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Biomass-derived hard carbon materials are considered as the most promising anode materials for sodium-ion batteries (SIBs) due to their abundant sources, environmental friendliness, and excellent electrochemical performance. Although much research exists on the effect of pyrolysis temperature on the microstructure of hard carbon materials, there are few reports that focus on the development of pore structure during the pyrolysis process. In this study, corncob is used as the raw material to synthesize hard carbon at a pyrolysis temperature of 1000~1600 °C, and their interrelationationship between pyrolysis temperature, microstructure and sodium storage properties are systematically studied. With the pyrolysis temperature increasing from 1000 °C to 1400 °C, the number of graphite microcrystal layers increases, the long-range order degree rises, and the pore structure shows a larger size and wide distribution. The specific capacity, the initial coulomb efficiency, and the rate performance of hard carbon materials improve simultaneously. However, as the pyrolysis temperature rises further to 1600 °C, the graphite-like layer begins to curl, and the number of graphite microcrystal layers reduces. In return, the electrochemical performance of the hard carbon material decreases. This model of pyrolysis temperatures–microstructure–sodium storage properties will provide a theoretical basis for the research and application of biomass hard carbon materials in SIBs.

Carbon-based microwave-absorbing materials with a low cost, simple preparation process, and excellent microwave absorption performance have important application value. In this paper, biomass-based carbon fibers were prepared using cotton fiber, hemp fiber, and bamboo fiber as carbon sources. Then, the precise loading of NiFe2O4 nanoparticles on biomass-based carbon fibers with the loading amount in a wide range was successfully realized through a sustainable and low-cost route. The effects of the composition and structure of NiFe2O4/biomass-based carbon fibers on electromagnetic parameters and electromagnetic absorption properties were systematically studied. The results show that the impedance matching is optimized, and the microwave absorption performance is improved after loading NiFe2O4 nanoparticles on biomass-based carbon fibers. In particular, when the weight percentage of NiFe2O4 nanoparticles in NiFe2O4/carbonized cotton fibers is 42.3%, the effective bandwidth of NiFe2O4/carbonized cotton fibers can reach 6.5 GHz with a minimum reflection loss of −45.3 dB. The enhancement of microwave absorption performance is mainly attributed to the appropriate electromagnetic parameters with the ε’ ranging from 9.2 to 4.8, and the balance of impedance matching and electromagnetic loss. Given the simple synthesis method, low cost, high output, and excellent microwave absorption performance, the NiFe2O4/biomass-based carbon fibers have broad application prospects as an economic and broadband microwave absorbent.

A simple low-cost hydrothermal method has been developed to fabricate uniformly dispersed octahedral Fe 3 O 4 nanoparticles with tunable size. The particle size can be reduced to 20–30 nm under the effect of phosphate, meanwhile, the edetate disodium can improve the dispersivity of particles. High-resolution transmission electron microscope showed that the octahedral Fe 3 O 4 nanoparticle was enclosed by eight (111) planes. Octahedral γ-Fe 2 O 3 nanoparticles were obtained by reoxidizing the as-synthesized Fe 3 O 4 nanoparticles. The microwave absorption properties of the octahedral Fe 3 O 4 and γ-Fe 2 O 3 nanoparticles were measured in the frequency range of 2–18 GHz. A minimum reflection loss of −28 dB was observed at 8.6 GHz for octahedral Fe 3 O 4 nanoparticles.

In this paper, MOF derivatives@3D graphene hybrid materials have been prepared by the electrostatic adsorption of GO and ZIF-8 together with in-situ self-assembly of GO. The hybrid materials are systematically characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscope. The result shows that the obtained hybrid materials have a well-defined and cross-linking porous structure. The MOF-derived particles with diameter of about 100 μm are dispersed in the network structure of 3D graphene. The hybrid materials as electrode exhibit good specific capacitance of 214 F/g (0.5 A/g), superior to the individual graphene (171 F/g) and MOF derivatives electrode (104 F/g). Furthermore, an asymmetric supercapacitor has been developed using MOF derivatives@3D graphene hybrids as positive electrode and graphene aerogel as negative electrode in 6 M KOH electrolyte. Due to the excellent structure of hybrid materials, asymmetric device could be reversibly cycled in the voltage range of 0–1.6 V, and exhibits a maximum energy density of 22.4 Wh/kg for a power density of 160 W/kg. The excellent electrochemical properties indicate that the obtained hybrids are expected to become potential electrode material for practical applications.

