Highly Efficient Photothermal Icephobic/de-Icing MOF-Based Micro and Nanostructured Surface.

Photothermal materials have gained considerable attention in the field of anti-/de-icing due to its environmental friendliness and energy saving. However, it is always significantly challenging to obtain solar thermal materials with hierarchical structure and simultaneously demonstrate both the ultra-long icing delay ability and the superior photothermal de-icing ability. Here, a photothermal icephobic MOF-based micro and nanostructure surface (MOF-MNS) is presented, which consists of micron groove structure and fluorinated MOF nanowhiskers. The optimal MOF-M250 NS can achieve solar absorption of over 98% and produce a high temperature increment of 65.5 °C under 1-sun illumination. Such superior photothermal-conversion mechanism of MOF-M250 NS is elucidated in depth. In addition, the MOF-M250 NS generates an ultra-long icing delay time of ≈3960 s at -18 °C without solar illumination, achieving the longest delay time, which isn't reported before. Due to its excellent solar-to-heat conversation ability, accumulated ice and frost on MOF-M250 NS can be rapidly melted within 720 s under 1-sun illumination and it also holds a high de-icing rate of 5.8 kg m-2 h-1 . MOF-M250 NS possesses the versatility of mechanical robustness, chemical stability, and low temperature self-cleaning, which can synergistically reinforce the usage of icephobic surfaces in harsh conditions.

Mechanistic investigation of photocatalytic degradation of organic dyes by a novel zinc coordination polymer.

A new coordination polymer {[Zn(TIPA)(seb)0.5](NO3)·3.5H2O} n (1) (TIPA = tris(4-(1H-imidazol-1-yl)phenyl)amine, seb = sebacic acid) is prepared and characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) and single crystal X-ray diffraction. Complex 1 has a three-dimensional (3D) 2-fold interpenetrating diamondoid network, and can be represented by the Schläfli symbol {33·43·54·64·7}. The luminescent, optical, and thermal properties of 1 in the solid state are investigated. Significantly, 1 assists in the photo-degradation of organic dyes in the presence of H2O2 and upon irradiation with UV light (λ = 254 nm). A mechanistic study toward understanding the photocatalytic degradation of organic dye molecules is carried out. The study reveals that the band gap of the fluorophore TIPA is lowered by the charge interaction between the Zn2+ cation and ligand seb2- dianion. The enhanced photocatalysis of 1 is also accompanied by the selective sensing of polar organic solvent nitromethane (NM) and antibiotic ofloxacin (OFX) by a luminescence quenching process. Concurrently, 1 demonstrates excellent ability to adsorb inorganic pollutant permanganate ions likely due to the presence of its unique 3D structural network.

Crystalline Covalent Organic Frameworks from Triazine Nodes as Porous Adsorbents for Dye Pollutants.

The development of covalent organic frameworks (COFs) with nodes and spacers, designed to maximize their functional properties, is a challenge. Triazines exhibit better electron affinity than benzene-based aromatic rings; therefore, structures based on 1,3,5-substituted triazine-centered nodes are more stable than those from 1,3,5-benzene-linked COFs. Compared to COFs prepared from flat, rigid sp2 carbon-linked triazine nodes, the O-linked flexible tripodal triazine-based COF demonstrates several unpredictable properties such as an increase in crystallinity and cavity size. In this study, the COF prepared from O-linked flexible 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine serves as an excellent absorbent for removing methylene blue from water. Our results demonstrate that COF is highly stable in water and functions as a robust adsorbent. Its adsorption isotherm is consistent with the Langmuir model and its adsorption kinetics follows a pseudo-second order model. Moreover, the COF was characterized using elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, solid-state ultraviolet-visible spectroscopy, and X-ray diffraction. It exhibited permanent porosity, a high specific surface area (279.5 m2·g-1), and was chemically and thermally stable. Photophysical studies revealed that the COF exhibits a low bandgap energy value of 3.07 eV, indicating its semiconducting nature.