In most cases, layered transition metal dichalcogenides (LTMDs), containing metallic phases, show electrochemical behavior different from their semiconductor counterparts. Typically, two-dimensional layered metallic 1T-MoS₂ demonstrates better electrocatalytic performance for water splitting compared to its 2H counterpart. However, the characteristics of low metallic phase concentration and poor stability limit its applications in some cases. Herein, we demonstrate a simple and efficient bottom-up wet-chemistry strategy for the large-scale synthesis of nanoscopic ultrathin Mo_1–x W _x S₂ nanosheets with enlarged interlayer spacing and high metallic phase concentration. Our characterizations, including X-ray absorption fine structure spectroscopy (XAFS), high-angle annular dark-fieldscanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS) revealed that the metallic ultrathin ternary Mo_1–x W _x S₂ nanosheets exhibited distorted metal–metal bonds and a tunable metallic phase concentration. As a proof of concept, this optimized catalyst, with the highest metallic phase concentration (greater than 90%), achieved a low overpotential of about–155 mV at a current density of –10 mA/cm², a small Tafel slope of 67 mV/dec, and an increased turnover frequency (TOF) of 1.3 H₂ per second at an overpotential of –300 mV (vs. reversible hydrogen electrode (RHE)), highlighting the importance of the metallic phase. More importantly, this study can lead to a facile solvothermal route to prepare stable and high-metallicphase-concentration transition-metal-based two-dimensional materials for future applications.

中文翻译：

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具有扩展夹层的高金属相浓度Mo 1–x W x S 2纳米片作为有效的电催化剂

在大多数情况下，含有金属相的层状过渡金属二硫化氢（LTMD）表现出的电化学行为与其半导体对应物不同。通常，二维分层金属1T-MoS ₂与2H相比具有更好的水分解电催化性能。但是，在某些情况下，金属相浓度低和稳定性差的特征限制了其应用。在这里，我们演示了一种简单有效的自下而上的湿化学策略，用于大规模合成纳米超薄Mo _{1– x} W _x S ₂ 层间间距增大且金属相浓度较高的纳米片。我们的表征包括X射线吸收精细结构光谱（XAFS），高角度环形暗场扫描透射电子显微镜（HAADF-STEM）和X射线光电子能谱（XPS）揭示了金属超薄三元Mo _{1- x} W _x S ₂纳米片表现出扭曲的金属-金属键和可调节的金属相浓度。作为概念验证，这种优化的催化剂具有最高的金属相浓度（大于90％），在–10 mA / cm ²的电流密度下实现了约–155 mV的低过电势，Tafel斜率较小，为67 mV / dec，并且增加的周转频率（TOF）为1.3 H ₂每秒的超电势-300毫伏（相对于可逆氢电极（RHE）），突出的金属相的重要性。更重要的是，这项研究可以导致一种容易的溶剂热途径，以制备稳定且高金属相浓度的过渡金属基二维材料，以备将来应用。