Solid-state borohydride was one of the promising solid-state hydrogen storage materials, but the reversibility and kinetics of hydrogen de/absorption in borohydrides still need improvement. In this study, a new strategy of repeated ball milling and melting was first used to produce LiBH-Mg(BH) nanocomposites (LMBH) effectively loaded on VC Mxene as the matrix. The LMBH-20VC composite released 8.1 wt% of hydrogen at 350 °C while un-doped LMBH only released 4.3 wt% under the same conditions. Two-step dehydrogenation with lower activation energies (118.2 and 125.2 kJ/mol) were found in LMBH-VC composites. More than 5 wt% reversible hydrogen capacity was discovered in LMBH-VC samples, which was 138 % more than that of un-doped LMBH. The nano-sized LMBH-VC composite retained unaggregated, and VH species was formed during cycling as an active “hydrogen pump”. The outstanding hydrogen storage performance of LMBH-VC composites could be attributed to the combination of nano-sizing and catalysis from VC Mxene.

中文翻译：

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增强 LiBH4-Mg(BH4)2 复合材料与 V2C-Mxene 的可逆储氢

固态硼氢化物是一种有前途的固态储氢材料，但硼氢化物的可逆性和氢解吸动力学仍需改进。在这项研究中，首先采用重复球磨和熔化的新策略来生产有效负载在VC Mxene作为基体上的LiBH-Mg(BH)纳米复合材料(LMBH)。 LMBH-20VC 复合材料在 350 °C 时释放了 8.1 wt% 的氢气，而未掺杂的 LMBH 在相同条件下仅释放了 4.3 wt%。 LMBH-VC 复合材料中发现具有较低活化能（118.2 和 125.2 kJ/mol）的两步脱氢。 LMBH-VC 样品中发现了超过 5 wt% 的可逆氢容量，比未掺杂的 LMBH 高出 138%。纳米级LMBH-VC复合材料保持未聚集状态，并且VH物质在循环过程中形成，作为活性“氢泵”。 LMBH-VC 复合材料出色的储氢性能可归因于纳米尺寸和 VC Mxene 催化作用的结合。