Coal-derived carbon/Ni 3 Fe magnetic composites with frequency dependent microwave absorption performance were prepared at low temperatures (750–850 °C) using coal as the carbon source. The Ni 3 Fe alloy was successfully formed due to the carbothermal reaction and reducing gas. SEM images indicate the surface becomes rougher and the number of interlayer of the composites increases with increasing reaction temperature. Consistently, high degree of graphitization of the coal-derived carbon was confirmed by using Raman spectroscopy. Specifically, coal-derived carbon/Ni 3 Fe magnetic composites exhibit frequency-dependent microwave absorption characteristics at 2–18 GHz, that is, as the reaction temperature rises from 750 °C to 850 °C, the minimum reflection loss gradually shifts to low frequencies. Among them, CC/Ni 3 Fe (8 0 0) -0.4 exhibits a minimum reflection loss of −60.76 dB at 16.64 GHz, while the thickness is only 1.28 mm. Such a clean strategy provides experience for the environmental application of coal and microwave absorption. Meanwhile, a lightweight, stable and efficient microwave absorber has been developed.
Kai Ma,Yao Luo,Jietao Wang,Xu Chang,Tong Liu,Yao Wang,Mingyue Ding
Developing robust fuel electrodes with high catalytic activity and stability under CO/CO 2 atmospheres is critical for reversible solid oxide fuel cells (RSOFCs). Here, we report a novel A-site-deficient perovskite Sr 1.95 Fe 1.5 Mo 0.3 Ni 0.2 F 0.1 O 6-δ (SFMNF) synthesized via electrospinning, combining Ni 2+ (B-site cation) and F - (anion) co-doping to enhance CO 2 electrolysis and syngas oxidation performance. Physicochemical characterization reveals that F-doping lowers the crystallization temperature, increases oxygen vacancy concentration, and strengthens CO 2 chemisorption. Reduction under H 2 induces exsolution of Ni 3 Fe alloy nanoparticles. The SFMNF electrode achieves a current density of 233 mA cm -2 at 1.3 V and 750°C in CO:CO 2 =2:1 atmosphere, with 36.2% higher activity than the pre-reduced state. Electrochemical impedance and distribution of relaxation time analyses identify CO 2 adsorption/dissociation as the rate-limiting step. The cell demonstrates exceptional durability over 50 redox cycles and 85-hour of operation without carbon deposition. This work highlights dual doping as an effective strategy to tailor perovskite properties for efficient CO 2 utilization in RSOFCs.
危险品化学品经营许可证（带存储）