As surfaces are to bulk materials, edge configurations greatly influence the properties and ensuing applications of two-dimensional (2D) materials. Being a large family of “beyond graphene”, 2D transition metal dichalcogenides (TMDCs) have many potential applications due to diverse phases and tunable properties. Unlike the well-studied H phase TMDCs initiated by MoS₂, the edge structures of T phase TMDCs remain poorly studied. Herein, taking freestanding T phase PtSe₂ as a prototype, we rationally construct 43 edge structures on the basis of conventional zigzag (ZZ) and armchair (AC) edges, and systematically evaluate their thermodynamic stabilities and relevant properties using density functional theory. Twelve most stable reconstructed edges (five ZZ-oriented and seven AC-oriented) are found to be highly stable at different experimental conditions, which can be achieved by precise control of synthesis conditions. Further Wulff constructions suggest hexagonal shapes with ZZ edges would be the equilibrium structures of the freestanding T phase PtSe₂ clusters or quantum dots. Electronic structure calculations show tunable band gap via edge reconstruction. Some reconstructed edges also exhibit excellent catalytic activity for hydrogen evolution reaction. Our work is expected to advance the knowledge of edge structures of T-phase TMDCs, and motivates materials design via TMDC edge engineering.

由于表面是散装材料，因此边缘配置会极大地影响二维（2D）材料的性能和后续应用。作为“超越石墨烯”的一大族，二维过渡金属二硫化碳（TMDC）由于具有不同的相和可调节的特性而具有许多潜在的应用。与由MoS ₂引发的经过充分研究的H相TMDC相比，T相TMDC的边缘结构仍然缺乏研究。在此，采用独立的T相PtSe ₂作为原型，我们在常规的锯齿形（ZZ）和扶手椅（AC）边缘的基础上合理构造了43个边缘结构，并使用密度泛函理论系统地评估了它们的热力学稳定性和相关特性。发现十二个最稳定的重构边（五个面向ZZ和七个面向交流）在不同的实验条件下都是高度稳定的，这可以通过精确控制合成条件来实现。进一步的Wulff构造表明具有ZZ边缘的六边形形状将成为独立的T相PtSe ₂的平衡结构。簇或量子点。电子结构计算通过边缘重建显示出可调节的带隙。一些重建的边缘还显示出优异的催化活性，用于氢气释放反应。我们的工作有望增进T相TMDC边缘结构的知识，并通过TMDC边缘工程促进材料设计。