Constructing Conductive Bridge Arrays between Ti3C2Tx MXene Nanosheets for High-Performance Lithium-Ion Batteries and Highly Efficient Hydrogen Evolution.

Ti3C2Tx is a member of the MXene family with high potential for electrochemical applications, including lithium-ion batteries (LIBs) and hydrogen evolution reaction (HER). However, severe interlayer restacking not only causes a great loss of the active sites but also decreases the ionic diffusion channels, both of which significantly degrades the electrochemical performances of LIBs and HER. The common interlayer spacers could increase interlayer space but reduce the conductivity. Herein, we introduce in situ carbon nanotube (CNT) arrays between Ti3C2Tx MXene nanosheets (3D CNTs@Ti3C2Tx) as the conductive bridges for achieving a unique architecture with high conductivity, fast ion/mass transfer channels, and high exposure of the activity sites. In this architecture, 1D CNTs can not only be viewed as the interlayer spacer that prevents Ti3C2Tx MXene nanosheets from recombining but also connect with the neighbor Ti3C2Tx MXene nanosheets providing more ion/electron transport channels. Benefiting from this unique structure that could improve ion/electron transfer kinetics and capacitive contribution, 3D CNTs@Ti3C2Tx displays high specific capacity as an anode for LIBs (491 mA h g-1 at 320 mA g-1). Furthermore, 3D CNTs@Ti3C2Tx also exhibits excellent HER performance in alkaline medium (the overpotential is 93 mV at 10 mA cm-2) and excellent water splitting performance. This strategy that in situ construction of CNT arrays between the MXene nanosheets proves an effective method for the rational design of multifunctional energy storage/conversion materials.