Synthesis of nano-sized urchin-shaped LiFePO4 for lithium ion batteries

In this article, the facile synthesis of sea urchin-shaped LiFePO₄ nanoparticles by thermal decomposition of metal-surfactant complexes and application of these nanoparticles as a cathode in lithium ion secondary batteries is demonstrated. The advantages of this work are a facile method to synthesize interesting LiFePO₄ nanostructures and its synthetic mechanism. Accordingly, the morphology of LiFePO₄ particles could be regulated by the injection of oleylamine, with other surfactants and phosphoric acid. This injection step was critical to tailor the morphology of LiFePO₄ particles, converting them from nanosphere shapes to diverse types of urchin-shaped nanoparticles. Electron microscopy analysis showed that the overall dimension of the urchin-shaped LiFePO₄ particles varied from 300 nm to 2 μm. A closer observation revealed that numerous thin nanorods ranging from 5 to 20 nm in diameter were attached to the nanoparticles. The hierarchical nanostructure of these urchin-shaped LiFePO₄ particles mitigated the low tap density problem. In addition, the nanorods less than 20 nm attached to the edge of urchin-shaped nanoparticles significantly increased the pathways for electronic transport.

In this article, the facile synthesis of sea urchin-shaped LiFePO₄ nanoparticles by thermal decomposition of metal-surfactant complexes and application of these nanoparticles as a cathode in lithium ion secondary batteries is demonstrated.     

Doping strategy,properties and application of heteroatom-doped ordered mesoporous carbon

To date, tremendous achievements have been made to produce ordered mesoporous carbon (OMC) with well-designed and controllable porous structure for catalysis, energy storage and conversion. However, OMC as electrode material suffers from poor hydrophilicity and weak electrical conductivity. Numerous attempts and much research interest have been devoted to dope different heteroatoms in OMC as the structure defects to enhance its performance, such as nitrogen, phosphorus, sulphur, boron, and multi heteroatoms. Unfortunately, the “how–why–what” question for the heteroatom-doped OMC has not been summarized in any published reports. Therefore, this review focuses on the functionalization strategies of heteroatoms in OMC and the corresponding process characteristics, including in situ method, post treatment method, and chemical vapor deposition. The fundamentally influencing mechanisms of various heteroatoms in electrochemical property and porous structure are summarized in detail. Furthermore, this review provides an updated summary about the applications of different heteroatom-doped OMC in supercapacitor, electrocatalysis, and ion battery during the last decade. Finally, the future challenges and research strategies for heteroatom-doped OMC are also proposed.

To date, tremendous achievements have been made to produce ordered mesoporous carbon (OMC) with well-designed and controllable porous structure for catalysis, energy storage and conversion.     

Fabrication of high B-doped ordered mesoporous carbon with 4-hydroxyphenylborate phenolic resin for supercapacitor electrode materials

The high B-doped ordered mesoporous carbon (HPB-OMC) was prepared by using 4-hydroxyphenylboronic acid-modified phenolic resin (HPBPF) as a boron and carbon precursor via the evaporation-induced self-assembly (EISA) approach. The chemical composite, mesoporous structure, and electrochemical properties of the as-prepared HPB-OMC are investigated. The results show that both highly boron-doped and well-ordered mesoporous structure are achieved for HPB-OMCs, owing to the improvement of solubility of the resins in ethanol, and the enhancement of thermal stability of pore channels during carbonization. Moreover, the HPB-OMCs exhibit an ideal electric double-layer capacitor performance. With the increase of the B-doped content, the specific capacitance of the HPB-OMC electrode rises gradually, then drops off a little. The HPB-OMC with a high B content (3.96 wt%) shows a much high specific capacitance of 183 F g⁻¹ at a current density of 1 A g⁻¹, suggesting its promising application in the field of supercapacitors.

The HPB-OMCs, with 3.96 wt% boron-doped and well-ordered structure, show a much high specific capacitance of 183 F g⁻¹ at the current density of 1 A g⁻¹ and ideal electrochemical performances.     

