Huang Po-Chia, Wu Chia-Ling, Brahma Sanjaya, Shaikh Muhammad Omar, Huang Jow-Lay, Lee Jey-Jau, Wang Sheng-Chang
X-ray Scattering Group, National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan.
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Nanomaterials (Basel). 2020 Jul 17;10(7):1389. doi: 10.3390/nano10071389.
The ability to generate hydrogen in an economic and sustainable manner is critical to the realization of a future hydrogen economy. Electrocatalytic water splitting into molecular hydrogen using the hydrogen evolution reaction (HER) provides a viable option for hydrogen generation. Consequently, advanced non-precious metal based electrocatalysts that promote HER and reduce the overpotential are being widely researched. Here, we report on the development of MoS-carbon inter-overlapped structures and their applicability for enhancing electrocatalytic HER. These structures were synthesized by a facile hot-injection method using ammonium tetrathiomolybdate ((NH)MoS) as the precursor and oleylamine (OLA) as the solvent, followed by a carbonization step. During the synthesis protocol, OLA not only plays the role of a reacting solvent but also acts as an intercalating agent which enlarges the interlayer spacing of MoS to form OLA-protected monolayer MoS. After the carbonization step, the crystallinity improves substantially, and OLA can be completely converted into carbon, thus forming an inter-overlapped superstructure, as characterized in detail using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A Tafel slope of 118 mV/dec is obtained for the monolayer MoS-carbon superstructure, which shows a significant improvement, as compared to the 202 mV/dec observed for OLA-protected monolayer MoS. The enhanced HER performance is attributed to the improved conductivity along the c-axis due to the presence of carbon and the abundance of active sites due to the interlayer expansion of the monolayer MoS by OLA.
以经济且可持续的方式制氢的能力对于实现未来氢经济至关重要。利用析氢反应（HER）将水电催化分解为分子氢为制氢提供了一个可行的选择。因此，促进HER并降低过电位的先进非贵金属基电催化剂正在被广泛研究。在此，我们报告了MoS - 碳相互重叠结构的开发及其在增强电催化HER方面的适用性。这些结构通过一种简便的热注射方法合成，使用四硫代钼酸铵（(NH)MoS）作为前驱体，油胺（OLA）作为溶剂，随后进行碳化步骤。在合成过程中，OLA不仅起到反应溶剂的作用，还作为插层剂扩大MoS的层间距以形成OLA保护的单层MoS。碳化步骤后，结晶度大幅提高，并且OLA可以完全转化为碳，从而形成相互重叠的超结构，这通过X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、拉曼光谱、透射电子显微镜（TEM）和X射线光电子能谱（XPS）进行了详细表征。单层MoS - 碳超结构的塔菲尔斜率为118 mV/dec，与OLA保护的单层MoS所观察到的202 mV/dec相比有显著改善。HER性能的增强归因于由于碳的存在而沿c轴提高的导电性以及由于OLA使单层MoS层间膨胀而产生的丰富活性位点。
