Electrocatalysis is a promising approach for sustainable hydrogen generation, and the exploration of effective electrocatalysts for hydrogen evolution reactions (HER) is of great significance for exploiting and utilizing renewable energy. Herein, the magnetic FeMo/MoC@C composites with multi-heterostructure interfaces and hierarchical structure are first designed and fabricated via molybdenum blue preassembly strategy by using Keplerate polyoxomolybdate {MoFe} and melamine as precursors. Benefiting from its unique characteristics, FeMo/MoC@C catalyst exhibits superior HER electrocatalytic activity than pure MoC@C. Interestingly, the optimized FeMo/MoC@C presents the HER magnetic reinforcement by simply applying an magnetic field, characteristic of 97 mV@10 mA cm, 201 mV@50 mA cm, and a robust durability for more than 18 h, which are 120 and 85 mV less than that of FeMo/MoC@C without magnetization, and greatly lower than comparative MoC@C catalyst (272 mV@10 mA cm and 396 mV@50 mA cm). This may be attributed to that the FeMo/MoC@C can afford fast electrons transmitting from electrode to active sites during HER process when imposing an external magnetic field. This work offers a novel design direction to develop magnetic transition metal based-materials for electrochemical applications and paves a new way to utilize the magnetic enhancement to further improve the hydrogen evolution performance.

中文翻译：

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Keplerate 多钼酸衍生多界面 FeMo/Mo2C@C 催化剂上电催化 HER 性能的磁增强

电催化是一种有前途的可持续制氢方法，探索有效的析氢反应（HER）电催化剂对于开发和利用可再生能源具有重要意义。在此，首先以Keplerate多钼酸{MoFe}和三聚氰胺为前驱体，通过钼蓝预组装策略设计和制备了具有多异质结构界面和分级结构的磁性FeMo/MoC@C复合材料。得益于其独特的特性，FeMo/MoC@C 催化剂表现出比纯 MoC@C 更优异的 HER 电催化活性。有趣的是，优化后的 FeMo/MoC@C 通过简单地施加磁场即可呈现 HER 磁增强，特性为 97 mV@10 mA cm、201 mV@50 mA cm，并且具有超过 18 小时的耐用性，即 120比未磁化的 FeMo/MoC@C 低 85 mV，大大低于对比 MoC@C 催化剂（272 mV@10 mA cm 和 396 mV@50 mA cm）。这可能是由于在施加外部磁场时，FeMo/MoC@C 可以在 HER 过程中提供快速的电子从电极传输到活性位点的能力。这项工作为开发用于电化学应用的磁性过渡金属基材料提供了新颖的设计方向，并为利用磁增强进一步提高析氢性能铺平了新途径。