Enhanced cycling performance of nanostructure LiFePO4/C composites with in situ 3D conductive networks for high power Li-ion batteries

In this work, reduced nano-sized LiFePO₄ precursor particles were fabricated via a green chemistry approach without the use of any organic solvent or surfactants by accelerating the feeding speed of ferrous sulfate. After carbon coating, a 4 nm thick high graphitic degree carbon layer was deposited uniformly on the surface of reduced nano-sized LiFePO₄ particles and constructed in situ 3D conductive networks among the adjacent LiFePO₄ particles, as a result of an elevated self-catalytic effect of the reduced nano-size LiFePO₄ particles that promoted the formation of the conductive networks. The reduced nano-size LiFePO₄/C particles with in situ 3D conductive networks were shown to have an excellent high rate discharge capacity and long cycle life, delivering a high initial reversible discharge capacity of 163 mA h g⁻¹ at 0.2C and an even high rate discharge capacity of 104 mA h g⁻¹ at 30C. Additionally, a capacity of 101.7 mA h g⁻¹ with a capacity retention of 97% remained after 850 cycles at 30C. This work suggests that the enhanced electrochemical performance of the LiFePO₄/C composite was improved via the combination of the reduced nano-sized and 3D conductive networks, facilitating the electron transfer efficiency and diffusion of lithium ions, especially over an extended cycling performance at a high rate.

Excellent cycling performance for a high rate LiFePO4/C composite with in situ 3D conductive networks.     

Preparation of sulfonated ordered mesoporous carbon catalyst and its catalytic performance for esterification of free fatty acids in waste cooking oils

Sulfonated ordered mesoporous carbon (SO₃H-OMC) solid acid catalysts from sucrose were prepared using hard-template method, and their catalytic performance as well as the deactivation mechanism for esterification of free fatty acids (FFAs) in waste cooking oils (WCOs) were evaluated. Effects of sulfonation time, sulfonation temperature and hard template structure type for the textural properties and acid properties of SO₃H-OMC were systematically investigated by N₂ adsorption–desorption, FT-IR, NH₃-TPD, TEM and strong acid density analysis. The results indicated that, SO₃H-OMC(s)-6-160 catalyst, which was prepared by using SBA-15 as hard template at sulfonation time of 6 h and sulfonation temperature of 160 °C, had well-ordered mesoporous structure and high –SO₃H groups density (2.32 mmol g⁻¹). Compared with SO₃H-APC-6-160 catalyst, cation-exchange resin D072 and SO₃H-OMC(k)-6-160 catalyst, it was found that the SO₃H-OMC(s)-6-160 catalyst exhibited highest activity (FFAs conversion was 93.8%) and good stability for the FFAs esterification, attributed to its 2D-hexagonal channels and hydrophobic surface. The –SO₃H groups being leached out of SO₃H-OMC catalysts into the liquid phase (especially methanol) would be the main reason causing catalyst deactivation.

Sulfonated ordered mesoporous carbon solid acid catalysts had excellent catalytic performance for esterification of methanol with FFAs in WCOs.     

Nitrogen-doped graphene-activated metallic nanoparticle-incorporated ordered mesoporous carbon nanocomposites for the hydrogenation of nitroarenes

Herein, nanoscale metallic nanoparticle-incorporated ordered mesoporous carbon catalysts activated by nitrogen-doped graphene (NGr) were fabricated via an efficient multi-component co-assembly of a phenolic resin, nitrate, acetylacetone, the nitrogen-containing compound 1,10-phenanthroline, and Pluronic F127, followed by carbonization. The obtained well-dispersed nitrogen-doped graphene-activated transition metal nanocatalysts possess a 2-D hexagonally arranged pore structure with a high surface area (∼500 m² g⁻¹) and uniform pore size (∼4.0 nm) and show excellent activity for the selective hydrogenation–reduction of substituted nitroarenes to anilines in an environmentally friendly aqueous solution. The high catalytic performance and durability is attributed to the synergistic effects among the components, the unique structure of the nitrogen-doped graphene layer-coated metallic nanoparticles, and electronic activation of the doped nitrogen.

The non-noble M/NGr@OMC-T catalyst exhibits excellent catalytic activity and chemoselectivity for the hydrogenation of nitroarenes to anilines in water with hydrogen.     

