Laifei Cheng

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Electromagnetic (EM) absorbing and shielding composites with tunable absorbing behaviors based on Ti3C2 MXenes are fabricated via HF etching and annealing treatment. Localized sandwich structure without sacrificing the original layered morphology is realized, which is responsible for the enhancement of EM absorbing capability in the X-band. The composite(More)
The surface relaxations and oxygen adsorptions on C- and Si-terminated 3C-SiC(111) and 2H/4H/6H-SiC(0001) surfaces are systematically studied using density functional theory (DFT) calculations. First, the general surface relaxation trends of different SiC surfaces are explained using the electrostatic interaction and the calculation results of spin density(More)
In this work, mesoporous carbon hollow microspheres (PCHMs) with designable mesoporous shell and interior void are constructed by a facile in situ stöber templating approach and a pyrolysis-etching process. The PCHMs are characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, Raman spectroscopy, and(More)
Fe/SiC hybrid fibers have been fabricated by electrospinning and subsequent high-temperature (1300 °C) pyrolysis in Ar atmosphere using polycarbosilane (PCS) and Fe3O4 precursors. It is found that the introduction of Fe has had a dramatic impact on the morphology, crystallization temperature, and microwave electromagnetic properties of the hybrid fibers. In(More)
The microstructural effects of SiC swelling, mechanisms of He diffusion and aggregation in C-rich SiC are studied using an in situ helium ion microscope. The additive carbon interface provides improved swelling resistance in SiC to ∼270 nm, and defect formation is not observed until very high He implantation doses.
The gas-phase reaction pathways in preparing pyrolytic carbon with propene pyrolysis have been investigated in detail with a total number of 110 transition states and 50 intermediates. The structure of the species was determined with density functional theory at B3PW91/6-311G(d,p) level. The transition states and their linked intermediates were confirmed(More)
The reaction rate of propene pyrolysis was investigated based on the elementary reactions proposed in Qu et al., J Comput Chem 2009, 31, 1421. The overall reaction rate was developed with the steady-state approximation and the rate constants of the elementary reactions were determined with the variational transition state theory. For the elementary reaction(More)
Materials with an ultralow density and ultrahigh electromagnetic-interference (EMI)-shielding performance are highly desirable in fields of aerospace, portable electronics, and so on. Theoretical work predicts that 3D carbon nanotube (CNT)/graphene hybrids are one of the most promising lightweight EMI shielding materials, owing to their unique(More)
High-k dielectric materials are important as gate oxides in microelectronics and as potential dielectrics for capacitors. In order to enable computational discovery of novel high-k dielectric materials, we propose a fitness model (energy storage density) that includes the dielectric constant, bandgap, and intrinsic breakdown field. This model, used as a(More)
Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs(More)