Large Mesoporous Carbon Research Articles

Nanosized CeO2C2 with rich oxygen vacancies embedded in hollow mesoporous carbon as a multifunctional sulfur-loaded matrix for lithium-sulfur batteries

The innovative structural and compositional design of sulfur-loaded matrices is an effective strategy to improve the performance of lithium-sulfur batteries (LSBs). Herein, nanosized CeO2C2 with rich oxygen vacancies embedded in hollow mesoporous carbon composites (HMC/CeO2C2) were synthesized by hydrothermal and annealing reduction processes. This structure has several advantages: the large specific surface area and mesoporous carbon walls facilitate sulfur penetration and electron/ion transport; the abundant mesopores and hollow inner cavities provide the structural basis for sulfur storage and buffer its volume expansion; the oxygen vacancy-rich CeO2C2 nanoparticles grown in situ in HMC and in close contact with carbon form an electrically favorable CeO2C2/C heterointerface as an efficient catalyst, which is conducive to catalyzing the redox reaction of sulfur. Consequently, the retention capacity of the HMC/CeO2C2/S electrode is 728 mAh g−1 after 500 cycles at 0.5 C with a decay rate of 0.056 % per cycle, and it maintains a high reversible area capacity of 3.18 mAh cm−2 and excellent cycling performance even under a high sulfur loading of 4.7 mg cm−2. It provides an idea for the development of multifunctional sulfur-loaded materials with high sulfur loading, high conductivity, and high catalytic activity.

Boosting the potassium storage property of spongia-like copper phosphide anode via nano-in-micro construction

Metal phosphides (MPs) show great promise as anode material in potassium-ion batteries (PIBs) owing to their cost-effectiveness and high theoretical capacity. Despite that, MPs anode usually manifests inferior poor cyclability as a result of dramatic volume fluctuation during discharge–charge cycling. Herein, a scalable salt template-assisted spray-drying method is developed to fabricate the porous carbon microspheres wrapped CuP2 nanoparticles (p-CuP2/C) with a nano-in-micro structure. The combination of the CuP2 nanoparticles, large meso-porous carbon microspheres can simultaneously offer plenty of reactive sites, promote electrolyte penetration, and maintain structural integrity. Additionally, the proposed synthesis strategy is suit for the industrial manufacture. As an anode for PIBs, the p-CuP2/C anode presents a high reversible capacity (494 mAh/g at 0.05 A/g), excellent cycling stability (a capacity degradation rate of 0.04 % per cycle during 2000 cycles at 2 A/g), and superior rate capability (244 mAh/g at 2 A/g). More impressively, pairing with a potassium Prussian blue cathode, the potassium-ion coin cell shows an excellent cycling lifespan with 87.1 % capacity retention after 200 cycles at a current density of 0.1 A/g, the assembled pouch cell also maintains stable cycling at 0.3 A/g over 80 cycles. This research could offer a facile approach to develop other advanced anodes with industrial practicability for alkali ion batteries.

The role of Vorasurf 504 surfactant in the production of large mesoporous carbon using solvent-free method and its application in the removal of emergent contaminants

This work reports using the solvent-free method for the first time in the literature using the surfactant Vorasurf504 (V504) to produce mesoporous carbons (MC). In addition to V504, resorcinol was used as a carbon source, and terephthalaldehyde as a cross-linking agent. Three materials were produced with different proportions of resorcinol: V504, 1:1 (R1V), 1:2 (R2V), and 1:3 (R3V). V504 enabled the production of large mesoporous carbon, mainly for the materials with higher proportions of surfactant. The average pore diameters of the materials varied between 5 and 29 nm, and the mesopore volumes were on the order of 0.922 cm3 g−1. The three produced materials were applied to remove emerging contaminants (EC) with different structural dimensions: paracetamol (PA), atrazine (AT), tenofovir (TF), and ceftriaxone (CF). During the contact test, R2V and R3V showed removals above 90 % for all EC. However, due to its limited mesoporosity, the R1V material had its removal capacity reduced for contaminants of larger structural dimensions. Through kinetic and isotherm studies for systems involving paracetamol and ceftriaxone, it was proven that, in fact, not only the specific surface area but also the pore size and pore volume influence adsorption. As a result of this study, large mesoporous carbon could be produced using a surfactant that has not previously been investigated for the solvent-free method. Furthermore, the materials produced can be used as effective adsorbents for emerging contaminants of various structural dimensions.