Hydrothermal synthesis of nitrogen-doped ordered mesoporous carbon via lysine-assisted self-assembly for efficient CO2 capture

Nitrogen-doped ordered mesoporous carbons (NOMCs) were synthesized by single-step hydrothermal self-assembly using F127 as a soft template, hexamine as a formaldehyde source, l-lysine as a polymerization catalyst, and 3-aminophenol as both carbon and nitrogen sources. The microstructure of the NOMCs was characterized by XRD, N₂ adsorption/desorption, TEM, FTIR, and XPS. The results indicated that the obtained NOMCs exhibited a large specific surface area, uniform pore size distribution and highly ordered 2-D hexagonal mesostructure (P6mm). Besides, the nitrogen was uniformly doped into the carbon framework in the form of various nitrogen species. The adsorption isotherms of CO₂ and N₂ were also determined and could be well fitted by a DSL model. The capture capacity of CO₂ was affected by both the nitrogen content and mesostructure of the adsorbents. Overall, NOMC-L-0.5 displayed excellent CO₂ capture capacity (0 °C, 3.32 mmol g⁻¹; 25 °C, 2.50 mmol g⁻¹), and still demonstrated great regenerability with only 2% loss after several CO₂ adsorption/desorption cycles. Moreover, the CO₂/N₂ selectivity calculated by IAST was as high as 43.2 at 25 °C in a typical composition of flue gas (binary mixtures with 15% CO₂). The superior adsorption performance enables NOMCs to be a promising CO₂ adsorbent in practical applications.

Synthesis process of nitrogen-doped ordered mesoporous carbon through lysine-assisted single-step hydrothermal self-assembly for CO₂ capture.     

Electrochemical and structural characterization of lithiation in spray deposited ordered mesoporous titania as an anode for Li ion batteries

Ordered mesoporous titania, prepared via low-temperature spray deposition, was examined as an anode material for lithium ion batteries. The material exhibits an exceptionally high electrochemical capacity of 680 mA h g⁻¹ during the first discharge, which rapidly decreases over the following cycles. The capacity stabilizes at around 170 mA h g⁻¹ after 50 cycles and the material delivers 83 mA h g⁻¹ at high charge/discharge rates (10C). A combination of electrochemical and structural characterization techniques were used to study the charge/discharge behavior of the material and the origin of the irreversible capacity. To determine the effect of cycling on the structure of the material, X-ray absorption spectroscopy (XAS) and energy filtered TEM were carried out on pristine and cycled samples in intercalated and deintercalated states. Titanium K-edge XAS measurements showed that intercalated lithium affects the NEXAFS region. By comparing peak intensity ratios, we propose a method to quantify the amount of lithium inserted into the titania structure and to differentiate between lithium bound in close proximity to titanium, and lithium bound further away from titanium. Additionally, we suggest that the irreversible loss in capacity is due to the formation of phases that are stable, and thereby electrochemically inactive, over the electrochemical cycling conditions applied.

A combination of electrochemical and structural characterization techniques were used to study the lithiation in spray deposited amorphous mesoporous titania.     

One-step fabrication of nanosized LiFePO4/expanded graphite composites with a particle growth inhibitor and enhanced electrochemical performance of aqueous Li-ion capacitors

It is reported that olivine-type lithium iron phosphate (LFP) for Li-ion batteries is one of the most widely utilized cathode materials, but its high-power applications are limited due to its intrinsically poor ion transfer rate and conductivity. Therefore, it is highly desired to fabricate LFP Li-ion capacitors (LICs) with high power performance and excellent cyclic reversibility, especially in safe, low cost and environmentally friendly aqueous electrolytes. Here, we fabricate LFP/expanded graphite (EG) nanocomposites by a one-step process, in which polyethylene glycol (PEG) is used as the particle growth inhibitor combined with vacuum infiltration of the LFP precursor into EG as a conductive sub-phase, and further investigate their high-power performance in aqueous LICs. Embedding spherical LFP nanoparticles with well-controlled size and agglomeration into the pores of EG and wrapping LFP nanoparticles by EG films contribute to the rapid electron and ion diffusion in LFP/EG composites, resulting in excellent cyclic reversibility and rate performance of LFP/EG composites. The aqueous LFP/EG//active carbon (AC) LICs were assembled in LiNO₃ electrolytes with LFP/EG composites and AC as the positive and negative electrodes, respectively. The optimal LIC shows a power density of 2367.9 W kg⁻¹ at an energy density of 6.5 W h kg⁻¹, dramatically favorable rate characteristics and excellent cycle life with 82.1% capacitance retention of its primary capacitance at 2 A g⁻¹ after 6000 cycles, markedly higher than those of the commercial LFP LIC. The presented aqueous LFP/EG//AC LICs with excellent electrochemical performance are expected to have broad high-power appliances that are cost-sensitive and highly secure.

