Zeolite-templated Carbon Research Articles

Adsorption and energy storage characteristics of ionic liquids in porous zeolite-templated carbon materials

The energy storage capacity of supercapacitors is closely related to the capacity of their electrode materials to adsorb electrolytes. Porous zeolite-templated carbon (ZTC) materials are a type of porous carbon material with a well-defined spatial structure and are thus promising electrode materials. This study utilizes molecular dynamics simulations to compare the ion number density and charge density distributions of the [EMI][BF4] ionic liquid for various ZTC materials, while also examining the ion adsorption characteristics for different electrode charges. Parameters such as the degree of confinement (DOC) and the charge compensation per carbon (CCpC) are introduced to represent the ion adsorption and charge storage capacity of the materials, with a higher DOC indicating a greater number of encapsulated ions and a higher CCpC indicating a more efficient charge storage. The findings suggest that materials with a larger pore size tend to exhibit increased ion adsorption. However, many CCpC adsorption sites that can store more charge are then found in positions with a smaller DOC. This work unveils the ion adsorption characteristics of ZTC materials in charged electrode and presents the differential capacitance curves of various materials, thereby providing a theoretical foundation for the utilization of ZTC materials as electrodes in supercapacitors.

A Zeolite-Templated Carbon Synthesized from Extralarge-Pore Zeolite ZEO-1.

A new member of the zeolite-templated carbon (ZTC) family with unprecedented properties has been developed using extralarge-pore zeolite ZEO-1 (JZO) as a template. The resulting ZTC-JZO exhibits strong X-ray diffraction long-range order, replicating three distinct zeolite planes with different lattice spacings. By harnessing the enhanced micropore void volume in the ZEO-1 template, we achieved the first ZTC with a bimodal micropore size distribution, resulting in superior skeleton density and thickness. The ZTC-JZO presents high electrical conductivity and demonstrates improved electrocatalytic activity in the oxygen reduction reaction.

Spectroscopic characterization of black N- and P-doped zeolite templated carbons

The incorporation of heteroatoms (X) into the zeolite-templated carbon (ZTC) structure is a widely used technique to tailor its properties for specific applications such as gas adsorption, methane and hydrogen storage, and catalysis. However, the literature lacks sufficient data on Fourier-transform infrared spectroscopy (FTIR) analysis of ZTCs due to the challenge in obtaining high-quality FTIR spectra required for accurate assignment of the C–X bands, primarily caused by the black mass effect. In this work we prepared nitrogen (N) and phosphorus (P) doped ZTC samples using FAU type zeolite as a template and furfuryl alcohol as a carbon precursor. The Raman results confirmed the presence of medium-sized aromatic structures and also showed that doping these structures with N and P leads to some defects, although the overall conformation remains structurally intact. The FTIR spectra of the ZTC materials were obtained by controlling the preparation procedure and humidity, enabling clear analysis of the black samples. A Density Functional Theory (DFT) model based on the dimeric buckybowl structure was developed and complemented by experimental results obtained from X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and FTIR. The proposed DFT model was then used for deconvolution and precise band assignment of the experimental FTIR spectra. The FTIR deconvolution study also supported the incorporation of N and P into the ZTC as well as the presence of primarily two types of nitrogen species, amide (primary and secondary) and pyridine-like, while P was mainly incorporated as triphenylphosphine oxide and phosphonic acid.

Enhanced hydrogen adsorption properties of Zeolite Templated Carbon via chemical activation: DFT study

In this study, Density Functional Theory (DFT) simulation method was applied to show that hydrogen-storage properties of Zeolite Templated Carbon (ZTC) can be enhanced via chemical activation. Study results calculated via simulation and the Monte Carlo integration technique showed that in comparison to unactivated ZTC, the theoretical specific surface area (SSA) for Zeolite Templated Activated Carbon (ZTAC) increased by 4.79 and 2.13 %, when activated with either Zinc dichloride (ZnCl2) or Potassium Hydroxide (KOH), respectively. In addition, calculation of accessible surface area (ASA) resulted in 7809.40 m2/g and 7611.74 m2/g, correspondingly. Simulations of H2 adsorption revealed that H2 molecules were adsorbed primarily on the concave region of the ZTAC. Also, it was found the that the largest amountof H2 adsorbed molecules on ZTAC activated with either ZnCl2 or KOH were13 and 15, and the average binding energies were 0.184 eV and 0.202 eV, respectively. In this regard, the maximum hydrogen storage capacity obtained in this study was 5.2 wt% (ZTAC-13H2) and 5.95 wt% (ZTAC-15H2) with a volumetric density of 0.065 kg H2/L and 0.074 kg H2/L for the ZTAC activated with either ZnCl2 or KOH. These results are in accordance with the U.S. Department of Energy (DOE) ultimate target by the 2025 year. In addition, thermal stability and desorption temperatures of ZTAC structures were determined via molecular dynamics simulations and through the van’t Hoff equation, showing that hydrogen molecules were easy to desorb at room temperature (T=300 K). These results pose these systems suitable for automotive onboard applications, leading to future research on synthesis techniques of ZTAC materials which certainly require more experimental investigation.

