Elevating the Photothermal Conversion Efficiency of Phase-Change Materials Simultaneously toward Solar Energy Storage, Self-Healing, and Recyclability

Abstract

To alleviate the predicament of resource shortage and environmental pollution, efficiently using abundant solar energy is a great challenge. Herein, we prepared unique photothermal conversion phase-change materials, namely, CNT@PCMs, by introducing carbon nanotubes (CNTs) used as photothermal conversion materials into the recyclable matrix of phase-change materials (PCMs). These devised CNT@PCMs cleverly combine the photothermal conversion capability of CNTs and the thermal energy storage capability of traditional PCMs. Especially, the surface temperature of the prepared CNT@PCMs can be raised to 100 °C within 165 s under the solar simulator (150 mW cm −2 ), showing a surprising heating rate that is much higher than that of the reported works and achieving a higher photothermal conversion efficiency for solar energy in this work. Furthermore, these CNT@ PCMs can hold high melting latent heat with a maximum value at 110.0 J g −1 , exhibiting remarkable thermal storage ability aside from preeminent photothermal conversion capability. Intriguingly, the introduction of dynamic oxime group−carbamate bonds into the molecular structure can endow CNT@PCMs with an outstanding self-healing performance and recyclability. The broken CNT@PCMs sample can be healed in 2 min under IR-laser irradiation. Importantly, the phase-change and mechanical properties and photothermal conversion efficiency of CNT@PCMs can also remain virtually unchanged after multiple recycles. It is of great significance to design this style of CNT@PCMs for achieving the efficient utilization of solar energy and environmental protection.

Photothermal Conversion of Hydrogel‐Based Biomaterial

“…The main photo-thermal conversion agents of typical hydrogels for photo-thermal conversion materials include metal nanoparticles such as Au, [38][39][40] Ag, [41][42] Cu, [43][44] and metal ion compounds, semiconductor materials such as TiO 2 , [45,46] CuS, [47,48] MoS 2 [49][50] containing transition metal elements, inorganic carbon materials mainly composed of graphene oxide [51][52] and carbon nanotubes, [53][54] as well as organic polymer materials such as polydopamine [55][56] and polythiophene (Figure 3). [57] The advantages and disadvantages of these different types of photothermal agents are summarized in Table 1.…”

Reprocessable, Photothermal Phase Change Material-Based Hybrid Polymeric Networks for Solar-to-Thermal Energy Storage

“…On the other hand, inorganic particles are preferred for the preparation of photothermal PCMs, such as carbon nanotubes, carbon black (CB), and metal nanoparticles, due to their high photothermal conversion efficiency (φ), outstanding thermal conductivity, and excellent stability. , In many reports, polymeric PCM networks have high φ by adding a small amount of photothermal particles. − However, it is difficult to disperse inorganic particles uniformly in the polymer substrates due to the weak interfacial interaction between the particles and the substrates, resulting in poor film-forming properties and phase separation of polymeric photothermal PCMs. During the preparation of the photothermal PCMs, ultrasonic-assisted dispersion or even ball-milling dispersion of inorganic particles is usually required, which not only increases the cost and complexity but also yields unsatisfactory byproducts. , Therefore, once the poor dispersion of inorganic particles in the polymer matrix is resolved, the development of polymeric photothermal PCM networks will be greatly promoted.…”

“…During the preparation of the photothermal PCMs, ultrasonic-assisted dispersion or even ball-milling dispersion of inorganic particles is usually required, which not only increases the cost and complexity but also yields unsatisfactory byproducts. 49,50 Therefore, once the poor dispersion of inorganic particles in the polymer matrix is resolved, the development of polymeric photothermal PCM networks will be greatly promoted.…”

Intrinsic Flame Retardancy and Flexible Solid–Solid Phase Change Materials with Self-Healing and Recyclability

“…However, SSPCMs also have intrinsic flammability due to numerous aliphatic hydrocarbons in the molecular chains. Although the physical blending of the flame retardant into SSPCM is a facile way to obtain a flame-retardant composite SSPCM, the blending will deteriorate the mechanical performance and thermal stability of PCMs due to the interface incompatibility between fillers and substrates. , Additionally, conventional SSPCMs cannot be recycled or healed because of the permanent chemical cross-linking, which causes resource waste and environmental issues. − Therefore, designing a kind of intrinsic flame-retardant SSPCMs with good mechanical properties, self-healing, and recyclability is imperative for improving thermal management service life and environmental protection.…”