Nanoporous Carbon Research Articles

Disordered carbon structures enhance capacitive storage

Electrochemical energy storage (EES) is one of the key technologies in global research, focusing on the efficient storage and utilization of electrical energy generated from intermittent sources. The development of EES systems with high energy and power density is essential for meeting future energy demands electrochemical capacitors, such as capacitors, are capable of storing electrical energy obtained from intermittent sources and enabling the rapid energy transfer and transformation. Among these, electrical double-layer capacitances (EDLCs) within porous carbon materials (Fig. 1a), are commercially popular due to their excellent conductivity and relatively low cost. Despite their advantages, the complex structure of nanoporous carbon materials challenges in optimizing supercapacitor performance. While previous research has suggested that adjusting the pore size of nanoporous in carbon materials can enhance capacitive performance [1], conflicting reports and the lack of a definitive correlation between capacitance and pore size remain issues [2]. Understanding the relationship between the structure of carbon materials and their capacitance is crucial for the design of devices with high energy density effectively.

Iron oxide Green synthesized nanoparticles for improved performance in Monolithic Dye Sensitized Solar Cells

In order to improve photovoltaic efficiency in Monolithic Dye-Sensitized Solar Cells (MDSSCs), this study examined the effects of incorporating green produced iron oxide nanoparticles to a nanoporous carbon counter electrode. An extract from the leaves of Ocimum gratissimum was effectively used to synthesize iron oxide nanoparticles. The development of iron oxide nanoparticles was verified by optical absorption in the 350–450 nm range. With an average crystallite size of 47.9 nm, XRD patterns demonstrated the crystalline nature of the Iron oxide nanoparticles. Chemical bonds that may responsible for the nanoparticle production were found using FTIR investigations. An impressive 135.3% boost in efficiency was recorded for cell containing the Iron oxide nanoparticles, according to the MDSSC performance evaluation where DSSC without nanoparticles had a lower solar-to-electric power conversion efficiency of 1.7%, an open circuit voltage of 0.2625 V, a short-circuit current of 0.0723 mA/cm2, and a fill factor of 0.3630. The FeO CEs cell had an open-circuit voltage of 0.4274 V, a short-circuit current of 0.1042 mA/cm2, and a fill factor of 0.46. Their solar-to-electric power conversion efficiency was 4.0%. The potential of incorporating green-synthesised iron oxide nanoparticles into MDSSC counter electrode was shown by their great biocompatibility and even dispersion.

Synthesis and Characterization of Nanoporous Carbon Mg-MOF-C and Carbon Dioxide Adsorption Performance

A porous carbon material (Mg-MOF-C) was prepared by carbonization in the N2 atmosphere using Mg-MOF-74 as the precursor. Physicochemical properties of Mg-MOF-C materials were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FIRT), Thermogravimetric analyzer (TG), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), N2 adsorption/desorption isotherms (BET) and EDS. The adsorption properties of the products were studied Mg-MOF-C has a high specific surface area of up to 1739.29[Formula: see text]m2/g, and the pore volume of micropores was 0.98[Formula: see text]m3/g. Besides, 95% of the first adsorption is retained after five cycles. The adsorption processes agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model.

Improved Capacitive Performance of High‐Voltage Electric Double‐Layer Capacitors by Electrolyte Optimization Using Hierarchically Porous Carbon Electrodes

Advancement of the voltage window with stringent safety concerns is an imperative strategy to enhance the energy densities and output power delivery of electrical double‐layer capacitors (EDLCs). Solid‐state, water‐in‐salt (WIS), and ionic liquid‐based electrolytes are attractive and ideal choices for high‐voltage EDLCs due to their superior voltage window, electrochemical performance, and predominant safety aspects. Mindful of this, the current report demonstrates the electrochemical performance of new nanoporous carbon electrodes derived from waste dry leaves of Swietenia macrophylla with a high specific surface area (SSA) (1834 m2 g−1) in polymer–gel, WIS, and ionic liquids‐based electrolytes. Symmetric EDLC devices are fabricated using polymer gel solid‐state (PVA–Na2SO4), ionic liquids (EMIMBF4), and WIS (21 m LiTFSI) electrolytes with the electrochemical stability windows of (ESW) 2, 2.5, and 2 V, respectively. The assembled devices with Na2SO4/PVA, EMIMBF4, and 21 m LiTFSI (WIS) electrolytes‐based devices exhibit high energy densities of 40, 31, and 25 Wh kg−1 at 0.5 A g−1 and good output power delivery of 5, 6.23, and 3 kW kg−1 at 5 A g−1 with better cyclability features. Self‐discharging studies and systematic evaluation of high‐voltage EDLCs offer a sustainable method to develop high‐performance aqueous and diverse electrolyte‐based supercapacitors.

