Xinyan Lv,Zhonglin Wei,Canyu Cui,Wenwen Wang,Yumei Tan,Shihui Jiao,Guangsheng Pang
Developing superhydrophobic material with good chemical stability, non-toxic and low-cost for effectively handling oil spill incidents, chemical leakages and industrial oily wastewater has become an urgent need. In this work, superhydrophobic Fe3O4@C microspheres have been successfully anchored on polyurethane (PU) sponge skeleton surface with polyvinylidene fluoride (PVDF) as intermediate layer. The superhydrophobic Fe3O4@C/PVDF/PU sponge possesses outstanding superhydrophobic performance with water contact angle (WCA) of 156.5° and sliding angle (SA) of 6°. Meanwhile, the Fe3O4@C/PVDF/PU sponge shows excellent chemical, thermal and mechanical stabilities under harsh conditions, high separation efficiencies for surfactant-stabilized organic solvent/water emulsions (more than 99.6% for both O/W and W/O emulsions) and preferable recyclability (more than 15 cycles). The comprehensive performances of the Fe3O4@C/PVDF/PU sponge make it a promising candidate for the treatment of industrial oily wastewater.
Due to the volume expansion effect during charge and discharge processes, the application of transition metal oxide anode materials in lithium-ion batteries is limited. Composite materials and carbon coating are often considered feasible improvement methods. In this study, three types of TiO2@Fe3O4@C microspheres with a core–double-shell structure, namely TFCS (TiO2@Fe3O4@C with 0.0119 g PVP), TFCM (TiO2@Fe3O4@C with 0.0238 g PVP), and TFCL (TiO2@Fe3O4@C with 0.0476 g PVP), were prepared using PVP (polyvinylpyrrolidone) as the carbon source through homogeneous precipitation and high-temperature carbonization methods. After 500 cycles at a current density of 2 C, the specific capacities of these three microspheres are all higher than that of TiO2@Fe2O3with significantly improved cycling stability. Among them, TFCM exhibits the highest specific capacity of 328.3 mAh·g−1, which was attributed to the amorphous carbon layer effectively mitigating the capacity decay caused by the volume expansion of iron oxide during charge and discharge processes. Additionally, the carbon coating layer enhances the electrical conductivity of the TiO2@Fe3O4@C materials, thereby improving their rate performance. Within the range of 100 to 1600 mA·g−1, the capacity retention rates for TiO2@Fe2O3, TFCS, TFCM, and TFCL are 27.2%, 35.2%, 35.9%, and 36.9%, respectively. This study provides insights into the development of new lithium-ion battery anode materials based on Ti and Fe oxides with the abundance and environmental friendliness of iron, titanium, and carbon resources in TiO2@Fe3O4@C microsphere anode materials, making this strategy potentially applicable.
Xinjie Yun,Qifan Wu,Lei Feng,Jiancang Shen,Jian Chen,Paul K. Chu,Lizhe Liu,Xinglong Wu
Magnetic particles can be combined with carbon materials to prepare core-shell microwave absorbers and the proper core/shell weight ratio yields the optimal absorption effects. However, few studies have focused on the influence of core surface modification on the microwave absorption performance. In this work, e-Fe 3 O 4 @C composite microspheres are synthesized by surface etching of core Fe 3 O 4 microspheres in HCl followed by polymerization/carbonization. Core surface modification improves the microwave absorption capability of the e-Fe 3 O 4 @C microsphere films. The minimal reflection loss (RL min ) is −54.38 dB at 12.4 GHz for a film thickness of 2.6 mm and the maximum effective bandwidth is extended to 4.1 GHz (3 mm). Etching of the Fe 3 O 4 core surface increases the interfacial contact area consequently enhancing interface polarization and defects created by surface etching produce additional dipole polarization to further increase the dielectric loss. The underlying mechanism is investigated and described. The results reveal a novel and effective strategy to enhance the properties of core-shell microwave absorption materials.
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