In this work, brookite TiO2 nanocrystals with co-exposed 001 and 120 facets (pH0.5-T500-TiO2 and pH11.5-T500-TiO2), rutile TiO2 nanorod with exposed 110 facets and anatase TiO2 nanocrystals with exposed 101 facets (pH3.5-T500-TiO2) and 101/010 facets (pH5.5-T500-TiO2, pH7.5-T500-TiO2 and pH9.5-T500-TiO2) were successfully synthesized through a one-pot solvothermal method by using titanium (V) iso-propoxide (TTIP) colloidal solution as the precursor. The crystal structure, morphology, specific surface area, surface chemical states and photoelectric properties of the pHx-T500-TiO2 (x = 0.5, 1.5, 3.5, 5.5, 7.5, 9.5, 11.5) were characterized by powder X-ray diffraction (XRD), field scanning transmission electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), nitrogen adsorption instrument, X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectra and electrochemical impedance spectroscopy (EIS). The photocatalytic activity performance of the pHx-T500-TiO2 samples was also investigated. The results showed that as-prepared pH3.5-T500-TiO2 nanocrystal with exposed 101 facets exhibited the highest photocatalytic activity (95.75%) in the process of photocatalytic degradation of methyl orange (MO), which was 1.1, 1.2, 1.2, 1.3, 1.4, 1.6, 10.7, 15.1 and 27.8 fold higher than that of pH5.5-T500-TiO2 (89.47%), P25-TiO2 (81.16%), pH9.5-T500-TiO2 (79.41%), pH7.5-T500-TiO2 (73.53%), pH0.5-T500-TiO2 (69.10%), CM-TiO2 (61.09%), pH11.5-T500-TiO2 (8.99%), pH1.5-T500-TiO2 (6.33%) and the Blank (3.44%) sample, respectively. The highest photocatalytic activity of pH3.5-T500-TiO2 could be attributed to the synergistic effects of its anatase phase structure, the smallest particle size, the largest specific surface area and exposed 101 facets.

In this work, brookite TiO[sub.2] nanocrystals with co-exposed 001 and 120 facets (pH0.5-T500-TiO[sub.2] and pH11.5-T500-TiO[sub.2]), rutile TiO[sub.2] nanorod with exposed 110 facets and anatase TiO[sub.2] nanocrystals with exposed 101 facets (pH3.5-T500-TiO[sub.2]) and 101/010 facets (pH5.5-T500-TiO[sub.2], pH7.5-T500-TiO[sub.2] and pH9.5-T500-TiO[sub.2]) were successfully synthesized through a one-pot solvothermal method by using titanium (V) iso-propoxide (TTIP) colloidal solution as the precursor. The crystal structure, morphology, specific surface area, surface chemical states and photoelectric properties of the pHx-T500-TiO[sub.2] (x = 0.5, 1.5, 3.5, 5.5, 7.5, 9.5, 11.5) were characterized by powder X-ray diffraction (XRD), field scanning transmission electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), nitrogen adsorption instrument, X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectra and electrochemical impedance spectroscopy (EIS). The photocatalytic activity performance of the pHx-T500-TiO[sub.2] samples was also investigated. The results showed that as-prepared pH3.5-T500-TiO[sub.2] nanocrystal with exposed 101 facets exhibited the highest photocatalytic activity (95.75%) in the process of photocatalytic degradation of methyl orange (MO), which was 1.1, 1.2, 1.2, 1.3, 1.4, 1.6, 10.7, 15.1 and 27.8 fold higher than that of pH5.5-T500-TiO[sub.2] (89.47%), P25-TiO[sub.2] (81.16%), pH9.5-T500-TiO[sub.2] (79.41%), pH7.5-T500-TiO[sub.2] (73.53%), pH0.5-T500-TiO[sub.2] (69.10%), CM-TiO[sub.2] (61.09%), pH11.5-T500-TiO[sub.2] (8.99%), pH1.5-T500-TiO[sub.2] (6.33%) and the Blank (3.44%) sample, respectively. The highest photocatalytic activity of pH3.5-T500-TiO[sub.2] could be attributed to the synergistic effects of its anatase phase structure, the smallest particle size, the largest specific surface area and exposed 101 facets.

