Gas-solid Reaction Research Articles

Coupling CFD-DEM with cohesive force and chemical reaction sub-models for biomass combustion in a fluidized bed

The present study employs the CFD-DEM method coupled with cohesive force and chemical reaction sub-models to investigate the hydrodynamic and thermal behaviors in a biomass-fired fluidized bed combustor containing bed particles with cohesive features resulting from the high levels of inorganic alkalis in the biomass. The CFD-DEM simulations effectively reproduce the characteristic phenomena in a cohesive fluidized bed, such as particle agglomeration, gas bubbles with irregular boundaries, rat-holes, and gas channels. The results indicate that the particle kinetic energy continuously decreases with increasing particle cohesion, and the pressure-drop profile flattens suddenly at the onset of complete de-fluidization. Additionally, larger cohesive forces occur at coarse bed-particle conditions, while the particle-averaged cohesive force at the onset of de-fluidization weakens as the bed-particle size increases at the same superficial gas velocity. The regions near the bed bottom and sidewall are more sensitive to the hydrodynamic and thermal alterations resulting from increasing particle cohesion, making them more favorable for early detection. The convection heat and reaction heat dominate the heat transfer of bed particles and biomass particles, respectively. As the particle cohesion becomes more pronounced, the biomass-particle reaction heat flux decreases because biomass trapped in agglomerates experiences oxygen-deficient conditions due to the hindering effects of large agglomerates on the gas and the occurrence of gas channels. Overall, the present study indicates that the particle mixing and inter-phase heat transfer capacity, along with reaction intensity in the biomass-fired fluidized bed, deteriorates as particle cohesion increases. The extended model provides a particle-scale approach to analyze complex cohesive gas–solid reaction flow systems.

In situ construction of cyano-modified g-C3N4 nanolayer-coated SrTiO3 nanotubes by gas-solid reaction for efficient photocatalytic solar fuel production

For the transformation of the global energy structure, photocatalyst-based artificial photosynthesis for solar-to-chemical energy conversion has been regarded as promising. Herein, we report the homogenous construction of cyano-modified g-C3N4 ultrathin nanolayers onto SrTiO3 nanotubes using a simple one-step gas–solid reaction, as well as their application to photocatalytic H2 evolution and CO2 reduction. The creation of one-dimensional core–shell nanostructures and type II heterojunctions broaden visible light absorption range and shorten charge transfer path. The electron-absorbing cyano introduced in situ without any auxiliary salts can not only provide an appropriate driving force for electron transport and extend the active site of photocatalytic reaction, but also alter the band gap to accomplish energy band alignment. Moreover, in-situ irradiation X-ray photoelectron spectroscopy (ISI-XPS) was used to confirm the dual active site system consisting of cyano and SrTiO3. This work aims to promote the development of the surface modification of core-shell nanostructured photocatalysts.

Cu3N-derived hydrophobic porous CuO hollow nanospheres for NO2 detection at room temperature

Good humidity resistance property are crucial for gas sensors to achieve high-performance sensing characteristics at room temperature. In this work, porous raspberry-like CuO hollow nanospheres were produced by calcining the Cu3N nanosphere precursors through a solid-gas displacement reaction involving the Kirkendall effect. The raspberry-like CuO hollow nanospheres had spherelike microstructure with nanoparticle-built rough surface, thereby showing a hydrophobic characteristic with a high static contact angle (143.0°). The CuO hollow nanospheres exhibited a high response of 26.2–300 ppb NO2 even under a high relative humidity of 80% at room temperature, 18.7 times greater than the commercial CuO powder. In addition, the response/recovery times of CuO hollow nanospheres were shorter than those of the CuO powder, with 1.9-fold/3.2-fold improvements in response/recovery kinetic coefficients. CuO hollow nanospheres also displayed good NO2 selectivity and cycling repeatability. The improved NO2 sensing characteristics of the CuO hollow nanospheres were primarily attributable to their increased specific surface area and porosity, increased response/recovery kinetics, and hydrophobic surface.