A novel oil-water microemulsion strategy for controllable synthesis of large mesoporous carbon nanoparticles

Recently, the carbon nanoparticles with defined architecture, small particle diameter and large mesopore size, have aroused people's enormous interests on account of their laudable properties. Here, it is novel mesoporous carbon nanoparticles (MCNs) that have been successfully fabricated in a neoteric oil-water microemulsion system, which is developed to synchronously adjust the surface roughness, particle diameter, and large mesopore size through accommodating the emulsion polarity. Besides, pentanol as a cosurfactant not only significantly affects the evolution of mesopore size but also acts an vital role in the interfacial interaction between carbon precursors and soft templates, leading to the fluffy growth of particles. Interestingly, an extended swelling-penetration mechanism is subtly put forward to explain the formation and transformation of MCNs, which would provide a simple and unique ingenuity for this material species. Remarkably, to fulfill the multifunctional properties of such MCNs, MCNs-2 is further utilized as a fluorescent probe platform to detect mutated nucleic acids with high selectivity and low detection limit, as well as a medical carrier to work well in drug delivery system with high adsorption/release properties and extremely low cytotoxicity, which would empower it with luciferous prospects for the applications in biosensor and biomedical fields.

Synthesis of large mesoporous carbon from cotton stalk for use as an anode for lithium-ion batteries

There has been increasing attention to the method of preparing anode materials for lithium-ion batteries from biomass resources which can more effectively use agricultural waste as resources. In this paper, cotton stalks are used as the precursor and ZnCl2 is used as the activator. A simple one-step carbonization technique is used to prepare porous carbon with high electrochemical performance. We found that the increase of ZnCl2 content is conducive to the development of large mesopore structure (>6 nm), and high content of ZnCl2 facilitates the retention of heteroatoms. The pore size distribution is the most important factor in all kinds of physical structures. Moreover, it can be concluded that physical structure is more important than chemical structure. Cotton stalk: ZnCl2 = 1:4 prepared porous carbon has the best electrochemical performance. After being cycled for 100 times at a current density of 0.1 Ag-1, it still maintains a specific capacity of 328.3 mAhg−1. In addition, compared with graphite, the above-mentioned carbon sample exhibits excellent high-power performance.

(PEFC&E 2022 Student Poster Award Winner - 2nd Place) Investigation of a Correlation Between IV Performance and Cathode Structure for MEAs Using Mesoporous Carbon Supports