Auto-reduction of Au(III) on Fe-Doped, Pyrrolic-N-Modified nanoporous carbon derived from ZIF-8 for the electrochemical immunosensing of CA-125

Ovarian cancer (OC) is associated with high late mortality owing to hidden symptoms in the early stages and limited screening measurements. Therefore, it is urgent to develop a highly efficient label-free immunosensor for targeting cancer antigens. In this study, we developed a gold-loaded iron-doped nanoporous carbon (denoted as Au@Fe-NC) as an ideal substrate for cancer antigen detection with high specificity and sensitivity. First, an Fe, N-doped nanoporous carbon (Fe-NC) material was synthesized by carbonizing a Fe-doped metal-organic framework at 900 °C under continuous nitrogen flow. The resultant Fe-NC contains pyrrolic-N, which facilitates the auto-reduction of Au3+ to Au⁰ without requiring an external reducing agent. Thus, the Au@Fe-NC was spontaneously formed by mixing an aqueous HAuCl₄ solution with Fe-NC. The immunosensor developed using Au@Fe-NC exhibits outstanding stability as well as high sensitivity to carbohydrate antigen 125 (CA-125), a tumor marker, presenting a linear dynamic range of 0.1 pg mL−1 to 1 µg mL−1 and a detection limit of 0.1 pg mL−1. The proposed Au@Fe-NC-based immunosensor has the ability to detect CA-125 in human serum samples and is a promising material for OC diagnosis.

Typical MOFs-derived nanoporous carbon: Insight into structures, properties and Pb(II) adsorption mechanism

A series of nanoporous carbon (NC) materials were synthesized by direct carbonization of traditional metal organic frameworks (MOFs) including copper-based (HKUST-1), nickel-based (Ni-MOF), zinc-based (ZIF-8), zirconium-based (UiO-66) and iron-based (Fe-BTC) for the removal of Pb(II) from simulated waste water. The physical and chemical characteristics before and after adsorption were thoroughly investigated by Fourier transforms infrared spectroscopy (FTIR), X-Ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption analyses. The adsorption kinetics and isothermal thermodynamic properties and the effects of five central different cations on the removal of Pb(II) were compared. The adsorption kinetics were well described by the quasi-second-order model and the adsorption isotherm consistent with the Langmuir equation. The adsorption process of Pb (II) is feasible, spontaneous, endothermic and reusable on the five nanoporous carbons. Among them, Fe-BTC-NC showed the best adsorption performance for Pb (II), and the maximum adsorption capacity was 479.93 mg/g. This work highlights the applications of MOFs derived nanocarbon in heavy metal contaminated water treatment and offers a facile method for the design of novel nanocarbon materials.

Water Confinement in Nitrogen‐Rich Nanoporous Carbon Materials Revealed by In Situ Scanning Transmission X‐Ray Microscopy

AbstractThe interaction between water molecules and surfaces in porous carbon‐based materials plays a significant role in various fields including but not limited to catalysis, gas sorption, or electrochemical energy storage and conversion. The incorporation of nitrogen enhances the hydrophilicity of typically rather nonpolar carbon‐based materials but the molecular understanding of water chemical configuration in such porous materials remains incomplete. Water adsorption on nitrogen‐containing nanoporous carbon surfaces is governed by a subtle balance between water–water and water–surface hydrogen bonding interactions, which together determine the water structures formed and their stability. In this work, in situ Scanning Transmission X‐ray microscopy performed on individual nanoporous carbon particles under a humid atmosphere is used to elucidate the interactions between nitrogen‐containing carbon surfaces and water molecules. The hydrogen bonding of water is found to be nonuniform within the particles and to depend on the nanopore size and the chemical bonding of nitrogen atoms. The nature of the nitrogen sites interacting with water is further characterized by resonance inelastic X‐ray Scattering and near ambient pressure X‐ray Photoelectron Spectroscopy. This study provides new perspectives on water interaction when confined in nanoporous nitrogen‐rich carbons.

