3D-Printing of Freestanding Pure MXene Microarchitectures

Since their discovery, titanium-based MXenes (Ti₃C₂T_x) have attracted significant attention. Several studies have presented versatile, cost-effective, and scalable approaches for fabricating Ti₃C₂T_x-based functional components. However, most previous studies only allowed the realization of 2D patterns or required diverse additives to produce 3D architectures. Herein, a 3D-Printing approach for producing 3D microarchitectures composed entirely of Ti₃C₂T_x. Ti₃C₂T_x additive-free aqueous ink consists of 0.1 wt.% Ti₃C₂T_x nanosheets is proposed. The diameter (d_s) of the printed Ti₃C₂T_x 3D microarchitectures can be determined by controlling the meniscus channel size, which is influenced by the diameter (d_p) of the micropipette opening and pipette-pulling rate (v). Through optimized control of the pipette, a minimum d_s of 1.3 µm is obtained, and complex shapes such as zigzag, helix, bridge, and pyramid shapes can be implemented. To demonstrate the feasibility of realizing functional Ti₃C₂T_x 3D components, three electrical components are demonstrated: 3D micro-interconnects and 3D transducers for photodetectors and humidity sensors. It is believed that this facile approach can be used for nano 3D-Printing as well as micro printing of Ti₃C₂T_x architectures.