Introduction Polymer Electrolyte Fuel Cell (PEFC) is a promising energy technology for a future decarbonized society. PEFC is composed of porous electrode catalyst layers, which largely determines current-voltage (IV) performance. However, the optimal structure of porous catalyst layers is still unknown. Carbon supports are the main component to build up such porous structure. Mesoporous carbon (MC) supports are recently paid more attention to since they are used in Toyota’s fuel cell vehicles, MIRAI. We are also studying MC whose diameter is about 10 nm. Therefore, we are interested in a correlation between IV performance and the structure of catalyst layers based on MC supports. The aim of this study is to clarify the optimal structure of cathode catalyst layers for high IV performance. In this study, we synthesized two types of MC, MC bulk and fibers, and evaluated the IV performance and cathode structure of MC based cathode catalyst layers. Experimental MC bulk was prepared based on self-organization of Pluronic F127 and carbon precursors (resorcinol, formaldehyde, and triethyl orthoacetate). They were mixed in the acid solution, and then the supernatant was removed after centrifugation. The remaining portion was heated in the oven for polymerization of carbon precursors. The resulting material was heated by stepwise in the oven under the nitrogen atmosphere in order to decompose Pluronic F127 and carbonized precursors. MC fibers were made by electrospinning of the similar precursor solution mentioned in the above, but for electrospinning phloroglucinol instead of resorcinol was in use, and PVA was added. Then, after MC bulk and fibers were milled by hands or zirconia balls, Pt nanoparticles were deposited on MC supports by using Pt(acac)2 as a precursor. MEAs with 1cm2 electrodes were fabricated by spray-printing of catalyst dispersions on the Nafion film. Prepared MC based catalysts were used for the cathode, and 46.5% Pt/KB (TEC10E50E) was used for the anode. Results and discussion IV performance of MEAs using MC based cathodes was evaluated and compared to that of a standard MEA. MEA with MC bulk support showed slightly lower IV performance than that of standard MEA. By analyzing each overvoltage separately, ohmic overvoltage was found to be a biggest problem, and low concentration overvoltage was realized as an advantage. In order to find out the reason of low concentration overvoltage, the structure of cathode layers was evaluated using FIB-SEM. The 300 cross-sectional SEM images were obtained by slicing cathodes every 10 nm, and the cathode was reconstructed into a three dimensional image. As a result, the size of MC support was found to be much larger than that of KB. When pore diameter distribution was evaluated based on the reconstructed image, as shown in Figure 1, rather large pores expressed in red in the figure was observed for MC bulk based cathode probably owing to large MC particles. The low concentration most likely comes from the existence of such large pores. In this structural analysis, the analysis of mesopores is not included, and so in reality mesopores might have contributed to lowering concentration overvoltage. Similar analyses were done for MC fiber based cathodes. We have found that the IV performance and structure of cathodes is rather influenced by the milling processes, which will be discussed in detail. Figure 1

3D printed solid-state composite electrodes and electrolytes for high-energy-density flexible microsupercapacitors

Although flexible microsupercapacitors (MSCs) have attracted significant attention for wearable electronics, their energy storage performance and energy density need to be improved for widespread applications. In this study, flexible MSCs displaying enhanced areal capacitance and energy density with high active material loading were fabricated; to realize this, three-dimensional (3D) printing was utilized to deposit an electrochemically stable ionic liquid (IL)-based solid-state ionogel electrolyte and a 3D interconnected large mesoporous carbon (3DMC)-based composite electrode. The ionogel consisting of 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ([EMI][TFSI]) and polyvinylidene fluoride-co-hexafluoropropylene (P(VDF-HFP)) was employed to increase an operating potential range of the MSCs. The 3DMC composite electrode, which consists of 3DMC, single-walled carbon nanotubes (SWCNTs), P(VDF-HFP), and [EMI][TFSI], was successfully printed to facilitate ion transport of the ionogel and to customize 3D structures. 3D printed MSCs exhibited outstanding supercapacitive energy storage performance, including very high specific capacitance of 110.4 mF cm−2, energy density of 60.6 μWh cm−2, power density of 0.89 mW cm−2, and outstanding mechanical durability of 97% capacitance retention after 1000 successive 90° bending/releasing cycles. These results provide a promising strategy for fabricating flexible MSCs based on composite electrolytes and electrodes for superior supercapacitive energy storage performance.

Synthesis of Carbon Foam Using Xanthan-Gum Additive and Characterization for its Heat Absorbing and Retarding Properties

In this work a facile synthesis method is adopted to demonstrate the large mesoporous carbon foam. The green foam was made from fine flour, yeast and xanthan gum were used as a base, leaving agent and binding agent respectively. After the blowing process the foam is placed in a tube furnace for pyrolysis. Finally, the foam heat absorption properties as well as heat retarding properties were established in contrast to traditional aluminum-based heat sink as well as K23 (aluminosilicate refractory) brick.

