In this work, for the first time, the quantum capacitance of an artificial two-dimensional (2D) material system based on van der Waals (vdW) bilayer heterostructures of Janus Molybdenum Di-chalcogenides, MoXY (X≠Y, X/YS, Se, Te) have been extensively investigated for electrode design of electrical double-layer (EDL) supercapacitor. The effects of different interlayer stacking orientations on local charge distribution, interlayer charge transfer, energy band structure, and density of states (DOS) have been comprehensively analyzed and correlated with the excess charge density and quantum capacitance variation with local electrode potential. Furthermore, the total capacitance reduction with respect to EDL capacitance has been analyzed over a wide range of EDL capacitance, and the performance of vdW Janus bilayers has been systematically benchmarked against the natural monolayers/bilayers and Janus monolayers of Molybdenum Di-chalcogenides. The results demonstrate that the large interlayer charge transfer induced built-in interlayer electric field significantly reduces the energy band gap of vdW Janus bilayers for S–Te and Se–Te interlayer stacking, thus leading to a significantly superior quantum capacitance. Finally, the favorable valley-dependent effective mass and band-degeneracy in MoSTe/MoSeTe have greatly enhanced quantum capacitance in S–Te and Se–Te stacking, rendering these bilayers a highly attractive candidate for supercapacitor electrode design.

中文翻译：

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用于超级电容器电极设计的 Janus 钼二硫属化物基范德华双层 - 层间堆叠方向对量子电容的影响

在这项工作中，首次研究了基于 Janus Molybdenum Di-chalcogenides MoXY (X≠Y, X/YS, Se、Te）已被广泛研究用于双电层（EDL）超级电容器的电极设计。全面分析了不同层间堆叠方向对局部电荷分布、层间电荷转移、能带结构和态密度（DOS）的影响，并将过剩电荷密度和量子电容随局部电极电势的变化联系起来。此外，我们在广泛的 EDL 电容范围内分析了相对于 EDL 电容的总电容降低，并且已将 vdW Janus 双层的性能与钼二硫属化物的天然单层/双层和 Janus 单层系统地进行了基准测试。结果表明，大的层间电荷转移引起的内置层间电场显着降低了 S-Te 和 Se-Te 层间堆叠的 vdW Janus 双层的能带隙，从而产生了显着优异的量子电容。最后，MoSTe/MoSeTe 中有利的谷相关有效质量和能带简并性极大地增强了 S-Te 和 Se-Te 堆叠中的量子电容，使这些双层成为超级电容器电极设计极具吸引力的候选者。