Nitrogen Anchoring Effect Triggering Improved Reversible Hydrogen Storage of Mg(BH4)2

en This research uncovered the influence of nitrogen-doped MXene Ti 3 CN on the reversible hydrogen storage properties of Mg(BH 4 ) 2 . The Mg(BH 4 ) 2 -20Ti 3 CN composite began releasing hydrogen at a temperature of 80°C. In addition, the composite discharged over 8.8 wt% hydrogen at a comparatively lower temperature of 270°C, whereas the pure Mg(BH 4 ) 2 emitted merely 5.9 wt% hydrogen under identical circumstances, which exhibited remarkably enhanced dehydrogenation kinetics. Furthermore, upon completion of four cycles, Mg(BH 4 ) 2 -20Ti 3 CN retained a reversible hydrogen storage capacity of 4.5 wt%, representing an 80% improvement over the undoped Mg(BH 4 ) 2 . In the course of the dehydrogenation phase, the boron atoms in Mg(BH 4 ) 2 were anchored by nitrogen atoms in Ti 3 CN to form B-N bonds, which helped suppress the formation of MgB 12 H 12 . During the subsequent rehydrogenation process, the B-N bonds broke, and the boron atoms reparticipated in the reversible transformation into [BH 4 ] − clusters. Meanwhile, the formation of Ti 0 by the reaction of Mg(BH 4 ) 2 with Ti 3 CN weakened the B-H bond energy, and the layered structure provided an effective way for hydrogen spillover. These factors collectively improved the reversible hydrogen storage capabilities of Mg(BH 4 ) 2 . 摘要 zh 本研究揭示了氮掺杂MXene Ti 3 CN对Mg(BH 4 ) 2 可逆储氢性能的影响。Mg(BH 4 ) 2 -20Ti 3 CN复合材料在温度80°C时开始放氢。此外,在270°C的较低温度下,该复合材料的氢排放量超过8.8 wt%,而在相同的条件下,纯Mg(BH 4 ) 2 的氢排放量仅为5.9 wt%,脱氢动力学显著增强。在完成四个循环后,Mg(BH 4 ) 2 -20Ti 3 CN保留了4.5 wt%的可逆储氢容量,比未掺杂的Mg(BH 4 ) 2 提高了80%。在脱氢过程中,Mg(BH 4 ) 2 中的硼原子被Ti 3 CN中的氮原子锚定形成B-N键,有助于抑制MgB 12 H 12 的形成。在随后的再氢过程中,B-N键断裂,硼原子重新参与可逆转化为[BH 4 ] − 簇。同时,Mg(BH 4 ) 2 与Ti 3 CN反应生成Ti 0 ,削弱了B-H键能,层状结构也为氢溢出提供了有效路径。这些因素共同提高了Mg(BH 4 ) 2 的可逆储氢能力。