Increasing fresh water demand for drinking and agriculture is one of the grand challenges of our age. Graphene oxide (GO) membranes have shown a great potential for desalination and water purification. However, it is challenging to further improve the water permeability without sacrificing the separation efficiency, and the GO membranes are easily delaminated in aqueous solutions within few hours. Here, we report a class of reduced GO membranes with enlarged interlayer distance fabricated by using theanine amino acid and tannic acid as reducing agent and cross-linker. Such membranes show water permeance over 10,000 L m−2 h−1 bar−1, which is 10–1000 times higher than those of previously reported GO-based membranes and commercial membranes, and good separation efficiency, e.g., rhodamine B and methylene blue rejection of ~100%. Moreover, they show no damage or delamination in water, acid, and basic solutions even after months.

Ultrathin, lightweight, high‐strength, and thermally conductive electromagnetic interference (EMI) shielding materials with high shielding effectiveness (SE) are highly desired for next‐generation portable and wearable electronics. Pristine graphene (PG) has a great potential to meet all the above requirements, but the poor processability of PG nanosheets hinders its applications. Here, efficient synthesis of highly aligned laminated PG films and nacre‐like PG/polymer composites with a superhigh PG loading up to 90 wt% by a scanning centrifugal casting method is reported. Due to the PG‐nanosheets‐alignment‐induced high electrical conductivity and multiple internal reflections, such films show superhigh EMI SE comparable to the reported best synthetic material, MXene films, at an ultralow thickness. An EMI SE of 93 dB is obtained for the PG film at a thickness of ≈100 µm, and 63 dB is achieved for the PG/polyimide composite film at a thickness of ≈60 µm. Furthermore, such PG‐nanosheets‐based films show much higher mechanical strength (up to 145 MPa) and thermal conductivity (up to 190 W m−1 K−1) than those of their MXene counterparts. These excellent comprehensive properties, along with ease of mass production, pave the way for practical applications of PG nanosheets in EMI shielding.

Lithium-sulfur (Li-S) batteries are attracting increasing interest due to their high theoretical specific energy density, low cost, and eco-friendliness. However, most reports of the high gravimetric specific capacity and long cyclic life are not practically reliable because of their low areal specific capacity derived from the low areal sulfur loading and low sulfur content. Here, we fabricated a highly porous graphene with high pore volume of 3.51 cm(3) g(-1) as the sulfur host, enabling a high sulfur content of 80 wt %, and based on this, we further proposed an all-graphene structure for the sulfur cathode with highly conductive graphene as the current collector and partially oxygenated graphene as a polysulfide-adsorption layer. This cathode structural design enables a 5 mg cm(-2) sulfur-loaded cathode showing both high initial gravimetric specific capacity (1500 mAh g(-1)) and areal specific capacity (7.5 mAh cm(-2)), together with excellent cycling stability for 400 cycles, indicating great promise for more reliable lithium-sulfur batteries.

It is crucial to align two-dimensional nanosheets to form a highly compact layered structure for many applications, such as electronics, optoelectronics, thermal management, energy storage, separation membranes, and composites. Here we show that continuous centrifugal casting is a universal, scalable and efficient method to produce highly aligned and compact two-dimensional nanosheets films with record performances. The synthesis  mechanism, structure  control and property  dependence of alignment and compaction of the films are discussed. Significantly, 10-μm-thick graphene oxide films can be synthesized within 1 min, and scalable synthesis of meter-scale films is demonstrated. The reduced graphene oxide films show super-high strength (~660 MPa) and conductivity (~650 S cm−1). The reduced graphene oxide/carbon nanotube hybrid-film-based all-solid-state flexible supercapacitors exhibit ultrahigh volumetric capacitance (407 F cm−3) and energy density (~10 mWh cm−3) comparable to that of thin-film lithium batteries. We also demonstrate the production of highly anisotropic graphene nanocomposites as well as aligned, compact films and vertical heterostructures of various nanosheets.

Proton transport in nanochannels under humid conditions is crucial for the application in energy storage and conversion. However, existing materials, including Nafion, suffer from limited conductivity of up to 0.2 siemens per centimeter. We report a class of membranes assembled with two-dimensional transition-metal phosphorus trichalcogenide nanosheets, in which the transition-metal vacancies enable exceptionally high ion conductivity. A Cd0.85PS3Li0.15H0.15 membrane exhibits a proton conduction dominant conductivity of ~0.95 siemens per centimeter at 90° Celsius and 98% relative humidity. This performance mainly originates from the abundant proton donor centers, easy proton desorption, and excellent hydration of the membranes induced by cadmium vacancies. We also observed superhigh lithium ion conductivity in Cd0.85PS3Li0.3 and Mn0.77PS3Li0.46 membranes.

No abstract

Here, a facile, low-cost, and high-efficiency method to construct a vertically aligned hexagonal boron nitride nanosheet (hBNN) thermal conduction channel structure is proposed to improve the thermal conductivity. First, exfoliated negatively charged BNNs and positively charged FeCo nanocubes self-assemble to form complex nanomaterials by strong electrostatic interactions. Then, the BNNs can orient with FeCo nanocubes in magnetic field, and the {001} facets of BNNs adsorb on the {100} facets of FeCo nanocubes. The large scale range and high-density FeCo/hBN-aligned structures are observed by scanning electron microscopy, which can act as thermal dissipation channels by conveying more phonons through a preponderant thermally conductive direction. The thermal conductivity of the composite films with 30 wt % FeCo and 50 wt % BN filler is 2.25 W m −1 K −1 , 7 times higher than that of the films only containing 50 wt % randomly distributed hBN filler (0.325 W m −1 K −1 ) and 20 times higher than pure polydimethylsiloxane films (0.114 W m −1 K −1 ). The thermal management capability of the composite films is evaluated as a thermal conducting substrate of a light-emitting diode chip and the infrared thermal technology. Apart from the surprising thermal conductivity, FeCo−BNNs composite films also exhibit superb flexibility.

No abstract