A mesoscale model for heterogeneous reactions in porous media applied to reducing porous iron oxide

A mesoscale model based on the lattice gas cellular automata (LGCA) is proposed for heterogeneous reaction in porous media. This model features an entirely discretized reaction system, including discrete space, time, gas phases, and solid particle. To describe gas diffusion at solid nodes and gas–solid heterogeneous reaction on the phase boundary, two local probabilities are proposed, which are verified by the analytical solutions for gas diffusion and gas–solid reaction problems. This model was then applied to the hydrogen reduction of porous Fe3O4. The effects of the porosity, reaction rate constant (kl), and initial H2 concentration on the reduction were analyzed. The results indicate that the reaction rate increased with increasing porosity, kl, and H2 concentration. The solid product Fe was randomly distributed on the framework of Fe3O4 at smaller kl and concentrated around the unreacted Fe3O4 at higher kl, which is consistent with our experimental results.

Highly compressible and hydrophobic nanofibrillated cellulose aerogels for cyclic oil/water separation

Nanofibrillated cellulose (NFC)-based aerogels are ideal oil-sorbent materials, but the poor structural stability and hydrophilicity restrain their practical applications in the fields of oil/water separation. In the present work, we report a facile strategy for constructing a hydrophobic nanofibrillated cellulose aerogel for cyclic oil/water separation. Briefly, an aerogel matrix of C-g-PEI with multiple cross-linked network structures was constructed via the combined use of oxidized-NFC (ONC), polyethyleneimine (PEI), and ethylene glycol diglycidyl ether (EGDE), followed by rapid in situ deposition of poly(methyl trichlorosilane) (PMTS) through a low-temperature gas-solid reaction. The resulting ONC-based aerogel (C-g-PEI-PMTS) exhibits the advantages of ultralight (53.80 mg/cm3), high porosity (95.73 %), hydrophobicity (contact angle of 130.0°) and remarkable elasticity (95.86 %). Meanwhile, the composite aerogel of C-g-PEI-PMTS is extremely suitable for oil sorption-desorption by a simple mechanical squeezing method. After 10 cycles of sorption-desorption, the sorption capacity of the aerogel towards various oils reached almost the same level as in the first cycle. The filtration separation efficiency for the trichloromethane-water mixtures remained at 99 % after 50 cycles, demonstrating encouraging reusability. In summary, an efficient strategy to prepare NFC-based aerogel with highly compressible and hydrophobic properties is developed, which expands the applications of NFC in the fields of oil/water separation.

A hybrid CFD-RMD multiscale coupling framework for interfacial heat and mass simulation under hyperthermal ablative conditions

Under hypersonic flow conditions, the heat and mass transfer at the gas-solid interface of thermal protection material becomes highly complicated due to the strong chemical and thermal non-equilibrium phenomena, associated with the real gas effect, the high temperature effect and various heterogeneous reactions occurring at the interface or inside the TPM. Interfacial heat and mass transfer is strongly coupled with non-linear reactions at different spatiotemporal scales. Based on the traditional macroscopic Computational Fluid Dynamics (CFD) and microscopic Reactive Molecular Dynamics (RMD) methods, a hybrid CFD-RMD multiscale simulation framework is established in this work to improve the accuracy of aerothermal prediction by considering the heat and mass transfer at the gas-solid interface under hyperthermal non-equilibrium conditions. To validate the proposed multiscale framework, phenolic resin composite is investigated in this work with particular interest in the pyrolysis gas injection effects. Benchmarking ablation studies are conducted under three representative altitudes of 40, 60 and 80 km, respectively, and the recession rates of 7.47 × 10−4, 1.53 × 10−3 and 1.08 × 10−3 mm/s are obtained which are comparable with the experimental results. Much higher computational efficiency of the hybrid CFD-RMD multiscale framework is achieved comparing to a full RMD simulation method at the same spatial and temporal level. Not only to the pyrolysis study, the established framework can also potentially be extended to other gas-solid interfacial reaction situations, which is of great help in improving the mechanism understanding of various physics-derived microscopic models for macroscopic predication of hypersonic aerothermal characteristics.

