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Application‐oriented assembly of two‐dimensional nanosheets with uniform nanochannels is critical for fabricating sophisticated, high‐performance membranes for water treatment. However, fabricating the desired membranes by a simple, fast, and effective method is a challenge as most of the previous methods are based on batch processes rather than a continuous roll‐to‐roll process. Here, a simple Meyer rod‐coating approach to continuously fabricate large‐size and flat MXene membranes at a scale up to 5 m is introduced. This study demonstrated that a high MXene concentration, above 10 mg mL−1, is critical in processability due to the desired viscosity, surface tension, and viscoelastic properties. The as‐made MXene membranes show that shearing and solutal‐Marangoni flow can considerably improve the ordering of the stacked MXene nanoflakes. Thus, the rod‐coated MXene membranes demonstrate a smaller surface roughness and interlayer distance compared to the MXene membranes fabricated by the most commonly vacuum‐assisted filtration. The rod‐costed MXene membranes show superior performance in dye and mono/divalent cation separation. The proposed roll‐to‐roll Meyer rod‐coating method can also be used to fabricate MXene‐based composites, such as MXene/carbon nanotubes and MXene/polymer, using the inks containing high concentration MXene and other desired compositions. This roll‐to‐roll method will promote an industry‐level fabrication and application of MXene‐based membranes. [ABSTRACT FROM AUTHOR]

The inherently intermittent feature of solar energy requires reliable energy conversion and storage systems for utilizing the most abundant solar energy. Phase change materials are potential solutions to store a large amount of heat produced by solar light. However, few of the phase change materials have the ability to efficiently convert solar energy into heat; additionally, phase change materials need to be encapsulated in porous substrates for enhancing their leaking resistance and photo-to-thermal performance. In this work, monolithic MXene aerogels, fabricated by Al3+ cross-linking and freeze-drying, were used as the encapsulation and photothermal materials. The composites phase change materials of MXene/polyethylene glycol can be made with a large polyethylene glycol loading above 90 wt% with the maximum of 97 wt%, owing to the large porosity of MXene aerogels. The low content of MXene has a limited impact on the phase transition temperature and enthalpy of polyethylene glycol, with an enthalpy retention rate ranging from 89.2 to 96.5% for 90–97 wt% polyethylene glycol loadings. MXene aerogels greatly improve the leaking resistance of polyethylene glycol above its melting point of 60 °C, even at 100 °C. The composites phase change materials also show outstanding cycling stability for 500 cycles of heat storage and release, retaining 97.7% of the heat storage capability. The optimized composite phase change material has a solar energy utilization of 93.5%, being superior to most of the reported results. Our strategy produces promising composite phase change materials for solar energy utilization using the MXene aerogels as the encapsulation and photothermal materials. [ABSTRACT FROM AUTHOR]

The scarcity of water and increasing water pollution are the pressing challenge human being facing. Recovering water and valuable heavy metals is highly desired for treating heavy metal containing wastewater. We proposed a novel hydrate-based process to treat Ni2+ containing wastewater. The water recovery, Ni2+ enrichment factor, desalination efficiency were studied using this cyclopentane hydrate-based method. A water recovery of 43% can be obtained with a desalination efficiency of round 88% and an enrichment factor of 1.6. The desalination efficiency and the quality of the as-made water via the hydrate-based process can be further improved to above 99% via three-stage hydrate reaction. The proposed hydrate-based water treatment process may find wide applications in waste water treatment and heavy metal recycling.

The excellent motion performance of gallium-based liquid metals (LMs) upon the application of a modest electric field has provided a new opportunity for the development of autonomous soft robots. However, the locomotion of LMs often appears in an alkaline solution, which hampers the application under other different conditions. In this work, a novel robot arm is designed to transfer the motion of the LM from an alkaline solution in a synchronous drive mode. The liquid metal droplet (LMD) at the bottom of the robot arm is actuated using a DC voltage to provide the driving force for the system. By introducing an end effector at the center of the robot arm, the synchronous motion of the system is replicated and can be applied to different situations. The theoretical understanding of continuous electrowetting (CEW) at the LM interface is explained, and then the motion performance of the robot arm against the function of the applied voltage and driving direction is investigated. Moreover, several applications using this robot arm, such as pattern drawing, cargo transportation, and drug concentration detection, are demonstrated. The presented robot arm has the potential to observably expand the application fields of the LM. [ABSTRACT FROM AUTHOR]

