Carbon Template Research Articles

Waste catkins-derived graphitic carbon/Co3O4 composites as long-life and high-rate anodes for lithium-ion battery

Upgrading waste re-utilization has been regarded as an important concept to promote the sustainable development of social economy. Herein, waste catkins were used as carbon source and template to prepare graphitic carbon/Co3O4 composites through cobalt salt immersion, in-situ carbonization and calcination. The obtained Co3O4/C composites inherit the microtubular structure of catkins with ultra-thin tube wall and large tube cavity. Particularly, the sample (Co3O4/C-280) calcined at 280 °C in air shows a morphology of the hollow Co3O4 spheres (av. 50 nm) evenly embedded on the biocarbon tube. As an anode for lithium-ion battery, such unique structure is more conductive to alleviate volume expansion. As expected, Co3O4/C-280 electrode has excellent rate capability at 5 A g−1 and stable long-cycle performance (647.3 mA h g−1, 1800 cycles, 1 A g−1). The presence of pseudo-capacitance behavior plays an important role in improving the capacity of material. The good electrochemical properties of Co3O4/C-280 can be ascribed to the synergistic effect of hollow tubular structure and graphitic carbon. Therefore, the strategy of making waste profitable is in line with the theme of green and sustainable development, and provides a reference for improving lithium storage performance of Co3O4-based anode materials.

Polyaniline-Coated Mesoporous Carbon Nanosheets with Fast Capacitive Energy Storage in Symmetric Supercapacitors.

Polyaniline-capped mesoporous carbon nanosheets with high conductivity and porosity are synthesized by vapor deposition polymerization. The mesoporous carbon template is prepared by removing ordered cubic iron oxide nanocrystals embedded in the carbon matrix obtained by thermal decomposition of an iron-oleate complex in a sodium chloride matrix. The evaporated aniline monomers are slowly polymerized on the carbon surface pretreated with FeCl3 as an initiator, partially filling the carbon pores to improve conductivity. The resulting products exhibit efficient hybrid energy storage mechanisms of electric double-layer capacitance and pseudocapacitance. When the nanosheets are assembled for a symmetric supercapacitor, the device capacitance reaches 107.8 F g-1 , at a current density of 0.5 A g-1 , and a capacitance retention of 69.6% is achieved at a ten times higher current density of 5 A g-1 . Electrochemical impedance spectroscopy reveals that the transition from resistive to capacitive behavior occurs within 0.63 s, indicating that fast ion and charge transport results in high capacitance and rate capability. The corresponding energy and power densities are 9.59 Wh kg-1 and 200.1 W kg-1 at a current density of 0.5 A g-1 , demonstrating efficient energy storage in a symmetric supercapacitor.

Enhanced adsorptive removal of thiophenic sulfur compounds by nitrogen-doped surfactant modified mesoporous templated carbons

Adsorptive desulfurization is a greenway for sulfur removal from fossil fuels due to its ambient operating conditions and easy recyclable usage of spent adsorbent. This paper studied the effect of nitrogen doping in mesoporous templated carbon for the adsorptive removal of sulfur compounds from model fuel. The undoped and nitrogen-doped templated carbons were synthesized using alumina and surfactant-modified alumina as templates via the chemical vapor deposition method. Modification by nitrogen enhanced both the surface area and pore volume of templated carbon. The nitrogen-doped surfactant-modified alumina templated carbon, AS-N, showed the highest surface area of 1373 m2/g and pore volume of 1.15 cm3/g. The AS-N showed adsorptive removal of sulfur compounds (thiophene 92.15%, benzothiophene 82.90% and dibenzothiophene 82.38%) at 70 °C. This may be attributed to the highest surface area and presence of nitrogen (8.2 wt%), which improved the adsorption capability by increasing the π-π interaction between the sulfur compounds and carbon matrix. Further increase in nitrogen content in templated carbon enhanced the π-π interaction resulting in higher removal capacity. The AS-N-U adsorbent prepared in the presence of urea had 15.2 wt% nitrogen and showed enhanced removal of thiophene 97.7%, benzothiophene 92.4%, and dibenzothiophene 89.3%. The adsorptive desulfurization over AS-N-U for all sulfur compounds were best fitted to pseudo-second order kinetic model and Langmuir adsorption isotherm model. The templated carbon was regenerated successfully using the thermal regeneration process. After five adsorption-regeneration cycles, the removal efficiency was lowered only by 4–10% for all sulfur compounds.