Polyelectrolyte-coated zeolite-templated carbon electrodes for capacitive deionization and energy generation by salinity exchange

As global demands for freshwater and renewable energy intensify, capacitive deionization (CDI) emerges as a promising technique for water purification, desalination, and ionic separation. Reciprocally, energy harvesting has been made possible from exchanging solutions with different salinity, using the so-called capacitive mixing (CapMix) methods, now taking their first steps towards a wider range of application. In all the techniques mentioned, porous electrodes are used in order to maximize the stored charge, making it essential to properly select the material of which the electrode is composed. This work focuses on exploring the performance of zeolite-templated carbon (ZTC) as a highly promising electrode material. ZTC offers ordered pore distribution and high electrical conductivity, making it in principle ideal for energy harvesting and water purification applications. In order to optimize its performance, the surface of the ZTC is for the first time modified by application of polyelectrolyte coatings, resulting in so-called soft electrodes or SEs. This combination of electrode material and functionalization gives rise to a highly efficient and low energy-consuming strategy to fully realize the potential of this carbon material in CDI and CapMix techniques for tackling global freshwater and energy challenges. Energy and power generation values up to 25 mJ and 7.5 mW m−2 have been obtained (with measured potential rises of 131 mV by only exchanging salinities of the bathing solution), which overcome values such as 4.3 mW m−2 previously found in our laboratory under similar conditions.

Controlling the structure of nitrogen-doped zeolite-templated carbon for CO2 capture based on the synthesis conditions

The surface chemistry and the textural properties of nitrogen-doped zeolite-templated carbon materials (N-ZTC) are decisive for their functionality in CO2 capture. This study analyses how the synthesis conditions affect the structure, formation of N-containing functional groups, thermal stability and CO2 capture of N-ZTC in comparison with nitrogen-free ZTC. Faujasite as a hard template and chemical vapour depositions (CVD) with propene and acetonitrile were used for the synthesis of ZTC and N-ZTC, respectively. XRD, SEM, N2 and CO2 sorption, XPS and TG/DSC analyses showed that the structural ordering and microporous volume in N-ZTC increases with increasing synthesis temperature. Conversely, at higher temperatures, the content of basic pyridinic groups in N-ZTC decreases in favour of stable graphitic nitrogen. The Lewis acid−base interaction of CO2 with the pyridinic groups provides the highest adsorption heats, the highest affinity for CO2 compared to N2 and enhances CO2/N2 selectivity (CO2/N2 selectivities of 127, 95, 89, and 66 for N-ZTC750°C, N-ZTC800°C, N-ZTC850°C and ZTC, respectively). The maximum adsorption capacity was achieved for N-ZTC800°C still yielding a high content of basic groups and a larger micropore volume compared to N-ZTC750°C. The decisive factor for the selectivity is thus the presence of basic centers attainable in N-ZTC at a lower synthesis temperature. The maximum adsorption capacity is associated with a large microporous volume and basic centers in N-ZTC synthesized at medium temperatures. The energy of CO2 adsorption by Lewis acid−base interactions and well-developed micropores are decisive for high selectivity and large adsorption capacity for efficient CO2 capture using N-ZTC materials.

