The morphology of nanocrystals is crucial in modulating their properties including optical, chemical and catalytic ones. For the intensively studied sheet‐like structures, it is also important to engineer their detailed nanostructures on sheet surfaces. In this work, micron‐sized bismuth oxychloride (BiOCl) thin square sheets in tetragonal matlockite‐like phase and the corner‐truncated ones were successfully synthesized by using a simple wet‐chemical method. These square sheets could be partially etched, forming surface cracks with the size and density easily tuned. Two different types of cracks were observed on the surfaces of the corner un‐truncated and truncated BiOCl square sheets. Surprisingly, radial cracks formed on the corner‐truncated BiOCl sheets, which is attributed to the existence of physical stress during the etching and is highly related to the original nanostructure of the BiOCl sheets. This work provides a wet‐chemical method for engineering surface cracks, especially radial cracks, on the surfaces of BiOCl nanosheets, which may be expanded to surface engineering of other nanosheets and will show a great potential in various fields.

中文翻译：

---

湿式化学方法在晶体氯氧化铋薄板上形成裂纹

纳米晶体的形态对于调节其性质（包括光学，化学和催化性质）至关重要。对于经过深入研究的片状结构，在片材表面上设计其详细的纳米结构也很重要。在这项工作中，使用简单的湿化学方法成功地合成了四方马氏体状相和角截短相的微米尺寸的三氧化二铋（BiOCl）薄方片。这些正方形板可能会被部分蚀刻，形成表面裂纹，其尺寸和密度易于调整。在未截断和截断的BiOCl方板的角表面上观察到两种不同类型的裂纹。出乎意料的是，在截短的BiOCl薄板上形成了径向裂纹，这归因于蚀刻期间存在的物理应力，并且与BiOCl片材的原始纳米结构高度相关。这项工作为BiOCl纳米片表面上的工程表面裂纹特别是径向裂纹的工程提供了湿化学方法，该方法可能会扩展到其他纳米片的表面工程，并将在各个领域显示出巨大的潜力。