Zongli Wan

Bio: Zongli Wan is an academic researcher from Anhui University of Science and Technology. The author has contributed to research in topics: Graphene & Reflection loss. The author has an hindex of 8, co-authored 15 publications receiving 412 citations.

Facile Design of Three-Dimensional Nitrogen-Doped Reduced Graphene Oxide/Multi-Walled Carbon Nanotube Composite Foams as Lightweight and Highly Efficient Microwave Absorbers.

Abstract: Graphene foams with three-dimensional (3D) network structure, high porosity, and ultralow density have been regarded as lightweight microwave absorption materials. Herein, nitrogen-doped reduced graphene oxide/multi-walled carbon nanotube composite foams were prepared through a two-step strategy of hydrothermal self-assembly and subsequent high-temperature calcination. Morphology analysis indicated that the 3D networks were composed of overlapped flaky reduced graphene oxide. In addition, the influences of nitrogen doping, calcination temperature, and filler ratios on microwave absorption of composite foams were explored. Results manifested that the microwave absorption of composite foams was remarkably improved with the calcination temperature increased. Dramatically, it was noteworthy that the composite foam obtained under 600 °C calcination (bulk density of ∼10.8 mg/cm3) with an 8 wt % mass filler ratio presented the strongest microwave absorption of -69.6 dB at 12.5 GHz and broadest absorption bandwidth achieved 4.3 GHz (13.2-17.5 GHz) at an extremely low matching thickness equal to 1.5 mm. Moreover, the microwave absorption performance could be conveniently adjusted through modifying the thicknesses, filler ratios, and calcination temperature. The excellent microwave absorption performance of as-prepared composite foams was greatly derived from a well-constructed 3D network structure, significant nitrogen doping, enhanced polarization relaxation, and improved conduction loss. This work proposed a new strategy for fabricating graphene-based composites with a 3D network structure as high-efficiency microwave absorbers.

Facile synthesis of nitrogen-doped cobalt/cobalt oxide/carbon/reduced graphene oxide nanocomposites for electromagnetic wave absorption

Abstract: Electromagnetic wave absorption materials with strong absorption, thin thickness, broad bandwidth and low filler loading are highly desirable in the field of electromagnetic absorption. In this work, graphene oxide (GO) was firstly used as a template for growth of cobalt, zinc–zeolitic imidazolate frameworks (Co, Zn–ZIFs), and then nitrogen-doped cobalt/cobalt oxide/carbon/reduced graphene oxide (Co/CoO/C/RGO) nanocomposites were further constructed by the high-temperature pyrolysis strategy. Results of morphology observations demonstrated that numerous carbon frameworks with a slightly contracted polyhedron morphology were anchored on the crumpled surfaces of sheet-like RGO. Moreover, well-constructed structure of RGO loaded with carbon nanotubes wrapping carbon frameworks was observed, and considerable nitrogen atoms had been in situ doped into the porous carbon matrix of attained nanocomposites. Furthermore, the influences of filler loadings, calcination temperature, and addition of GO on the electromagnetic parameters and absorption performance of obtained nanocomposites were investigated. Results revealed that the addition of GO notably strengthened the electromagnetic absorption performance. Remarkably, the percolation transition was observed in the filler loading range of 20–25 wt%. The as-synthesized nanocomposite under 700 °C calcination treatment exhibited superior electromagnetic absorption performance with an optimal reflection loss of −63.0 dB and effective absorption bandwidth of 4.0 GHz (12.2–16.2 GHz) at a thin matching thickness of merely 1.6 mm and filler loading as low as 25 wt%. In addition, the underlying electromagnetic absorption mechanisms were proposed. This work provided a facile strategy for fabricating the carbon-based magnetic composites derived from metal–organic frameworks as light weight and high-performance electromagnetic absorption materials.

Synthesis of nitrogen-doped reduced graphene oxide/cobalt-zinc ferrite composite aerogels with superior compression recovery and electromagnetic wave absorption performance.