Zeolite-templated carbon synthesized with ion-exchanged FAU-zeolite using alkaline earth metal ions for the selective adsorption of C2 hydrocarbons over C1 hydrocarbon

In this study, zeolite-templated carbon (ZTC) was synthesized using ion-exchanged faujasite-Y (FAU, NaY) zeolites with different alkali earth metals (Mg2+, Ca2+, Sr2+, and Ba2+) to investigate the effects of these metals on the synthesis, characteristics, and C2/C1 hydrocarbon separation performance of ZTC. Thermogravimetric and temperature-programmed desorption of NH3 (TPD-NH3) analyses showed that carbon deposition tends to occur outside the pores because of the increasing number of moderate acid sites as the atomic number increases. In particular, in the case of FAU-ZTC(Ca) synthesized using CaY as the ZTC template, carbon accumulated inside the pores owing to the distribution of the appropriate acid strength, resulting in the highest specific surface area of 2,835 m2/g among the synthesized ZTCs. The combined X-ray photoelectron and Raman spectroscopy results confirm that these defect sites of ZTC act as adsorption sites for large molecules such as C2H4 and C2H6. The isothermal adsorption of CH4, C2H4, and C2H6 showed that FAU-ZTC(Ca) exhibited the highest adsorption capacity ratios of C2H4 and C2H6 to CH4, with a C2H6/CH4 ratio of 5.897 and C2H4/CH4 ratio of 5.288, respectively. The effective pore size ranges affecting the adsorption of CH4, C2H4, and C2H6 determined using linear regression analysis are 0.4 to 0.6 nm for CH4 and 0.6 to 1.1 nm for C2H4 and C2H6. Molecular simulations confirmed that the adsorption energy was maximized by the interaction between the hydrogen atoms of the hydrocarbons and the carbon atoms of ZTC. Furthermore, C2H4 and C2H6 require larger pores than CH4 adsorption because C2H4 and C2H6 prefer to lie horizontally rather than vertically in the pores of the ZTC.

Optimization of Porous Structures of Carbon Matrices for Loading Red Phosphorus to Achieve High-Capacity and Long-Life Anodes for All-Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLIBs) using sulfide electrolytes and high-capacity alloy-type anodes have attracted sizable interest due to their potential excellent safety and high energy density. Encapsulating insulating red phosphorus (P) inside nanopores of a carbon matrix can adequately activate its electrochemical alloying reaction with lithium. Therefore, the porosity of the carbon matrix plays a crucial role in the electrochemical performance of the resulting red P/carbon composites. Here, we use zeolite-templated carbon (ZTC) with monodisperse micropores and mesoporous carbon (CMK-3) with uniform mesopores as the model hosts of red P. Our results reveal that micropores enable more effective pore utilization for the red P loading, and the P@ZTC material can achieve a record-high content (65.0 wt %) of red P confined within pores. When used as an anode of ASSLIBs, the P@ZTC electrode delivers an ultrahigh capacity of 1823 mA h g-1 and a high initial Coulombic efficiency of 87.44%. After 400 deep discharge-charge cycles (running over 250 days) at 0.2 A g-1, the P@ZTC electrode still holds a reversible capacity of 1260 mA h g-1 (99.92% capacity retention per cycle). Moreover, a P@ZTC||LiNi0.8Co0.1Mn0.1O2 full cell can deliver a reversible areal capacity of over 3 mA h cm-2 at 0.1C after 100 cycles.

A novel zeolite template carbon (ZTC) for pharmaceutical removal in advanced wastewater treatment

This scientific article investigates the adsorption of Ketoprofen using a novel zeolite template carbon (ZTC) characterized by X-ray diffraction (XRD) as a type 2 zeolite with a high surface area confirming its ZTC nature. The material exhibits excellent thermal stability, and scanning electron microscopy (SEM) reveals a well-defined and homogeneous structure. Kinetic studies indicate that the pseudo-first-order (PFO) model best describes adsorption, demonstrating rapid adsorption with high removal efficiency. Isotherm results reveal a theoretical maximum adsorption capacity of 280 mg g−1 at 298 K, which is spontaneous, favorable, and exothermic. The ZTC can be efficiently utilized for up to 5 adsorption cycles, demonstrating its stability. Moreover, practical application in treating real effluents from a river water source showed a removal efficiency exceeding 84 % for the contaminants. The findings suggest the promising potential of ZTC in environmental remediation processes and advanced wastewater treatment.

