Vanadium flow batteries (VFBs) have great potential for application in energy storage systems. However, the sluggish cathode redox kinetics still greatly restricts their operation at high current densities. Herein, we boost cathode redox chemistry by modulating single-atom sulfur-vacancy (S-vacancy) defect of MoS in-situ grown on carbon felts via a facile chemical etching method. Firstly, the optimized S-vacancy concentration is figured out via high throughput calculations based on -band center theory. By precisely controlling etching duration, we achieve a tailored S-vacancy concentration, leading to highly dispersed S-vacancies, increased specific surface area, and improved hydrophilicity. Electrochemical characterizations demonstrate that optimized S-vacancy state can significantly facilitate the VO/VO kinetics. Moreover, analysis of electron density difference and integrated crystal orbital Hamiltonian group further reveals that dispersed S-vacancy distribution also contribute to efficient surface electronic structure and enhanced adsorption process. Benefiting from enhanced VO/VO kinetics, VFB single cell achieves a superior EE of 78.73 % at 300 mA cm and is able to last for 500 cycles without decay. This work demonstrates the promising potential of single-atom S-vacancies catalysts in the fabrication of flow battery electrodes and more importantly sheds light on the fundamental modulation essence of -band center in MoS towards enhanced cathode redox kinetics.

中文翻译：

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调节MoS2-x催化剂中的单原子硫空位缺陷以增强钒液流电池的阴极氧化还原动力学


全钒液流电池（VFB）在储能系统中具有巨大的应用潜力。然而，缓慢的阴极氧化还原动力学仍然极大地限制了它们在高电流密度下的运行。在这里，我们通过一种简单的化学蚀刻方法调节碳毡上原位生长的MoS的单原子硫空位（S空位）缺陷，从而促进阴极氧化还原化学反应。首先，基于能带中心理论，通过高通量计算得出优化的S空位浓度。通过精确控制蚀刻时间，我们实现了定制的 S 空位浓度，从而获得高度分散的 S 空位、增加的比表面积和改善的亲水性。电化学表征表明，优化的 S-空位态可以显着促进 VO/VO 动力学。此外，电子密度差和集成晶体轨道哈密顿群的分析进一步表明，分散的S空位分布也有助于有效的表面电子结构和增强的吸附过程。受益于增强的 VO/VO 动力学，VFB 单电池在 300 mA cm 下实现了 78.73% 的优异 EE，并且能够持续 500 个循环而不衰减。这项工作展示了单原子S空位催化剂在液流电池电极制造中的巨大潜力，更重要的是揭示了MoS2中带中心的基本调制本质，以增强阴极氧化还原动力学。