Engineering a Hierarchy of Disorder: A New Route to Synthesize High-Performance 3D Nanoporous All-Carbon Materials*.

A new nanoporous amorphous carbon (NAC) structure that achieves both ultrahigh strength and high electrical conductivity, which are usually incompatible in porous materials is reported. By using modified spark plasma sintering, three amorphous carbon phases with different atomic bonding configurations are created. The composite consisted of an amorphous sp2-carbon matrix mixed with amorphous sp3-carbon and amorphous graphitic motif. NAC structure has an isotropic electrical conductivity of up to 12000Sm-1, Young's modulus of up to ≈5GPa, and Vickers hardness of over 900MPa. These properties are superior to those of existing conductive nanoporous materials. Direct investigation of the multiscale structure of this material through transmission electron microscopy, electron energy loss spectroscopy, and machine learning-based electron tomography revealed that the origin of the remarkable material properties is the well-organized sp2/sp3 amorphous carbon phases with a core-shell-like architecture, where the sp3-rich carbon forms a resilient core surrounded by a conductive sp2-rich layer. This research not only introduces novel materials with exceptional properties but also opens new opportunities for exploring amorphous structures and designing high-performance materials.

Exploring Nanomaterials for Hydrogen Storage: Advances, Challenges, and Perspectives.

Hydrogen energy heralded for its environmentally friendly, renewable, efficient, and cost-effective attributes, stands poised as the primary alternative to fossil fuels in the future. Despite its great potential, the low volumetric density presents a formidable challenge in hydrogen storage. Addressing this challenge necessitates exploring effective storage techniques for a sustainable hydrogen economy. Solid-state hydrogen storage in nanomaterials (physically or chemically) holds promise for achieving large-scale hydrogen storage applications. Such approaches offer benefits, including safety, compactness, lightness, reversibility, and efficient generation of pure hydrogen fuel under mild conditions. This article presents solid-state nanomaterials, specifically nanoporous carbons (activated carbon, carbon fibers), metal-organic frameworks, covalently connected frameworks, nanoporous organic polymers, and nanoscale metal hydrides. Furthermore, new developments in hydrogen fuel cell technology for stationary and mobile applications have been demonstrated. The review outlines significant advancements thus far, identifies key barriers to practical implementation, and presents a perspective for future sustainable energy research. It concludes with recommendations to enhance hydrogen storage performance for cost-effective and long-lasting utilization.

Biomass nanoarchitectonics with activated rice husk char for nanoporous carbon as electrode material: Enhancing supercapacitor electrochemical performance

Nanoporous carbon from activated rice husk char was prepared via KOH activation at different ratios of rice husk: KOH, for using as electrode material in supercapacitor. The electrode could exhibit high performance in 6 M KOH aqueous electrolytes, particularly in terms of specific capacitance and power density. The Brunauer-Emmett-Teller (BET) analysis showed a high specific surface area of 2833 m²/g with a mesoporous structure in a sample activated with a 1:3 ratio of rice husk to KOH. In this sample, a high specific capacitance of 195.36 F/g was obtained at a current density of 1 A/g with excellent cycle stability of 99.87 % after continuous charge/discharge test for 10,000 cycles at 10 A/g. Furthermore, the fabricated symmetric coin cell exhibits a power density of 526.88 W/kg and an energy density of 14.77 Wh/kg. The practical application of this cell is demonstrated by its ability to power a 3 V LED light bulb for over 900 s.