It is reported that olivine-type lithium iron phosphate (LFP) for Li-ion batteries is one of the most widely utilized cathode materials, but its high-power applications are limited due to its intrinsically poor ion transfer rate and conductivity.     

Experimental and modelling studies of carbon dioxide capture onto pristine,nitrogen-doped,and activated ordered mesoporous carbons

The search for suitable materials for carbon dioxide capture and storage has attracted the attention of the scientific community in view of the increased global CO₂ levels and its after-effects. Among the different materials under research, porous carbons and their doped analogues are extensively debated for their ability to store carbon dioxide at high pressures. The present paper examined high-pressure carbon dioxide storage studies of 1-D hexagonal and 3-D cubic ordered mesoporous pristine and N-doped carbons prepared using the nano-casting method. Excess carbon dioxide sorption isotherms were obtained using the volumetric technique and were fitted using the Toth model. Various parameters that influence CO₂ storage on metal-free ordered mesoporous carbons, such as the effect of pore size, pore dimension, pyrolysis temperature, the impact of nitrogen substitution, and the effect of ammonia activation are discussed. It was observed that the carbon dioxide storage capacity has an inverse relation to the total nitrogen doped, the amount of pyridinic nitrogen functionality, and the pyrolysis temperature, whereas the pore size seems to have a linear relationship. On the other hand, the presence of oxygen has a positive effect on the sorption capacity. Among the prepared ordered mesoporous carbons, the ammonia-treated one has shown the highest adsorption capacity of 37.8 mmol g⁻¹ at 34 bar and 0 °C.

The present paper discusses the shaping factors of metal-free ordered mesoporous carbon synthesis for carbon dioxide sorption at high pressures. These results can be used as future guidelines in preparing carbon for gas adsorption studies.     

Multiwalled carbon nanotube network connected Mg0.5Ti2(PO4)3 composites to improve sodium storage performance

The research on sodium-ion batteries (SIDs) has aroused intensive attention. In this work, the Mg_0.5Ti₂(PO₄)₃ (MTP) composite material with NASICON structure has been studied as an anode material in SIDs. The sol–gel method is used to synthesize the Mg_0.5Ti₂(PO₄)₃ with a conductive network that can be constructed by using carbon nanotubes (CNTs) and phenolic resin as the amorphous source of carbon coating. The CNT network is used not only to improve the outcome of electrolyte penetration and reduce the internal resistance to diffusion but also to create a fast path for electron transport, thereby elevating the level of electronic conductivity. The phenolic resin is generated on the surface of MTP which extends its cycle life. The carbon-coated Mg_0.5Ti₂(PO₄)₃ with 0.10 g CNTs (MTP–CNT10) displays optimal performance as an anode material in SIDs, and shows a discharge capacity of 298.8 mA h g⁻¹, 258.3 mA h g⁻¹ and 254.8 mA h g⁻¹ at 0.1C, 0.5C and 1C, respectively. Besides, the capacity retention rate reaches 92% after 300 cycles at 10C. This study contributes an effective solution to improving the electrochemical performance of electrode materials through the introduction of carbon coating and highly conductive materials.

Carbon coated Mg_0.5Ti₂(PO₄)₃ embedded in the CNTs network.     

Three-dimensionally ordered macro–mesoporous CoMo bulk catalysts with superior performance in hydrodesulfurization of thiophene

The introduction of surfactants during the fabrication of hydrodesulfurization catalysts could not only tune the microstructure but also promote the dispersion of active components. In this work, CoMo bulk catalysts with the hierarchical structure of three-dimensionally ordered macro–mesopores were successfully fabricated by using a colloidal crystal template with the addition of PEG 400 and/or F127 surfactants. The obtained samples were characterized by various techniques, and the possible mechanism of the structure formation was also discussed. The characterization and evaluation results reveal that the addition of surfactants can promote the formation of the mesopores (3–4 nm) inside the macroporous walls of these bulk catalysts, which is essential for the increase of catalyst surface area, and the active sites for reaction. The CoMo–PF-1 catalyst displayed superior catalytic performance for thiophene hydrodesulfurization with the thiophene conversion of 99.4% under 1 MPa at 360 °C, which is much higher than that (77.8%) at 0.1 MPa. This result is even comparable to our previous report with the thiophene conversion of 99.2% over the 3DOM CoMo catalyst under 3 MPa.