Tracing the transient reaction kinetics of adsorbed species by in situ/operando infrared spectroscopy

The dynamic reaction behavior (i.e., transient responses) of IR-observable adsorbed species and gaseous products obtained from transient kinetic studies provide valuable kinetic and mechanistic information, namely: the abundance of active intermediates and their reactivity distribution, the chemical structure of IR-observable active and spectator species, the sequence of their formation, and the kinetically significant and rate-determining step under reaction conditions of practical catalysis. We discuss the use of transient response data to elucidate the reaction mechanisms of several gas-solid reactions: CO/H2, CO/H2/C2H4, photocatalytic oxidation of ethanol, and the CO2-amine reaction. The IR coupled with transient kinetic techniques is especially useful for investigating the mechanisms of photocatalytic reactions because both photogenerated electrons and many adsorbed species are IR-active (exhibiting measurable IR bands), and their evolution occurs on a time scale of seconds at ambient temperature. We highlight the key features and limitations of in situ IR with transient kinetics, as well as their significance in catalyst design.

Design of Z-scheme polymeric carbon nitride/Bi2WO6 heterojunctions for efficient visible-light-driven antibiotic degradation

The use of heterojunctions with Z-scheme photocatalysts holds great promise for enhancing the photocatalytic degradation efficiency of antibiotics. In this study, we report the construction of a novel heterostructure by in-situ growth of the ultrathin polymeric carbon nitride (PCN) on the electrospun Bi2WO6 nanofibers for improved photocatalytic tetracycline (TC) degradation under visible light. Our gas–solid reaction strategy enables the formation of uniform and intimate junctions between the PCN nanosheets and the Bi2WO6 nanofibers, resulting in a well-contacted interface that remarkably accelerates the separation and transfer of the photogenerated charge carriers. The optimized PCN/Bi2WO6 photocatalyst exhibits a significant TC degradation rate of 89.5 % under visible light, which is 1.4-fold and 2.0-fold of the pure PCN and Bi2WO6 photocatalysts, respectively. Our innovative design philosophy opens up a new horizon for the development of efficient Z-scheme heterostructured photocatalysts for antibiotic degradation.

Sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries via selective sulfation with waste copperas

Spent lithium-ion batteries (LIBs) are essential secondary resource, containing valuable metal elements including lithium, cobalt, nickel, manganese. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. Herein, a sustainable and facile process for Li2CO3 and Mn2O3 recovery from spent LiMn2O4 batteries (LMO) was proposed via sulfation roasting with waste copperas. The leaching efficiencies of Li and Mn reached approximately 100 % and 82 % under the optimal conditions, and the final recovered products were Li2CO3 and Mn2O3 with high purities. The sulfation reaction between LMO and copperas was the transition from solid-solid to gas-solid reaction. During the sulfation reaction, LMO spinel structure was decomposed into MnO2 and Mn2O3 crystal structures, and the anti-fluorite structure Li2O embedded in the spinel structure was released. The Li2O was easily to be sulfated, while MnO2 was partly reduced by Fe2+ to more stable spinel structure Mn2O3. Furthermore, FeSO4 decomposed into SO2 gas, which greatly improved the sulfation reaction through permeating into the unreacted core of LMO. As a result, the spinel structure of Mn2O3 was broken, and Mn was escaped to combine with SO42- to form MnSO4. This research provided an alternative technological route for green recovery of spent LMO batteries, demonstrating high potential for broad application.

Microstructure evolution and reaction mechanism of reactive plasma sprayed Ti–C–N coatings

This investigation focuses on the feasibility of the reaction synthesis of Ti–C–N phase using plasma spraying powder mixture of Ti and graphite under nitrogen ion flame flow. To regularize the microstructure and properties of the sprayed Ti–C–N coating, the microstructure evolution of the Ti-graphite-N2 system was analyzed based on water quenching tests. The reaction pathway of the Ti-graphite-N2 system has been investigated by thermodynamic calculations and thermal analysis, revealing the mechanisms of the reaction during plasma spraying. The results show that the as-deposited coatings exhibit a typical layered structure consisting mainly of TiCxNy and TiO2. The quenched powders exhibit a melting process from irregular particles to smooth spherical particles, forming complete droplets with increasing spray distance. Based on phase evolution of the quenched powders and the thermal analysis of Ti powders or Ti/graphite powders under N2/Ar atmosphere, it found that the Ti powder can reacted with graphite or N2 by solid-solid or solid-gas reaction to form TiCx and TiNy, and TiNy can be formed preferentially as compared with TiCx phase. As the spraying distance increases, the Ti and graphite reactions are enhanced, and a pronounced TiCx phase can be detected once a large liquid Ti phase is formed. As the spray distance increases, formed TiNy and TiCx phases aggregate into droplets and rapidly transform into TiCxNy phase by solid-solution reactions. In addition, titanium oxide coexists in lamellae of Ti–C–N coatings due to the absorption and dissociation of O₂ from the atmosphere at the droplet surface.

