Search

Abstract: By using simple mixed solvents, the morphologies of hematite (α-Fe2O3) particles could be manipulated, and the spherical, mulberry-like, nanospherical and top-like products could be controllably obtained. The as-obtained products were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometer. The results indicated that the morphology manipulation could be achieved by systematically adjusting the polarity of the mixed solvent via the ratio control. And the magnetic properties of the products were critically affected by their grain size and assembly morphologies. [Copyright &y& Elsevier]

[Display omitted] • MoN@CMK-5 with a bimodal pore was employed as polar host for sulfur cathode. • MoN@CMK-5/S shows an excellent inhibition effect for LiPSs. • The electrochemical reaction kinetics is effectively enhanced. • MoN@CMK-5/S delivers superior durability and a high charge capacity. Lithium-sulfur batteries (LSBs) have attracted considerable research attention because of their high theoretical capacity and energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides hinders the commercialization of LSBs. Effectively improving the electrochemical reaction kinetics of the sulfur cathode still represents a significant challenge. Here, a MoN@CMK-5 composite with a bimodal pore system was designed to electrocatalytically mediate Li/S conversion chemistry. MoN@CMK-5 presents a large specific surface area (1012 m2 g−1) and two sets of tunnels with pore sizes of 3.63 and 3.47 nm, which efficiently adsorb polysulfides and accelerate the mass transfer of electrolytes. Furthermore, MoN has high intrinsic catalytic activity and enables the rapid conversion of polysulfides. Owing to the synergistic "adsorption-conversion-mass transfer" effect, the electrochemical reaction kinetics are effectively enhanced. Consequently, the MoN@CMK-5/S electrode achieves excellent performance with an initial capacity of 1582 mAh g−1 at 0.1C and retains a reversible capacity of 658.4 mAh g−1 after 200 cycles at 1C. The cathode delivers a specific capacity of 475.8 mAh g−1 at a high current density of 5C, with a capacity decay as low as 0.027% per cycle during 1000 cycles. In addition, theoretical calculations reveal that MoN@CMK-5/S exhibits low activation energy for Li 2 S decomposition and effectively inhibits the shuttling of polysulfides. This work provides a new avenue for the development of high-performance LSBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pressurized pyrolysis/co-pyrolysis of OS and SWR was investigated. • SWR/OS pressurized co-pyrolysis with BA aided in the formation H 2 and CH 4. • The OS chars obtained under high-pressure has serious melting phenomenon. • The LHV of syngas increased about 8.5 times after the catalytic process. Oil sludge (OS) and waste tires were studied widely with pyrolysis technology. However, the influence and characteristics of OS and waste tires were not studied with the pressurized co-pyrolysis technology. The pressurized pyrolysis of OS, combined with pressurized co-pyrolysis of side wall rubber (SWR), and catalytic cracking over bottom ash (BA) and SWR char (SWRC), were studied. First, the influence of pressure and temperature on the product distribution of OS pyrolysis was investigated. Then, the effect of the SWR/OS ratio on the pressurized co-pyrolysis product distribution was tested. Finally, the influence of BA on the product distribution of SWR/OS co-pyrolysis under high pressure was evaluated. The OS char obtained under high pressure exhibited serious melting phenomena, whose catalytic effect on the SWR pyrolysis in the pressurized co-pyrolysis process was investigated with TG-FTIR and SEM. The high activity and CO 2 adsorption effect of bottom ash were confirmed. The CH 4 content in the SWR/OS 5/5 gas reached 45.55 vol%. The single ring aromatics concentration reached 57.11% in the SWR/OS 6/4 oil. The naphthalene concentration reached 39.31% with the SWRC catalyst. [ABSTRACT FROM AUTHOR]