Voltage regulation toward stable cycling of sodium vanadium oxy-fluorophosphates for high-performing, mechanically robust aqueous sodium-ion hybrid capacitors

Sodium vanadium oxy-fluorophosphates (Na3V2O2x(PO4)2F3−2x, NVOPF, 0 ≤ x ≤ 1) are promising cathodes for aqueous sodium-ion hybrid capacitors (ASIHCs) due to their high theoretical capacity and operation potential. However, the extremely poor cycle life and unclear failure mechanism greatly hinder their application in ASIHCs. Here, the intrinsic capacity degradation mechanism of NVOPF is elucidated and a unique voltage regulation strategy is proposed. By slightly compressing the charge cut-off voltage to 1.0 V (vs. SCE, saturated calomel electrode), the vanadium dissolution of NVOPF nanocomposite is significantly suppressed and superior cycling stability is achieved (79.67 % after 800 cycles), among the best reported for NVOPF operating in aqueous electrolytes. Microporous zeolite-templated carbon (ZTC) with ultra-large surface area is selected as a unique capacitive anode for pairing and intentionally activated via an electrochemical oxidation, providing huge pseudocapacitance that is ∼23 times higher than pristine ZTC. Furthermore, a high-performing 2.1 V quasi-solid-state NVOPF-based ASIHC is developed by designing an electrode-compatible polyacrylamide (PAM)-17 m (mol kg−1) NaClO4 hydrogel electrolyte with high ionic conductivity and adhesiveness, which not only provides recordable cycle stability, superior rate performance and high energy/power density, but also demonstrates exceptional safety, flexibility, and robust durability against extreme conditions, including short circuit, nail penetration and mechanical damage.

Zeolite-Templated Carbons Supported Rh and Ru Electrocatalysts for Highly Active Hydrogen Evolution Reaction.

Here, we report the systematical synthesis of zeolite-templated carbon (ZTC) supported Ru and Rh mono- or bi-metallic electrocatalysts towards hydrogen evolution reaction (HER). The zeolite A or ZSM-5 derived ZTC supports and metal sites were adjusted, and all electrocatalysts outperformed the commercial Pt/C electrocatalyst for HER performance. In particular, the RhRu/(ZTC/ZSM5) sample exhibited superior catalytic performance with the overpotential of 24.8 mV@10 mA ⋅ cm-2, and outstanding stability with 1 mV drop after 20000 cyclic voltammetry circles. This work offers a simple impregnation method for the synthesis of highly performed HER electrocatalysts supported on porous zeolite-templated carbon.

Insights into the removal of volatile organic compounds by three-dimensional ordered microporous zeolite-templated carbon: A combined experimental study and density functional theory calculation

Volatile organic compounds (VOCs) threaten human health and the ecological environment, requiring to be removed timely. Zeolite-templated carbon with and without sulfur (ZTC and S-doped ZTC) was prepared by the chemical vapor deposition (CVD) method in a rotating bed reactor and used to remove VOCs. ZTC samples showed narrow and ordered microporous structure (0–2 nm), high specific surface area (2049.05–1732.06 m2/g), abundant pore volume (1.28 – 1.16 cm3/g), and uniform sulfur distribution (S-doped ZTC). Afterwards, the VOCs adsorption capacity was tested at 30, 60, and 90 °C. The results showed that S-doped ZTC exhibited higher benzene (138.2 mg/g) and toluene (171.8 mg/g) adsorption capacities at 30 °C than those performed at 60 and 90 °C owing to the exothermic process. Moreover, S-doped ZTC showed better VOCs adsorption capacity than ZTC-RC due to the combination of physical and weak chemical adsorption. Subsequently, S-doped ZTC captured more toluene (171.8 mg/g) than benzene (138.2 mg/g) because of the dipole–dipole interaction. Furthermore, Fourier transform infrared spectrum (FTIR) and density functional theory (DFT) calculation revealed that inorganic components (NH3, NO, and SO2) imposed a negative effect on VOCs adsorption due to the comparative adsorption. This study offered insights into how ZTC structure and sulfur modification affected the adsorption of VOCs, providing a reliable guideline for the preparation and utilization of adsorbents used to remove VOCs.