Reduction mechanism of bamboo powder pyrolysis in selective lithium extraction from spent lithium-ion batteries

In light of the increase in demand for lithium resources, selective recovery of lithium from spent lithium-ion batteries (LIBs) is becoming increasingly important. In the preferential lithium extraction process, the choice of reducing agent is crucial, which affects the efficiency of Li+ release. Here, a novel biomass reducing agent waste bamboo powder (BP) is proposed. The thermal reduction mechanism of BP on spent cathode powder (SCP) is explored in detail, and the effect of BP before and after carbonization on the lithium extraction effect is investigated. Based on the regulation of roasting parameters, the SCP can be reduced to Li2CO3, Ni, Co and MnO under the optimal conditions of 650 ℃ for 1.5 h with 1:1 mass ratio of BP/SCP. Furthermore, through thermodynamic calculations and physicochemical characterizations, it is found that the addition of gas-solid reaction in the BP reduction process is superior to the carbonized non-activated carbon (NC) and activated carbon (AC). Moreover, the large specific surface area of 1145.725 m2 g−1 for AC will lead to partial adsorption of lithium during the water leaching process. Finally, more than 99% of lithium is preferentially recovered from the reducing residue through a two-stage leaching process of water leaching and low concentration acid leaching. Water leaching process can recover 82.6% of lithium and the model of physical dissolution kinetics are constructed and systematically studied. This research achieves low-cost, green and selective recovery of lithium from spent LIBs, which has broad industrial application prospects.

Performance evaluation of gas maldistribution mitigation via baffle installation: Computational study using ozone decomposition in low-velocity dense fluidized beds

Gas maldistribution is an operational challenge peculiar to all industrial fluidized bed applications, resulting in poor reactor performance. In the present work, the multi-phase particle-in-cell (MP-PIC) method was used to simulate an induced-gas maldistribution condition in a low-velocity batch mode fluidized bed of ozone (O3) decomposition process. The effects of mesh and single-turn Louver baffles on gas maldistribution mitigation were compared with baffle-free condition across different superficial gas velocities (Ugs) under similar reactive conditions. Hydrodynamics of the gas-solid flow and reaction performance were examined. Initial simulations agreed well with the experimental data reported in the literature. Baffles installation resulted in a range of favorable impacts, including obstruction of gas channelling, expansion of the bed, enhanced gas-solids contact efficiency, reduced pressure fluctuation and decreased effluent O3. The single-turn Louver baffle showed the best performance due to its stronger bubble-breaking and gas redistribution effects spurred by the inclined vanes; its simulated superiority agreed strongly with previous experimental results. Present study demonstrates the effectiveness of baffle installation in resolving gas maldistribution and/or intensifying industrial processes.

Enhancing Low-Temperature SOFC Performance and Durability via Surface Modification

The development of active cathodes is one of the most critical challenges to lowering the operating temperature for SOFCs. By modifying the cathode surface chemistry the activity and durability can be simultaneously enhanced on high-performing, low-temperature cathodes. This low-temperature modification using multi-valent cations activates the highly defected surface and maintains the nanoscale electrocatalysts by bypassing the high-temperature sintering procedure for SOFC fabrication. The modified cathode at 600 °C shows an order of magnitude reduction in impedance to only 0.05 Ωcm2 with a peak power density of 1.1 W/cm2 and increases stability over 2000 hours. The combination of in situcharacterization, distribution of relaxation time analysis on impedance spectroscopy, and surface chemistry analysis reveals the importance of surface chemistry control on the gas-solid reaction activity and durability and provides the design principle for future solid oxide cells.

