Wang Haiqing, Xu Zhongfei, Zhang Zengfu, Hu Shuxian, Ma Mingjun, Zhang Zhicheng, Zhou Weijia, Liu Hong
Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan, 250022, China.
Nanoscale. 2020 Nov 19;12(44):22541-22550. doi: 10.1039/d0nr06354a.
The precise control over the geometric and electronic structures of active materials on flexible substrates is of great importance to address the current challenges in optimizing and developing high-performance flexible devices for energy conversion and storage. In this work, an addressable surface was demonstrated to engineer structurally controllable active nanomaterials for electrocatalytic hydrogen evolution. The nanostructures of WS2/MOF/metal hydroxide/oxide with different formation energy barriers electrodes could be tuned by modifying the ratio of O/C and the concentration of carbon defects at the surface of carbon cloth. The morphological structure of the vertical WS2 nanosheets that are favorable to electrocatalysis was found to be highly related to the addressable surface of carbon cloth though heterogeneous nucleation and the interactions between the monomers and surface functional groups. Moreover, the electronic structure of WS2 was further modified with N doping (N-WS2) to deliver an addressable surface for the reaction species involved in the electrocatalytic hydrogen evolution reaction (HER), and the resultant N-WS2 exhibited enhanced HER activity compared with the original WS2. The systematic experimental research and electronic-structure density functional theory (DFT) calculations demonstrated the interesting features of the N dopant: (i) the strong hybridization of the p orbital of dopant N with d orbital of W and p orbital of S atoms (W d-S p-N p hybridization) close to the Fermi level can disperse the conducting charges, thus leading to an improved conductivity across the basal plane of WS2 nanosheets; (ii) the local electron transfer from W to N atoms provides the local charge, thus promoting the H adsorption process in the HER for N-WS2. Our research can be expected to offer new perspectives in the precise construction of highly reactive nanostructures toward high-efficiency and highly stable flexible devices for energy conversion and storage.
精确控制柔性基板上活性材料的几何和电子结构对于应对当前在优化和开发用于能量转换与存储的高性能柔性器件方面的挑战至关重要。在这项工作中，展示了一种可寻址表面，用于设计结构可控的活性纳米材料以进行电催化析氢。通过改变碳布表面的O/C比和碳缺陷浓度，可以调节具有不同形成能垒电极的WS2/MOF/金属氢氧化物/氧化物的纳米结构。发现有利于电催化的垂直WS2纳米片的形态结构与碳布的可寻址表面高度相关，这是通过异质成核以及单体与表面官能团之间的相互作用实现的。此外，通过N掺杂（N-WS2）进一步修饰WS2的电子结构，为参与电催化析氢反应（HER）的反应物种提供可寻址表面，并且所得的N-WS2与原始WS2相比表现出增强的HER活性。系统的实验研究和电子结构密度泛函理论（DFT）计算证明了N掺杂剂的有趣特征：（i）靠近费米能级的掺杂剂N的p轨道与W的d轨道和S原子的p轨道的强杂化（W d-S p-N p杂化）可以分散传导电荷，从而提高WS2纳米片基面的电导率；（ii）从W到N原子的局部电子转移提供了局部电荷，从而促进了N-WS2在HER中的H吸附过程。我们的研究有望为精确构建高反应性纳米结构以实现用于能量转换和存储的高效且高度稳定的柔性器件提供新的视角。
