HIGHLIGHTS• Hierarchically porous Fe-Co/N-doped carbon/rGO (Fe-Co/NC/rGO) composites were successfully prepared. Macropores, mesopores, and micropores coexisted in the composites.• Hierarchically porous Fe-Co/NC/rGO showed effective bandwidth of 9.29 GHz.ABSTRACT Developing lightweight and broadband microwave absorbers for dealing with serious electromagnetic radiation pollution is a great challenge. Here, a novel Fe-Co/N-doped carbon/reduced graphene oxide (Fe-Co/NC/rGO) composite with hierarchically porous structure was designed and synthetized by in situ growth of Fe-doped Cobased metal organic frameworks (Co-MOF) on the sheets of porous cocoon-like rGO followed by calcination. The Fe-Co/NC composites are homogeneously distributed on the sheets of porous rGO. The Fe-Co/NC/rGO composite with multiple components (Fe/Co/NC/rGO) causes magnetic loss, dielectric loss, resistance loss, interfacial polarization, and good impedance matching. The hierarchically porous structure of the Fe-Co/NC/rGO enhances the multiple reflections and scattering of microwaves. Compared with the Co/NC and Fe-Co/NC, the hierarchically porous Fe-Co/NC/rGO composite exhibits much better microwave absorption performances due to the rational composition and porous structural design. Its minimum reflection loss (RL min ) reaches − 43.26 dB at 11.28 GHz with a thickness of 2.5 mm, and the effective absorption frequency (RL ≤ − 10 dB) is up to 9.12 with the same thickness of 2.5 mm. Moreover, the widest effective bandwidth of 9.29 GHz occurs at a thickness of 2.63 mm. This work provides a lightweight and broadband microwave absorbing material while offering a new idea to design excellent microwave absorbers with multicomponent and hierarchically porous structures.
Reasonable design and construction of low-cost overall water splitting catalyst with high efficiency is of great significance to green chemistry industry. Herein, a CoFeP/NC@CoP/Ni2P heterostructure is constructed via phosphiding CoFe-Prussian...
In this paper, micro-mesoporous HZSM-5/MCM-41 zeolites were prepared by a
two-step hydrothermal method using commercial HZSM-5 with two different
silica/alumina ratios (38 and 50) as starting materials. The structures,
morphologies and acidity of as-prepared zeolites were analyzed using XRD,
FT-IR, SEM, N2-adsorption/desorption and NH3-TPD. The HZSM-5/MCM-41 zeolites
combined the acidity of microporous HZSM-5 with the pore advantages of
mesoporous MCM-41. Mesopores and microspores of 3.34 and 0.95 nm in diameter
were found to be present in HZSM-5/MCM-41 zeolites. When they were used to
catalyze the pyrolysis of waste tires, the selectivity of light olefins for
HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as
starting materials was 21.42%, higher than 18.43% of
HZSM-5/MCM-41synthesized using HZSM-5 with the silica/alumina ratio of 38.
In order to further overcome the pore size constraints and mass transfer
limitations of HZSM-5/MCM-41 zeolites for catalyzing pyrolysis of waste
tires, macroporous ?-Al2O3 were mixed with HZSM-5/MCM-41 and used as
catalysts. The selectivity to light olefins for the mixture of ?-Al2O3 and
HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as
starting materials was 33.65%, which was obviously enhanced by the
introduction of ?-Al2O3.
Catalytic cracking is a promising approach to realize the resource utilization of waste tires. Herein, a new composite catalyst, nano-ZSM-5/MgAl-LDO, is synthesized, and catalytic cracking of waste tires over the composite catalyst is explored. Experimental results indicate that nano-ZSM-5/MgAl-LDO composite catalyst is characterized by high dispersion of nano-ZSM-5 on the surface of LDO, large Brunauer-Emmett-Teller-specific surface area, large pore diameter and volume, and suitable acid and basic properties. Moreover, not only does the nano-ZSM-5/MgAl-LDO composite catalyst increase the conversion rate (62.04%) and degradation rate (1.33 Â 10 À3 s À1 ) of waste tires, but it also enhances the selectivity (33.32%) of light hydrocarbons in pyrolysis products, which was nearly 10% higher than that of thermal pyrolysis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.