Room-Temperature Assembled MXene-Based Aerogels for High Mass-Loading Sodium-Ion Storage.

Highlights: Room temperature graphene oxide-assisted assembly of 3D Ti₃C₂T_x MXene aerogels have been realized by introducing interfacial mediators (amino-propyltriethoxysilane, Mn²⁺, Fe²⁺, Zn²⁺, and Co²⁺). The methodology not only suppresses the oxidation degradation of Ti₃C₂T_x, but also generates porous aerogels with a high Ti₃C₂T_x content (87 wt%) and robustness. As freestanding electrode of the as-prepared Ti₃C₂T_x-based aerogel with a practical-level mass loading of 12.3 mg cm^-2 still delivers an areal capacity of 1.26 mAh cm^-2 at a current density of 0.1 A g^-1. Low-temperature assembly of MXene nanosheets into three-dimensional (3D) robust aerogels addresses the crucial stability concern of the nano-building blocks during the fabrication process, which is of key importance for transforming the fascinating properties at the nanoscale into the macroscopic scale for practical applications. Herein, suitable cross-linking agents (amino-propyltriethoxysilane, Mn²⁺, Fe²⁺, Zn²⁺, and Co²⁺) as interfacial mediators to engineer the interlayer interactions are reported to realize the graphene oxide (GO)-assisted assembly of Ti₃C₂T_x MXene aerogel at room temperature. This elaborate aerogel construction not only suppresses the oxidation degradation of Ti₃C₂T_x but also generates porous aerogels with a high Ti₃C₂T_x content (87 wt%) and robustness, thereby guaranteeing the functional accessibility of Ti₃C₂T_x nanosheets and operational reliability as integrated functional materials. In combination with a further sulfur modification, the Ti₃C₂T_x aerogel electrode shows promising electrochemical performances as the freestanding anode for sodium-ion storage. Even at an ultrahigh loading mass of 12.3 mg cm⁻², a pronounced areal capacity of 1.26 mAh cm⁻² at a current density of 0.1 A g⁻¹ has been achieved, which is of practical significance. This work conceptually suggests a new way to exert the utmost surface functionalities of MXenes in 3D monolithic form and can be an inspiring scaffold to promote the application of MXenes in different areas. [ABSTRACT FROM AUTHOR]