• Pre-oxidation strategy is proposed to regulate bituminous coal based hard carbon. • The introduced oxygen functional group is demonstrated to block the graphitization. • Na+ plateau capacity of obtained hard carbon is improved by the enlarged d-spacing. • Kinetics analysis demonstrates the enhanced Na+ diffusion in the hard carbon anode. Middle metamorphic coal has the advantages of high earth abundance and easily-adjusted aromatic units and thus is a feasible raw material for the development of functional carbon materials. For the preparation of high-performance Na+ storage hard carbon, the key is to inhibit the long-range graphitization of internal microcrystalline in coal structure during thermal conversion process. Herein, we introduce a simple gas/liquid-phase pre-oxidation procedure to graft oxygen-containing cross bonds into bituminous coal, by which the growth of long-range graphitization process during high-temperature carbonization can be suppressed and thereby enable the preparation of hard carbon with short-range microcrystalline distribution and enlarged interlayer distance of 0.38 ∼ 0.385 nm. Benefiting the regulated microcrystalline environment, the fabricated hard carbon anode delivers a high reversible capacity of 274.2 mAh g−1, which is 24 % higher than the carbon anode prepared without pre-oxidation treatment. Electrochemical kinetics analyses further reveal that the improved Na+ storage capacity mainly stems from the enhanced Na+ diffusion and intercalation into microcrystalline interlayers at the low voltage region, which is of significance for the construction of high energy–density full cell for practical applications. [ABSTRACT FROM AUTHOR]

Abstract: (MgO) x (ZnO)1−x materials have been synthesized using mesoporous carbon as template. By increasing the MgO content in the materials greater than 25%, the (MgO) x (ZnO)1−x materials began to form the mesoporous structure. Pore size distribution curves indicated that the BJH pore diameter decreased with increasing MgO content. In photoluminescence spectra, all the samples except pure ZnO showed both the band-edge emission and the deep-level emission (green band). It was interesting to note that the UV emission peak energy (E UV) had a red-shift of about 48meV at the low MgO content range of 0–25%, while when the MgO content varied from 25 to 75%, the E UV displayed a blue-shift of about 36meV to the higher energy direction. The optical band gap (E g) of the (MgO) x (ZnO)1−x calculated from the absorption spectra was far smaller than that in literature, and this may be related to the formation of mesoporous structure. [Copyright &y& Elsevier]

[Display omitted] • Fern-like mesoporous In 2 O 3 /ZnO nanocomposite was prepared by template method using MOFs as template. • In 2 O 3 /ZnO nanocomposite exhibited excellent gas sensing performance to triethylamine at only 100 °C. • Its enhanced gas-sensing properties was due to fern-like mesoporous heterojunction with nanowires. Fern-like In 2 O 3 /ZnO nanocomposite with mesoporous structure was derived from MIL-68/ZIF-8 via a simple template method. Abundant nanowires grew on the surface of microrods to form novel fern-like structure. The effect of MIL-68 concentration on component, structure, morphology and gas-sensing properties of In 2 O 3 /ZnO nanocomposite were studied. The results of gas tests exhibited that the sensor based on In 2 O 3 /ZnO (the mass of MIL-68 is 0.3 g) showed excellent sensing properties to TEA, which included superior response (44.6), ultralow work temperature (100 °C) and fast response-recovery time. The enhanced gas sensing properties of fern-like In 2 O 3 /ZnO nanocomposites were due to mesoporous structure, a large specific surface area, the specific structure of abundant nanowires growing on microrods and the n-n heterojunction formed at the interface of In 2 O 3 and ZnO, which all accelerated the gas sensing reaction between TEA molecules and adsorbed oxygen on the surface of materials. The fern-like In 2 O 3 /ZnO composite with mesoporous structure was an ideal gas sensing material for the detection of TEA. [ABSTRACT FROM AUTHOR]

The Au/ZnSe/ZnO heterojunction material with less transition zone on the two-phase interface was successfully prepared by the in-situ replacement of zinc oxide by Se2-. Moreover, the heterojunction formed by in-situ substitution can effectively reduce the interface transfer resistance and increase the life of carriers. The photocurrent of Au/ZnSe/ZnO is almost twice that of Au/ZnO, due to the formation of heterojunction ZnSe interface. As a result, the carrier lifetime of the material is increased by nearly 2.7 times (126.26 s/46.83 s) compared to Au/ZnO. Ascorbic acid is a very important compound for human metabolism, but there is no simple and rapid method to detect ascorbic acid. Au/ZnSe/ZnO is used as the photoanode of the photoelectric non-enzymatic sensor system for AA detection. The sensitivity of Au/ZnSe/ZnO/FTO-based PEC AA sensor is 113.75 μA mM−1 cm−2, exhibiting its advantages of fast, sensitive and high response. • Au/ZnSe/ZnO multi-element composite material changes the electron transport path and improves the carrier transfer. • 2. ZnSe resistance to interface recombination effectively hindered the recombination of carriers. • Enhancing the absorption of visible light, improving the carrier lifetime and forming the two-phase low interface transition zone all enhance the photoelectrochemical performance. [ABSTRACT FROM AUTHOR]

