Monolithic Porous Carbon Research Articles

Integrated hierarchical porous lignin-based carbon electrode for boosting membrane-free capacitive deionization areal adsorption capacity

The development of high value-added lignin-based functional porous carbon electrodes with excellent properties from sustainable industry lignin powder remains a challenge. This work aims to create robust, binder-free, conductive additives-free, and current collector-free monolithic porous carbon electrodes using industrial lignin powder for membrane-free capacitive deionization (CDI). The material exhibits high mechanical strength, hierarchical porosity structure, large uniform size, and thickness of just a few millimetres (<2.6 mm). In a three-electrode supercapacitor system, the areal specific capacitance of CLCA300-3-1.0 reaches 5.03–1.02 F cm−2 when the scan rate between 1 and 20 mV s−1 in 1 M NaCl solution. As CDI electrodes, the charge efficiency of CLCA300-3-1.0 at different voltages of 1.2 V, 1.4 V and 1.6 V is 0.53, 0.72 and 0.71, respectively. The energy consumption of CLCA280-3-1.0, CLCA300-3-1.0 and CLCA320-3-1.0 tested at 1.2 V are 3.27, 3.40 and 3.25 Wh m−3, respectively. In addition, with thickness increasing to 1.5 mm, the developed CLCA300-3-1.5 electrode exhibits an areal adsorption capacity of 0.46 mg cm−2, and relative highly capacity retention of 84.78 % after 70 cycles. The impressive desalination performance is attributed to the well-designed hierarchical porosity, superhydrophilicity and robust monolithic structure.

Monolithic porous carbon membrane-based hybrid electrodes with ultrahigh mass loading carbon-encapsulated Co nanoparticles for high-performance supercapacitors

Monolithic carbon membrane-based hybrid electrodes with an ultrahigh active mass loading are developed by carbonization of Co-adsorbed Pleurotus eryngii (PE) for directly assembling a supercapacitor with high energy density and cycling stability.

3D-hierarchical porous functionalized carbon aerogel from renewable cellulose: An innovative solid-amine adsorbent with high CO2 adsorption performance

A novel solid amine sorbent has been developed based on polyethylenimine (PEI)-grafted monolithic porous carbon aerogel supports for efficient removal of CO2 from industrial flue gas at 313K. The high pore volume, proper pore distribution and the interconnected 3D framework of monolithic porous carbon aerogel allow the easy dispersion of PEI and ensure the diffusion of CO2 in its pore structure. In addition, the monolithic porous structure can reduce the influence of the pressure difference of large fixed bed on the adsorption performance in industrial applications. More importantly, the reasonable design of pore effect and functionalized molecular configuration of PEI grafted cellulose based porous carbon aerogel (PEI-CPCa) guarantees the maximization of synergistic effect thus may achieve the efficient separation of CO2 from industrial flue gas. Results shows that the CO2 adsorption capacity of PEI-CPCa reached 5.58 mmol/g and the separation coefficient reached 113.1 at 313K for simulated gas consisting of CO2 (15 vol%) and N2 (85 vol%). Furthermore, the low energy consumption, excellent stability and water resistance of the PEI-CPCa make it possess great prospects and advantages in practical industrial applications. Comprehensively, this new functional carbon aerogel is a highly efficient and environmentally friendly adsorbent for the adsorption and separation of CO2.

Boosting Capacitive Deionization Performance of Commercial Carbon Fibers Cloth via Structural Regulation Based on Catalytic‐Etching Effect

