Since the first observation of fullerene nearly three decades ago, allotropes of carbon, including carbon nanotube and graphene, have been the focus of considerable research because of their remarkable physical and chemical properties that suggest the potential for a wide variety of practical applications. Well known, in terms of carbon-atom hybridization, well-established forms of carbon are diamond with the three-dimensional sp³-hybridized carbon atoms and graphite with the two-dimensional sp²-hybridized carbon atoms which have been known and utilized for millennia. Additionally, more carbon allotropes, such as fullerenes, nanotubes and graphene composed of sp²-hybridized carbon, and Lonsdaleite and C₈ composed of sp³-hybridized carbon each show unique properties, usually different from those of either diamond or graphite, offering technological breakthroughs. Sequentially, there is the third carbon, i.e., carbyne with the one-dimensional sp-hybridization, which would result in an allotrope of carbon, whereas diamond and graphite feature three- and two-dimensional ones, respectively. Recently, carbyne nanocrystals (CNCs), the condensed phase of carbyne with the finite chain length and the one-dimensional sp-hybridized carbon atoms with the alternating carbon–carbon single and triple bonds, the dubbed the third carbon, have been synthesized in the laboratory (Science Advances 2015; 1 (9): e1500857), and these CNCs are white powders, so they are called white carbon. Interestingly, there have been many works showing that CNCs possess potential applications in luminescence, nonlinear optics, optoelectronic sensing and biomedicine probes. Therefore, these findings above imply that we have being on the threshold of a new era of carbyne science and technology. This review aims to be a comprehensive, authoritative, critical, and accessible review of general interest to the material community. Therefore, the review will survey the latest progresses of CNCs, provide a comprehensive understanding of synthesis, structure, property, and applications of CNCs, and put forward the perspective for the further development of CNCs. Firstly, we will present the basic understanding of classification and definition of carbyne. The history of carbyne research will be introduced and different definitions of carbyne in different periods are summarized. Next, a reasonable classification of carbyne research is proposed. Secondly, we will briefly introduce various approaches for the synthesis of carbyne and focus on describing LAL technique which is more suitable to produce CNCs compared with other methods. Thirdly, we will summarize structure, properties, and related applications of CNCs, including electronics, optics and magnetism, and optoelectronic and biomedical applications. Finally, we will summarize the development and unresolved issues so far, and suggest the future direction in this emerging and promising research field.

自近 30 年前首次观察到富勒烯以来，碳的同素异形体（包括碳纳米管和石墨烯）一直是大量研究的焦点，因为它们具有显着的物理和化学性质，表明其具有广泛的实际应用潜力。众所周知，就碳原子杂化而言，公认的碳形式是具有三维sp ³杂化碳原子的金刚石和具有二维sp ²杂化碳原子的石墨，这已为人们所知并用于千年。此外，还有更多的碳同素异形体，如富勒烯、纳米管和由sp ²杂化碳组成的石墨烯，以及 Lonsdaleite 和 C ₈由sp ³杂化碳组成的每一种都显示出独特的特性，通常不同于金刚石或石墨的特性，从而提供了技术突破。随后，存在第三个碳，即具有一维sp杂化的卡炔，这将导致碳的同素异形体，而金刚石和石墨分别具有三维和二维的特征。最近，碳炔纳米晶体（CNCs），具有有限链长的碳炔凝聚相和具有交替的碳 - 碳单键和三键的一维sp杂化碳原子，被称为第三碳，已在实验室（科学进展2015；1（9）：e1500857），而且这些CNC是白色粉末，所以叫白碳. 有趣的是，有许多工作表明 CNCs 在发光、非线性光学、光电传感和生物医学探针方面具有潜在应用。因此，以上这些发现意味着我们正处于卡宾科技新时代的门槛上。这篇评论旨在对物质界的普遍兴趣进行全面、权威、批判和易于理解的评论。因此，本综述将对CNCs的最新进展进行综述，全面了解CNCs的合成、结构、性能和应用，并为CNCs的进一步发展提出展望。首先，我们将介绍对卡宾分类和定义的基本理解。介绍了卡宾研究的历史，总结了不同时期对卡宾的不同定义。接下来，提出了卡宾研究的合理分类。其次，我们将简要介绍合成卡宾的各种方法，并重点描述与其他方法相比更适合生产 CNC 的 LAL 技术。第三，我们将总结CNC的结构、性能和相关应用，包括电子、光学和磁性，以及光电子和生物医学应用。最后，我们将总结迄今为止的发展和未解决的问题，并提出这个新兴和有前途的研究领域的未来方向。我们将简要介绍合成卡宾的各种方法，并重点描述与其他方法相比更适合生产 CNC 的 LAL 技术。第三，我们将总结CNC的结构、性能和相关应用，包括电子、光学和磁性，以及光电子和生物医学应用。最后，我们将总结迄今为止的发展和未解决的问题，并提出这个新兴和有前途的研究领域的未来方向。我们将简要介绍合成卡宾的各种方法，并重点描述与其他方法相比更适合生产 CNC 的 LAL 技术。第三，我们将总结CNC的结构、性能和相关应用，包括电子、光学和磁性，以及光电子和生物医学应用。最后，我们将总结迄今为止的发展和未解决的问题，并提出这个新兴和有前途的研究领域的未来方向。