Hafnium-Zirconium Carbonitride (Hf,Zr)(C,N) by One Step Mechanically Induced Self-Sustaining Reaction: Powder Synthesis and Spark Plasma Sintering

Nanostructured single-phase hafnium-zirconium carbonitride powders were synthesized using a simple and fast mechanochemical synthesis approach. The critical milling duration, after which a (Hf,Zr)(C,N) solid solution formation inside a jar occurred via mechanically induced self-sustained reaction (MSR), was 10 min. After 30 min of treatment, a solid-gas reaction was completed, and as a result, a homogeneous (Hf,Zr)(C,N) powder consisting of 10–500 nm submicron particles was obtained. The phase and structure evolution of the powders after different treatment durations allowed for the establishment of possible reaction mechanisms, which included the formation of Hf/Zr/C-layered composite particles, their interaction via MSR, and further grinding and nitridization. Spark plasma sintering (SPS) was used to produce bulk hafnium-zirconium carbonitride ceramics from nanostructured powder. The sample had higher values of relative density, hardness, and fracture toughness than those for binary compounds of a similar composition.

A Review of Oxygen Carrier Materials and Related Thermochemical Redox Processes for Concentrating Solar Thermal Applications.

Redox materials have been investigated for various thermochemical processing applications including solar fuel production (hydrogen, syngas), ammonia synthesis, thermochemical energy storage, and air separation/oxygen pumping, while involving concentrated solar energy as the high-temperature process heat source for solid-gas reactions. Accordingly, these materials can be processed in two-step redox cycles for thermochemical fuel production from H2O and CO2 splitting. In such cycles, the metal oxide is first thermally reduced when heated under concentrated solar energy. Then, the reduced material is re-oxidized with either H2O or CO2 to produce H2 or CO. The mixture forms syngas that can be used for the synthesis of various hydrocarbon fuels. An alternative process involves redox systems of metal oxides/nitrides for ammonia synthesis from N2 and H2O based on chemical looping cycles. A metal nitride reacts with steam to form ammonia and the corresponding metal oxide. The latter is then recycled in a nitridation reaction with N2 and a reducer. In another process, redox systems can be processed in reversible endothermal/exothermal reactions for solar thermochemical energy storage at high temperature. The reduction corresponds to the heat charge while the reverse oxidation with air leads to the heat discharge for supplying process heat to a downstream process. Similar reversible redox reactions can finally be used for oxygen separation from air, which results in separate flows of O2 and N2 that can be both valorized, or thermochemical oxygen pumping to absorb residual oxygen. This review deals with the different redox materials involving stoichiometric or non-stoichiometric materials applied to solar fuel production (H2, syngas, ammonia), thermochemical energy storage, and thermochemical air separation or gas purification. The most relevant chemical looping reactions and the best performing materials acting as the oxygen carriers are identified and described, as well as the chemical reactors suitable for solar energy absorption, conversion, and storage.

Acid-free extraction of valuable metal elements from spent lithium-ion batteries using waste copperas

A large amount of hazardous spent lithium-ion batteries (LIBs) is produced every year. Recovery of valuable metals from spent LIBs is significant to achieve environmental protection and alleviate resource shortages. In this study, a green and facile process for recovery of valuable metals from spent LIBs by waste copperas was proposed. The effects of heat treatment parameters on recovery efficiency of valuable metals and the redox mechanism were studied systematically through phase transformation behavior and valence transition. At low temperature (≤460 °C), copperas reacted with lithium on the outer layer of LIBs preferentially, but the reduction of transition metals was limited. As the temperature rose to 460–700 °C, the extraction efficiency of valuable metals was greatly enhanced due to the generation of SO2, and the gas–solid reaction proceeded much fast than the solid–solid reaction. In the final stage (≥700 °C), the main reactions were the thermal decomposition of soluble sulfates and the combination of decomposed oxides with Fe2O3 to form insoluble spinel. Under the optimum roasting conditions, i.e., at a copperas/LIBs mass ratio of 4.5, and a roasting temperature of 650 °C and roasting time of 120 min, the leaching efficiencies of Li, Ni, Co and Mn were 99.94%, 99.2%, 99.5% and 99.65%, respectively. The results showed that valuable metals can be selectively and efficiently extracted from the complex cathode materials by water leaching. This study used waste copperas as an aid to recover metals and provided an alternative technical route for green recycling of spent LIBs.

Minimizing Temperature Bias through Reliable Temperature Determination in Gas-Solid Photothermal Catalytic Reactions.