Monolithic carbon electrodes with robust mechanical integrity and porous architecture are highly desired for capacitive deionization but remain challenging. Owing to the excellent mechanical strength and electroconductivity, commercial carbon fibers cloth demonstrates great potential as high‐performance electrodes for ions storage. Despite this, its direct application on capacitive deionization is rarely reported in terms of limited pore structure and natural hydrophobicity. Herein, a powerful metal‐organic framework‐engaged structural regulation strategy is developed to boost the desalination properties of carbon fibers. The obtained porous carbon fibers features hierarchical porous structure and hydrophilic surface providing abundant ions‐accessible sites, and continuous graphitized carbon core ensuring rapid electrons transport. The catalytic‐etching mechanism involving oxidation of Co and subsequent carbonthermal reduction is proposed and highly relies on annealing temperature and holding time. When directly evaluated as a current collector‐free capacitive deionization electrode, the porous carbon fibers demonstrates much superior desalination capability than pristine carbon fibers, and remarkable cyclic stability up to 20 h with negligible degeneration. Particularly, the PCF‐1000 showcases the highest areal salt adsorption capacity of 0.037 mg cm−2 among carbon microfibers. Moreover, monolithic porous carbon fibers‐carbon nanotubes with increased active sites and good structural integrity by in‐situ growth of carbon nanotubes are further fabricated to enhance the desalination performance (0.051 mg cm−2). This work demonstrates the great potential of carbon fibers in constructing high‐efficient and robust monolithic electrode for capacitive deionization.

Hydrophilic carbon monoliths derived from metal-organic frameworks@resorcinol-formaldehyde resin for atmospheric water harvesting

Atmospheric water harvesting (AWH) is considered a promising technique to address the problem of global water shortage. Adsorption-based AWH technology, has the advantages of a simple device structure, high energy efficiency, wide application range, etc., and has attracted much attention. For the adsorption, one of the key issues is to find high-performance porous adsorbents. Porous carbons have exceptional stability, high porosity and low cost, but are usually highly hydrophobic with a low affinity for polar water molecules. A class of monolithic porous carbons with good hydrophilicity was prepared by the pyrolysis of composites consisting of a metal-organic framework in a resorcinol-formaldehyde resin matrix, in which the metal-organic parts developed polar sites in the final products. AWH tests showed that in a relative humidity of 40%-80%, the water capture capacity of the adsorbents reached 20 wt.%.

Electrochemically enhanced adsorption of organic dyes from aqueous using a freestanding metal–organic frameworks/cellulose-derived porous monolithic carbon foam

Monolithic carbon foams are promising materials for adsorption due to the easy recyclability and without secondary-pollution. However, poor adsorption efficiency for organic pollutants limits its practical application. Hence, this work proposed a novel monolithic porous carbon foam by a facile carbonization approach as freestanding electrodes to remove the organic dyes. The prepared carbon foam derived from waste cigarette filters and zeolitic-imidazolate frameworks-8 with well-developed pores, and the calculated surface area is 1457 m2·g−1, and exhibited an outstanding removal efficiency for methylene blue in aqueous. The maximum adsorption capacity for methylene blue can reach up to 1846.7 mg·g−1 under the applied voltage of −1.2 V. Importantly, as-prepared carbon foams possessed excellent stability, and the removal efficiency can remain above 85% after 5 cycles. Thus, obtained porous carbon foams in this paper as a free standing electrode is expected to be promising materials of adsorbent besides supercapacitors.

Novel Magnetically Interconnected Micro/Macroporous Structure of Monolithic Porous Carbon Adsorbent Derived from Sodium Alginate and Wasted Black Liquor and Its Adsorption Performance**

The novel and facile preparation of magnetically interconnected micro/ macroporous structure of monolithic porous carbon adsorbent (MPCA) were designed and presented herein. The synthesis was achieved via conventional freeze-drying and pyrolysis processes. In this study, sodium alginate and wasted black liquor were employed as starting precursors. Sodium alginate acts as a template of materials, whereas black liquor, the wasted product from the paper industry with plentiful of lignin content and alkaline solution, played an essential role in the reinforcement and activation of porosity for the resulting materials. Moreover, both the precursors were well dissolved in Fe3+ solution, providing a simple addition of a magnetic source in a one-pot synthesis. The interconnected micro/macroporous structures were generated through freeze-drying and, subsequently the pyrolysis process. The obtained cylindrical-shaped monolithic porous carbon adsorbent (MPCA-700) showed high mechanical stability, a high BET specific surface area (902 m2 /g). Such aforementioned features were considered suitable to make the synthesized monolith as an adsorbent for the removal of heavy metal ions. The maximum adsorption capacity of MPCA-700 towards Pb2+ ions was 76.34 mg/g at pH 5. The adsorption studies illustrated that adsorption kinetics and isotherm perfectly fitted with the pseudo-second-order kinetics model and Langmuir isotherm, respectively. This work presents a promising protocol to reduce the overall costs in the preparation of renewable adsorbents with good adsorption efficiency and regeneration.