A novel template processing method for preparing spinel oxides with various morphologies to assemble high-performance supercapacitors

With the increasing complexity of the application scenarios of nanomaterials, transition metal oxides (TMOs) have shown excellent development potential. However, the synthesis of TMOs with customized morphologies for different application environments is still challenging. Herein, an acid-alcohol treatment based on the different intensities of the redox reactions between nitric acid and ethanol was developed to prepare different carbon templates. Through impregnation and annealing of the templates, NiCo2O4 (NCO) materials with hollow spherical (NCO-HS), multi-shell spherical (NCO-MS), and lamellar (NCO-L) morphologies were obtained. The characterization was performed through different analytical methods, which revealed various structures, morphologies, and surface chemistry of the materials. NCO-HS, NCO-MS, and NCO-L were tested for supercapacitor applications and exhibited a high specific capacitance of 402.6, 1037.1, and 531.4 F g−1, respectively. Overall, the proposed method can be used to customize the synthesis of functional materials with various morphologies for future advanced applications.

Effects of Carbon Templates in Tetraethyl Orthosilicate-Derived Superhydrophobic Coatings

Superhydrophobic coatings have garnered significant research interest due to their potential applications in areas such as ant-icing and windows. This study focuses on the development of superhydrophobic coatings using air-assisted electrospray and the effect of different carbon additives as templates in the coating. Carbon templates, with their unique topological varieties, offer a cost-effective alternative to other patterning technologies such as photolithography. By introducing dispersed carbon black, carbon nanotubes, and graphene additives in TEOS solution, silica is given the ability of localized secondary growth on or around the carbon surfaces as well as the building structure to provide adequate roughness on the substrate surface. The templated silica formations provide a thin coating with nano-scale roughness for heightened water resistance. As compared with the template-free coating that has small silica particles, a surface roughness of 135 nm, and a water contact angle (WCA) of 101.6° (non-superhydrophobic), the carbon templating effect allowed for increased silica particle size, a surface roughness as high as 845 nm, a WCA above 160°, and the ability to maintain superhydrophobicity over 30 abrasion cycles. The morphological characteristics that resulted from the templating effect correlate directly with heightened performance of the coatings. Herein, the carbon additives have been found to serve as cheap and effective templates for silica formation in thin TEOS-derived superhydrophobic coatings.

Enhanced Electro-Oxidation of Ethylene Glycol over Cu/C Catalysts Using Different Forms of Carbon

In present work copper has been studied as the active material supported on different forms of carbons, such as activated carbon (AC), reduced graphene oxide (RGO), alumina based templated carbon (TC) and vulcan carbon (VC), for electro-oxidation of ethylene glycol (EG). Different carbon supports were observed to impart different physical and electrochemical characteristics to the catalysts in spite of presence of same active metal with similar loadings of 20 wt%. 20Cu-RGO showed highest current density of 5.61 mA/cm2 followed by 20Cu-VC at 2.59 mA/cm2 in acidic medium. The higher electrochemical surface area, pore size, metal dispersion, work function and content of oxygen containing functional groups were observed to favour better performance for electro-oxidation. The time constants for all the catalysts decreased in acidic medium and increased in basic medium upon addition of ethylene glycol. It was observed that electrochemical reaction was slower process in comparison to charge transfer irrespective of the type of medium. Oxalic acid was obtained as the main product during electro-oxidation of EG in both medium. The glyoxylic acid was detected as intermediate only in basic medium. The catalysts proved to be physically and chemically stable in both mediums.

