Tuning the Electrical Conductivity of a Flexible Fabric-Based Cu-HHTP Film through a Novel Redox Interaction between the Guest-Host System.

Integration of metal-organic frameworks (MOFs) and flexible fabrics has been recently considered as a promising strategy applied in wearable electronic devices. We synthesized a flexible fabric-based Cu-HHTP film consisted of Cu2+ ions and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) via a self-sacrificial template method. The obtained Cu-HHTP film displays an outstanding nanostructured surface and uniformity. Iodine molecules are first introduced into the pores of Cu-HHTP to investigate the influence of guest molecules on electrical conductivity in a 2D guest-host system. After doping, the conductivity of the Cu-HHTP film shows an increased dependent on the doping time, and the maximum value is more than 30 times that of the original MOFs. The enhanced electrical conductivity results from an intriguing redox interaction occurred between the confined iodine molecules and the framework. The organic ligands are oxidized by iodine molecules, and generating new ions allows for subsequent participation in the regulation of the mixed valence bands of copper ions in MOFs, changing the ratio of Cu2+/Cu+, promoting the charge transport of the framework, and then synergistically enhancing the electronic conductivity. This study successfully prepared a flexible fabric-based conductive I2@Cu-HHTP film and presented insights into revealing the behavior of iodine molecules after entering the Cu-HHTP pores, expanding the possibilities of Cu-HHTP used in flexible wearable electronics.

Greatly increased electrical conductivity of PBTTT-C14 thin film via controllable single precursor vapor phase infiltration.

Doping is an important strategy for effectively regulating the charge carrier concentration of semiconducting materials. In this study, the electronic properties of organic-inorganic hybrid semiconducting polymers, synthesized viain situcontrolled vapor phase infiltration (VPI) of poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT-C14) with the metal precursors molybdenum pentachloride (MoCl5) and titanium tetrachloride (TiCl4), were altered and characterized. The conductivities of the infiltration-doped PBTTT-C14 thin films were enhanced by up to 9 and 4 orders of magnitude, respectively. The significantly improved electrical properties may result from interactions between metal atoms in the metal precursors and sulfur of the thiophene rings, thus forming new chemical bonds. Importantly, VPI doping has little influence on the structure of the PBTTT-C14 thin films. Even if various dopant molecules infiltrate the polymer matrix, the interlayer spacing of the films will inevitably expand, but it has negligible effects on the overall morphology and structure of the film. Also, Lewis acid-doped PBTTT-C14 thin films exhibited excellent environmental stability. Therefore, the VPI-based doping process has great potential for use in processing high-quality conductive polymer films.

Universal Strategy to Prepare a Flexible Photothermal Absorber Based on Hierarchical Fe-MOF-74 toward Highly Efficient Solar Interfacial Seawater Desalination.

Solar-driven interfacial steam generation (SDISG), as an emerging green and renewable approach to overcome water shortage, is very suitable for remote locations, developing countries, and disaster zones because it does not require an additional energy supply. However, the traditional metal-based and carbon-based absorbers always suffered from fragility (or rigidity) and the complex preparation process, which dramatically inhibited their transportation and installation in areas with poor infrastructure. Therefore, there is an urgent need to develop a universal method to fabricate flexible solar evaporators. Herein, a novel solar evaporator that integrates a flexible matrix (Cu mesh or textile) and a hierarchical Fe-MOF-74 photothermal absorber component is perfectly prepared for the rapid and efficient SDISG. Notably, the results show that Fe-MOF-74-based flexible textile matrix composites exhibit outstanding light absorption (83.81%), low thermal conductivity (0.1730 W/m K), super hydrophilic properties (within 50 ms, the contact angle is close to 0°), excellent salt resistance, high evaporation rate (1.35 kg/m2 h), and photothermal conversion efficiency (η is 81.5% under one sun, stable for 30 days). Owing to the flexibility, recyclability, and above-mentioned excellent performance, the prepared hierarchical Fe-MOF-74-based flexible composite systems are more practical for transportation, large-scale production, and stable and efficient applications. As a result, this work offers new insight into the future development of the combination of a MOF-based photothermal absorber and flexible substrates, as well as for the application of interfacial solar seawater desalination, and provides a new reference for other applications.