Construction of a Microchannel Electrochemical Reactor with a Monolithic Porous-Carbon Cathode for Adsorption and Degradation of Organic Pollutants in Several Minutes of Retention Time

A monolithic porous-carbon (MPC) electrode was fabricated to simultaneously intensify mass transfer and enhance reaction activity. The MPC involved channel arrays (about 50 μm of diameter for each channel) with mesopores and micropores in channel walls. The abundant surface pores may improve the reaction efficiency of the reduction of O2 to produce H2O2 and •OH. The function of channel arrays was to shorten the mass-transfer distance not only from O2 to the electrode surface but also from pollutants to the electrode surface and •OH. A microchannel electrochemical reactor was assembled to evaluate the performance of the MPC cathode. For 20 mg/L of phenol, sulfamethoxazole or atrazine, effluent concentration and total organic carbon (TOC) decreased down to 1.5 and 3 mg/L, respectively, in a retention time of only 100-300 s. Phenol removal was dominated by the MPC cathode, and the contribution of cathodic adsorption, cathodic degradation, and anodic reaction was 46, 33, and 8%, respectively. The proper working potential for the MPC cathode was +0.26 to +0.6 V versus reversible hydrogen electrode; in this potential range, no scaling was observed. For the real surface water (the initial TOC was 41.5 mg/L), TOC in effluent (the retention time was 335 s) was stable at 31.0 mg/L.

Efficient H2O2 generation and electro-Fenton degradation of pollutants in microchannels of oxidized monolithic-porous-carbon cathode.

A monolithic-porous carbon (MPC) was fabricated by carbonizing a pine rod, and then the oxidized monolithic-porous carbon (O-MPC) was obtained via alkaline heat treatment of MPC. With well-ordered axial channels (diameters were 6-14 μm and 40-50 μm) and oxygen-containing functional groups, O-MPC as a flow-through cathode exhibited good capability in continuously generating H2O2 (422 μmol/L) via oxygen reduction. O-MPC and additional Fe2+ composed an electro-Fenton system and the performance of the system in degradation of organic pollutants was evaluated. For phenol, bisphenol A or sulfamethoxazole at initial concentration of 10 mg/L the removal efficiency reached 74%-82% in a hydraulic retention time of 100 seconds, nearly close to that of the homogeneous Fenton process (90%). This efficiency may be maintained for at least 10 hours, indicating a good stability of O-MPC. The results demonstrate the potential of O-MPC as a flow-through electrode to realize homogeneous-like degradation of organic pollutants in wastewater.

High pseudocapacitance boosts the performance of monolithic porous carbon cloth/closely packed TiO2nanodots as an anode of an all-flexible sodium-ion battery

A monolithic TiO2nanodot/porous carbon cloth electrode with high pseudocapacitance was prepared, and it showed excellent sodium storage properties.

Versatility of a Nitrogen‐Containing Monolithic Porous Carbon for Lithium‐Based Energy Storage.

AbstractN‐containing monolithic porous carbon material with dual micro and mesoporous structures was synthesized using an innovative, cheap and easy synthesis route based on the classical resorcinol‐formaldehyde synthesis. A completely chemical, structural and morphological characterization was carried out. The N content in the carbonaceous material was 7.3% and XPS data showed that is present in two different surrounds, as N‐pyrrolic and N‐pyridinic atoms. Is known that, the last one, can acts as a catalyst at surface level in heterogeneous reactions. In addition, using this material, we were able to fabricate lithium‐ion and lithium‐sulfur batteries obtaining high values of discharge capacity and cycle stability and demonstrating the multifunctional character of this carbon in energy storage devices.

