To achieve fire-resistant epoxy resin (EP), a UiO-66-based novel flame retardant coating (CS@APP@UiO-66) was prepared by modifying UiO-66 with chitosan (CS) and ammonium polyphosphate (APP) through a layer-by-layer (LbL) self-assembly method, which was then introduced into an EP system to improve its fire safety. The results of scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy show that the unsaturated Zr atoms in the UiO-66 framework provide many active sites conducive to modification, so that the UiO-66 particles, which originally had a regular octahedral structure, are more dispersed by LbL modification without causing doping or distortion issues. The thermogravimetric analysis results indicate that the char residue of EP/2% UiO-66 is increased by 2.52% compared with that of pure EP, indicating that the thermal properties of the EP composite are improved after modification. In addition, the cone test results indicate that EP/2%UiO-66-5L has good flame retardancy and smoke suppression properties, and the peak heat release rate, total smoke production and rate of CO generation values are 25.2%, 5.7% and 38.5% lower than those of the unmodified EP. Moreover, it can be concluded from the Raman test that the graphitization degree of the modified EP composite is strengthened. The above results indicated that after the incorporation of CS@APP@UiO-66 into the EP composites, more char layers formed as physical barriers to prevent the transfer of mass and heat, thus reducing the speed of flame propagation. Therefore, the flame resistance and smoke suppression of the EP composites improved. These favorable characteristics, including high flame retardant efficiency and good smoke suppression, make LbL-functionalized UiO-66 promising for flame retardant polymer applications.
Copper-based catalysts play a pivotal role in CO2 electroreduction (CER) toward multi-carbon (C2+) products. However, achieving a high selectivity for C2+ products remains a formidable challenge. In this work, a facile electrochemical oxidation-reduction technique was developed to modulate the surface morphology of a copper foil using sulfur and oxygen as auxiliary atoms. Optimization of this approach resulted in an atomically reconstructed copper electrode (denoted as Cu-50) with a surface tensile strain of 1.1% and preferential exposure of Cu(100) facets. Cu-50 delivered remarkable Faradaic efficiencies (up to 72%) for C2+ products during CER, with a 53% selectivity for ethylene (10-fold higher than for a non-reconstructed Cu foil). This work guides the design of advanced copper-based catalysts that promote C–C coupling, demonstrating the potential of tailored copper structures for efficient conversion of CO2 to valuable C2+ products.
In this work, Fe/Ru-catalyst supported on hyper-crosslinked polystyrene (HPS) synthesized via hydrothermal deposition was proposed for the Fischer-Tropsch synthesis (FTS) to obtain a high yield of gasoline-ranged hydrocarbons. According to the characterization results, the obtained monometallic 2%Fe-HPS catalyst contains Fe3O4 particles with a multimodal distribution (mean particle size of 11, 30, and 45 nm). The addition of Ru leads to a decrease in the particle size with a narrower distribution (ca. 5 nm). Ru was shown to serve as a nucleating agent for Fe3O4 crystalline since it has a higher affinity to the HPS surface and strongly anchors to the benzene rings of the polymer. This prevents a leaching of the active phase from the support increasing the catalyst stability. Ru addition also brings supplemental sites for CO and H2 chemisorption resulting in 1.5-fold increased activity in FTS reaction compared to monometallic 2%Fe-HPS composite. 2%Fe-1%Ru-HPS composite showed ~20% higher selectivity toward the formation of C5–C11 alkanes at about 30% conversion of CO in comparison with monometallic one. Moreover, the branched hydrocarbons with a selectivity of approximately 17.5 mol% were observed in the FTS products in the presence of a 2%Fe-1%Ru-HPS catalyst.