• At the initial feeding (0–20 min), self-gasification leads to biochar weight loss. • The size of coke particles is mainly in the range of 2–5 nm in mesopores. • The in-situ conversion routes of main tar compounds over biochar were analyzed. • Char surface promotes WGSR and CH 4 -H 2 O reaction to change syngas component. The two-stage fluidized bed/fixed bed reaction system was used to study the evolution characteristics of catalytic tar reforming process over biochar. The effect of different interaction time (feeding time varies within 10–50 min) between volatiles and char on the characteristics of char/tar is considered. InVia-Reflex Raman spectrometer (Raman), Fourier transform infrared spectrometer (FTIR), automatic specific surface and porosity analyzer, X-ray photoelectron spectrometer (XPS), inductively coupled plasma optical emission spectrometer (ICP-OES) were used to characterize the structural characteristics and alkali metal and alkaline earth metal species (AAEMs) content of biochar. The tar components were analyzed by gas chromatography-mass spectrometry (GC–MS) and the gas components were monitored by MCA 100 SYN synthetic gas analyzer. The results indicate that the tar removal efficiency of gasification char is over 70% when the interaction time is within 30 min. When corn straw is fed for 40 min, the carbon deposition on the surface of biochar reaches saturation. The size of coke particles is mainly in the range of 2–5 nm, and the structure is mainly small aromatic ring within five rings. During catalytic tar reforming over biochar, the content number of O-containing functional groups and surface K element decrease rapidly. The main removal path of toluene, styrene, phenol and indene in tar is heterogeneous reforming on biochar surface. Carbon deposition results in the increase of biochar external surface area (73.8 m2/g to 158.1 m2/g). The homogeneous reforming of styrene and toluene on biochar surface is enhanced. Under the catalysis of biochar surface, the self-gasification of biochar, water–gas shift reaction and methane steam reforming reaction are all promoted. This results in the increase of CO, CO 2 and H 2 yield (9.68%, 52.38% and 69.63%), as well as the decrease of CH 4 yield (25.23%) in the syngas of corn straw gasification. [ABSTRACT FROM AUTHOR]

Single atom metal-nitrogen-carbon materials have emerged as remarkably potent catalysts, demonstrating unprecedented potential for the photo-driven reduction of CO 2 . Herein, a unique Cu@g-C 3 N 5 catalyst obtained by cooperation of single atom Cu and nitrogen-rich g-C 3 N 5 is proposed. The particular CuN diatomic active sites (DAS) in Cu@g-C 3 N 5 contribute to the formation of highly stable CuOCN adsorption, a key configuration for CO 2 activation and CC coupling. The synergistic diatomic active sites interaction is found responsible for the efficient photoreduction of CO 2 to C 2 H 4 which has been demonstrated in our Gibbs free energy calculation and COHP analysis. The CO 2 activation mechanism was studied, the charge density difference and DOS analysis show that the low oxidation state Cu atom significantly affects the electronic structure of g-C 3 N 5 and then enhance the catalytic activity of CO 2 hydrogenation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The rational construction of photocatalysts possesses tremendous potential to solve the energy crisis and environmental pollution; however, designing a catalyst for solar-driven overall water-splitting remains a great challenge. Herein, we propose a new MoS 2 -based photocatalyst (Co-P@MoS 2 ), which skillfully uses the cobalt (Co) atom to stimulate in-plane S atoms and employs the phosphorus (P) atom to stabilize the basal plane by forming the Co-P bands. Using density functional theory (DFT), it was found that oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) can occur at the P site and S2 site of the Co-P@MoS 2 , respectively, and the dual-active sites successfully makes a delicate balance between the adsorption and dissociation of hydrogen. Furthermore, the improved overall water-splitting performance of Co-P@MoS 2 was verified by analyzing the results of the electron structure and the dynamics of photogenerated carries. It was found that the imbalance of electron transfer caused by the introduction of the Co atom was the main contributor to the catalytic activity of Co-P@MoS 2 . Our study broadens the idea of developing photocatalysts for the overall water-splitting.