Rigid sensors are a mature type of sensor, but their poor deformation and flexibility limit their application range. The appearance and development of flexible sensors provide an opportunity to solve this problem. In this paper, a resistive flexible sensor utilizes gallium−based liquid metal (eutectic gallium indium alloy, EGaIn) and poly(dimethylsiloxane) (PDMS) and is fabricated using an injecting thin−line patterning technique based on soft lithography. Combining the scalable fabrication process and unique wire−shaped liquid metal design enables sensitive multifunctional measurement under stretching and bending loads. Furthermore, the flexible sensor is combined with the glove to demonstrate the application of the wearable sensor glove in the detection of finger joint angle and gesture control, which offers the ability of integration and multifunctional sensing of all−soft wearable physical microsystems for human–machine interfaces. It shows its application potential in medical rehabilitation, intelligent control, and so on. [ABSTRACT FROM AUTHOR]

To simplify the production process of thermoplastic polyurethane (TPU)/methyl vinyl silicone rubber (VMQ)‐based thermoplastic vulcanizate (TPV), a series of block TPUs with different hydroxybutanyl terminated polydimethylsiloxane (PDMS) content were used as the matrix to increase the essential compatibility. The impact of microstructure and macroscopic properties was explored. PMDS promoted the microphase separation of TPU, which increased the essential compatibility in TPVs. The essential compatibilization effect of PDMS made the tensile strength retention proportion of TPV relative to the raw material TPU at 40%, but the elongation at break could reach 192%, which had an excellent toughening effect. Moreover, PDMS made the limiting oxygen index of TPV‐323 reach 27%. The analysis of the carbon layer proved that the Si element formed a silicon oxycarbon layer with excellent flame retardancy on the surface. [ABSTRACT FROM AUTHOR]

Ultrathin, transparent, and free‐standing films assembled from low‐dimensional nanomaterials (LDMs) are promising for various applications, including transparent heaters and membranes. However, the intact separation of the assembled films, especially those with controlled ultrathin thickness from deposited substrates, is a tremendous challenge, particularly for fast peeling off via self‐detaching. Herein, we propose a versatile method to rapidly peel off ultrathin assembled LDM films, including three types of carbon nanotubes, vermiculite, Ag nanowires, and carbon nanotube@graphene, by dissolving the MXene interlayer from the layer‐by‐layer filtered MXene/LDM Janus films using diluted H2O2. The MXene sacrificial interlayers play dual roles, including physical isolation of LDM films from filter membranes and the production of bubbles that buoy ultrathin LDM films, making them free‐standing. The integrality and self‐detaching rate of the LDM films are determined by the loading and reactivity of the MXene interlayers. The intact LDM films can self‐detach in 80 s by dissolving the optimized MXene interlayer and producing bubbles. The as‐made free‐standing ultrathin LDM films can be transferred to arbitrary substrates and exhibit outstanding performance as transparent heaters. This scalable method provides an efficient and versatile method to produce ultrathin, transparent, and free‐standing LDM films and finds new applications for the growing MXene family. [ABSTRACT FROM AUTHOR]

Self-assembly of two-dimensional (2D) nanosheets into three-dimensional (3D) aerogels, can solve the problems of recovery and re-stacking, and fully utilize the potential of high specific surface areas and easily accessible surface sites. However, organic binders have to be added to fabricate aerogels using 2D nanosheets as building blocks, which inevitably limit the performance of 2D nanosheets due to covered surfaces. Herein, we proposed a new strategy to fabricate vermiculite aerogels (VAs) assembled from delaminated vermiculite nanosheets (VNSs) via metal ion induced fast gelation. The cheap and earth-abundant vermiculite was used as the raw materials to produce high-quality nanosheets by high speed shear-mixing. VNSs with a concentration as high as 15 mg/mL were produced. The concentration-dependent gelation performance was studied and showed a critical concentration of 6 mg/mL for gelation and fabricating monolithic aerogels without cracks. It is also found metal ions played critical roles in formation mechanically stable and robust aerogels with trivalent cations, particularly Al3+ being most effective. The edge-surface intertwining VNSs induced by the Al3+ cross-linking endow the VAs good mechanical strength and excellent environmental stability. As fixed adsorbent beds, the VAs show promising performance in fast removing organic dyes from water due to the developed pore structures, large specific surface area, and exposed surface sites. [Display omitted] • Vermiculite aerogels were successfully assembled using a fast and scalable method. • Both nanosheet concentration and the ion type play critical roles in gelation. • Vermiculite aerogels have shown excellent performance in removing organic dyes. [ABSTRACT FROM AUTHOR]

