CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China.
University of Chinese Academy of Sciences , Beijing 100049 , China.
ACS Appl Mater Interfaces. 2018 May 2;10(17):15304-15313. doi: 10.1021/acsami.8b03390. Epub 2018 Apr 20.
Nano-heterostructures are widely used in the field of optoelectronic devices, and an optimal proportion usually exists between the constituents that make up the structures. Investigation on the mechanism underlying the optimal ratio is instructive for fabricating nano-heterostructures with high efficiency. In this work, BiOCl/BiS type-II nano-heterostructures with different BiS/BiOCl ratios have been prepared via epitaxial growth of BiS nanorods on BiOCl nanosheets with solvothermal treatment at different sulfuration temperatures (110-180 °C) and their photoelectrochemical (PEC) performances as photoanodes have been studied. Results indicate that the BiS content increases with the sulfuration temperature. BiOCl/BiS-170 (i.e., sulfurized@170 °C) exhibits the highest PEC performance under visible-light illumination, whereas BiOCl/BiS-180 with the maximum BiS content shows the highest visible-light absorption, i.e., possessing the best potential for charge generation. Further analysis indicates that the BiOCl/BiS heterojunction interface is also crucial in determining the PEC performance of the obtained heterostructures by influencing the charge separation process. With increasing BiS content, the interface area in the BiOCl/BiS nano-heterostructures increases first and then decreases due to the mechanical fragility of the nanosheet-nanorod structure and the structural instability in the [010] direction of BiS with higher BiS content. Therefore, the increasing content of the BiS does not necessarily correspond to higher heterojunction area. The optimal performance of BiOCl/BiS-170 results from the maximum of the synthetic coordination of the charge generation and separation. This is the first time ever to figure out the detailed explanation of the optimal property in the nano-heterostructures. The result is inspiring in designing high-performance nano-heterostructures from the point of synthesizing morphological mechanically robust heterostructure and structurally stable constituents to reach a high interfacial area, as well as high light-absorption ability.
纳米异质结构在光电设备领域得到了广泛的应用，而且组成结构的各成分之间通常存在一个最佳比例。对这种最佳比例背后的机制进行研究，对于制备高效率的纳米异质结构具有指导意义。在这项工作中，通过在 BiOCl 纳米片上外延生长 BiS 纳米棒，采用溶剂热法在不同硫化温度（110-180°C）下制备了不同 BiS/BiOCl 比的 BiOCl/BiS 型 II 纳米异质结构，并研究了它们作为光阳极的光电化学（PEC）性能。结果表明，BiS 的含量随硫化温度的升高而增加。BiOCl/BiS-170（即 170°C 硫化）在可见光照射下表现出最高的 PEC 性能，而具有最大 BiS 含量的 BiOCl/BiS-180 表现出最高的可见光吸收，即具有最好的电荷产生潜力。进一步的分析表明，BiOCl/BiS 异质结界面在确定所获得的异质结构的 PEC 性能方面也很重要，这是通过影响电荷分离过程来实现的。随着 BiS 含量的增加，由于纳米片-纳米棒结构的机械脆性以及较高 BiS 含量的 BiS 在[010]方向上的结构不稳定性，BiOCl/BiS 纳米异质结构中的界面面积先增加后减小。因此，BiS 的含量增加并不一定对应更高的异质结面积。BiOCl/BiS-170 的最佳性能源于电荷产生和分离的综合协调的最大值。这是首次阐明纳米异质结构中最佳性能的详细解释。该结果在从合成形态力学上坚固的异质结构和结构稳定的成分的角度设计高性能纳米异质结构方面具有启示意义，以达到高的界面面积和高的光吸收能力。
