Xuetong Zhang’s research while affiliated with Jiangnan University and other places

Silica aerogel, as the earliest synthetic and commercially available one among all known aerogels, holds significant value in fields including thermal and acoustic insulation, optics, catalysis, sorption, etc. However, throughout its nearly century-long history, the influence of solvent used during synthesis on the properties of silica aerogels has been neglected, resulting in inaccurate and ambiguous performance evaluation. Herein, we have uncovered and systematically investigated the solvent-regulable interfacial groups that enable on-demand superhydrophobicity/superhydrophilicity of silica aerogels. During either sol-gel transition or solvent exchange process both required for aerogel synthesis, the alteration of solvent either from water to ethanol or vice versa leads to silica interfacial groups switch from superhydrophilic Si-OH to superhydrophobic Si-OEt or reversely due to reversible esterification, thus enabling on-demand superhydrophobic/superhydrophilic silica aerogels. It is worth noting that on-demand solvent-regulated hydrophilicity/hydrophobicity holds true regardless of used silica precursors (the mixture of trimethoxymethylsilane (MTMS)/tetramethoxysilane (TMOS), MTMS/tetraethyl orthosilicate (TEOS), or sodium methicosilicate (SMS)/TMOS), thereby indicating its universality, which wakes up considerable attention for producers involved in silica aerogels. Additionally, the discovery also provides a green, economical, and efficient way to achieve silica aerogels with on-demand hydrophilic/hydrophobic performance for specific sorption, etc.

Electrodes with high active areas often compromise with limited ion transport kinetics in flow electrochemical devices. Herein, hierarchically porous carbon colloidal aerogels (HPCCAs) are constructed with multiscale porosities to meet the tradeoff between highly active areas and efficient mass transfer behavior. It is realized by introducing multiphase co‐separation in a sol‐gel transition process of aramid nanofibers/polyvinylpyrrolidone/carbon nanotubes followed by subsequent freeze‐drying and carbonization. The resulting HPCCA possesses a high volumetric electrochemically accessible surface area (3.27 × 10⁷ m⁻¹) and excellent mass transfer efficiency, 2–3 times higher permeability than commercial Toray carbon paper and 9.86 times higher than bare aerogel. An all‐vanadium single cell with HPCCAs as electrodes possesses a high energy efficiency of 83.18% under the current density of 100 mA cm⁻², which is 10–31% higher than most of the state‐of‐the‐art carbon electrode materials including commercial carbon papers. In addition, the cell with HPCCAs shows outstanding long‐term stability up to 1000 cycles. Notably, HPCCAs are applicable to more flow battery systems, such as iron/chromium (Fe/Cr), iron/vanadium (Fe/V), zinc/bromine (Zn/Br), vanadium/methylene blue (V/MB), sodium salt of flavin mononucleotide/potassium ferrocyanide (FMN‐Na/K4[Fe(CN)6]), and methyl viologen/4‐hydroxy‐2,2,6,6‐tetramethyl‐piperidin‐1‐oxyl (MV/4‐HO‐TEMPO). This work offers a new chemistry paradigm for developing advanced nanoporous aerogel materials and paves the way toward highly efficient flow electrochemical devices.

Current strategies for constructing sparse nanostructures for fabricating superblacks are only suitable for a few light‐absorbing materials, severely limiting their applications. Herein, ultra‐low reflective silica aerogels with ultra‐high light transparency are used as solid smokes to individually or simultaneously suspend at least 100 species of light‐absorbing nanoparticles with a volume fraction as low as 0.005%, for creating > 100 superblacks in practice and one billion superblacks in theory if taken permutation and combination among these 0D, 1D, or 2D nanoparticles into account. Depending on the composition of suspended nanoparticles and the structure of solid smoke, the resulting mechanically robust superblacks with supplementary properties including magnetism, full‐spectrum absorption, high thermal stability, and excellent mechanical strength, are first observed. The wide choice of metallic or semiconductive LNs allows as‐made superblacks to glitter in different catalytic reactions, and the resulting superblacks have been on‐demand modified for endowing the self‐cleaning performance in some contaminable environments. Benefiting from the superblack feature and porous network, these superblack monoliths have shown high‐efficiency solar‐heat conversion in some emerging light harvesting and managing fields. This powerful synthetic strategy for superblacks is expected to inspire researchers to conduct in‐depth investigations on super‐black optics, functional materials, etc.