All-round utilization of biomass derived all-solid-state asymmetric carbon-based supercapacitor

All-round utilization of resources is proposed for maximizing environmental and economic benefits. Herein, the concept of all-round utilization on biomass derivations applying to carbon-based supercapacitors is demonstrated. Orange peel is used for all subassemblies of supercapacitor, including electrodes, separator and electrolyte. A monolithic porous carbon (OPHPC) is prepared by one-step carbonization of orange peel and another composite electrode is further synthesized by a simple hydrothermal process, based on sufficient utilization of natural structure and chemical components. OPHPC exhibits a high specific surface area of 860 m2 g−1 and naturally doped nitrogen. The composite electrode shows the homogeneous and high mass loading of MnO2. Orange peel also affords the role of separator benefited from the natural porous channel structure and high porosity of 74.6%. Orange peel juice is exploited to produce the electrolyte, and exhibits the best retention in natural separator. All-orange peel all-solid-state supercapacitor shows the high areal capacitance of 3987 mF cm−2. Furthermore, the flexibility of orange peel is also utilized to achieve the shape-tailored monolithic porous carbon electrode and device, which further extends the utilized dimensionality in biomass applying to supercapacitors. The work starts with all dimensional utilization for biomass derived supercapacitor.

Template-free synthesis of monolithic carbon xerogels with hierarchical porosity from resorcinol and formaldehyde via hydrothermal reaction.

Monolithic carbon xerogels with hierarchical porosity were prepared from resorcinol (R) and formaldehyde (F) via a base-catalysed hydrothermal polycondensation reaction, without a template and supercritical drying. First, an aqueous solution of resorcinol, formaldehyde and sodium carbonate was prepared by varying R/W (25–45) and R/C (1–10k) ratios to produce monolithic RF gels. The reaction was carried out in a pressurized Teflon mould at 100 °C for 6 h to give a co-continuous pore structure via spinodal decomposition and a tenacious gel to avoid supercritical drying. Next, the RF gels were dried for 42 h at 60 °C and another 6 h at 100 °C to produce RF xerogels without cracks, followed by pyrolysis in a tube furnace at 900 °C for 2 h under N2 flow, and then activation at 1000 °C for 2, 4 or 6 h under CO2 flow. Finally, the carbon xerogels were characterized by SEM and N2 adsorption–desorption measurements. Monolithic RF gels were obtained from all combinations of R/W and R/C, but the gels from R/W = 45 exhibited a co-continuous large-pore structure, providing a specific surface area (SSA) of ∼650 m2 g−1, which increased to 3311 m2 g−1 (for R/C = 10k) at 6 h of CO2 activation without exhibiting cracks. N2 isotherms demonstrated that micro- and meso-pores were introduced via activation, forming hierarchical porosity in combination with large pores from spinodal decomposition without using a template.

Synthesis of monolithic porous carbon aerogels from sorghum straw and their application in rapid oil removal

Synthesis of monolithic porous carbon aerogels from sorghum straw and their application in rapid oil removal

Monolithic porous carbon materials prepared from polyurethane foam templates

Monolithic carbon foams with hierarchical porosity were prepared from polyurethane templates and resol precursors. Mesoporosity was achieved through the use of soft templating with surfactant Pluronic F127, and macroporosity from the polyurethane foams was retained. Conditions to obtain high porosity materials were optimized. The best materials have high specific surface areas (380 and 582 m2 g–1, respectively) and high electrical conductivity, which make them good candidates for supports in sensors. These materials showed an almost linear dependence between the potential and the pH of aqueous solutions.

Monolithic porous carbon derived from polyvinyl alcohol for electrochemical double layer capacitors

Monolithic porous carbon (MPC) materials are fabricated through a facile hydrotherm- carbonization method by employing tin oxide as porogen and polyvinyl alcohol as carbon precursor. In addition, the effects of preparation conditions on the samples⿿ specific surface area (SSA) and pore size have been investigated in detail. The MPCs exhibit a fairly large SSA of about 674.15⿿1176.21m2g⿿1 and a pore volume of about 0.43⿿0.71cm3g⿿1 according to the preparing conditions. As electrodes for electrochemical capacitors, the as-prepared optimum MCP exhibits a relatively high specific capacitance of about 225Fg⿿1 together with remarkable high-rate capability and long-term cycling stability owing to its large SSA and the oxygen-containing groups on the surface. The fairly good capacitive performances of the prepared MCPs can be mainly attributed to their relatively large SSA and uniform pore distribution which can maximize the ion accumulation on the electrode surface and facilitate efficient electron and ion transportation. This easy method for MPCs with uniform porous structure will provide a promising opportunity to prepare high-performance electrode materials for energy storage.

