Kwon Ik Seon, Kwak In Hye, Debela Tekalign Terfa, Abbas Hafiz Ghulam, Park Yun Chang, Ahn Jae-Pyoung, Park Jeunghee, Kang Hong Seok
Department of Chemistry, Korea University, Sejong 339-700, Republic of Korea.
Institute for Application of Advanced Materials, Jeonju University, Chonju, Chonbuk 55069, Republic of Korea.
ACS Nano. 2020 May 26;14(5):6295-6304. doi: 10.1021/acsnano.0c02593. Epub 2020 May 7.
Two-dimensional MoSe has emerged as a promising electrocatalyst for the hydrogen evolution reaction (HER), although its catalytic activity needs to be further improved. Herein, we report Se-rich MoSe nanosheets synthesized using a hydrothermal reaction, displaying much enhanced HER performance at the Se/Mo ratio of 2.3. The transition from the 2H to the 1T' phase occurred as Se/Mo exceeded 2. Structural analysis revealed the presence of Se adatoms as well as the formation of Se-Se bonding. Based on first-principles calculations, we propose two equally stable Se-rich structures. In the first one, excess Se atoms bridge two MoSe layers the interlayer Se-Se bonds. In the second one, the Se atoms substitute for the Mo atoms, and extra Se atoms are added closest to the Mo-substituted Se. Calculation of Gibbs free energy along the reaction path indicates that the Se adatoms of the second model are the most active sites for HER.
二维MoSe₂已成为一种有前景的析氢反应（HER）电催化剂，尽管其催化活性仍需进一步提高。在此，我们报道了通过水热反应合成的富硒MoSe₂纳米片，在硒/钼比为2.3时表现出大大增强的HER性能。当硒/钼超过2时，发生了从2H相向1T'相的转变。结构分析表明存在硒吸附原子以及硒-硒键的形成。基于第一性原理计算，我们提出了两种同样稳定的富硒结构。在第一种结构中，过量的硒原子桥接两个MoSe₂层，形成层间硒-硒键。在第二种结构中，硒原子取代钼原子，并在最靠近被钼取代的硒的位置添加额外的硒原子。沿反应路径的吉布斯自由能计算表明，第二种模型中的硒吸附原子是HER最活跃的位点。