Abstract: Graphene aerogels possessing a three-dimensional (3D) porous netlike structure, good electrical conductivity and ultralow density have been widely regarded as a promising candidate for high-efficiency electromagnetic wave (EMW) absorption. Herein, nitrogen-doped reduced graphene oxide/cobalt-zinc ferrite (NRGO/Co0.5Zn0.5Fe2O4) composite aerogels were synthesized through a solvothermal and subsequent hydrothermal self-assembly two-step method. The results of micromorphology analysis showed that the 3D networks were well constructed through the partial stacking of adjacent NRGO sheets, which were decorated with numerous Co0.5Zn0.5Fe2O4 microspheres. The as-synthesized NRGO/Co0.5Zn0.5Fe2O4 composite aerogels have a very low density (12.1-14.6 mg cm-3) and good compression recovery. Moreover, excellent EMW absorption performance could be achieved through facilely regulating the additive volume of ethylenediamine (i.e. nitrogen doping contents) and filler contents. Impressively, the composite aerogel with a doped nitrogen content of 2.5 wt% displayed the optimal minimum reflection loss (RLmin) of -66.8 dB in the X-band at a thickness of 2.6 mm and the broadest effective absorption bandwidth of 5.0 GHz under an ultrathin thickness of merely 1.6 mm. Meanwhile, the RLmin of NRGO/Co0.5Zn0.5Fe2O4 composite aerogels below -20 dB could be reached in almost the whole tested thickness range (1.4-5.0 mm). Additionally, the potential EMW absorption mechanisms were revealed, which was mainly due to the unique 3D porous netlike structure, synergistic effects among conduction loss, magnetic resonance loss and polarization loss, as well as the balanced attenuation capacity and impedance matching. It was believed that this work provided an alternative way for fabricating strong mechanical graphene-based 3D magnetic/dielectric composites as light-weight and high-efficiency EMW absorbers.

Multifunctional Magnetic Ti3C2Tx MXene/Graphene Aerogel with Superior Electromagnetic Wave Absorption Performance.

Abstract: Ingenious microstructure design and a suitable multicomponent strategy are still challenging for advanced electromagnetic wave absorbing (EMA) materials with strong absorption and a broad effective...

Hierarchical Ti3C2Tx MXene/Ni Chain/ZnO Array Hybrid Nanostructures on Cotton Fabric for Durable Self-Cleaning and Enhanced Microwave Absorption.

Abstract: The increasing demand for wearable electronics and the intensification of electromagnetic pollution have boosted the exploration of high-performance flexible microwave absorption (MA) materials Herein, the hierarchical Ti3C2Tx MXene/Ni chain/ZnO array hybrid nanostructures are rationally constructed on cotton fabric for acquiring enhanced MA performance and durable self-cleaning ability Based on the high dielectric loss capacity of MXenes and ZnO arrays, by controlling dip-coating numbers of Ni chains, the magnetic loss can be manipulated to modulate the impedance matching, reflection loss (RL), and effective absorption bandwidth (EAB, the bandwidth of RL < -10 dB) The minimum RL value of the designed fabric can reach -351 dB at 83 GHz with a thickness of 28 mm, and its EAB can cover the whole X-band with only a 22 mm thickness In addition, the designed fabric also exhibits superior liquid repellency and durable self-cleaning ability due to the combination of the hybrid nanostructures and a superhydrophobic coating This work provides an insight for rational design of textile-based MA materials, showing potential applications in flexible and wearable functional electronics

A review of three-dimensional graphene-based aerogels: Synthesis, structure and application for microwave absorption

Abstract: Graphene aerogels (GAs) offer a distinctive combination of high porosity, low density, large specific surface area and high compressibility, which make it grab considerable attention in various applications, in particular for high performance electromagnetic wave attenuation. The internal porous structure and three-dimensional (3D) network of GAs solve the phenomenon of graphene sheet layer agglomeration, high conductivity and impedance mismatch in two-dimensional graphene, which is conducive to the improvement of microwave absorption performance. In addition, GAs incorporate other lossy materials as a framework have been widely studied to achieve more efficient microwave absorption. Herein, the latest advances in the synthetic strategies and structural characteristics of graphene-based materials are reviewed. Furthermore, we summarized recent advances in graphene-based aerogels as microwave absorbing materials, including pure GAs and hybrid aerogels with other lossy materials. In addition, we also highlighted the multifunctional microwave absorbing materials. On this basis, we summarized the research status of graphene-based microwave absorbing aerogels and put forward the challenges and outlook of graphene-based microwave absorbing aerogels.

A Review on Metal-Organic Framework-Derived Porous Carbon-Based Novel Microwave Absorption Materials.

Abstract: The development of microwave absorption materials (MAMs) is a considerable important topic because our living space is crowed with electromagnetic wave which threatens human’s health. And MAMs are also used in radar stealth for protecting the weapons from being detected. Many nanomaterials were studied as MAMs, but not all of them have the satisfactory performance. Recently, metal–organic frameworks (MOFs) have attracted tremendous attention owing to their tunable chemical structures, diverse properties, large specific surface area and uniform pore distribution. MOF can transform to porous carbon (PC) which is decorated with metal species at appropriate pyrolysis temperature. However, the loss mechanism of pure MOF-derived PC is often relatively simple. In order to further improve the MA performance, the MOFs coupled with other loss materials are a widely studied method. In this review, we summarize the theories of MA, the progress of different MOF-derived PC‑based MAMs, tunable chemical structures incorporated with dielectric loss or magnetic loss materials. The different MA performance and mechanisms are discussed in detail. Finally, the shortcomings, challenges and perspectives of MOF-derived PC‑based MAMs are also presented. We hope this review could provide a new insight to design and fabricate MOF-derived PC-based MAMs with better fundamental understanding and practical application.