Hydrate-based CO2 capture from large emission sources is considered a promising process for greenhouse gas mitigation. The addition of nanoparticles may promote or inhibit the formation of hydrates. In this work, CO2 hydrate formation experiments were performed in a dual-cell high-pressure reactor. Non-modified, hydrophilic modified and hydrophobic modified aluminum oxide (Al2O3) nanoparticles at different concentrations were added to assess their promoting or inhibitory effects on CO2 hydrate formation. The equilibrium temperature and pressure, induction time, and total gas consumption during CO2 hydrate formation were measured. The results show that the presence of Al2O3 nanoparticles exerts little effect on the phase equilibrium of CO2 hydrates. Under the experimental conditions, the addition of all Al2O3 nanoparticles imposes an inhibitory effect on the final gas consumption except for the 0.01 wt% addition of hydrophilic modified Al2O3 nanoparticles. The induction time required for the nucleation of CO2 hydrates mainly ranges from 70 to 90 min in the presence of Al2O3 nanoparticles. Compared to the absence of nanoparticles, the addition of non-modified and hydrophilic modified Al2O3 nanoparticle reduces the induction time. However, the hydrophobic modified Al2O3 nanoparticles extend the induction time. [ABSTRACT FROM AUTHOR]

• High water recovery can be obtained via cyclopentane hydrate formation. • Halide ions have different capability in hindering hydrate formation. • High purity fresh water can be produced via multi-stage hydrate desalination. Hydrate-based desalination is an attractive and energy-effective method. In order to obtain high water recovery and purity, the desalination and Li+ enrichment performance were examined using single-stage desalination via graphite-promoted cyclopentane (CP) hydrate formation. LiCl, LiBr and LiI aqueous solutions with concentration ranging from 0.01 to 0.6 mol/L were used as brine. The rate for CP hydrate formation is determined by concentration, independent of the type of used salts. Halide ions were found to have the different capability in hindering CP hydrate-based desalination, with an order of Cl− < Br− < I−. The desalination efficiency was improved with increased concentration. Water recovery of 40% can be obtained in 1 h reaction, demonstrating the high efficiency of hydrate-based desalination. The desalination efficiency remains constant at around 70% over 24 h reaction, which can be dramatically enhanced by multi-stage desalination. The graphite powder, as the promoter for hydrate formation shows impressive recycling stability. The finding in this study would be of great help for developing effective desalination processes to produce fresh water and enrich high-value salts via CP hydrates. [ABSTRACT FROM AUTHOR]

Methane hydrate (MH) makes it possible to store methane using the cheapest and safest solvent: water. However, the sluggish formation kinetics hinders its practical utilization. Recently, the use of nanomaterials has been suggested as a potential solution; however, there is still a lack of high-efficiency kinetic promotors, and the promoting mechanism remains unclear. Herein, we demonstrated that MXene dispersion is promising for the storage of methane via MH with rapid formation kinetics, high storage capacity, and impressive cyclic stability. MXene can significantly shorten the induction time for MH formation. The enhanced kinetics was achieved by providing extra nucleation sites and enhancing thermal conductivity, although the increased surface tension of MXene dispersion could impede the MH formation via limited mass transfer. We confirmed that the concentration-dependent promoting effect of MXene dispersions results from regulating the assembly of water molecules. The insight of this work can apply to develop high-efficiency additives to control the formation kinetics of MH.