Two-dimensional transition metal dichalcogenides have recently attracted much attention as excellent electrocatalysts for the hydrogen evolution reaction (HER). Herein, Re_1−xMo_xS₂ alloy nanosheets in the entire composition range were synthesized using a hydrothermal reaction. High-resolution scanning transmission electron microscopy revealed anisotropic atomic distribution of the alloy phase, in which the Re and Mo atoms tend to segregate along a crystallographic axis. The phase transition occurs from the triclinic phase (1T′′) ReS₂ to the monoclinic phase (1T′) MoS₂ at 50% Mo. Re_0.5Mo_0.5S₂ exhibited the highest electrocatalytic HER activity, which was characterized by a current density of 10 mA cm⁻² at an overpotential of 98 mV (vs. RHE) and a Tafel slope of 54 mV dec⁻¹ in 0.5 M H₂SO₄. Extensive calculations using spin-polarized density functional theory showed that the most energetically stable configuration consists of separated MoS₂ and ReS₂ domains along the b axis, and the 1T′′ → 1T′ phase transition at 50% Mo, which agrees with the experimental results. The Gibbs free energy along the HER pathway indicates that the best performance at Mo 50% is due to the formation of S–H or Mo–H (at S vacancies) on the MoS₂ domain.

中文翻译：

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Re1-xMoxS2纳米片的各向异性合金化以促进电化学放氢反应

二维过渡金属二卤化物作为氢释放反应（HER）的优良电催化剂最近引起了广泛关注。在此，使用水热反应合成了整个组成范围内的Re _{1- x} Mo _x S ₂合金纳米片。高分辨率扫描透射电子显微镜显示合金相的各向异性原子分布，其中Re和Mo原子倾向于沿结晶轴偏析。在50％Mo时从三斜晶相（1T''）ReS _2发生到单斜晶相（1T'）MoS ₂的相变。Re _0.5 Mo _0.5 S ₂表现出最高的电催化HER活性，其特征是在0.5 MH ₂ SO _4中在98 mV（相对于RHE）的超电势下的电流密度为10 mA cm ^-2和54 mV dec ^-1的Tafel斜率。使用自旋极化密度泛函理论的大量计算表明，最能稳定的构型由沿b轴的分离的MoS ₂和ReS ₂域组成，并且在50％Mo时1T''→1T'相变，这与实验一致结果。沿着HER途径的吉布斯自由能表明，Mo 50％处的最佳性能是由于MoS上形成了S–H或Mo–H（在S空位处）_2个域。