Optimizing Electrochemically Active Surfaces of Carbonaceous Electrodes for Ionogel Based Supercapacitors

AbstractIonic liquids (ILs) or solidified ionic liquids, known as ionogels, have been actively employed in supercapacitors (SCs) owing to their superior electrochemical stabilities to aqueous and organic electrolytes. However, initial efforts of using ILs and ionogels in SCs were not successful because bulky and sluggish ions cannot effectively access tiny pores of conventional microporous carbons. To address this, a strategy is developed to optimize the electrochemically active surfaces of carbonaceous electrodes and thus to improve the energy storage performance by incorporating 3D ordered/interconnected large mesoporous carbons with ionogel electrolytes. Precisely designed large mesopores interconnected via windows promote mass transport of the electrolyte ions within the solid ionogel electrolytes and effectively utilize the surface of the carbon electrodes for capacitive energy storage, giving rise to record‐high energy storage performance that surpasses the upper bound of the Ragone plots of the current state‐of‐the‐art SCs. In addition, all‐solid‐state SCs with outstanding bending/folding durability are successfully demonstrated. Overall, these results provide critical insight into surface utilization of carbon electrodes as well as capacitive energy storage, when viscous and bulky ILs or ionogels are used as electrolytes.

High-Molecular-Weight PLA-b-PEO-b-PLA Triblock Copolymer Templated Large Mesoporous Carbons for Supercapacitors and CO2 Capture

High-molecular-weight PLA440-b-PEO454-b-PLA440 (LEL) triblock copolymer was synthesized through simple ring-opening polymerization (ROP) by using the commercial homopolymer HO-PEO454-OH as the macro-initiator. The material acted as a single template to prepare the large mesoporous carbons by using resol-type phenolic resin as a carbon source. Self-assembled structures of phenolic/LEL blends mediated by hydrogen bonding interaction were determined by FTIR and SAXS analyses. Through thermal curing and carbonization procedures, large mesoporous carbons (>50 nm) with a cylindrical structure and high surface area (>600 m2/g) were obtained because the OH units of phenolics prefer to interact with PEO block rather than PLA block, as determined by FTIR spectroscopy. Furthermore, higher CO2 capture and good energy storage performance were observed for this large mesoporous carbon, confirming that the proposed approach provides an easy method for the preparation of large mesoporous materials.

Controlled Growth of N-Doped and Large Mesoporous Carbon Spheres with Adjustable Litchi-Like Surface and Particle Size as a Giant Guest Molecule Carrier.

N-doped mesoporous carbon nanospheres (NMCNs) with tunable particle size, pore size, surface roughness, and inner cavity are extremely important for the future development of new carriers for nanoencapsulation, high-performance giant molecule transport, and cell uptake. However, constructing such a multifunctional material via a simple method still remains a great challenge. Herein, a controlled growth technology was developed for the first time to synthesize such NMCNs based on the initial reaction temperature (IRT) and solution polarity. In this strategy, the IRT not only can adjust the micelle aggregation to obtain NMCNs with large mesopores but also can make the F127 micelle more lyophobic to prepare hollow N-doped mesoporous carbon spheres, which is a great breakthrough. Inspiringly, by varying the solution polarity to make nonuniform growth of nanoparticles, the litchi-like rough surface of NMCNs was obtained, which could significantly improve the cell uptake performance of NMCNs. The current understanding of nucleation and growth mechanism of nanospheres was further extended and realized the development of NMCNs with large mesopores and litchi-like rough surface, which provided a new and interesting fundamental principle for the synthesis of NMCNs. The mesoporous structure of NMCNs was successfully reverse-replicated by nanocasting of tetraethylorthosilicate to obtain mesoporous silica spheres (MSNs), revealing the easy transformation between NMCNs and MSNs. Insulin as a peptide drug cannot be directly administered orally. But it can be used as oral preparation after being loaded into NMCNs, which has never been reported before. Interestingly, the results of the animal experiment showed an excellent in vivo hypoglycemic activity. This finding provides a new paradigm for the fabrication of structurally well-defined NMCNs with a great promise for drug carriers.

