Wang Xiaoxia,Yu Jianhua,Dong Hongzhou,Yu Mingxun,Zhang Baoqin,Wang Wen,Dong Lifeng
In this work, metal oxide (MnO 2 , SnO 2 and Co 3 O 4 )–graphene composite materials were successfully prepared via different synthesis methods. Uniform metal oxide nanoparticles were well dispersed on graphene sheets, and transmission electron microscopy characterizations showed that the average sizes of MnO 2 , SnO 2 , and Co 3 O 4 particles were about 60, 5, and 10 nm, respectively. Reflection losses of graphene composites and pure graphene were systematically evaluated between 2 and 18 GHz, which revealed that all composites exhibited enhanced microwave absorption properties compared to pure graphene. The minimum reflection losses of MnO 2 -graphene, SnO 2 –graphene, and Co 3 O 4 –graphene composites with a thickness of 2.0 mm were −20.9, −15.28, and −7.3 dB at the frequency of 14.8, 15.94, and 9.6 GHz, respectively, whereas −4.5 dB for pure graphene. The enhanced absorption ability probably originated from the combined advantage of metal oxide particles and graphene, which proved beneficial to improve the impedance matching of permittivity and permeability. Besides, the intrinsic characteristics of MnO 2 , SnO 2 , and Co 3 O 4 nanoparticles, the interface between nanostructured metal oxides and graphene sheets, and the multi-dielectric relaxation processes are all influence factors to improve the properties of microwave absorption.
Zhou X. J.,Shi P. H.,Qin Y. F.,Fan J. C.,Min Y. L.,Yao W. F.
Co 3 O 4 /graphene composites were synthesized and their high catalytic activity for the activation of peroxymonosulfate to remove the azo dye (Orange II) in aqueous solutions was found. As for the poor quality of rGO by the chemical process of graphene oxide, here, pristine graphite was exfoliated into graphene flakes through direct sonication with assistance of cetyltrimethyl ammonium bromide, which serves as a dispersant in the solvothermal procedure. The physical and chemical performance of Co 3 O 4 /graphene was characterised by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. The obtained Co 3 O 4 nanocrystals were 15–25 nm in size and connected with each other to form the shape of sticks dispersing on graphene sheets. The Co 3 O 4 /graphene composites completely degraded Orange II solutions within 10 min, the catalyst can be reutilized, and the catalytic activity of the Co 3 O 4 /graphene dropped slightly after four successive runs. In addition, the mechanism for the formation of Co 3 O 4 /graphene nanostructures is also illustrated.
危险品化学品经营许可证（带存储）