Vertical Graphene Nanowalls Anchored on Ti₃C₂T_x MXene as a Hierarchical Composite with Enhanced Supercapacitive...

MXene composites have gained considerable attention for their potential application in energy storage devices. An important limitation arises from the fact that MXene nanosheets are prone to restacking and self-aggregation during electrochemical operation, which reduces electrolyte accessibility and limits practical charge storage. This limitation can be mitigated by introducing suitable intercalation scaffolds. In this work, a hierarchical architecture is developed by integrating vertical graphene nanowalls (GNWs) with Ti₃C₂T_x MXene. The GNWs/Ti₃C₂T_x hybrid structure is fabricated through a stepwise route involving selective acid etching of Ti₃AlC₂, film assembly by filtration, and subsequent growth of GNWs via inductively coupled plasma chemical vapor deposition (ICP-CVD). Owing to their large accessible surface area and rigid vertical morphology, GNWs act as effective spacers that stabilize the Ti₃C₂T_x interlayer framework, expand the intersheet spacing, and create multidirectional, continuous ion-transport pathways. Consequently, a greater fraction of ion-accessible electroactive sites is exposed and utilized more efficiently. The electrochemical performance of the GNWs/Ti₃C₂T_x electrode was evaluated in aqueous H₂SO₄ within a 0.7 V potential window. At a scan rate of 10 mV s^-1, the hybrid delivers an areal capacitance of 163.17 mF cm^-2, corresponding to a 1.2-fold enhancement relative to Ti₃C₂T_x and a 7.3-fold increase compared with GNWs on graphite sheets. These results demonstrate that the GNWs/Ti₃C₂T_x combines structural stability with improved charge-storage kinetics, highlighting its promise for high-performance supercapacitors. More broadly, the design strategy presented here offers a practical framework for enhancing the electrochemical properties of MXene-based composites and can be extended to other hybrid electrode systems.