Search

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]

• V-aerogels can be easily fabricated on a large scale by ion-induced fast gelation. • V-aerogels show excellent thermal insulation and infrared stealth performance. • The V-aerogels demonstrate robust structural stability up to 1300 °C. Low thermal conductivities and high fire resistance are highly desired for the materials used in energy-efficient buildings with high-level safety. Traditional inorganic insulating materials are either fragile or have high thermal conductivities, while organic insulating materials or hybrids with inorganic ones are limited by poor fire resistance and significant volume shrinkage after heating. Herein we report mechanically robust vermiculite aerogels with a thermal conductivity as low as 0.033 W/(m·K), excellent fire resistance, and robust structural stability at high temperatures. The aerogels were assembled from delaminated two-dimensional vermiculite nanosheets via trivalent cations, such as Al3+, Fe3+, and La3+, induced fast gelation. The nanosheet concentration and ion cross-linking play critical roles in forming monolithic and robust aerogels. The vermiculite aerogels can resist a high-temperature flame without disintegration and show almost no volume shrinkage after long-time heat treatment at 700 °C. The excellent robustness and super-insulating performance (0.021 W/(m·K)) remain and even are improved after heating at 900 °C for 1 h. The as-made vermiculite aerogels show low-bulk density, high-porosity, super-insulating performance, excellent fire resistance, and environmental safety, endowing them with great potential as ideal thermal insulators for various applications, such as energy-efficient buildings. [ABSTRACT FROM AUTHOR]

Purification of seawater and wastewater by solar-driven interfacial evaporation is a promising way to alleviate water scarcity. However, the high cost, complex fabrication methods, and short service life of the materials limit their practical application. Herein, a novel three-dimensional (3D) photothermal aerogel composited of vermiculite nanosheets and polyvinyl alcohol (PVA) precursors have been prepared via freeze-drying and treated by quick pyrolysis for highly efficient solar-driven interfacial evaporation. The vermiculite nanosheets exfoliated from natural clay were used as the skeletal support of the composite aerogels, which are cheap and abundant natural materials. The introduced PVA improves the mechanical properties and produces carbon derivatives after pyrolysis, enhancing the light absorption capacity. The as-prepared aerogels have hierarchical porous structures, impressive mechanical properties, great light absorption capacity, and outstanding salt-rejection ability. The optimized aerogel not only exhibits a high evaporation rate of 2.64 kg m−2 h−1 (normalized to top and side surfaces) under 1.0 sun irradiation with excellent cost-effectiveness at 361.64 g h−1 $−1 but also shows superior performance in treating high-salt (15.0 wt%) brine water and organic dye-contained wastewater. The proposed method provides an attractive and effective way to prepare photothermal aerogels for efficient solar steam generation for mitigating water scarcity issues. • 3D clay-based solar evaporators for desalination were made. • Scalable and low-cost PVPA was prepared via a simple and quick pyrolysis strategy. • The as-prepared PVPA shows excellent evaporation performance and reusability. • The PVPA can treat different concentrations of brine and dye-contained wastewater. [ABSTRACT FROM AUTHOR]

• Aerogels can be easily fabricated via cross-linking vermiculite and MXene. • The pore structures and surface compositions of aerogels can be finely tuned. • Monolithic aerogel has excellent CO 2 storing capacity by boosted hydrate formation. • Degree of water saturation plays the most vital role in hydrate formation. Gas hydrate provides an ideal way for CO 2 capture and storage using water by forming cages via an environment-friendly and energy-efficient hydrate formation process. However, the practical utilization and upscaling of hydrate-based gas storage are impeded by the slow formation kinetics of gas hydrate due to the limited multiphase interface for mass transfer and reaction. Herein, we demonstrated a simple strategy to fabricate composite aerogels assembled of natural vermiculite and MXene nanosheets as the ideal substrate for boosting CO 2 hydrate formation. The structure and surface compositions of vermiculite/MXene composite aerogels were analyzed by XRD, FT-IR, SEM, and XPS. It shows that monolithic pore structures and surface functional groups can be finely tuned by controlling the mass ratio of vermiculite and MXene, leading to an outstanding CO 2 storage capacity of 136.9 v/v (corresponding to 0.121 mol CO 2 /mol water) with enhanced hydrate formation kinetics. The degree of water saturation plays the most vital role in controlling formation kinetics and gas storage capacity. This work provides a reliable method to synthesize aerogels for boosting CO 2 storage via enhanced hydrate formation and sheds light on the structure performance relationship of porous materials for enhancing gas hydrate formation. [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]