Dynamics of spinodal decomposition coupled with chemical reaction in thermosetting phenol-formaldehyde resin-based solutions and its application in monolithic porous materials

A model comprised of a rate equation for polymerization and cross-linking reaction and the time-dependent Ginzburg–Landau equation for spinodal decomposition was utilized to describe reaction-induced spinodal decomposition (RISD). The effects of initial composition, curing temperature, and scaled diffusion coefficient and rate constant on the RISD dynamics were investigated numerically in thermosetting phenol-formaldehyde resin (PF)-based polymer solutions. As the initial composition increased, the final morphology varied from the regular droplet-like to interconnected pattern, and then transformed into another droplet-like one. The greater initial composition or higher curing temperature contributed to accelerate the RISD dynamics and caused the smaller dominant wavelength. When the curing point was determined, the increase of scaled diffusion coefficient gave rise to reduction of characteristic size and maximum structure factor, while the raise of scaled rate constant merely resulted in acceleration of the curing reaction. Based on the theoretical analyses, experiments were carried out to verify the influence of initial composition and curing temperature on the morphology of monolithic porous carbons. The results were in good agreement with the theoretical analyses and can provide guidance for synthesizing monolithic porous polymer and carbon materials with tunable pore morphology.

Monolithic carbons with spheroidal and hierarchical pores produced by the linkage of functionalized graphene sheets

We report a novel monolithic porous carbon constructed by the hydrothermal self-assembly of graphene oxide sheets with poly (vinyl alcohol) as the linker in the formation process of a three-dimensional (3D) structure. All the pores in this carbon have circular cross-sections and range from micropores to mesopores to macropores and are formed by the gradual removal of trapped water. This 3D graphene network together with unique spheroidal and hierarchical pore structure with macropore openings at the surface allows fast ion and electron transport into the innermost micropores. The carbon not only exhibits excellent capability for removal of dye pollutants and oils but also shows a good performance as an electrode material in lithium ion batteries. Moreover, it is also proved to be an ideal buffer for expanded active materials in electrochemical energy storage.

Monolithic coal-based carbon counter electrodes for highly efficient dye-sensitized solar cells

A novel method for the preparation of monolithic coal-based porous carbon counter electrodes (CEs) for high performance dye-sensitized solar cells has been reported. Rigid monolithic coal-based carbon CE has been synthesized by preferential densification of one side of porous carbon plate formulated by caking bituminous coal powder. The phase, surface composition, and surface micro&nanotexture of the monolithic porous carbon plates have been characterized by X-ray diffraction, X-ray photoelectron energy spectroscopy, nitrogen sorption, scanning electron microscopy, and transmission electron microscopy. The coal-based carbon monolithic CEs exhibit a low internal resistance and high energy conversion efficiency (up to 6.38%). When the surface of the porous substrate was modified with mesoporous carbon as catalytic layer, the energy conversion efficiency can be further enhanced up to 8.73%, which is comparable to that of the platinized fluorine-doped tin oxide glass based device.

Polymerization-induced spinodal decomposition of ethylene glycol/phenolic resin solutions under electric fields

Temporal evolution of polymerization-induced spinodal decomposition (PISD) under electric fields was investigated numerically in ethylene glycol∕phenolic resin solutions with different initial composition. A model composed of the nonlinear Cahn-Hilliard-Cook equation for spinodal decomposition and a rate equation for curing reaction was utilized to describe the PISD phenomenon. As initial composition varied, deformed droplet-like and aligned bi-continuous structures were observed in the presence of an electric field. Moreover, the anisotropic parameter (D), determined from the 2D-FFT power spectrum, was employed to quantitatively characterize the degree of morphology anisotropy. The value of D increased quickly in the early stage and then decreased in the intermediate stage of spinodal decomposition, which was attributed to the resistance of coarsening process to morphology deformation and the decline of electric stress caused by polymerization reaction. The results can also provide a guidance on how to control the morphology of monolithic porous polymer and carbon materials with anisotropic structures.