The addition of surfactants can promote the formation of mesopores and improve the dispersion of MoS₂ slabs.     

Facile synthesis of mesoporous carbon microspheres/graphene composites in situ for application in supercapacitors

Mesoporous carbon/graphene composites (MCG) have exhibited good electrochemical performances; however, the fixed mesoporous carbon, the low specific surface area, and porosity are the main obstacles in their application in supercapacitors. In this paper, mesoporous carbon microspheres/graphene composites (MCMG) were synthesized in situ via a soft template method and subsequent thermal reduction by using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent, and aqueous mesophase pitch (AMP) and graphene oxide (GO) as the carbon sources. The strong electrostatic interaction between GO/CTAB and AMP promoted the self-assembly of CTAB and AMP to form the MCMG precursor. The results showed that the CTAB concentration and aging temperature have an important effect on the morphology and pore structure of the synthesized MCMG. The high aging temperature promoted the formation of mesoporous carbon spheres and its diameter increased with the increase in the concentration of CTAB. The as-prepared MCMG at the aging temperature of 140 °C had obvious spherical and layered carbon materials after carbonization at 900 °C. When the concentration of CTAB was 10.6 g L⁻¹, the formed mesoporous carbon spheres with the diameter of 30–40 nm were uniformly dispersed among the layered graphenes in MCMG-140-0.2 (the aging temperature of 140 °C and the CTAB content of 0.2 g). In addition, its specific surface area was 1150.5 m² g⁻¹ and the mesopore size was centered at 4.3 nm, 7.9 nm, and 17.1 nm. Compared with the MCMG precursor, the ordered degree of the mesopores for MCMG was reduced due to the high temperature carbonization. Importantly, the specific capacitance of MCMG-140-0.2 at the current density of 0.1 A g⁻¹ was as high as 356.3 F g⁻¹. Moreover, the specific capacitance of MCMG-140-0.2 at 1 A g⁻¹ remained at 278.5 F g⁻¹, the capacitance retention was 92.1% after 6000 cycles, and the coulombic efficiency was over 98% at a high current density of 2 A g⁻¹. Therefore, the as-prepared MCMG can be an excellent candidate for electrode materials in supercapacitors.

MCMG were in situ synthesized via a soft template method and subsequent thermal reduction by using CTAB as structure-directing agent, AMP and GO as carbon sources. As-prepared MCMG samples exhibited excellent electrochemical performances.     

Simultaneous determination of 114 pesticides in complex Chinese herbal medicine Fritillaria using ordered mesoporous carbon CMK-3 as a reversed-dispersive solid phase extraction sorbent

Fritillaria, a traditional Chinese herbal medicine, is classified into many medicinal species and contains numerous complex components. It is thus difficult to simultaneously detect multiple pesticide residues in different Fritillaria species. An easy, reliable, and widely applicable analytical method based on a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method coupled with LC-MS/MS was developed to solve these problems encountered during pesticide residue analysis in complex Fritillaria matrices. Ordered mesoporous carbon CMK-3 and a primary secondary amine (PSA) were used as efficient purification sorbents by optimization of the QuEChERS process. Systematic method validation was performed for four species of Fritillaria. The matrix effect of pesticides varied among different Fritillaria species, and matrix-matched standard solutions were thus employed for quantitative analysis. The mean recoveries of all pesticides ranged from 88.6% to 95.5%, with mean relative standard deviations (RSD) lower than 6% at spiked concentrations of 30, 120, and 240 μg kg⁻¹. The limits of quantification (LOQ) for the developed method were in the range of 30–120 μg kg⁻¹. This method was further used to analyze 47 Fritillaria samples from Zhejiang province, China, and seven pesticides were detected in 22 Fritillaria samples. These results demonstrate that the developed method is suitable for an accurate analysis of multiple pesticide residues in various Fritillaria.

Fritillaria, a traditional Chinese herbal medicine, is classified into many medicinal species and contains numerous complex components.     

