Although two-dimensional boron (B) has attracted much attention in electronics and optoelectronics due to its unique physical and chemical properties, in-depth investigations and applications have been limited by the current synthesis techniques. Herein, we demonstrate that high-quality few-layer B sheets can be prepared in large quantities by sonication-assisted liquid-phase exfoliation. By simply varying the exfoliating solvent types and centrifugation speeds, the lateral size and thickness of the exfoliated B sheets can be controllably tuned. Additionally, the exfoliated few-layer B sheets exhibit excellent stability and outstanding dispersion in organic solvents without aggregates for more than 50 days under ambient conditions, owing to the presence of a solvent residue shell on the B sheet surface that provides excellent protection against air oxidation. Moreover, we also demonstrate the use of the exfoliated few-layer B sheets for high-performance supercapacitor electrode materials. This as-prepared device exhibits impressive electrochemical performance with a wide potential window of up to 3.0 V, excellent energy density as high as 46.1 Wh/kg at a power density of 478.5 W/kg, and excellent cycling stability with 88.7% retention of the initial specific capacitance after 6000 cycles. This current work not only demonstrates an effective strategy for the synthesis of the few-layer B sheets in a controlled manner but also makes the resulting materials promising for next-generation optoelectronics and energy storage applications.

Poly(vinyl alcohol) (PVA) hydrogels with tissue-like viscoelasticity, excellent biocompatibility, and high hydrophilicity have been considered as promising cartilage replacement materials. However, lack of sufficient mechanical properties is a critical barrier to their use as load-bearing cartilage substitutes. Herein, we report hydroxylated boron nitride nanosheets (OH-BNNS)/PVA interpenetrating hydrogels by cyclically freezing/thawing the aqueous mixture of PVA and highly hydrophilic OH-BNNS (up to 0.6 mg/mL, two times the highest reported so far). Encouragingly, the resulting OH-BNNS/PVA hydrogels exhibit controllable reinforcements in both mechanical and thermal responses by simply varying the OH-BNNS contents. Impressive 45, 43, and 63% increases in compressive, tensile strengths and Young's modulus, respectively, can be obtained even with only 0.12 wt% (OH-BNNS:PVA) OH-BNNS addition. Meanwhile, exciting improvements in the thermal diffusivity (15%) and conductivity (5%) can also be successfully achieved. These enhancements are attributed to the synergistic effect of intrinsic superior properties of the as-prepared OH-BNNS and strong hydrogen bonding interactions between the OH-BNNS and PVA chains. In addition, excellent cytocompatibility of the composite hydrogels was verified by cell proliferation and live/dead viability assays. These biocompatible OH-BNNS/PVA hydrogels are promising in addressing the mechanical failure and locally overheating issues as cartilage substitutes and may also have broad utility for biomedical applications, such as drug delivery, tissue engineering, biosensors, and actuators.

In the emerging Internet of Things, stretchable antennas can facilitate wireless communication between wearable and mobile electronic devices around the body. The proliferation of wireless devices transmitting near the human body also raises interference and safety concerns that demand stretchable materials capable of shielding electromagnetic interference (EMI). Here, an ultrastretchable conductor is fabricated by depositing a crumple-textured coating composed of 2D Ti 3 C 2 T x nanosheets (MXene) and single-walled carbon nanotubes (SWNTs) onto latex, which can be fashioned into high-performance wearable antennas and EMI shields. The resulting MXene-SWNT (S-MXene)/latex devices are able to sustain up to an 800% areal strain and exhibit strain-insensitive resistance profiles during a 500-cycle fatigue test. A single layer of stretchable S-MXene conductors demonstrate a strain-invariant EMI shielding performance of ≈30 dB up to 800% areal strain, and the shielding performance is further improved to ≈47 and ≈52 dB by stacking 5 and 10 layers of S-MXene conductors, respectively. Additionally, a stretchable S-MXene dipole antenna is fabricated, which can be uniaxially stretched to 150% with unaffected reflected power <0.1%. By integrating S-MXene EMI shields with stretchable S-MXene antennas, a wearable wireless system is finally demonstrated that provides mechanically stable wireless transmission while attenuating EM absorption by the human body.existing mobile devices. [1] To enable highperformance wireless communication between wearable sensors, displays, and data processing devices around the body, new routes to fabricating for stretchable antennas that exhibit mechanically stable performance are needed. Furthermore, the proliferation of mobile and wearable devices based on various wireless technologies, including GPS, Bluetooth, Wi-Fi, and near-field communication, is increasing the frequency and duration of the human body exposed to electromagnetic (EM) fields, which raises interference and safety concerns that may require certain suitable materials for EM protection. [2] Therefore, in addition to the growing demand for stretchable antennas, electromagnetic interference (EMI) shielding materials that are stretchable, durable, and can be integrated closely with wearable wireless technologies are needed to reduce the exposure of the human body to EM fields. Integrating such stretchable antennas with on-site EMI shields not only provides protection against EM fields, but also prevents unauthorized wireless transmission between wearable electronics and mobile devices for enhanced wireless privacy.Both wearable antennas and stretchable EMI shields face similar technological challenges, where the key materials awaiting to be developed are the stretchable conductors with high strain tolerance and strain-invariant electrical conductivities.Metals (e.g., Cu and Al) are the conventionally used materials for EMI shields and antennas on many occasions. As the trend in today's electronic devices becomes faster, lighter, and...