The energy and environmental crises have forced us to search for a new green energy source and develop energy storage and environmental restoration technologies. Fabrication of carbon functional materials derived from coal has attracted increasing attention in the energy storage and gas adsorption fields. In this study, an N, O-co-doped porous carbon/carbon nanotube composite was prepared by functionalizing coal-based porous carbon with carbon nanotubes (CNTs) and ionic liquid via annealing. The resulting material not only inherited the morphology of CNTs and porous carbon, but also developed a three dimensional (3D) hierarchical porous structure with numerous heteroatom groups. The N, O co-doped porous carbon/CNT composite (N, O-PC-CNTs) showed a surface area of 2164 m 2 g -1 , and a high level of N/O dopants (8.0 and 3.0 at%, respectively). Benefiting from such merits, N, O-PC-CNTs exhibited a rather high specific capacitance of 287 F g -1 at a current density of 0.2 A g -1 and a high rate capability (70% and 64% capacitance retention at 10 and 50 A g -1 , respectively) in a three electrode system. Furthermore, an N, O-PC-CNT symmetrical supercapacitor showed a high cycling stability with 95% capacitance retention after 20 000 cycles at 20 A g -1 and an energy density of 4.5 W h kg -1 at a power density of 12.5 kW kg -1 in 6 mol L -1 KOH electrolyte. As a CO 2 adsorbent, N, O-PC-CNTs exhibited a high CO 2 uptake of 5.7 and 3.7 mmol g -1 at 1 bar at 273 and 298 K, respectively. Moreover, N, O-PC-CNTs showed cycling stability with 94% retention of the initial CO 2 adsorption capacity at 298 K over 10 cycles. This report introduces a strategy to design a coal based porous carbon composite for use in efficient supercapacitor electrodes and CO 2 adsorbents., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Porous solid with multimodal pore size distribution provides plenty of advantages including large specific surface area and superior mass transportation to achieve high gas-sensing performances. In this study, α-Fe 2 O 3 nanoparticles with bimodal porous structures were prepared successfully through a nanocasting pathway, adopting the bicontinuous 3D cubic symmetry mesoporous silica KIT-6 as the hard template. Its structure and morphology were characterized by X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, and so on. Furthermore, the gas sensor fabricated from this material exhibited excellent gas-sensing performance to several volatile organic compounds (acetone, ethyl acetate, isopropyl alcohol, n-butanol, ethanol, and methanol), such as ultrahigh sensitivity, rapid response speed (less than 10 s) and recovery time, good reproducibility, as well as stability. These would be associated with the desirable pore structure of the material, facilitating the molecules diffusion toward the entire sensing surface, and providing more active sensing sites for analytical gas.

Highly sensitive and selective detection against specific target gases, especially at low-ppb (part per billion) level, remain a great number of challenges in gas sensor applications. In this paper, we first present an ordered mesoporous NiFe 2 O 4 for highly sensitive and selective detection against low-ppb toluene. A series of mesoporous NiFe 2 O 4 materials were synthesized by templating from mesoporous silica KIT-6 and its framework thickness was reduced from 8.5 to 5 nm by varying the pore size of KIT-6 from 9.4 to 5.6 nm, accompanied with the increase of the specific surface area from 134 to 216 m 2  g -1 . The ordered mesoporous NiFe 2 O 4 with both ultrathin framework of 5 nm and large specific surface area of up to 216 m 2  g -1 exhibits a highest response (R gas /R air  - 1 = 77.3) toward 1,000 ppb toluene at 230 °C and is nearly 7.3 and 76.7 times higher than those for the NiFe 2 O 4 replica with thick framework and its bulk counterpart respectively, which also possesses a quite low limit of detection (<2 ppb), and good selectivity., (Copyright © 2018 Science China Press. Published by Elsevier B.V. All rights reserved.)