A facile one-pot microwave-assisted hydrothermal synthesis of rutile TiO2 quadrangular prisms with dominant 110 facets, anatase TiO2 nanorods and square nanoprisms with co-exposed 101/[111] facets, anatase TiO2 nanorhombuses with co-exposed 101/010 facets, and anatase TiO2 nanospindles with dominant 010 facets were reported through the use of exfoliated porous metatitanic acid nanosheets as a precursor. The nanostructures and the formation reaction mechanism of the obtained rutile and anatase TiO2 nanocrystals from the delaminated nanosheets were investigated. The transformation from the exfoliated metatitanic nanosheets with distorted hexagonal cavities to TiO2 nanocrystals involved a dissolution reaction of the nanosheets, nucleation of the primary [TiO6]8− monomers, and the growth of rutile-type and anatase-type TiO2 nuclei during the microwave-assisted hydrothermal reaction. In addition, the photocatalytic activities of the as-prepared anatase nanocrystals were evaluated through the photocatalytic degradation of typical carcinogenic and mutagenic methyl orange (MO) under UV-light irradiation at a normal temperature and pressure. Furthermore, the dye-sensitized solar cell (DSSC) performance of the synthesized anatase TiO2 nanocrystals with various morphologies and crystal facets was also characterized. The 101/[111]-faceted pH2.5-T175 nanocrystal showed the highest photocatalytic and photovoltaic performance compared to the other TiO2 samples, which could be attributed mainly to its minimum particle size and maximum specific surface area.

Carbon-based microwave-absorbing materials with a low cost, simple preparation process, and excellent microwave absorption performance have important application value. In this paper, biomass-based carbon fibers were prepared using cotton fiber, hemp fiber, and bamboo fiber as carbon sources. Then, the precise loading of NiFe O nanoparticles on biomass-based carbon fibers with the loading amount in a wide range was successfully realized through a sustainable and low-cost route. The effects of the composition and structure of NiFe O /biomass-based carbon fibers on electromagnetic parameters and electromagnetic absorption properties were systematically studied. The results show that the impedance matching is optimized, and the microwave absorption performance is improved after loading NiFe O nanoparticles on biomass-based carbon fibers. In particular, when the weight percentage of NiFe O nanoparticles in NiFe O /carbonized cotton fibers is 42.3%, the effective bandwidth of NiFe O /carbonized cotton fibers can reach 6.5 GHz with a minimum reflection loss of -45.3 dB. The enhancement of microwave absorption performance is mainly attributed to the appropriate electromagnetic parameters with the ' ranging from 9.2 to 4.8, and the balance of impedance matching and electromagnetic loss. Given the simple synthesis method, low cost, high output, and excellent microwave absorption performance, the NiFe O /biomass-based carbon fibers have broad application prospects as an economic and broadband microwave absorbent.

Carbon-based microwave-absorbing materials with a low cost, simple preparation process, and excellent microwave absorption performance have important application value. In this paper, biomass-based carbon fibers were prepared using cotton fiber, hemp fiber, and bamboo fiber as carbon sources. Then, the precise loading of NiFe[sub.2]O[sub.4] nanoparticles on biomass-based carbon fibers with the loading amount in a wide range was successfully realized through a sustainable and low-cost route. The effects of the composition and structure of NiFe[sub.2]O[sub.4]/biomass-based carbon fibers on electromagnetic parameters and electromagnetic absorption properties were systematically studied. The results show that the impedance matching is optimized, and the microwave absorption performance is improved after loading NiFe[sub.2]O[sub.4] nanoparticles on biomass-based carbon fibers. In particular, when the weight percentage of NiFe[sub.2]O[sub.4] nanoparticles in NiFe[sub.2]O[sub.4]/carbonized cotton fibers is 42.3%, the effective bandwidth of NiFe[sub.2]O[sub.4]/carbonized cotton fibers can reach 6.5 GHz with a minimum reflection loss of −45.3 dB. The enhancement of microwave absorption performance is mainly attributed to the appropriate electromagnetic parameters with the ε’ ranging from 9.2 to 4.8, and the balance of impedance matching and electromagnetic loss. Given the simple synthesis method, low cost, high output, and excellent microwave absorption performance, the NiFe[sub.2]O[sub.4]/biomass-based carbon fibers have broad application prospects as an economic and broadband microwave absorbent.

A simple low-cost hydrothermal method has been developed to fabricate uniformly dispersed octahedral Fe^sub 3^O^sub 4^ nanoparticles with tunable size. The particle size can be reduced to 20-30 nm under the effect of phosphate, meanwhile, the edetate disodium can improve the dispersivity of particles. High-resolution transmission electron microscope showed that the octahedral Fe^sub 3^O^sub 4^ nanoparticle was enclosed by eight (111) planes. Octahedral γ-Fe^sub 2^O3 nanoparticles were obtained by reoxidizing the as-synthesized Fe^sub 3^O^sub 4^ nanoparticles. The microwave absorption properties of the octahedral Fe^sub 3^O^sub 4^ and γ-Fe^sub 2^O3 nanoparticles were measured in the frequency range of 2-18 GHz. A minimum reflection loss of -28 dB was observed at 8.6 GHz for octahedral Fe^sub 3^O^sub 4^ nanoparticles.[PUBLICATION ABSTRACT]