Capacitive deionization (CDI) is a competent water desalination technique offering an appropriate route to obtain clean water. However, a rational designed structure of the electrode materials is essentially required for achieving high CDI performance. Here, a novel sponge‐templated strategy is developed for the first time to prepare graphene sheets with high specific surface area and suitable pore size distribution. Sponge is used as the support of graphene oxide to prevent the restack of graphene sheets, as well as to suppress the agglomerate during the annealing process. Importantly, the as‐fabricated graphene sheets possess high specific surface area of 305 m2 g−1 and wide pore size distribution. Ultrahigh CDI performance, a remarkable electrosorptive capacity of 4.95 mg g−1, and siginificant desorption rate of 25 min, is achieved with the sponge‐templated prepared graphene electrodes. This work provides an effective solution for the synthesis of rational graphene architectures for general applications in CDI, energy storage and conversion.

The high occurrence of trapped unreactive charges due to chemical defects seriously affects the performance of g-C 3 N 4 in photocatalytic applications. This problem can be overcome by introducing ultrasmall red phosphorus (red P) crystals on g-C 3 N 4 sheets. The elemental red P atoms reduce the number of defects in the g-C 3 N 4 structure by forming new chemical bonds for much more effective charge separation. The product shows significantly enhanced photocatalytic activity toward hydrogen production. To the best of our knowledge, the hydrogen evolution rate obtained on this hybrid should be the highest among all P-containing g-C 3 N 4 photocatalysts reported so far. The trapping and detrapping processes in this red P/g-C 3 N 4 system are thoroughly revealed by using time-resolved transient absorption spectroscopy. P modification was thoroughly investigated by using timeresolved transient absorption (TA) experiments.The authors declare no conflict of interest.

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In this work, we have prepared a p-type semiconductor of Cu2O decorated with MoS2 nanosheets as cocatalyst for efficient solar hydrogen production under visible light. Results show that Cu2O decorated with 1.0 wt % MoS2 presents the maximum reduction photocurrent density of 0.17 mA cm–2, which is 7-fold higher than pristine Cu2O. Furthermore, the as-prepared MoS2@Cu2O exhibits remarkable photostability with only 7% loss of its original photocurrent after 9 h of continuous work. The excellent performance of MoS2@Cu2O is ascribed to the introduction of active sites of MoS2 nanosheets as cocatalyst to the surface of Cu2O nanoparticles, which activates the photocatalyst by lowering the electrochemical proton reduction overpotential and also inhibits photoinduced corrosion during the measurement.

Layered transition metal (Ti, Ta, Nb, etc.) dichalcogenides are important prototypes for the study of the collective charge density wave (CDW). Reducing the system dimensionality is expected to lead to novel properties, as exemplified by the discovery of enhanced CDW order in ultrathin TiSe . However, the syntheses of monolayer and large-area 2D CDW conductors can currently only be achieved by molecular beam epitaxy under ultrahigh vacuum. This study reports the growth of monolayer crystals and up to 5 × 10 µm large films of the typical 2D CDW conductor-TiSe -by ambient-pressure chemical vapor deposition. Atomic resolution scanning transmission electron microscopy indicates the as-grown samples are highly crystalline 1T-phase TiSe . Variable-temperature Raman spectroscopy shows a CDW phase transition temperature of 212.5 K in few layer TiSe , indicative of high crystal quality. This work not only allows the exploration of many-body state of TiSe in 2D limit but also offers the possibility of utilizing large-area TiSe in ultrathin electronic devices.