A series of ordered mesoporous chromium oxides (Cr 2 O 3 ) were synthesized by first replicating bicontinuous cubic Ia3d mesoporous silica (KIT-6), then a controlled mesostructural transformation from Ia3d to I4 1 32 symmetry during the replication from KIT-6 to Cr 2 O 3 was achieved by reducing the pore size and interconnectivities of KIT-6, accompanied with an increase in pore size from 3 to 12 nm and a decrease in framework thickness from 8.6 to 5 nm of the resultant Cr 2 O 3 replicas. The gas-sensing behavior of the Cr 2 O 3 replicas toward formaldehyde (HCHO) was systematically investigated. Ordered mesoporous Cr 2 O 3 with both large accessible pores (12 nm) and an ultrathin framework (5 nm) exhibits the best sensing performance, with a response (R gas /R air = 119) toward 9 ppm of HCHO 4.4 times higher than that (R gas /R air = 27) of its counterpart with small pores and a thick framework. Moreover, it possesses excellent selectivity for detecting HCHO over other interference gases such as CO, benzene, toluene, p-xylene, NH 3 , H 2 S, and moisture. The significantly enhanced sensing performance of ordered large-pore mesoporous Cr 2 O 3 with ultrathin framework suggests its great potential for the selective detection of HCHO.

NiCo 2 O 4 nanospheres, a type of conjugated reduced graphene oxide (rGO), are compounded by a simple and easy synthesis of Cu 2 O/GO and fabricated NiCo 2 O 4 /rGO nanocomposites based on a Cu 2 O/GO template. The structure and morphology of the hierarchical NiCo 2 O 4 /rGO are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemistry properties of NiCo 2 O 4 /rGO composites toward glucose are determined based on a glassy carbon electrode, and the results indicate that the hollow nanospheres of NiCo 2 O 4 /rGO could achieve high-sensitivity detections of glucose. The NiCo 2 O 4 /rGO composite has a detection range of 0.04 mM to 1.28 mM, a sensitivity of 2082.57 μA mM -1 cm -2 , and a detection limit of 0.7 μM. The composite further exhibits obvious stability, superior reproducibility, and excellent selectivity. This study demonstrates that NiCo 2 O 4 /rGO is a unique and material with high potential in glucose sensing.

We report a facile hydrothermal synthetic route to prepare a class of monodispersed lanthanide-based compound submicrospheres with controllable size, which employs raw lanthanide oxides as starting material, urea as precipitator and poly(N-vinyl-2-pyrrolidone) (PVP) as surfactant. Dependent on the intrinsic properties of respective lanthanide, the resulting products could be in the form of oxide, hydroxide or basic carbonate. These lanthanide hydroxides or basic carbonates can be easily transformed into their corresponding oxides by calcination, retaining the same morphology and size dispersion. The formation mechanism of these lanthanide-based compound submicrospheres is investigated and PVP plays a critical role in forming uniform and well-dispersed products. Furthermore, this method could be extended to a binary system by using two kinds of lanthanide oxides as starting material, resulting in doped-type lanthanide oxide submicrospheres (such as Y(2)O(3):Eu(3+)). The Y(2)O(3):Eu(3+) submicrospheres exhibit nearly uniform spherical morphology and narrow size distribution as well as good water solubility and sharp spectral emission at 610 nm (corresponding to the 5D(0)-7F(2) transition of Eu(3+)). This makes them attractive materials for applications in fields such as fluorescent lamps, field emission displays (FEDs) or LCDs, or as biomedical labels and molecular probes., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hierarchically ordered macro-mesoporous titania films have been produced through a confinement self-assembly method within the regular voids of a colloidal crystal with three-dimensional periodicity. Furthermore, graphene as an excellent electron-accepting and electron-transporting material has been incorporated into the hierarchically ordered macro-mesoporous titania frameworks by in situ reduction of graphene oxide added in the self-assembly system. Incorporation of interconnected macropores in mesoporous films improves the mass transport through the film, reduces the length of the mesopore channel, and increases the accessible surface area of the thin film, whereas the introduction of graphene effectively suppresses the charge recombination. Therefore, the significant enhancement of photocatalytic activity for degrading the methyl blue has been achieved. The apparent rate constants for macro-mesoporous titania films without and with graphene are up to 0.045 and 0.071 min(-1), respectively, almost 11 and 17 times higher than that for pure mesoporous titania films (0.0041 min(-1)).