Efficient removal of Pb(II) by iminodiacetic acid modified magnetic mesoporous carbon

Magnetic mesoporous adsorbent carbon modified with iminodiacetic acid (Fe3O4@mC-IDA), was prepared to remove Pb(II). The magnetic mesoporous carbon (Fe3O4@mC) was first synthesized by in-situ growing carbon layers on the surface of ferrosoferric oxide, which exhibited large specific surface area and mesoporous structure, and the template molecule and carbon source are both from rich and cheap magnesium citrate. Then, iminodiacetic acid (IDA) was attached to Fe3O4@mC by a ring opening reaction. Multiple characterization techniques were applied to demonstrate the synthesis of the adsorbent. The composite could achieve adsorption equilibrium of Pb(II) in 65 min, and had a maximum adsorption capacity of 429.23 mg g−1 for Pb(II). Langmuir isothermal, pseudo-2nd-order kinetics model and Elovich model could be relatively suitable for simulating the adsorption process. In addition, the adsorbent had fine reusability, and the removal rate of Pb (II) reached 90.67% after 5 cycles. The adsorption mechanistic study showed that COO− and tertiary amine formed tridentate chelates with Pb(II), and hydroxyl groups combined with Pb(II) through electrostatic attraction. These results suggested that Fe3O4@mC-IDA was a potential adsorbent for Pb(II) removal with fast adsorption speed, easy separation ability and fine reusability.

Template-Based Porous Hydrogel Microparticles as Carriers for Therapeutic Proteins.

Hydrogels have been extensively researched for over 60 years for their limitless applications in biomedical research. In this study, porous hydrogel microparticles (PHMPs) made of poly(ethylene glycol) diacrylamide were investigated for their potential as a delivery platform for therapeutic proteins. These particles are made using hard calcium carbonate (CaCO3) templates, which can easily be dissolved under acidic conditions. After optimization of the synthesis processes, both CaCO3 templates and PHMPs were characterized using a wide range of techniques. Then, using an array of proteins with different physicochemical properties, the encapsulation efficiency of proteins in PHMPs was evaluated under different conditions. Strategies to enhance protein encapsulation via modulation of particle surface charge to increase electrostatic interactions and conjugation using EDC/NHS chemistry were also investigated. Conjugation of bovine serum albumin to PHMPs showed increased encapsulation and diminished release over time, highlighting the potential of PHMPs as a versatile delivery platform for therapeutic proteins such as enzymes or antibodies.

Exploring novel p-n core/shell structure in single α-Fe2O3 nanorods of hierarchical hollow microspheres for ultrasensitive acetone gas sensor

Fabricating metal oxide sensors with super-sensitivity and good distinguishing properties for gases is a challenge due to the difficulties in controlling vacancy-type structural defects of nanomaterials and the data processing. In this paper, we reported the fabrication of hierarchical α-Fe2O3 hollow microsphere (HFHM)-based sensor using a facile and scalable method with uniform-micro spherical carbon templates, as well as the data analysis using artificial intelligence (AI). The shell of the unique hollow microspheres was built by connecting many α-Fe2O3 nanorods, so the superstructures have 0D, 1D, and 3D structural features. In these α-Fe2O3 nanorods, positron annihilation measurements revealed abundant oxygen-vacancy clusters (11 atoms), nanopores (0.53 nm) and p-n core/shell structure. The HFHM-based sensors, hence, exhibited an extremely high sensitivity toward acetone (Response = 320 (200 ppm), limited detection (DL) ∼ 250 ppt) and ethanol (Response = 300 (200 ppm), DL ∼ 500 ppt), as well as a super-fast response time (1–2 s). In particular, by using the Principal Component Analysis (PCA), an applied AI tool, we were able to significantly improve the distinguishing and selective abilities of acetone and ethanol (high-response gas groups) as well as H2, CO and NH3 (low-response gas groups).

Hierarchical Ni/N/C Single‐Site Catalyst Achieving Industrial‐Level Current Density and Ultra‐Wide Potential Plateau of High CO Faradic Efficiency for CO2 Electroreduction

AbstractThe practical applications of CO2 electroreduction to CO driven by renewable electricity should simultaneously meet the requests of industrial‐level CO partial current density (JCO) at least 100 mA cm−2, wide potential window of high CO faradic efficiency (FECO), and low cost. Herein, a new strategy is reported to construct porous hierarchical Ni/N/C single‐site catalyst with excellent catalytic activity via coating Ni‐containing ZIF‐8 on mesostructured basic magnesium carbonate template followed by pyrolysis. The abundant micropores facilitate the formation of numerous edge‐hosted Ni‐N4 sites with high intrinsic activity, and the interconnected macro/mesopores much promote CO2 delivery and CO release for the full expression of intrinsic activity. Consequently, the catalyst exhibits the industrial‐level JCO of 105–462 mA cm−2 at the potential range of −0.6∼−1.3 V with ultra‐wide high FECO plateau (>90%@−0.4∼−1.3 V), showing great promise for practical application. This study provides a general synthetic strategy to explore high‐performance hierarchical M/N/C electrocatalysts.