Enormous advances in photothermal catalysis have been made over the years, whereas the temperature assessment still remains controversial in the majority of photothermal catalytic systems. Herein, we methodically uncovered the phenomenon of temperature determination bias arising from prominent temperature differences in gas-solid photothermal catalytic systems, which extensively existed yet has been overlooked in most relevant cases. To avoid the interference of temperature bias, we developed a universal protocol for reliable temperature evaluation of gas-solid photothermal catalytic reactions, with emphasis on eliminating the temperature gradient and temperature fluctuation of catalyst layer via optimizing the reaction system. This work presents a functional and credible practice for temperature detection, calling attention to addressing the effects of temperature differences, and reassessing the actual temperature-based performances in gas-solid photothermal catalysis.

In-situ growth of g-C3N4 nanosheets on Nb2O5 nanofibers for enhanced performance in photocatalysis and lithium-sulfur battery

A Nb2O5/g-C3N4 composite with a controllable loading amount of g-C3N4 nanosheets is successfully prepared by a combination of electrospinning and the double crucible gas-solid reaction method. During the heat treatment process, the precursor molecules of melamine gas are in-situ polymerized on the surface of Nb2O5 nanofibers to form g-C3N4 nanosheets. The Nb2O5 nanofibers ultralong one-dimensional nanostructure can effectively avoid the aggregations of g-C3N4 and form tight heterojunction interfaces. The optimized Nb2O5/g-C3N4 composite material improved the photocatalytic activity for methylene blue degradation, with a rate constant twice that of Nb2O5 nanofibers and 3.8 times that of pure g-C3N4. Using the combination of DFT theoretical calculations and capture experiments, the transfer mechanism of the Nb2O5/g-C3N4 type-II heterojunction is confirmed. It was found that the d orbital of Nb and the p orbital of N were the main active site of the photocatalytic reaction. Meanwhile, the lithium-sulfur (Li-S) battery assembled with NOCN-8 as the host material exhibited a high initial discharge capacity of 900 mAh g−1 at 0.5 C, and its capacity decay rate was less than 0.1% after 500 cycles. It shows that NOCN-8 can effectively adsorb polysulfide and catalyze the conversion reaction of polysulfide. This work provides a novel route for the synthesis of the Nb2O5/g-C3N4 composite, and has great potential in the development of environmental remediation and energy applications.

Thermochemically driven layer structure collapse via sulfate roasting toward the selective extraction of lithium and cobalt from spent LiCoO2 batteries

With the rapid development of new energy devices, a large amount of spent lithium-ion batteries (LIBs) are produced every year. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. In this study, a novel approach by in situ thermal reduction technology with waste copperas is developed to recycle valuable metals from spent LiCoO2 (LCO) batteries. The mechanism study through in situ x-ray diffractometer and thermal analysis reveal that the sulfation of LCO underwent two pathways i.e., ion exchange and gas-solid reactions. In the ion exchange pathway, the layered structure of LCO collapse due to the reduction by divalent iron in copperas, and the detachment of lithium ions result in a larger lattice spacing of transition metal layer and formation of a stable spinel structure. Furthermore, the SO2 generated from the decomposition of iron sulfates reduces the unreacted LCO through gas-solid interactions, realizing the sulfation of lithium and cobalt completely. Economic analysis indicates the potential benefit of this process is approximately 8266$/t spent LCO. This study provides an alternative technological route and a new approach to green recovery of the spent LCO batteries, exhibiting great potential for wide applications.

Hierarchical Carbon Network Composites Derived from ZIF-8 for High-Efficiency Microwave Absorption.

Metal-organic framework (MOF)-derived composites have gained wide attention due to their specific structures and enhanced performance. In this work, we prepared carbon nanotubes with Fe nanoparticles connected to two-dimensional (2D) hierarchical carbon network composites via a low-pressure gas-solid reaction strategy. Specifically, the three-dimensional (3D) networks derived from ZIF-8 exploited the carbon nanotubes with the function of charge modulation. Meanwhile, we utilized the interconnected 2D nanostructures to optimize impedance matching and facilitate multiple scattering, ultimately improving the overall microwave absorption performance. Furthermore, based on the well-designed structures, the composites prepared at 800 °C (Fe-N-C@CNTs-800) achieved the best reflection loss (RL) of -58.5 dB, thereby obtaining superior microwave absorption performance. Overall, this study provides a good groundwork for further investigation into the modification and dimension design of novel hierarchical microwave absorbers.