Excellent supercapacitance performance of 3-D mesoporous carbon with large pores from FDU-12 prepared using a microwave method

Highly ordered and three-dimensional (3-D) mesoporous carbon materials were prepared through a nano-hard templating approach using FDU-12 silica with tunable pore sizes as a template, which was synthesized via a microwave-assisted method. Powder XRD and microscopic techniques such as HR-TEM, HR-SEM, and N₂ adsorption–desorption techniques were employed to characterize the structure and textural properties of the prepared mesoporous carbon samples. The characterization results reveal that all the mesoporous carbon samples show a 3-D porous mesostructure with tunable pore diameters (5.7 to 9.4 nm) and a large specific surface area in the range from 451 to 1251 m² g⁻¹. The supercapacitive behavior of the cubic structured mesoporous carbons was determined using cyclic voltammetry, electrochemical impedance and charge–discharge measurements. The cubic mesoporous carbon materials exhibit a superior capacitive performance with a high specific capacitance value of 315.3 F g⁻¹ at the current density of 1 A g⁻¹, which is much higher than that of hexagonally-ordered mesoporous carbon with large pore diameters, activated carbon, and carbon nanotubes. The materials also show excellent cyclic stability and extremely low resistance. The superior specific capacitance of these materials is attributed to the combination of excellent surface properties such as large specific surface area, large pore volume and uniform pore diameter, spherical morphology, and a 3-D porous system with cage-type pores.

Highly ordered and three-dimensional (3-D) mesoporous carbon materials were prepared through a nano-hard templating approach using FDU-12 silica with tunable pore sizes as a template, which was synthesized via a microwave-assisted method.     

Biomass porous carbon as the active site to enhance photodegradation of oxytetracycline on mesoporous g-C3N4

Graphitic carbon nitride (g-C₃N₄) is widely used in photocatalytic adsorption and degradation of pollutants, but there are still some problems such as low adsorption performance and high electron–hole recombination efficiency. Herein, we propose a new molten salt assisted thermal polycondensation strategy to synthesize biomass porous carbon (BPC) loaded on g-C₃N₄ composites (designated as BPC/g-C₃N₄) with a hollow tubular structure, which had a high surface area and low electron–hole recombination rate. The study shows that the morphology of g-C₃N₄ changes dramatically from massive to hollow tubular by molten salt assisted thermal polycondensation, which provides a base for the loading of BPC, to construct a highly effective composite photocatalyst. BPC loaded on g-C₃N₄ could be used as the active site to enhance Oxytetracycline (OTC) removal efficiency by adsorption and with higher electron–hole separation efficiency. As a result, the BPC(5%)/g-C₃N₄ sample presented the highest photocatalytic degradation efficiency (84%) for OTC degradation under visible light irradiation. The adsorption capacity and photocatalytic reaction rate were 3.67 and 5.63 times higher than that of the g-C₃N₄, respectively. This work provided a new insight for the design of novel composite photocatalysts with high adsorption and photocatalytic performance for the removal of antibiotic pollutants from wastewater.

A novel mesoporous g-C₃N₄ loaded with biomass porous carbon was synthesized by molten salt assisted thermal polycondensation, and the formation of hollow tubular structure increased the specific surface area.     

Synthesis of Ag nanoparticles/ordered mesoporous carbon as a highly efficient catalyst for the electroreduction of benzyl bromide

To develop efficient catalysts for the electroreduction of organic halides, a facile one-pot synthesis of Ag nanoparticles/ordered mesoporous carbon electrode materials via the self-assembly of CH₃COOAg and resol in the presence of triblock copolymer is proposed. The resultant electrode materials possess uniform mesopore sizes (3.3 nm) and pore volumes (∼0.28 cm³ g⁻¹), high specific surface areas (∼500 m² g⁻¹), and uniformly dispersed Ag nanoparticles (12–36 nm) loaded within the carbon matrix. Cyclic voltammetry, measurements of electrochemically active surface area, and electrolysis experiments were conducted to understand the correlations between the catalytic ability and the structural and textural features of the catalysts. Excellent bibenzyl yield (98%) and remarkable reusability were obtained under mild conditions. The results confirm that the prepared nanocomposites show outstanding performance in the electroreduction degradation of PhCH₂Br to bibenzyl.

To develop efficient catalysts for the electroreduction of organic halides, a facile one-pot synthesis of Ag nanoparticles/ordered mesoporous carbon electrode materials via the self-assembly is proposed.     