Wettability, imbibition and interdiffusion of lithium-based water-in-salt electrolytes in nanoporous carbon in relation to energy storage: A neutron radiography study

Superconcentrated lithium salt electrolytes, or lithium-based Water-in-Salt (WiS) electrolytes emerge as alternative electrolytes in supercapacitors and advanced batteries, such as the Li–O2 ones, especially when combined with a mesoporous carbon with very high surface area. In this work, we analyze the wettability, imbibition, and diffusivity of very concentrated lithium salts in a bimodal mesoporous carbon with pores of 5 nm and 25 nm in diameter. For the first time a neutron radiography technique is used to determine the imbibition and interdiffusion of lithium salts in mesoporous carbon. We found that a 20 m LiTFSI aqueous solution wets the surface of graphite and mesoporous carbon better than water. As a consequence, this WiS electrolyte is embedded rather fast in the mesoporous carbon by the action of capillary forces, exhibiting an intrinsic permeability K = (1.16 ± 0.03).10−18 m2. Finally, by resorting to the different cross-section of the 6Li and 7Li isotopes for the neutron capture, we could analyze the diffusion of LiCl in D2O confined in the mesoporous carbon. The interdiffusion coefficient of the confined LiCl is 5.0 10−7 cm2 s−1, corresponding to a tortuosity coefficient τ = 1.32. This moderate confinement effect results from the strong ion association of the LiCl that precludes the electrostatic interactions of Li+ ions with the negative charge on the pore walls. In summary, the combined properties of the lithium-based WiS electrolytes and the mesoporous carbon allow us to glimpse their use in supercapacitors and Li–O2 batteries.

Pure Hydrogen and Methane Permeation in Carbon-Based Nanoporous Membranes: Adsorption Isotherms and Permeation Experiments.

This paper presents the results of adsorption and permeation experiments of hydrogen and methane at elevated temperatures on a carbon-based nanoporous membrane material provided by Fraunhofer IKTS. The adsorption of pure components was measured between 90 °C and 120°C and pressures up to 45 bar. The Langmuir adsorption isotherm shows the best fit for all data points. Compared to available adsorption isotherms of H2 and CH4 on carbon, the adsorption on the investigated nanoporous carbon structures is significantly lower. Single-component permeation experiments were conducted on membranes at temperatures up to 220 °C. After combining the experimental results with a Maxwell-Stefan surface diffusion model, Maxwell-Stefan surface diffusion coefficients Dis were calculated. The calculated values are in line with an empirical model and thus can be used in future multi-component modeling approaches in order to better analyze and design a membrane system. The published adsorption data fill a gap in the available adsorption data for CH4 and H2.

Insights into the adsorption behavior of tetracycline in various shaped carbon nanopores: Interplay between mass transfer and adsorption

Porous carbon is commonly used in the effective removal of antibiotics from water. The geometry of nanopores plays a vital role in determining the adsorption properties of porous carbon. Aiming to reveal the adsorption mechanism and the dependence on the porous geometry, the mass transfer and adsorption performance of tetracycline (TC) in various shaped carbon nanopores was observed in this study by molecular dynamics (MD) simulation. The results show that the molecular diffusion of water and TC in nanopores is confined than that in bulk solution. The mass transfer in cylindrical through pores (THC) is more efficient than that in blind pores. The accumulated presence probability of TCs within the nanopore of THC is over twice as high as in the blind nanopores. THC exhibits the best adsorption rate and capacity in this study, and the adsorption ability of the blind nannopores follows the order BHC-Cy (cylindrical blind pore) > BHC-Co (conical blind pore) > BHC-Sp (spherical blind pore). Both the cylindrical and bottom surface in BHC-Cy are effective adsorption sites, while the adsorption is seldom found in the bottoms of BHC-Co and BHC-Sp. Surface diffusion of adsorbed TC molecules along the carbon surface was investigated. The sphere-shaped blind pore was found unfavorable for the adsorption of TC from water.

