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Herein, we report the synthesis of one-dimensional (1D) molybdenum carbide/cobalt nanorods that consist of multiple components including Mo 2 C, Co, and C (Mo 2 C/Co/C) based on a "MOFs plus MOFs" strategy. The 1D Mo-metal−organic frameworks (MOFs) were first prepared through reflux condensation. Then, a zeolitic-imidazolate framework (ZIF-67) was used as the Co source to decorate 1D Mo-MOFs to form the Mo-MOFs/ZIF-67 precursor. Finally, 1D Mo 2 C/Co/C ternary composite nanorods were obtained through pyrolysis of Mo-MOFs/ZIF-67 under an Ar atmosphere. The combination of multiple components including dielectric Mo 2 C, C, and magnetic Co could not only optimize the impedance matching but also provide multiple channels to attenuate the electromagnetic (EM) waves including conductive loss, dielectric polarization, and magnetic resonance. Besides, the interface polarization formed by abundant heterointerfaces between Mo 2 C and Co/C was confirmed using a high-frequency structure simulator. The adding amount of Mo-MOFs and pyrolysis temperature were found to have a significant influence on the impedance matching and microwave absorption. Consequently, the optimized Mo 2 C/Co/C nanorods displayed the strongest reflection loss (RL) of −54.6 dB at 16.2 GHz corresponding to a thickness of 1.77 mm. The SRL mt (RL/matching thickness) was calculated to be 30.9, exceeding those of reported MOF derivates. What is more, the Mo 2 C/Co/C nanorods exhibited broad and tunable bandwidth covering from the whole X band (8.0−12.08 GHz) to the Ku band (12.56−18.0 GHz) by adjusting the amount of Mo-MOFs and pyrolysis temperature, revealing great potential for fields of microwave absorption.

The TiO 2 /SnO 2 composite nanocrystal with different mol ratios was prepared using the sol-gel technology and the effect of SnO 2 addition on the phase transformation of TiO 2 photocatalyst was discussed in the study as the crystal phase affects the photocatalysis greatly. The phase transformation process of pure TiO 2 and SnO 2 /TiO 2 composite powders were characterized by using X-ray diffraction, differential scanning calorimetry and thermo-gravimetry analysis. A small quantity of SnO 2 in the form of chloride accelerates the anatase-to-rutile transformation greatly. The substitution of larger-size tetravalent tin ion Sn 4+ for titanium ion Ti 4+ induces the lattice dilatation of titania crystal while the rutile-structured cassiterite plays as nucleating agent and facilitates the formation of rutile phase.

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