Maughan Philip A, Bouscarrat Luc, Seymour Valerie R, Shao Shouqi, Haigh Sarah J, Dawson Richard, Tapia-Ruiz Nuria, Bimbo Nuno
Department of Engineering, Lancaster University Lancaster LA1 4YW UK
Department of Chemistry, Lancaster University Lancaster LA1 4YB UK
Nanoscale Adv. 2021 Apr 12;3(11):3145-3158. doi: 10.1039/d1na00081k.
In this work, we apply an amine-assisted silica pillaring method to create the first example of a porous MoTiC MXene with nanoengineered interlayer distances. The pillared MoTiC has a surface area of 202 m g, which is among the highest reported for any MXene, and has a variable gallery height between 0.7 and 3 nm. The expanded interlayer distance leads to significantly enhanced cycling performance for Li-ion storage, with superior capacity, rate capably and cycling stability in comparison to the non-pillared analogue. The pillared MoTiC achieved a capacity over 1.7 times greater than multilayered MXene at 20 mA g (≈320 mA h g) and 2.5 times higher at 1 A g (≈150 mA h g). The fast-charging properties of pillared MoTiC are further demonstrated by outstanding stability even at 1 A g (under 8 min charge time), retaining 80% of the initial capacity after 500 cycles. Furthermore, we use a combination of spectroscopic techniques ( XPS, NMR and Raman) to show unambiguously that the charge storage mechanism of this MXene occurs by a conversion reaction through the formation of LiO. This reaction increases by 2-fold the capacity beyond intercalation, and therefore, its understanding is crucial for further development of this family of materials. In addition, we also investigate for the first time the sodium storage properties of the pillared and non-pillared MoTiC.
在这项工作中，我们应用胺辅助二氧化硅柱撑法制备出首例具有纳米工程化层间距的多孔MoTiC MXene。柱撑后的MoTiC比表面积为202 m²/g，在所有报道的MXene中处于较高水平，其层间距在0.7至3 nm之间可变。层间距的扩大显著提高了锂离子存储的循环性能，与未柱撑的类似物相比，具有更高的容量、倍率性能和循环稳定性。柱撑后的MoTiC在20 mA/g（≈320 mA h/g）时的容量比多层MXene高出1.7倍以上，在1 A/g（≈150 mA h/g）时高出2.5倍。柱撑后的MoTiC即使在1 A/g（充电时间不到8分钟）时也具有出色的稳定性，在500次循环后仍保留初始容量的80%，进一步证明了其快速充电性能。此外，我们结合多种光谱技术（XPS、NMR和拉曼光谱）明确表明，这种MXene的电荷存储机制是通过形成LiO的转化反应实现的。该反应使容量比嵌入反应增加了2倍，因此，对其理解对于该材料家族的进一步发展至关重要。此外，我们还首次研究了柱撑和未柱撑的MoTiC的钠存储性能。
