Huan Liu

This study begins by exploring the typical practical applications of phase‐change materials (PCMs) in various industries, highlighting their importance in energy storage, temperature regulation, and thermal management. It then emphasizes the necessity of flame‐retardant functionalization tailored to the specific application scenarios of PCMs, especially considering their use in safety‐critical environments such as electronics, automotive, and construction. The classic characterization methods for assessing the flame‐retardant properties of PCM are introduced in detail, including the limiting oxygen index, the vertical burning test, and the cone calorimeter, which are widely recognized standards in material safety testing. Additionally, newly developed methods for evaluating combustion safety are discussed, such as direct combustion tests, candle combustion experiments, and back temperature response, which offer a more comprehensive understanding of the material's fire resistance. Following this, this study provides a thorough summary and categorization of the flame‐retardant strategies used in PCMs, divided into four main approaches: (1) incorporation of external flame retardants, (2) use of flame‐retardant microcapsules, (3) development of flame‐retardant support materials, and (4) creation of intrinsic flame‐retardant PCMs. Each strategy is critically analyzed in terms of effectiveness, applicability, and potential challenges. Lastly, the conclusion provides an overview of the current state of flame‐retardant PCMs, offering insights into future development directions, including the pursuit of more sustainable and efficient flame‐retardant solutions, as well as prospects for their broader adoption in various industries.

无机水合盐类相变储能材料具有储能密度高、无毒、经济等明显优势而受到广泛关注。针对无机水合盐的研究有望提高可再生能源的利用效率、缓解能源危机。然而此类材料存在着固有缺陷，包括相分离严重、过冷度高、热导率低等，阻碍了其应用。本文以无机水合盐的热物理性质为出发点，详细介绍了无机水合盐类相变储能材料的相变行为、导热性、过冷现象以及相分离等特征；针对其缺陷，总结了近年来性能优化的两大常用策略：与多孔材料复合和微胶囊化；并根据其特性，讨论了无机水合盐在太阳能热能储存和光电转换、建筑节能、储冷等方面的实际应用。

Waste heat and organic contaminants are significant issues in water pollution, which has caused ecological problems and threatened human health. To provide an effective solution for wastewater recovery, we designed a novel type of multifunctional phase-change microcapsule. This type of microcapsule was synthesized using n-docosane as a core and a SiO₂/Fe₃O₄ composite as a base shell through in situ interfacial polycondensation with the assistance of a Fe₃O₄ nanoparticle as a Pickering emulsion stabilizer, followed by the deposition of BiOI nanosheets on the surface of the SiO₂/Fe₃O₄ composite shell. Benefiting from the n-docosane core, the resultant microcapsules obtained phase-change enthalpies of 46.8–115.7 J/g for absorbing waste heat from wastewater. The deposited BiOI nanosheets promoted photocatalysis for the microcapsules to degrade organic contaminants in wastewater. Owing to the magnetic response of the Fe₃O₄ nanoparticles, the separability and recyclability of the microcapsules were improved significantly by magnetic separation. Moreover, the microcapsules demonstrate outstanding phase-change reversibility, thermal cycling stability, and shape stability due to the tight SiO₂/Fe₃O₄ composite shell. This study provides a promising approach for designing and developing multifunctional phase-change microcapsules for waste heat recovery and wastewater treatment.

We have developed an in situ thermal management strategy based on the cholesterol oxidase-immobilized MXene/sodium alginate/silica@n-docosane hierarchical microcapsule for ultrasensitive biosensing detection of cholesterol in harsh environments.

We have developed a novel type of solar-powered interfacial evaporation system based on MoS₂-decorated magnetic phase-change microcapsules for highly efficient seawater desalination and wastewater purification under intermittent solar illumination.

Electromagnetic (EM) and infrared (IR) stealth play an important role in the development of military technology and the defense industry. This study focused on developing a new type of multifunctional composite film based on polyimide (PI)/graphene/Fe₃O₄ hybrid aerogel and polyethylene glycol (PEG) as a phase change material (PCM) for EM and IR bi-stealth applications. The composite films were successfully fabricated by constructing a series of PI-based hybrid aerogels containing different contents of graphene nanosheets and Fe₃O₄ nanoparticles through prepolymerizaton, film casting, freeze-drying, and thermal imidization, followed by loading molten PEG through vacuum impregnation. The construction of PI/graphene/Fe₃O₄ hybrid aerogel films provides a robust, flexible, and microwave-absorption-functionalized support material for PEG. The resultant multifunctional composite films not only exhibit high microwave absorption effectiveness across a broad frequency range, but also show a good ability to implement thermal management and temperature regulation under a high latent-heat capacity of over 158 J/g. Most of all, the multifunctional composite films present a wideband absorption capability at 7.0–16.5 GHz and a minimum reflection loss of −38.5 dB. This results in excellent EM and IR bi-stealth performance through the effective wideband microwave absorption of graphene/Fe₃O₄ component and the thermal buffer of PEG. This study offers a new strategy for the design and development of high-performance and lightweight EM–IR bi-stealth materials to meet the requirement of stealth and camouflage applications in military equipment and defense engineering.