Facile preparation of regular truncated octahedral LiMn2O4 cathode with high rate cyclability and stability for Li-ion batteries

Spinel LiMn2O4, as a mainstream commercial cathode material for lithium-ion batteries, is still suffered from severe capacity fading caused by Mn dissolution and Jahn-Teller distortion during the cycle process, which can be solved by developing selectively exposed crystal planes. Herein, a perfect monocrystal LiMn2O4 with regular truncated octahedral structure has been synthesized via a facile and low-cost carbon template sol-gel method. The phase composition and morphology of LiMn2O4 can be regulated by carbon template content, ranging from irregular micro-aggregates to nanoporous network structure composed of truncated nano-octahedrons with high crystallinity. The high crystallinity suppresses Jahn-Teller distortion and the large presence of {111} surfaces inhibit Mn dissolution can both improve its cycle stability, the unique nanoporous network structure facilitates shortening the Li+ diffusion path and the truncated {100} and {110} surfaces promote Li+ diffusion can increase the discharge capacity and rate capability. Accordingly, the as-obtained LMO-0.5 sample achieves remarkable discharge specific capacity (135.8 mA h/g at 0.1 C), excellent rate capability (91.2 mA h/g even at 20 C) and prominent cycle stability (a capacity retention of 91.7 % after 2000 cycles at 20 C), which will be an ideal cathode material for developing long-lifespan lithium-ion batteries.

Phase control and induction of visible-light photocatalytic activity in hierarchical porous structure nanocrystalline TiO2 prepared using a MOF-5-derived nanoporous carbon template

BackgroundNanocasting is a powerful method to induce unique structural and morphological characteristics. It is known that the phase, morphology, and nanostructure of TiO2 facilitate its photocatalytic performance and band gap energy. In this context, we simultaneously controlled the TiO2 phase and improved its photocatalytic activity by choosing the appropriate carbon substrate and synthesis process. MethodsIn this study, a high surface area nanoporous carbon with an extremely interconnected mesoporous network and accessible pores in terms of depth and size was derived from MOF-5. This hard template used for the synthesis of titanium oxide (TiO2) nanoparticles by nanocasting. in addition to the anatase phase, the brookite phase was successfully produced using this nanocasting approach by penetrating NaF solution to the template pores under hydrothermal conditions. Significant FindingsThe results showed that, the interconnected mesoporous network of the carbon template led to the formation of brookite and anatase TiO2 with highly developed mesoporous and macroporous structures and very high surface areas of 109 and 126 m2g−1, respectively. Furthermore, the fabricated brookite and anatase showed enhanced photocatalytic efficiency in visible light because of the increase in light harvesting ability and the reduction in band gap energy to 2.84 and 2.60 eV, respectively.

Porous Carbon Nanofiber Flexible Membranes via a Bottlebrush Copolymer Template for Enhanced High-Performance Supercapacitors.

We report a method to construct ordered hierarchical porous structures in carbon nanofiber membranes using poly(ethylene oxide)-block-polydimethylsiloxane bottlebrush block copolymers (BBCPs) as templates. The BBCPs self-assemble into a spherical morphology driven by small-molecule hydrogen bond donors which act as bridges between carbon precursors and templates to promote uniform dispersion of the templates. We successfully obtained flexible, self-supporting, and porous carbon nanofiber membranes (PCNFs) with high porosity. Then, a supercapacitor electrode was independently prepared using PCNFs as an active substance without infiltrating any conductive agents or binders. The PCNFs exhibit excellent performance with a capacitance of 234.1 F g-1 at a current density of 1 A g-1 owing to the abundant hierarchical porous structures and high content of nitrogen and oxygen elements internally. The aqueous symmetric supercapacitor prepared using PCNFs electrodes maintains more than 95% capacitance retention after 55,000 charge-discharge cycles. Furthermore, the capacitance retention reaches up to 67.72% at a current density of 50 A g-1 (compared to 1 A g-1), exhibiting excellent cycling stability and rate capability. Based on the excellent electrochemical performance and flexible self-supporting ability of PCNFs, this work is expected to facilitate the development of flexible displays, flexible sensors, wearable devices, and electrocatalysis.

