Advancing the field of photocatalysis requires the elucidation of structural properties that underpin the photocatalytic properties of promising materials. The focus of the present study is layered, Bi‐rich bismuth oxyhalides, which are widely studied for photocatalytic applications yet poorly structurally understood, due to high levels of disorder, nano‐sized domains, and the large number of structurally similar compounds. By connecting insights from multiple scattering techniques, utilizing electron‐, X‐ray‐ and neutron probes, the crystal phase of the synthesized materials is allocated as layered Bi24O31X10 (X = Cl, Br), albeit with significant deviation from the reported 3D crystalline model. The materials comprise anisotropic platelet‐shaped crystalline domains, exhibiting significant in‐plane ordering in two dimensions but disorder and an ultra‐thin morphology in the layer stacking direction. Increased synthesis pH tailored larger, more ordered crystalline domains, leading to longer excited state lifetimes determined via femtosecond transient absorption spectroscopy (fs‐TAS). Although this likely contributes to improved photocatalytic properties, assessed via the photooxidation of benzylamine, increasing the overall surface area facilitated the most significant improvement in photocatalytic performance. This study, therefore, enabled both phase allocation and a nuanced discussion of the structure‐property relationship for complicated, ultra‐thin photocatalysts.

中文翻译：

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阐明超薄富铋卤氧化光催化剂中的结构紊乱

推进光催化领域的发展需要阐明支撑有前景材料的光催化特性的结构特性。本研究的重点是层状富铋卤氧化铋，它在光催化应用中被广泛研究，但由于高度无序、纳米级域和大量结构相似的化合物，人们对其结构了解甚少。通过结合多种散射技术的见解，利用电子、X 射线和中子探针，合成材料的晶相被分配为层状 Bi24氧31X10(X = Cl, Br)，尽管与报道的 3D 晶体模型存在显着偏差。该材料包含各向异性片状晶域，在二维上表现出显着的面内有序性，但在层堆叠方向上表现出无序和超薄形态。提高合成 pH 值可定制更大、更有序的晶域，从而通过飞秒瞬态吸收光谱 (fs-TAS) 确定更长的激发态寿命。尽管这可能有助于改善光催化性能（通过苄胺的光氧化进行评估），但增加总表面积有助于光催化性能的最显着改善。因此，这项研究使得复杂的超薄光催化剂的相分配和结构-性能关系的细致讨论成为可能。