2D transition metal‐dichalcogenides are emerging as efficient and cost‐effective electrocatalysts for the hydrogen evolution reaction (HER). However, only the edge sites of their trigonal prismatic phase show HER‐electrocatalytic properties, while the basal plane, which is absent of defective/unsaturated sites, is inactive. Herein, the authors tackle the key challenge of increasing the number of electrocatalytic sites by designing and engineering heterostructures composed of single‐/few‐layer MoSe₂ flakes and carbon nanomaterials (graphene or single‐wall carbon nanotubes) produced by solution processing. The electrochemical coupling between the materials that comprise the heterostructure effectively enhances the HER‐electrocatalytic activity of the native MoSe₂ flakes. The optimization of the mass loading of MoSe₂ flakes and their electrode assembly via monolithic heterostructure stacking provides a cathodic current density of 10 mA cm⁻² at overpotential of 100 mV, a Tafel slope of 63 mV dec⁻¹, and an exchange current density (j₀) of 0.203 µA cm⁻². In addition, thermal and chemical treatments are exploited to texturize the basal planes of the MoSe₂ flakes (through Se‐vacancies creation) and to achieve in situ semiconducting‐to‐metallic phase conversion, respectively, thus they activate new HER‐electrocatalytic sites. The as‐engineered electrodes show a 4.8‐fold enhancement of j₀ and a decrease in the Tafel slope to 54 mV dec⁻¹.

中文翻译：

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工程化的基于MoSe2的异质结构可实现高效的电化学氢释放反应

二维过渡金属二卤化碳正成为氢释放反应（HER）的高效且经济高效的电催化剂。但是，只有其三角棱柱相的边缘位点具有HER电催化特性，而缺乏缺陷/不饱和位点的基面则没有活性。本文中，作者通过设计和工程化由单层/少量MoSe ₂薄片和溶液加工产生的碳纳米材料（石墨烯或单壁碳纳米管）组成的异质结构，解决了增加电催化位点数量的关键挑战。构成异质结构的材料之间的电化学偶联有效增强了天然MoSe ₂的HER电催化活性片状。通过单片异质结构堆叠优化MoSe ₂薄片及其电极组件的质量负载，可在100 mV的超电势下提供10 mA cm ^-2的阴极电流密度，63 mV dec ^-1的Tafel斜率以及交换电流密度（j ₀）为0.203μAcm ^-2。此外，还利用热处理和化学处理来使MoSe ₂薄片的基面组织化（通过创建硒原子）并分别实现原位从半导体到金属的相转化，因此它们激活了新的HER电催化位点。工程电极显示j ₀的4.8倍增强Tafel斜率降低至54 mV dec ^-1。