Carbon template synthesis of CeO2 catalyst for direct conversion of methanol and carbon dioxide to dimethyl carbonate

Dimethyl carbonate (DMC) is an interesting, value added chemical and a high energy additive to fuels. In this study, several CeO2 catalysts were successfully synthesized through carbon template method using two renewable sources of activated carbon. The structure of catalysts was fully resolved by XRD, SEM, N2-adsorption, NH3-TPD, CO2-TPD and XPS. CeO2 catalysts prepared using coconut shell activated carbon (CAC) template exhibit better surface morphology and improved catalytic performance compared to walnut shell activated carbon (WAC)-supported catalysts. We demonstrated a correlation between the efficiency of DMC synthesis and the abundance of moderately acidic and moderately basic active sites on the catalyst. It was found that the presence of oxygen vacancies (Vo) facilitates carbonyl bond cleavage of CO2. The best-performing catalyst was 4% CeO2/CAC owing to the richest Vo and the optimum acid/base properties. Moreover, a plausible catalytic mechanism of DMC formation was proposed, and includes the interaction between methoxy carbonate (CH3OCO2−) formed with the aid of Vo and moderately basic sites and methyl cation (CH3+) formed on the moderately acidic sites.

Methanation of CO2 over High Surface Nickel/Aluminates Compounds Prepared by a Self-Generated Carbon Template

Catalytic gas-phase hydrogenation of CO2 into CH4 was tested under three different nickel/aluminate catalysts obtained from precursors of hexaaluminate composition (MAl16O19, M = Mg, Ca, Ba). These catalysts were prepared using a carbon template method, where carbon is self-generated from a sol-gel that contains an excess of citric acid and the Al and M salts (Ba2+, Ca2+, Mg2+) by two-step calcination in an inert/oxidizing atmosphere. This procedure yielded Ni particles decorating the surface of a porous high surface area matrix, which presents a typical XRD pattern of aluminate structure. Ni particles are obtained with a homogeneous distribution over the surface and an average diameter of ca 25–30 nm. Obtained materials exhibit a high conversion of CO2 below 500 °C, yielding CH4 as a final product with selectivity >95%. The observed trend with the alkaline earth cation follows the order NiBaAlO-PRx > NiCaAlO-PRx > NiMgAlO-PRx. We propose that the high performance of the NiBaAlO sample is derived from both an appropriate distribution of Ni particle size and the presence of BaCO3, acting as a CO2 buffer in the process.

Co-precipitation reaction: A facile strategy for designing hierarchical porous carbon nanosheets for EDLCs and zinc-ion hybrid supercapacitors

Hierarchical porous carbon is a valuable electrode material for electrochemical energy storage devices by virtue of its high specific surface area, excellent conductivity, and large pore volume. Herein, a simple, convenient and cheap self-made Fe-based template strategy is innovated to prepare hierarchical porous carbon employing coal chemical byproducts anthracene as carbon precursor, which is utilized as electrode materials of electrical double layer capacitors (EDLCs) and zinc ions hybrid supercapacitors (ZHSs). Benefiting from the high specific surface area (2085.1 m2 g−1), feasible micropore content (0.28 cm3 g−1), suitable oxygen content (11.57 at%) and two-dimensional nanosheet structure, the optimal sample delivered a high specific capacitance value of 183.5 F g−1 at 0.05 A/g and excellent rate capability (109.5 F g−1 at 20 A/g) for symmetric supercapacitor. Meanwhile, the as-fabricated ZHSs exhibited remarkable specific capacitance (181.67 mAh/g at 0.05 A/g), superior energy density (145.2 Wh kg−1), high power density (14.5 kW kg−1) and splendid cycling stability (∼91.25 % after 40,000 charge/discharge cycles at 2 A g−1). This work affords a new idea for the synthesis of template carbon using a feasible and low-cost co-precipitation reaction route and has great significance for the development of high-performance electrochemical energy storage device.