CO2 adsorption by coal fly ash zeolite and modified zeolite-templated carbon

Coal fly ash (CFA), as the main by-product of coal-fired power plants, has a high content of silica-aluminium elements that can be used to prepare zeolite by the alkali fusion method with sound CO2 adsorption capacity. Among the four effect factors of Si/Al, NaOH/CFA, H2O/AFP(alkali fusion product), and crystallisation time, NaOH/CFA had the greatest effect on the CO2 adsorption performance of coal fly ash zeolite (CFAZ), followed by Si/Al and H2O/AFP, and crystallisation time had the least effect. The CO2 adsorption performance of the samples was tested and analysed using the thermal analysis method, the CO2 adsorption amount of CFAZ reached 4.23 mmol g–1 (30 °C, 101 kPa). In addition, the CFAZ and the zeolite-templated carbon (ZTC) adsorption performance is poor at high temperatures. The co-precipitation method modification of CFAZ and ZTC can produce layered double hydroxide derived material, which can adsorb CO2 at high temperatures reached at 3.35 mmol/g (650 °C, 101 kPa). Moreover, ZTC modified with polydivinylbenzene as the hydrophobic material has a sound CO2 adsorption effect in high-humidity environments. Thus, different adsorbents also could be produced using CFA to capture CO2 with a wide temperature range between 25 and 650 °C.

Hierarchically porous zeolite-templated carbon embedded with manganese oxide for long-cycling asymmetric supercapacitor

Manganese oxide-carbon composite materials were prepared by impregnation of manganese nitrate solution into a hierarchically meso-microporous zeolite-templated carbon. The manganese component was majorly incorporated within the mesoporous region as encapsulated by an open microporous carbon framework. Analysis of the composite structure by electron microscopy and nitrogen adsorption showed a possibility for mitigating the manganese leaching problem while facile diffusion of the electrolyte ions was allowed through microporous carbon windows built with sp2 frameworks. This analysis was consistent with the enhanced cycling stability of the asymmetric supercapacitor in an aqueous medium.

MnN4 embedded zeolite-templated carbon for methylamine and trimethylamine sensing: Insights from DFT study

From the perspective of raw material losses and human health, monitoring fish-based food quality has become more prominent. As a nondestructive technology, gas sensors have received extensive attention for evaluating the freshness of fish. In this study, the sensing and electronic properties of methylamine (MA) and trimethylamine (TMA) molecule adsorption on MnN4 embedded zeolite templated carbon (MnN4-C) were studied by density functional theory (DFT) method. The results show that the MnN4-C exhibits good structural stability, and displays high sensitivity toward MA and TMA gases by analysis of the interaction distance, adsorption energy, charge transfer and sensing response. It is worth noting that the ambient humidity has demonstrated no effect on the gas-sensing properties of MnN4-C for the studied gases. Meanwhile, applying a positive electric field can increase the adsorption energy and charge transfer, which enhances the MA and TMA gas sensitivity of MnN4-C. The recovery time reveals that MnN4-C can be an excellent reusability sensor for MA and TMA gases. This study provides theoretical direction for exploring the sensing application of MnN4-C in evaluating freshness of fish.

Impact of thermal ethylene degradation in zeolite-templated carbon synthesis

Which is the best temperature for the synthesis of Zeolite-Templated Carbons (ZTCs)? This is the question which will be foregrounded in the present article. ZTCs were achieved using ethylene on protonic beta zeolite at different synthesis temperatures comprised between 490 and 890 °C. By comparing the results achieved from TGA, nitrogen physisorption at 77 K, XRD and XPS, an optimal ZTC synthesis temperature could be determined. For low temperature synthesis (i.e. 490 °C), textural defects arise in the carbon network, possibly related to the low reactivity of ethylene. At temperatures above 700 °C thermally induced ethylene transformation was evidenced, leading to the development of carbon species on the external surface of the zeolite and hence to the generation of composite materials. Below 700 °C, ZTC formation exclusively proceeds through a zeolite acid-site catalyzed mechanism, whilst with increasing temperature the thermally induced ethylene transformation path gains impact. We further prove that ZTC/turbostratic carbon composites can be achieved through a purely thermally induced ethylene transformation path by using an all-silica beta zeolite as template.

Molecular dynamic study on the transport properties of ionic liquids in ZTC porous carbon materials

The adsorption and diffusion behavior of ions within electrodes have a significant impact on the energy density and charging/discharging speed of supercapacitors. Zeolite-Templated Carbon (ZTC) material, a type of porous carbon material characterized by well-defined pore shape and spatial structure, is recognized as a promising electrode material owing to its numerous advantages. This study employs molecular dynamics simulations to investigate the diffusion and adsorption profiles of ionic liquids [EMI][BF4] in different types of ZTC materials as electrodes. Additionally, the effect of ion size, pore dimension, pore shape, and the properties of the adsorbed ions are discussed. The degree of confinement (DOC) and ion diffusivity are thoroughly analyzed to elucidate the transport behavior of ions within the ZTC pores. The results demonstrate that the diffusion coefficient and degree of confinement of ionic liquids predominantly depend on the anion size and the pore size of the porous carbon. Surprisingly, in certain cases, larger anions exhibit enhanced diffusion ability and adsorption effect. These findings unravel the underlying transport mechanism of ions in ZTC materials and provide valuable theoretical insights for the application of ZTC materials as electrodes in the field of supercapacitors.

