Miniaturization of electronics demands electromagnetic interference (EMI) shielding of nanoscale dimension. The authors report a systematic exploration of EMI shielding behavior of 2D Ti3C2Tx MXene assembled films over a broad range of film thicknesses, monolayer by monolayer. Theoretical models are used to explain the shielding mechanism below skin depth, where multiple reflection becomes significant, along with the surface reflection and bulk absorption of electromagnetic radiation. While a monolayer assembled film offers ≈20% shielding of electromagnetic waves, a 24‐layer film of ≈55 nm thickness demonstrates 99% shielding (20 dB), revealing an extraordinarily large absolute shielding effectiveness (3.89 × 106 dB cm2 g−1). This remarkable performance of nanometer‐thin solution processable MXene proposes a paradigm shift in shielding of lightweight, portable, and compact next‐generation electronic devices.

MXene has shown enormous potential in scientific fields, including energy storage and electromagnetic interference (EMI) shielding. Unfortunately, MXene-based material structures generally suffer from mechanical fragility and vulnerability to oxidation. Herein, musselinspired dopamine successfully addresses those weaknesses by improving interflake interaction and ordering in MXene assembled films. Dopamine undergoes in situ polymerization and binding at MXene flake surfaces by spontaneous interfacial charge transfer, yielding an ultrathin adhesive layer. Resultant nanocomposites with highly aligned tight layer structures achieve approximately seven times enhanced tensile strength with a simultaneous increase of elongation. Ambient stability of MXene films is also greatly improved by the effective screening of oxygen and moisture. Interestingly, angstrom thick polydopamine further promotes the innate high electrical conductivity and excellent EMI shielding properties of MXene films. This synergistic concurrent enhancement of physical properties proposes MXene/polydopamine hybrids as a general platform for MXene based reliable applications.

Nanoscale structure engineering is in high demand for various applications of 2D transition metal dichalcogenides (TMDs). An edge‐exposed 2D polycrystalline MoS2 nanomesh thin film is demonstrated via block copolymer (BCP) nanopatterning. Molybdenum nanomesh structure is formed by direct metal deposition of hexagonal cylinder BCP nanotemplate and the following lift‐off process. Subsequent sulfurization of the molybdenum nanomesh creates MoS2 nanomesh thin films without any degradative etching step. The approach is applicable to not only other metal sulfides and oxides but also other nanoscale structures of TMD thin films including nanodot and nanowire array by means of various BCP nanotemplate shapes. As the edge site of MoS2 is highly active for NO2 sensing, the edge‐exposed MoS2 nanomesh demonstrates sevenfold enhancement of sensitivity for NO2 molecules compared to uniform thin film as well as superior reversibility even under 80% relative humidity environment. This structure engineering method could greatly strengthen the potential application of 2D TMD materials with the optimal customized nanoscale structures.

Hybridization of low-dimensional components with diverse geometrical dimensions should offer an opportunity for the discovery of synergistic nanocomposite structures. In this regard, how to establish a reliable interfacial interaction is the key requirement for the successful integration of geometrically different components. Here, we present 1D/2D heterodimensional hybrids via dopant induced hybridization of 2D Ti3C2T x MXene with 1D nitrogen-doped graphene nanoribbon. Edge abundant nanoribbon structures allow a high level nitrogen doping (∼6.8 at%), desirable for the strong coordination interaction with Ti3C2T x MXene surface. For piezoresistive pressure sensor application, strong adhesion between the conductive layers and at the conductive layer/elastomer interface significantly diminishes the sensing hysteresis down to 1.33% and enhances the sensing stability up to 10 000 cycles at high pressure (100 kPa). Moreover, large-area pressure sensor array reveals a high potential for smart seat cushion-based posture monitoring application with high accuracy (>95%) by exploiting machine learning algorithm.

An effective pathway to build macroscopic scale functional architectures bearing diverse structural dimensions is one of the critical challenges in the two-dimensional (2D) MXene research area. Unfortunately, assembling MXene without adhesive binder is largely limited due to its innate brittle nature and the relatively weak inter-flake van der Waals contact, in contrast to other mechanically compliant 2D materials such as graphene. Herein, an electrochemical selfassembly of pure Ti 3 C 2 T x MXenes is presented for functional multidimensional MXene structures, effectively driven by layerby-layer spontaneous interfacial reduction at metal template surfaces and subsequent defunctionalization. A three-dimensional open porous aerogel as well as 2D highly stacked thin film structures could be readily obtained in this approach, along with largely enhanced electrical properties induced by spontaneous removal of charge-trapping oxygen functional groups. Accordingly, supercapacitors and electromagnetic interference shielding films based on the multidimensional assembly demonstrate excellent performances.

Graphene fibers (GFs) are promising elements for flexible conductors and energy storage devices, while translating the extraordinary properties of individual graphene sheets into the macroscopically assembled 1D structures. We report that a small amount of water addition to the graphene oxide (GO) N -methyl-2-pyrrolidone (NMP) dispersion has significant influences on the mesophase structures and physical properties of wet-spun GFs. Notably, 2 wt % of water successfully hydrates GO flakes in NMP dope to form a stable graphene oxide liquid crystal (GOLC) phase. Furthermore, 4 wt % of water addition causes spontaneous planarization of wet-spun GFs. Motivated from these interesting findings, we develop highly electroconductive and mechanically strong flat GFs by introducing highly crystalline electrochemically exfoliated graphene (EG) in the wet-spinning of NMP-based GOLC fibers. The resultant high-performance hybrid GFs can be sewn on cloth, taking advantage of the mechanical robustness and high flexibility.

Graphene-fiber (GF) supercapacitors attract significant research attention in the field of wearable devices. Unfortunately, there still remains a need for the active materials with increased energy density. Transition Metal Nitrides...

In article number 1906769, Yury Gogotsi, Sang Ouk Kim, Chong Min Koo, and co‐workers report systematic experimental and theoretical exploration of the electromagnetic interference (EMI) shielding behavior of two‐dimensional Ti3C2Tx MXene assembled films over a broad range of film thicknesses, monolayer by monolayer. A monolayer assembled film offers ≈20% shielding of electromagnetic waves, while a 55 nm thickness demonstrates 99% shielding, revealing that MXene is the best candidate for lightweight EMI shielding applications.