Transparent silica aerogel, serving as one typical porous and transparent material, possesses various unique features (e. g., large amounts of pores and interfaces, super‐lightweight, super thermal insulation, low refractive index similar to gas), and it has attracted great attention in the fields of science, technology, engineering, art, and others. Transparency is one important evaluation index of transparent silica aerogel, and it was influenced by various factors such as raw materials, sol‐gel reactions, phase separation, and drying methods. The structure design and fabrication of transparent silica aerogel is one huge and fine engineering. In this review, the optical/chemical guidance and design for the preparation of transparent silica aerogels are discussed, and typical applications, such as Cherenkov detectors, solar energy collection, lighting systems, and transparent fabric, were also discussed. Finally, a future outlook on the opportunities and challenges of transparent silica aerogels was proposed.

Aerogels with ultrahigh porosity and large specific surface area have demonstrated great potential for capturing volatile organic compounds (VOCs). Especially, aerogel fiber aggregates with macropores formed by overlapping aerogel fibers and mesopores in the aerogel fibers might realize fast sorption kinetics and high sorption capacity simultaneously. However, how to develop fast fabrication and large‐scale production of aerogel fibers remains a challenge. Herein, a generic sol‐gel centrifugal spinning (SCS) strategy with a spinning rate capable of reaching 700 m min⁻¹ is developed for producing aerogel fibers. The representative SCS aerogel fiber made from aramid nanofiber (ANF) dispersion exhibits a large specific surface area (313 m² g⁻¹) and high tensile strength (12.48 MPa). The SCS strategy is further applied to fabricate various kinds of aerogel fibers, including sodium alginate, cellulose, and chitosan. The ANF aerogel fiber aggregates exhibit superior VOC adsorption capacity of 438.0 mg g⁻¹ under an ultrafast gas flux of 3.8 × 10⁴ L m⁻² h⁻¹, which also has satisfactory cyclic stability. This work not only develops a powerful and generic strategy for fabricating aerogel fibers in large scale, but also provides inspiration for applying these SCS aerogel fibers in dynamic removal of VOCs and other environmental protection fields.

Natural plant leaves with multiple functions, for example, spectral features, transpiration, photosynthesis, etc., have played a significant role in the ecosystem, and artificial synthesis of plant leaves with multiple functions of natural ones is still a great challenge. Herein, this work presents an aerogel‐involved living leaf (AL), most similar to natural ones so far, by embedding super‐hydrophobic SiO2 aerogel microparticles in polyvinyl alcohol hydrogel in the presence of hygroscopic salt and chlorophyllin copper sodium to form solid‐liquid‐vapor triple‐state gel. The AL shows a high spectral similarity with all sampled 15 species of natural leaves and exhibits ≈4–7 times transpiration speed higher than natural leaves. More importantly, AL can achieve several times higher photosynthesis than natural leaves without the energy provided by the respiratory action of natural ones. This work demonstrates the feasibility of creating ALs with natural leaf‐like triple‐state gel structures and multiple functions, opening up new avenues for energy conversion, environmental engineering, and biomimetic applications.

Solid–liquid composite materials that confine a functional liquid within a porous solid have appeared in a wealth of emerging applications. However, creating dynamic liquid interfaces for efficient ion capture while stably retaining functional liquid in porous confinements is challenging. Here, an aerogel‐confined liquid‐based composite membrane (ALCM) for dynamic and highly efficient uranium capture is reported. As a proof of concept, Kevlar aerogel membrane is selected as the nanoporous solid, and calix[6]arene/tributyl phosphate (C6/TBP) is used as the guest liquid. The obtained ALCMs possess high stability, optimum adhesion between solid‐liquid interface, and high selectivity for uranyl ions (250–6510 times over other competing ions). Different dynamic interface regulating approaches are explored for ALCMs, and uranium extraction efficiency under alternating pressures can be up to 258.48 mg g⁻¹ h⁻¹, outperforming many reported uranium capture materials. This strategy can be applicable to develop a rich family of solid‐liquid composite materials and may spearhead a new paradigm for uranium capture from sustainable seawater resources.