MXene (e.g., Ti 3 C 2) represents an important class of two-dimensional (2D) materials owing to its unique metallic conductivity and tunable surface chemistry. However, the mainstream synthetic methods rely on the chemical etching of MAX powders (e.g., Ti 3 AlC 2) using hazardous HF or alike, leading to MXene sheets with fluorine termination and poor ambient stability in colloidal dispersions. Here, we demonstrate a fluoride-free, iodine (I 2) assisted etching route for preparing 2D MXene (Ti 3 C 2 T x , T= O, OH) with oxygen-rich terminal groups and intact lattice structure. More than 71 % of sheets are thinner than 5 nm with an average size of 1.8 mm. They present excellent thin-film conductivity of 1250 S cm À1 and great ambient stability in water for at least 2 weeks. 2D MXene sheets with abundant oxygen surface groups are excellent electrode materials for supercapacitors, delivering a high gravimetric capacitance of 293 F g À1 at a scan rate of 1 mVs À1 , superior to those made from fluoride-based etchants (< 290 F g À1 at 1 mV s À1). Our strategy provides a promising pathway for the facile and sustainable production of highly stable MXene materials.

Abstract2D conjugated metal‐organic frameworks (2D c‐MOFs) are emerging as a novel class of conductive redox‐active materials for electrochemical energy storage. However, developing 2D c‐MOFs as flexible thin‐film electrodes have been largely limited, due to the lack of capability of solution‐processing and integration into nanodevices arising from the rigid powder samples by solvothermal synthesis. Here, the synthesis of phthalocyanine‐based 2D c‐MOF (Ni2[CuPc(NH)8]) nanosheets through ball milling mechanical exfoliation method are reported. The nanosheets feature with average lateral size of ≈160 nm and mean thickness of ≈7 nm (≈10 layers), and exhibit high crystallinity and chemical stability as well as a p‐type semiconducting behavior with mobility of ≈1.5 cm2 V−1 s−1 at room temperature. Benefiting from the ultrathin feature, the nanosheets allow high utilization of active sites and facile solution‐processability. Thus, micro‐supercapacitor (MSC) devices are fabricated mixing Ni2[CuPc(NH)8] nanosheets with exfoliated graphene, which display outstanding cycling stability and a high areal capacitance up to 18.9 mF cm−2; the performance surpasses most of the reported conducting polymers‐based and 2D materials‐based MSCs.

2D materials are important building blocks for the upcoming generation of nanostructured electronics and multifunctional devices due to their distinct chemical and physical characteristics. To this end, large‐scale production of 2D materials with high purity or with specific functionalities represents a key to advancing fundamental studies as well as industrial applications. Among the state‐of‐the‐art synthetic protocols, electrochemical exfoliation of layered materials is a very promising approach that offers high yield, great efficiency, low cost, simple instrumentation, and excellent up‐scalability. Remarkably, playing with electrochemical parameters not only enables tunable material properties but also increases the material diversities from graphene to a wide spectrum of 2D semiconductors. Here, a succinct and critical survey of the recent progress in this research direction is presented, comprising the strategic design, exfoliation principles, underlying mechanisms, processing techniques, and potential applications of 2D materials. At the end of the discussion, the emerging trends, challenges, and opportunities in real practice are also highlighted.

Because of its thickness‐dependent direct bandgap and exceptional optoelectronic properties, indium(III) selenide (In2Se3) has emerged as an important semiconductor for electronics and optoelectronics. However, the scalable synthesis of defect‐free In2Se3 flakes remains a significant barrier for its practical applications. Here, a facile electrochemical strategy is presented for the ultrafast delamination of bulk layered In2Se3 crystals in nonaqueous media, resulting in high‐yield (83%) production of defect‐free In2Se3 flakes with large lateral size (up to 26 µm). The intercalation of tetrahexylammonium (THA+) ions mainly creates stage‐3 intercalated compounds in which every three layers of In2Se3 are occupied by one layer of THA molecules. The subsequent exfoliation leads to a majority of trilayer In2Se3 nanosheets. As a proof of concept, solution‐processed, large‐area (400 µm × 20 µm) thin‐film photodetectors embedded with the exfoliated In2Se3 flakes reveal ultrafast response time with a rise and decay of 41 and 39 ms, respectively, and efficient responsivity (1 mA W−1). Such performance surpasses most of the state‐of‐the‐art thin‐film photodetectors based on transition metal dichalcogenides.

Despite tremendous efforts toward fabrication of three-dimensional macrostructures of two-dimensional (2D) materials, the existing approaches still lack sufficient control over microscopic (morphology, porosity, pore size) and macroscopic (shape, size) properties of the resulting structures. In this work, a facile fabrication method for the wet-chemical assembly of carbon 2D nanomaterials into macroscopic networks of interconnected, hollow microtubes is introduced. As demonstrated for electrochemically exfoliated graphene, graphene oxide, and reduced graphene oxide, the approach allows for the preparation of highly porous (> 99.9%) and lightweight (<2 mg cm −3 ) aeromaterials with tailored porosity and pore size as well as tailorable shape and size. The unique tubelike morphology with high aspect ratio enables ultralow-percolation-threshold graphene composites (0.03 S m −1 , 0.05 vol%) which even outperform most of the carbon nanotube-based composites, as well as highly conductive aeronetworks (8 S m −1 , 4 mg cm −3 ). On top of that, long-term compression cycling of the aeronetworks demonstrates remarkable mechanical stability over 10 000 cycles, even though no chemical cross-linking is employed. The developed strategy could pave the way for fabrication of various macrostructures of 2D nanomaterials with defined shape, size, as well as micro-and nanostructure, crucial for numerous applications such as batteries, supercapacitors, and filters.