Although flexible, transparent, and conductive materials are increasingly required for electromagnetic interference (EMI) shielding applications in foldable and wearable electronics, it remains a great challenge to achieve outstanding shielding performances while retaining high light transmittances. Herein, a multiscale structure optimization strategy is proposed to fabricate a transparent and conductive silver nanowire (AgNW) film with both high EMI shielding performance and high light transmittance by a scalable spray-coating technique. By decorating with a Ti 3 C 2 T x MXene coating, the connection and integrity of the AgNW network are greatly improved by welding the nanowire junctions. Compared to a neat AgNW film (21 dB) with the same AgNW density, the Ti 3 C 2 T x MXene-welded AgNW film shows a much higher EMI shielding performance (34 dB) with better mechanical and environmental stabilities. Furthermore, the layered structure design on the macroscopic scale results in an even higher EMI shielding efficiency of 49.2 dB with a high light transmittance of ∼83%. With the Ti 3 C 2 T x MXene coating and the PET substrate as a triboelectric pair, the layered structure offers great flexibility for the transparent film to integrate smart sound monitoring capability. Therefore, the combination of excellent EMI shielding performance, high light transmittance, and sensitive pressure response makes the Ti 3 C 2 T x MXene-welded AgNW films promising for many potential applications in nextgeneration electronics.

Although Ti3C2T x MXene sheets are highly conductive, it is still a challenge to design highly stretchable MXene electrodes for flexible electronic devices. Inspired by the high stretchability of kirigami patterns, we demonstrate a bottom-up methodology to design highly stretchable and conductive polydimethylsiloxane (PDMS)/Ti3C2T x MXene films for electromagnetic interference (EMI) shielding and pressure sensing applications by constructing wrinkled MXene patterns on a flexible PDMS substrate to create a hierarchical surface with primary and secondary surface wrinkles. The self-controlled microcracks created in the valley domains of the hierarchical film via a nonuniform deformation during prestretching/releasing cycles endow the hierarchical PDMS/MXene film with a high stretchability (100%), strain-invariant conductivity in a strain range of 0%–100%, and stable conductivities over an 1000-cycle fatigue measurement. The stretchable film exhibits a highly stable EMI shielding performance of ≈30 dB at a tensile strain of 50%, and its EMI shielding efficiency increases further to 103 dB by constructing a two-film structure. Furthermore, a highly stretchable and sensitive iontronic sensor array with integrated MXene-based electrodes and circuits is fabricated by a stencil printing process, exhibiting high sensitivity (66.3 nF kPa–1), excellent dynamic cycle stability over 1000 cycles under different frequencies, and sensitive pressure monitoring capability under a tensile strain of 50%.

To diversify the motion modes of multifunctional soft robots capable of shape programming, we fabricate a biomimetic and programmable Ti 3 C 2 T x MXene/low-density polyethylene (LDPE) bilayer actuator by spraying an aqueous dispersion of MXenes onto a plasma-activated LDPE film, followed by optimal thermal regulations. Because of the eminent light absorption and photothermal/electrothermal features of MXenes and the extremely mismatched thermal expansion coefficients between the two layers, the MXene/LDPE actuator can be sensitively driven by many stimuli of near-infrared light, electricity, and heat. The initial configuration of the bilayer actuator can be programmed by tuning the thermal regulation temperature, thereby assembling multiple actuation units to achieve biomimetic functions, such as artificial iris, mechanical arms, and flying birds. More importantly, in virtue of free shape cutting and programmable configuration, the MXene/LDPE bilayer actuator can perform untethered locomotion including crawling, rolling, and sailing. The soft robots can not only move on the ground in different forms but also sail on water along any designated routes and complete the surface cargo transportation driven by a near-infrared laser via the photothermal Marangoni effect. The shapeprogrammable methodology for the three amphibious motion modes lays foundations for wide applications of the MXene-based soft robots.

Although two-dimensional transition-metal carbides (MXenes) and intrinsic conductive polymers have been combined to produce functional electromagnetic interference (EMI) shielding composites, acid/alkali-responsive EMI shielding textiles have not been reported. Herein, electrically conductive polyaniline (PANI)/MXene/cotton fabrics (PMCFs) are fabricated by an efficient vacuum filtration-assisted spray-coating method for acid/alkali-responsive and tunable EMI shielding applications on the basis of the high electrical conductivity of MXene sheets and the acid/alkali doping/de-doping feature of PANI nanowires. The as-prepared PMCF exhibits a sensitive ammonia response of 19.6% at an ammonia concentration of 200 ppm. The high EMI shielding efficiency of ∼54 dB is achieved by optimizing the decorated structure of the PANI/MXene coating on the cotton fabrics. More importantly, the PMCF can act adaptively as a “switch” for EMI shielding between the efficient strong shielding of 24 dB and the inefficient weak shielding of 15 dB driven by the stimulation of hydrogen chloride and ammonia vapors. This multifunctional fabric would possess promising applications for intelligent garments, flexible electronic sensors, and smart electromagnetic wave response in special environments.