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Electrochromic materials (ECMs) are capable of reversibly adjusting their transmittance or reflectance properties in response to changes in the external biasing voltages. In this study, we enhanced the electrochromic and electrochemical properties of polyaniline (PANi) effectively through the incorporation of MXene Ti 2 CT x using an in situ composite strategy. This improvement in the electrochromic and electrochemical properties observed can be attributed to the intermolecular forces between the aniline group of PANi and the terminal groups of MXene Ti 2 CT x sheets. The presence of hydrogen bonds between the PANi monomers and the MXene sheets was confirmed through theoretical calculations and photoluminescence results, which effectively improved the composite interfaces. Additionally, the PANi@MXene composite films were successfully prepared through a simple one-step in situ polymerization process, as verified by SEM and XPS characterization. The electrochemical studies revealed enhanced electronic conductivity, a high ion diffusion coefficient, and a narrow energy redox gap, all contributing to the excellent electrochemical properties observed. Overall, our results demonstrate that the MXene Ti 2 CT x composition effectively enhances the electrochromic performance of PANi. The PANi@MXene composite films exhibited a high optical modulation range, rapid switching response time, good thermal radiation regulation, and excellent operational stability. This composite strategy significantly improves the performance and practical applicability of ECMs.

Conventional electrochromic devices with a sandwich structure consist of multiple interfaces, which enhance electron trapping on the interfaces. Furthermore, crack generation in the electrochromic layer is inevitable due to repeated ion insertion and extraction during the service process. These problems increase the fabrication complexity and lead to poor performance and stability, which are severely limiting and prime concerns for the future development of the electrochromism field. Here, a strategy of synthesizing an all-in-one self-healing electrochromic material, TAFPy-MA, is presented, which has been utilized for the fabrication of a high-reliability, large-scale, and easy-assembly smart electrochromic window. The all-in-one self-healing electrochromic material can undergo in situ redox reactions with Li + ions to reduce resistance transfer and avoid interface obstacles, and the reversible Diels-Alder cross-linking network structure can heal the cracks to improve the reliability of the electrochromic layer. High ion diffusivity (1.13 × 10 -5 cm 2 s -1 ), rapid color switching (3.9/3.7 s), high coloration efficiency (413 cm 2 C -1 ), excellent stability (sustains 88.7% after 1000 cycles) and reliability (crack can be healed in 110 s), and large-scale smart windows (30 × 35 cm 2 ) are achieved using the all-in-one electrochromic material, which exhibits fascinating and promising features for a wide range of applications in buildings, airplanes, etc.

Animals such as chameleons possess a natural ability to adjust their skin color as a preventive measure to deter any potential threat and to self-heal damaged skin tissues. Inspired by this, we present here a copolymer film possessing biomimetic properties that simultaneously integrates electrochromic triphenylamine and self-healing Diels-Alder groups. The flexible and stretchable copolymer film acts like natural chameleon skin, which exhibits significant color variation and also possesses excellent self-healing properties. These remarkable features make it a promising material for overcoming the crack-generation issue inherited by conventional biomimetic chameleon skin. Moreover, a flexible and wearable skin device based on the copolymer film with silver fabric as a electrode has also been fabricated. The electrochromic and self-healing properties were verified for the copolymer film, and it has been elucidated that the intelligent biomimetic "chameleon skin" was a new step toward the development of highly advanced biomimetic materials and devices.