Dual single atomic Fe-Ni sites in N‑doped nanoporous carbon for high-efficiency potassium periodate activation toward pollutant abatement

Diatomic catalysts (DACs) with atomically isolated metal pairs hold the potential for activating potassium periodate (PI) in sustainable pollution control, yet their synthesis poses a significant challenge. In this study, Fe/Ni species anchored to a nitrogen-doped carbon as diatomic catalysts (FeNi-NC DACs) were precisely synthesized by direct carbonization of metal–organic frameworks (MOFs) assembled by Fe/Ni-doped ZnO nanoparticles and used for the effective decomposition of organic pollutants through PI activation. As anticipated, FeNi-NC exhibited superior catalytic properties due to the abundance of adjacent bimetallic active sites (Fe/Ni-Nx), rich doped nitrogen, high specific surface area, and electron transport conductivity, surpassing single-atom Fe-NC and Ni-NC, as well as nonmetallic NC catalysts. Free radical quenching, electron paramagnetic resonance, and electrochemical experiments have shown that the FeNi-NC/PI system can oxidize organic compounds through non-free radical oxidation pathways, including singlet oxygen (1O2) oxidation and mediated electron transfer processes. Electron transfer mediated by FeNi-NC/PI* complexes is the primary mechanism for organic oxidation. Additionally, the FeNi-NC catalyst demonstrated remarkable stability in both inorganic-containing and real water samples, as well as in continuous-flow microreactors. This study introduces a novel approach for designing highly efficient DACs and offers fundamental insights into the mechanism of PI-activated oxidation of organic pollutants.

The role of nanoporous carbon materials for thiophosphate-based all solid state lithium sulfur battery performance

Due to their high theoretical energy density, all solid state lithium sulfur batteries (LS-SSB) represent one of the most promising candidates for next-generation energy storage systems. Whilst high sulfur utilizations have been published for several cathode compositions and preparation methods in recent years, there is still a lack of clarity regarding the influence of the used carbon. Furthermore, LS-SSBs face challenges in up-scaling as the common preparation methods including high energy ball milling are time consuming, batch-wise and need high energy impact. In this study, high sulfur utilization >1600 mAh gS−1 and reversibility with 80 % of initial discharge capacity after 60 cycles is achieved, using a more time-efficient preparation method with drastically lowered energy impact by selecting a suitable carbon. Additionally, the influence of the carbon nanostructure on the electrochemical performance is discussed. This study provides guidance in selecting nanostructured carbon materials to enable cost-efficient, up-scalable preparation methods for LS-SSBs without compromising on the excellent electrochemical performance.

A Precursor-Derived Ultramicroporous Carbon for Printing Iontronic Logic Gates and Super-Varactors.

A liquid precursor for 3D printing ultramicroporous carbons (pore width <0.7nm) to create a novel in-plane capacitive-analog of semiconductor-based diodes (CAPodes) is presented. This proof-of-concept integrates functional EDLCs into microstructured iontronic devices. The working principle is based on selective ion-sieving, controlling the size of the electrolyte ions, and the nanoporous sieving carbon's pore size. By blocking bulky electrolyte ions from entering the sub-nanometer pores, a unidirectional charging characteristic with controllable ion flux is achieved, leading to diodic U-I characteristics with a high rectification ratio. The liquid precursor approach enables successful printing of miniaturized in-plane CAPodes. A combination of inkjet and extrusion printing techniques with suitable inks is explored to fabricate electrode materials with engineered porosity. Deliberate fine-tuning of the ultramicroporous carbon's porosity and surface area is achieved using a customized carbon precursor and CO2 etching techniques. Electrochemical evaluation of the printed CAPodes demonstrates successful miniaturization compared with macroscopic film assembly. 3D manufacturing and miniaturization allow for the integration of CAPodes into logic gate circuits (OR, AND). For the first time, these switchable devices are used as variable capacitors in a high-pass filter application, adjusting the cut-off frequency of applied alternating voltage analogous to an I-MOS varactor.

Thermochemical Activation of Wood with NaOH, KOH and H3PO4 for the Synthesis of Nitrogen-Doped Nanoporous Carbon for Oxygen Reduction Reaction.

Carbonization of biomass residues followed by activation has great potential to become a safe process for the production of various carbon materials for various applications. Demand for commercial use of biomass-based carbon materials is growing rapidly in advanced technologies, including in the energy sector, as catalysts, batteries and capacitor electrodes. In this study, carbon materials were synthesized from hardwood using two carbonization methods, followed by activation with H3PO4, KOH and NaOH and doping with nitrogen. Their chemical composition, porous structure, thermal stability and structural order of samples were studied. It was shown that, despite the differences, the synthesized carbon materials are active catalysts for oxygen reduction reactions. Among the investigated carbon materials, NaOH-activated samples exhibited the lowest Tafel slope values, of -90.6 and -88.0 mV dec-1, which are very close to the values of commercial Pt/C at -86.6 mV dec-1.