Exploring the Potential of Hierarchical Zeolite-Templated Carbon Materials for High-Performance Li-O2 Batteries: Insights from Molecular Simulations.

The commercialization of ultrahigh capacity lithium-oxygen (Li-O2) batteries is highly dependent on the cathode architecture, and a better understanding of its role in species transport and solid discharge product (i.e., Li2O2) formation is critical to improving the discharge capacity. Tailoring the pore size distribution in the cathode structure can enhance the ion mobility and increase the number of reaction sites to improve the formation of solid Li2O2. In this work, the potential of hierarchical zeolite-templated carbon (ZTC) structures as novel electrodes for Li-O2 batteries was investigated by using reactive force field molecular dynamics simulation (reaxFF-MD). Initially, 47 microporous zeolite-templated carbon morphologies were screened based on microporosity and specific area. Among them, four structures (i.e., RHO-, BEA-, MFI-, and FAU-ZTCs) were selected for further investigation including hierarchical features in their structures. Discharge product cluster analysis, self-diffusivities, and density number profiles of Li+, O2, and dimethyl sulfoxide (DMSO) electrolyte were obtained to find that the RHO-type ZTC exhibited enhanced mass transfer compared to conventional microporous ZTC (approximately 31% for O2, 44% for Li+, and 91% for DMSO) electrodes. This is due to the promoted formation of small-sized product clusters, creating more accessible sites for oxygen reduction reaction and mass transport. These findings indicate how hierarchical ZTC electrodes with micro- and mesopores can enhance the discharge performance of aprotic Li-O2 batteries, providing molecular insights into the underlying phenomena.

Effect of Particle Size on the Sodium Ions Utilization Efficiency of Zeolite-Templated Carbon as the Anode in a Sodium Ion Battery

A series of zeolite-templated carbon (ZTC) with particle sizes of 1 μm, 70 nm, and 10 nm have been prepared. The external surface area and diffusion path of Na+ inside the ZTC was varied by controlling the size of the zeolite crystals used as templates. The three ZTC samples have been used to store sodium cations (Na+) for the purpose of sodium-ion batteries (SIB). It was found that the ZTC with a particle size of 10 nm exhibited the highest first discharge capacity of 2116 mAh·g–1 at a current density of 0.1 mA·g–1 due to the highest external surface area and more complete filling of the internal pore volume of the ZTC. While the ZTC with 70 nm particle size showed better reversible capacity of 180 mAh·g–1 at a current density of 0.1 mA·g–1, and the 10 nm size ZTC caused more electrolyte decomposition reaction and more solid electrolyte interphase (SEI) layer on the external surface of the crystals, resulting in a low first Coulombic efficiency and poor Na+ extraction.

Quantitative study on catalysis of unpaired electrons in carbon edge sites

Carbon materials show incredible potential as environmentally friendly catalysts for numerous oxidation reactions. The presence of unpaired electrons (radicals) has also attracted significant research attention as they can act as catalytically active sites. However, the origin of these unpaired electrons in complex sp2-based carbon materials is still under debate, and this has hampered the development of high-performance carbon catalysts. Herein, we reveal the location of these unpaired electrons by advanced temperature-programmed desorption (TPD) coupled with magnetic susceptibility measurements. For this purpose, we use various porous carbon materials with vastly different numbers of edge sites, including activated carbon, carbon black, edge-site-free graphene mesosponge, and edge-site-rich zeolite-templated carbon. Interestingly, the ratio of unpaired electrons to the total edge-site number falls in the 0.52–1.83% range, regardless of the carbon materials investigated. A positive correlation exists between the number of unpaired electrons and the activity of the dehydrogenative oxidation reaction. The unpaired electron's turnover number is estimated to be up to 43, demonstrating that the unpaired electrons are not reactants but catalysts. This work provides the design guidelines for the development of radical-based carbon catalysts.