Synthesis of iron-based metal-organic framework@large mesoporous carbon composites and their electrocatalytic properties

An iron-based MOF (MIL-100 (Fe)) was synthesized and combined with large mesoporous carbon (LMC) by a solvothermal method. The composite was characterized in detail by a variety of characterization methods. The incorporation of large mesoporous carbon (LMC) significantly improves the electrocatalytic performance and electrochemical stability of MIL-100 (Fe)@LMC as compared to pure MIL-100 (Fe). The composite modified electrode exhibits superb electrocatalytic ability for the reduction of hydrogen peroxide and the oxidation of hydrazine. The smaller overpotential and larger peak current justify the excellent electrocatalytic ability of the composite. For hydrogen peroxide, the overpotential decreased by 0.205V. And for hydrazine, it reduced by 0.415V. The peak currents were increased by 21 times and 2.5 times respectively.

Tunable Large Pore Mesoporous Carbons for the Enhanced Adsorption of Humic Acid.

Tunable large pore soft templated mesoporous carbons (SMC) were obtained via the organic self-assembly of resorcinol/formaldehyde with the triblock copolymer F127 and by investigating the effect of carbon precursor to surfactant (p/s) ratio and carbonization temperature on the material characteristics. The p/s ratio and carbonization temperature were varied respectively from 0.83 to 0.25 and from 400 to 1200 °C. The resulting SMCs had various average pore sizes, tunable from 7 up to 50 nm. At lower p/s ratios, the pore size increased, pore size distributions broadened, and pore volumes increased. An increase of hydrophobicity was observed at elevated carbonization temperatures. A 2D hexagonal ordered SMC with a narrow pore size distribution was obtained at a ratio of 0.83. Lower ratios (0.5 and 0.25) transformed into disordered porous carbons containing micropores, mesopores, and even macropores. The SMCs were tested for adsorption of a large organic molecule, humic acid (HA), from water. The material characteristics that significantly affected HA adsorption capacity were pore size and mass % (wt %) carbon. The novel SMCs showed an unprecedented high adsorption of HA in the entire molecular weight distribution range. SMCs with large mesopores resulted in higher maximum adsorption capacities and improved HA adsorption kinetics compared to activated carbon.

Enabling fast electron transfer through both bacterial outer-membrane redox centers and endogenous electron mediators by polyaniline hybridized large-mesoporous carbon anode for high-performance microbial fuel cells

Both physical structure and chemical property of an electrode play critical roles in extracellular electron transfer from microbes to electrodes in microbial fuel cells (MFCs). Herein a novel polyaniline hybridized large mesoporous carbon (PANI-LMC) anode is fabricated from natural biomass by nanostructured CaCO3 template-assisted carbonization followed by in situ chemical polymerizing PANI to enable fast extracellular electron transfer, in which the LMC with rich disorder-interconnected large mesopores (∼20−50nm) and large surface area facilitates a fast mediated electron transfer through electron mediators, while the decorated PANI on LMC surface enables the direct electron transfer via bacterial outer-membrane redox centers. Owing to the unique synergistic effect from both excellent electron transfer paths, the PANI-LMC hybrid anode harvests high power electricity with a maximum output power density of 1280mWm−2 in Shewanella putrefaciens CN32 MFCs, 10-fold higher than that of conventional carbon cloth. The findings from this work suggest a new insight on design of high-efficient anode according to the multiple and flexible electrochemical process for practical MFC applications.

Large mesoporous carbons decorated with silver and gold nanoparticles by a self-assembly method: enhanced electrocatalytic activity for H2O2 electroreduction and sodium nitrite electrooxidation

The silver, gold nanoparticles were grown onto poly (diallyldimethyl ammoniumchloride, PDDA)-functionalized large mesoporous carbon (LMC) by simple self-assembly method. AuNPs or AgNPs/PDDA–LMC show superior electrocatalytic activity.

