Two-dimensional metal-organic frameworks (2D-MOFs) and their derivatives have emerged as promising candidates in catalysis, energy storage, gas separation, and electromagnetic (EM) wave absorption due to their tunable porosity, high surface area, and unique physicochemical properties. Despite significant progress, challenges remain in achieving high-yield synthesis with precise control over thickness and lateral size. This study presents a versatile strategy for the scalable fabrication of CoNi-MOF-71 nanosheet arrays through epitaxial, anisotropic, and confined growth, enabled by lattice-matched substrates, selective surfactant attachment, and spatial confinement. The resulting 2D-MOFs exhibit a high yield of 86.7%, uniform lateral dimensions of 0.5 × 1.0 μm², and tunable thickness ranging from 11.3 to 2100 nm. After reduction annealing under Ar atmosphere at 600 °C, the derived porous Co/Ni/C nanosheets demonstrate exceptional EM wave absorption performance. Compared to their bulk counterparts, the 2D derivatives exhibit enhanced surface area, improved electrical conductivity, and pronounced shape anisotropy, leading to synergistic contributions from interfacial polarization, conductive loss, and magnetic resonance. Optimal EM absorption is achieved with a minimum reflection loss (RLmin) of −49.8 dB and an ultrawide effective absorption bandwidth (EAB) of 7.6 GHz at a thickness of only 2.6 mm. These results highlight the critical role of multiple attenuation mechanisms in enhancing absorption efficiency and establish a robust, generalizable route for synthesizing high-quality, ultrathin MOFs with uniform morphology and high yield. This work opens new avenues for the application of 2D-MOF derivatives in advanced functional materials, including electrocatalysis, optoelectronics, and lightweight broadband EM absorbers.
The synthesis process involves hydrothermal reaction of Co²⁺, Ni²⁺, and 1,4-benzenedicarboxylate (H₂BDC) on pretreated Cu foil substrates in the presence of poly(vinylpyrrolidone) (PVP) as a structure-directing agent. The PVP selectively adsorbs onto the lateral facets of growing MOF crystals, inhibiting layer-by-layer stacking and promoting vertical growth into ultrathin nanosheets. X-ray diffraction (XRD) confirms the formation of crystalline CoNi-MOF-71, while scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) reveal the uniform, well-defined 2D morphology. The AFM height profile indicates a consistent thickness of 11.3 nm, and TEM analysis with selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS) confirms the homogeneous distribution of Co and Ni. Upon pyrolysis, the MOF-derived composites transform into a porous carbon matrix embedding crystalline Co and Ni nanoparticles, as evidenced by high-resolution TEM and XPS data showing metallic Co⁰ and Ni⁰ states. The BET surface area of the 2D derivative increases dramatically to 69.46 m² g⁻¹ compared to only 0.62 m² g⁻¹ for the bulk counterpart, indicating extensive pore development. Raman spectroscopy reveals a higher ID/IG ratio (0.88 vs. 0.73), confirming increased defect density in the carbon framework. Enhanced electrical conductivity and dielectric loss are attributed to the interconnected network and abundant interfaces, contributing to efficient conductive and interfacial polarization losses.202138-50-9 supplier Magnetic measurements show strong shape anisotropy, enabling natural and exchange resonance peaks at 5.CD34 Antibody Technical Information 3 GHz and ~14.PMID:34990480 1 GHz, respectively, which significantly enhance magnetic loss. Impedance matching analysis demonstrates that the real part of impedance approaches unity and the imaginary part nears zero across a broad frequency range, facilitating maximal EM wave entry. The combined effects of impedance matching, multi-scale polarization, conductive loss, and magnetic resonance result in superior absorption performance over a wide bandwidth. This work not only advances the design principles for high-performance 2D EM absorbers but also provides a scalable, controllable method for fabricating ultrathin MOF-based materials with broad applicability in next-generation functional devices.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com