High-performance hybrid supercapacitor-immobilized Wells-Dawson polyoxometalates on activated carbon electrodes.

The nanofabrication of electroactive hybrid materials for next-generation energy storage devices is becoming increasingly significant as supercapacitor (SC) technology develops rapidly. The present study utilizes activated carbon (AC) templates reinforced with Wells-Dawson polyoxotungstates (POMs) to produce nanohybrid electrodes for high-performance supercapacitors. This study analyzes Wells-Dawson polyoxotungstates (P2W18) for the first time integrated with AC, and its structural and electrochemical performances are discussed. First, the electrochemical performances of symmetric supercapacitors were characterized in an acidic aqueous electrolyte (0.5 M H2SO4). It was observed that a supercapacitor cell containing the 5 wt% AC-P2W18 hybrid symmetric displayed a noteworthy specific capacitance of 289 F g-1 and a remarkable energy density of 40 W h kg-1. Moreover, 5% AC-P2W18 symmetric supercapacitor cells showed 89% cyclic stability over 4000 cycles. Three LED lights were charged onto the electrode. The LEDs continued to illuminate continuously for red until 160 seconds, yellow until 20 seconds, and blue until 10 seconds after removing the electrode from the electrochemical workstation, demonstrating the device's power and energy density.

Highly-efficient photocatalytic hydrogen evolution triggered by spatial confinement effects over co-crystal templated boron-doped carbon nitride hollow nanotubes

Hollow nanotube-like boron-doped carbon nitride for efficient photocatalytic hydrogen evolution.

Chemistry of zipping reactions in mesoporous carbon consisting of minimally stacked graphene layers.

The structural evolution of highly mesoporous templated carbons is examined from temperatures of 1173 to 2873 K to elucidate the optimal conditions for facilitating graphene-zipping reactions whilst minimizing graphene stacking processes. Mesoporous carbons comprising a few-layer graphene wall display excellent thermal stability up to 2073 K coupled with a nanoporous structure and three-dimensional framework. Nevertheless, advanced temperature-programmed desorption (TPD), X-ray diffraction, and Raman spectroscopy show graphene-zipping reactions occur at temperatures between 1173 and 1873 K. TPD analysis estimates zipping reactions lead to a 1100 fold increase in the average graphene-domain, affording the structure a superior chemical stability, electrochemical stability, and electrical conductivity, while increasing the bulk modulus of the framework. At above 2073 K, the carbon framework shows a loss of porosity due to the development of graphene-stacking structures. Thus, a temperature range between 1873 and 2073 K is preferable to balance the developed graphene domain size and high porosity. Utilizing a neutron pair distribution function and soft X-ray emission spectra, we prove that these highly mesoporous carbons already consist of a well-developed sp2-carbon network, and the property evolution is governed by the changes in the edge sites and stacked structures.

A Computational Study of the Adsorptive Separation of Methane and Hydrogen in Zeolite Templated Carbons

Combustion of conventional energy sources produces pollutants such as SOx, NOx, and CO; the use of hydrogen and methane can eliminate these harmful emissions. In fuel cell technology and other uses, hydrogen must be refined by extracting methane from the methane/hydrogen combination, produced via dry or steam reforming. This study investigates the adsorption and separation capabilities of recently discovered zeolite-templated carbons (ZTCs) for binary mixtures consisting of hydrogen and methane. To assess the adsorption and separation performances of these carbon-based nanostructures, grand canonical Monte Carlo (GCMC) simulations were used. The simulation results revealed that AFY (|(C6H15N)3(H2O)7|[Co3Al5P8O32]) and RWY (|(C6H18N4)16| [Ga32Ge16S96]) structures could be viable alternatives for applications involving adsorptive gas separation based on selectivity and the CH4 uptake capacity. The selectivity of AFY was calculated to be 176, while its capacity to uptake CH4 was found to be 2.57 mmol/g, the selectivity of RWY was calculated to be 132, and its CH4 uptake was 3.49 mmol/g.