Catalytic wet peroxide degradation of acrylonitrile wastewater by ordered mesoporous Ag/CeO2: synthesis,performance and kinetics

Ordered mesoporous Ag/CeO₂ catalysts have been successfully synthesized by a microwave assisted soft template method. The morphology, structure and chemical composition of the catalyst were characterized by XRD, N₂ adsorption–desorption, SEM, EDS, TEM and XPS. The study of catalytic performance and reaction kinetics of organic matter degradation in acrylonitrile wastewater was performed in a catalytic wet peroxide (CWPO) system. The degradation pathways of organic matter in acrylonitrile wastewater were elucidated by temporal evolution of intermediates and final products detected by GC/MS analysis along with a continuous flow experiment study. The results show that the Ag/CeO₂ has an ordered mesoporous structure, the specific surface area is 91.4–118.2 m² g⁻¹ and the average pore size is 12.63–16.86 nm. 0.4-Ag/CeO₂ showed the best catalytic performance, the COD removal rate reached 94.6%, which was 30% higher than that of CeO₂. The degradation is in accordance with the second-order reaction kinetics of the Arrhenius empirical model and Langmuir–Hinshelwood kinetic model. However the latter fits better, and the linear correlation coefficient R² is more than 0.98, which describes the adsorption catalytic mechanism of Ag/CeO₂. According to the analysis by GC/MS, the organic compounds in acrylonitrile wastewater oxidized into intermediate compounds and other small compounds, then are further oxidized into carbon dioxide and water. The catalytic activity of Ag/CeO₂ was the result of the combination of Lewis acid–base position of CeO₂ and redox cycle of Ce³⁺/Ce⁴⁺.

Ordered mesoporous Ag/CeO₂ catalysts have been successfully synthesized by a microwave assisted soft template method.     

Rationally designed structure of mesoporous carbon hollow microspheres to acquire excellent microwave absorption performance

In this study, we used a novel and facile hard-template etching method to manufacture mesoporous carbon hollow microspheres (MCHMs). We prove that the dielectric ability and microwave absorption of MCHMs can be adjusted by structural characteristics. When the average particle size of MCHMs is 452 nm, the paraffin composite material mixed with 10 wt% MCHMs can achieve a maximum reflection loss value of −51 dB with a thickness of 4.0 mm at 7.59 GHz. When the average particle size of MCHMs is 425 nm, the effective absorption bandwidth of the paraffin composite material mixed with 10 wt% MCHMs can achieve a broad bandwidth of 7.14 GHz with a thickness of 2.5 mm. Compared with other microwave absorbers, MCHMs possess high microwave absorption capacity and broad microwave absorption bandwidth with as low as a 10 wt% filler ratio. This excellent microwave absorption performance is due to the internal cavity and the mesoporous shell of MCHMs. By rationally designing the structure of MCHMs, excellent microwave absorption performance can be acquired. Meanwhile, this design concept based on a rational design of spherical structure can be extended to other spherical absorbers.

In this study, we used a novel and facile hard-template etching method to manufacture mesoporous carbon hollow microspheres (MCHMs).     

Facile synthesis of ordered mesoporous zinc alumina catalysts and their dehydrogenation behavior

Ordered mesoporous Zn/Al₂O₃ materials with varying Zn content were simply prepared via an evaporation-induced self-assembly (EISA) method. Dehydrogenation of isobutane to isobutene was carried out on these materials; an isobutane conversion of 45.0% and isobutene yield of 39.0% were obtained over the 10%Zn/Al₂O₃ catalyst at 580 °C with 300 h⁻¹ GHSV. The obtained materials with Zn content up to 10% possess large specific surface area and big pore volume and zinc species can be highly dispersed on the surface or incorporated into the framework. The acidity of these catalysts was changed by the introduction of Zn, the decrease of strong acid sites is conducive to the promotion of isobutene selectivity and the weak and medium acidic sites played an important role in isobutane conversion. In addition, these catalysts exhibited good catalytic stability, due to the effective inhibition of coke formation by the ordered mesoporous structure.

Facile synthesis of ordered mesoporous zinc alumina catalysts that exhibited great catalytic activity (45.0% isobutane conversion, 86.7% isobutene selectivity) and stability.