Nanoporous Carbon Materials Derived from Zanthoxylum Bungeanum Peel and Seed for Electrochemical Supercapacitors.

In order to prepare biomass-derived carbon materials with high specific capacitance at a low activation temperature (≤700 °C), nanoporous carbon materials were prepared from zanthoxylum bungeanum peels and seeds via the pyrolysis and KOH-activation processes. The results show that the optimal activation temperatures are 700 °C and 600 °C for peels and seeds. Benefiting from the hierarchical pore structure (micropores, mesopores, and macropores), the abundant heteroatoms (N, S, and O) containing functional groups, and plentiful electrochemical active sites, the PAC-700 and SAC-600 derive the large capacities of ~211.0 and ~219.7 F g-1 at 1.0 A g-1 in 6 M KOH within the three-electrode configuration. Furthermore, the symmetrical supercapacitors display a high energy density of 22.9 and 22.4 Wh kg-1 at 7500 W kg-1 assembled with PAC-700 and SAC-600, along with exceptional capacitance retention of 99.1% and 93.4% over 10,000 cycles at 1.0 A g-1. More significantly, the contribution here will stimulate the extensive development of low-temperature activation processes and nanoporous carbon materials for electrochemical energy storage and beyond.

N/S Dually Doped Nanoporous Carbon for CO2 Adsorption

N/S Dually Doped Nanoporous Carbon for CO₂ Adsorption

Carbothermal reduction between MOF-derived carbon and spent battery powder for metal recovery: Thermogravimetric behavior and kinetic analysis

The combined hydrometallurgical and pyrometallurgical process is an innovative method for recycling spent batteries. This process includes a carbothermic reduction step that reduces the valence of valuable metals in the batteries, facilitating subsequent leaching, which is a crucial stage in the recycling process. Additionally, the use of new carbon materials in electrode materials for ternary lithium batteries, referred to as LIBs, is increasing. These materials typically have high porosity and a large specific surface area. In this study, two types of nanoporous carbon (NC) commonly used in electrodes, namely Al-PCP-800 and ZIF-8–800, were prepared to investigate their effects on the carbothermic reduction stage of recycling spent batteries. The carbothermal reduction reactions of spent LIBs powder mixed with activated carbon and the two types of NC were examined using a thermogravimetric balance (TG/DTG). Kinetic characteristics were calculated in the interval of maximum weight loss rate using five kinetic models: VM, RPM, URCM, KAS, and FWO. The kinetic analysis revealed that the KAS and FWO models, which exhibited higher correlation coefficients, more accurately described the carbothermic reduction reactions. TG analysis showed that the sample mixed with 25 % ZIF-8–800 achieved the lowest temperature at the weight loss peak for the maximum weight loss rate, 769°C at a heating rate of 20 °C/min. Additionally, the reaction activity of NC with the positive material in the spent LIBs powder was stronger than that of activated carbon. Among the models, the sample mixed with 25 % ZIF-8–800 exhibited the lowest activation energies, recorded at 171.83, 28.48, 122.22, 199.49, and 143.45 kJ/mol, respectively. XRD and XPS characterizations of the roasted products from the spent LIBs powder mixed with the three carbon materials at various roasting end temperatures demonstrated that the cathode materials initially decomposed into Mn3O4, NiO, CoO, Li2O, and Li2CO3. At higher temperatures, Mn3O4, NiO, and CoO were further reduced to MnO, pure metallic Co, and pure metallic Ni, respectively. The sample mixed with ZIF-8–800 showed the most substantial reduction of metallic elements, with the relative contents of pure metallic Ni, pure metallic Co, and low-valent Mn elements reaching 5.50 %, 4.41 %, and 71.29 %, respectively, at a final roasting temperature of 800 °C. Therefore, NC demonstrated greater reactivity in the reduction reactions with the cathode material in the spent LIBs powder, ranking in the order of ZIF-8–800 > Al-PCP-800 > activated carbon.