和应用的验证是必要的;仅仅演示具有卓越性能的单个设备是不够的，相反，应将重点放在这些设备的可重复性上，尤其是在它们在现实世界中的使用方式的背景下。此外，当表现出卓越的性能时，了解为什么会出现这种性能是必要的;简单的演示很重要，但只能提供对所发生现象的表面理解。最后，理解和考虑 2D 材料的末期使用至关重要。随着关于已经商业化数十年的不同化学品和材料的有害影响的报道浮出水面;2D 材质社区有责任避免这些问题。这需要专门用于完整生命周期分析的研究;确定真正的绿色合成途径，同时保持目标特性，同时最大限度地减少对环境的负面影响。2D 材料的报废降解或回收很重要;虽然 2D 材料具有令人兴奋的特性，但确保其用例对世界产生整体积极影响是一项道德义务。在许多情况下，几乎可以肯定这些材料会被排放到环境中，因此有必要在广泛使用之前了解它们是否对生态造成破坏。可以回收或再利用 2D 材料的新技术和方法提供了一个机会，可能会对未来世界产生巨大影响。在本期《化学研究报告》特刊中，我们邀请了来自不同类别的 2D 材料的领先科学家，介绍他们所在领域的最新进展。 通过这个系列，我们旨在促进跨学科对话，并揭示在这些快速发展的领域的交叉点上可能出现的新机会。本文尚未被其他出版物引用。