Researchers are increasingly drawn to WSe2 due to its wide-ranging applications in electronic, optoelectronic, and catalytic materials. Like other transition metal dichalcogenides, it has different polymorphs, viz., 1T, 1T′, and 2H phases. A hexagonal close-packed layer-type structure of 2H-WSe2 is well studied and possesses a semiconducting behavior. However, the literature lacks a detailed study of crystallographic structure, facile synthesis, and different physical properties of 1T′-WSe2 (or 1T-phase). In this article, we synthesized a stable flower-like 1T′-WSe2 nanosheet in a facile solvothermal process. We also tried to explore the structural details using the Rietveld refinement of the powder x-ray diffraction data. The different Raman vibrational modes and phonon calculation based on the density functional theory (DFT) were performed to understand the stability of the 1T′-WSe2 phase. The flower-like 1T′-WSe2 nanosheet shows better catalytic activity for the hydrogen evolution reaction (HER) with an onset potential of −0.21 mV and overpotential 0.47 mV in comparison with the 2H-phase of WSe2 nanosheet. The DFT calculations also support the experimental data on the HER of 1T′-WSe2, establishing the suitability of the 1T′-phase for HER activity with the lowest value of the change in Gibbs free energy of hydrogen adsorption, ΔGH = 0.43 eV, for the monolayer.

中文翻译：

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用于 HER 应用的稳定 1T′-WSe2 的简单合成


由于 WSe2 在电子、光电和催化材料中的广泛应用，研究人员越来越被它所吸引。与其他过渡金属二硫化物一样，它具有不同的多晶型物，即 1T、1T′ 和 2H 相。2H-WSe2 的六方密堆积层型结构得到了很好的研究，并具有半导体行为。然而，文献缺乏对 1T′-WSe2（或 1T 相）的晶体结构、简单合成和不同物理性质的详细研究。在本文中，我们在简单的溶剂热工艺中合成了稳定的花状 1T′-WSe2 纳米片。我们还尝试使用粉末 X 射线衍射数据的 Rietveld 精修来探索结构细节。进行了不同的拉曼振动模式和基于密度泛函理论 （DFT） 的声子计算，以了解 1T′-WSe2 相的稳定性。与 WSe2 纳米片的 2H 相相比，花状 1T′-WSe2 纳米片对析氢反应 （HER） 表现出更好的催化活性，起始电位为 -0.21 mV，过电位为 0.47 mV。DFT 计算还支持 1T′-WSe2 的 HER 实验数据，确定了 1T′ 相对 HER 活性的适用性，氢吸附的吉布斯自由能变化值最低，ΔGH = 0.43 eV，对于单层。