Cobalt(II) Schiff Base/Large Mesoporous Carbon Composite Film Modified Electrode as Electrochemical Biosensor for Hydrogen Peroxide and Glucose

AbstractA simple method was developed to prepare a cobalt(II) Schiff base (Co(salen))/large mesoporous carbon (LMC) composite film. The structure and electrocatalytic performance of the Co(salen)/LMC film were investigated by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The Co(salen)/LMC film exhibits high electrocatalytic activity toward H2O2, such as low detection limit (8.5×10−7 M) and wide linear concentration range (2.0×10−6–8.9×10−3 M). Furthermore, glucose oxidase (GOD) was self‐assembled on the surface of the Co(salen)/LMC film modified electrode. Determination of glucose in human blood serum with satisfying result was investigated by the resulting biosensor.

Simultaneous determination of theophylline and caffeine by large mesoporous carbon/Nafion modified electrode

In this work, a glassy carbon electrode (GCE) modified with large mesoporous carbon and Nafion composites (LMC/Nafion) was constructed and used for simultaneous determination of theophylline (TP) and caffeine (CF). The electrochemical behaviors of TP and CF on the LMC/Nafion/GCE were carefully investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results show that the DPV peaks of the two analytes can be distinguished at the modified electrode with peak-to-peak separation about 150mV, which means that LMC/Nafion/GCE is suitable for simultaneous determination of TP and CF. Under the optimized condition, the detection limits of TP and CF were 0.37 and 0.47μM (S/N=3) with linear ranges of 0.8–180.0μM and 1.3–230.0μM, respectively. The proposed method was successfully applied to the simultaneous determination of TP and CF in human blood serum and beverages with reliable recovery.

FePO4 nanoparticles embedded in a large mesoporous carbon matrix as a high-capacity and high-rate cathode for lithium-ion batteries

By using large mesoporous carbon (LMC) as a novel host matrix, LMC–FePO4 nanohybrid has been synthesized through a facile homogeneous precipitation process and subsequent annealing approach. When evaluated as a cathode for lithium-ion batteries (LIBs), the LMC–FePO4 nanohybrid exhibits higher specific capacities, improved rate capability, and better cycling performance by virtue of its unique structural characteristics.

Incorporating conductor paste in a low-temperature fabrication process for large mesoporous carbon counter electrode in dye-sensitized solar cells

A novel silver conductor paste modified mesoporous carbon (SCP-MC) counter electrode has been fabricated at low temperature using a large pore MC as catalytic material and the SCP as binder. The efficiency of dye-sensitized solar cells (DSCs) employing the SCP-MC counter electrode reaches the maximum of 5.93% when the SCP content is 6wt.%, which is 15.4% higher than that of DSCs with a pure MC counter electrode. The improved efficiency mainly results from the enhancement in the fill factor and the short-circuit photocurrent density. Electrochemical impedance spectroscopy (EIS) reveals evident decreases in charge transfer resistance, ohmic serial resistance and Nernst diffusion impedance of the SCP-MC electrode with the SCP content increasing. The contacts among the MC particles and between the catalytic film and the substrate are improved by introducing the SCP, which play a key role in reducing the impedance parameters of the SCP-MC electrode and further improving the photovoltaic parameters of the cells. Especially, the DSCs with the optimum SCP-MC electrode have comparable efficiency to the DSCs with Pt electrode under the same conditions. The high performance of the SCP-MC electrode can be attributed to the favorable characteristics of the MC, such as large sized mesopores, high surface area and low crystallinity as well as the high quality catalytic film caused by adding the SCP.

Electrochemistry and Simultaneous Detection of Metabolites of Purine Nucleotide Based on Large Mesoporous Carbon Modified Electrode

AbstractA large mesoporous carbon modified glassy carbon electrode (LMC/GCE) was prepared. The morphology and structure of the LMC were characterized. The LMC/GCE was used to investigate the electrochemical behaviors of metabolites of purine nucleotide, uric acid (UA), xanthine (XA) and hypoxanthine (HX). The LMC/GCE exhibited high electrocatalytic activity towards the three compounds when compared with those obtained at the GCE. Furthermore, the LMC/GCE realized simultaneous determination of UA, XA and HX at a physiological pH of 7.0 with wide linear range and low detection limit. The electrocatalytic activity of the LMC/GCE towards guanine (G) and adenine (A) was also investigated.