Microporous Carbon Research Articles

N/O/P Co-Doped Highly Microporous Carbons with Optimized Volumetric and Gravimetric Supercapacitive Performance

N/O/P Co-Doped Highly Microporous Carbons with Optimized Volumetric and Gravimetric Supercapacitive Performance

2D Mesoporous Carbon with Hollow Turtle Shell‐Like Morphology for Resolving Restacking Effect

AbstractIn this work, a unique 2D hollow turtle shell‐like mesoporous carbon (HTMC) synthesized via a ternary heterostructuring strategy to alleviate the restacking tendency of 2D materials is presented. The ternary 2D heterostructuring is achieved via an in situ growth of zeolitic imidazolate framework‐8 (ZIF‐8) on graphene oxide (GO) and a subsequent mesostructured polydopamine (mPDA) coating to obtain ternary heterostructured GO@ZIF‐8@mPDA, which is then converted to the hierarchically porous HTMC having macro‐, meso‐, and micropores via direct carbonization. Additionally, 2D turtle shell‐like microporous carbon (TMC) and 2D mesoporous carbon (MPC) derived from binary heterostructured GO@ZIF‐8 and GO@mPDA, respectively, are synthesized to investigate the porosity effect on alleviating the loss of accessible surface area of restacked 2D carbons. Among them, HTMC demonstrates superior structural advantages for alleviating the negative effects of restacking in 2D materials, exhibiting by far the highest specific capacitance (Csp) across all scan rates (93.7 F g−1 at 500 mV s−1 to 334.47 F g−1 at 1 mV s−1) in 1 M H2SO4. Furthermore, HTMC demonstrates outstanding rate capability while maintaining the greatest charge storage capacity over all scan rates.

Stochastic desorption of water molecules adsorbed inside single-wall carbon nanotube through nanowindows

Understanding water adsorption/desorption process through nanowindows provides new insights into membrane applications, supercapacitors and elucidation of biological ion separation mechanism. This study evidenced a new stochastic desorption mechanism of water molecules adsorbed inside highly pure single-wall carbon nanotube (SWCNT) through nanowindows, which evidently differs from conventional water desorption mechanism from carbon micropores. This new mechanism was clarified by the comparative analysis of water adsorption/desorption behaviors on endcap-closed SWCNT having nanowindows and endcap-open SWCNT without nanowindows. The water desorption for both open SWCNT samples was deeply associated with unique adsorbed water structures consisting of an ice-like adlayer akin to the graphene wall of SWCNT and core liquid-like water. Nanowindows destabilize the ice-like adlayer, leading to stochastic desorption of water molecules, followed by single-step desorption of adsorbed water through nanowindows of endcap-closed SWCNT having nanowindows. In contrast, water molecules are desorbed from ice-like adlayer and core liquid-like water separately for the endcap-open SWCNT without nanowindows.

Organic solvents tuned polymer derived-sulfonated microporous carbon structures enable resource regeneration and recovery in flow electrode capacitive deionization

Organic solvents tuned polymer derived-sulfonated microporous carbon structures enable resource regeneration and recovery in flow electrode capacitive deionization

Tea waste biomass-derived microporous carbon for improved microwave absorption

Tea waste biomass-derived microporous carbon for improved microwave absorption

Low-Temperature Molten Salt Electrochemical CO2upcycling for Advanced Energy Materials

CO2 upcycling into advanced energy materials represents a promising approach for mitigating the climate crisis stemming from CO2 emissions. In this study, we present a novel method involving molten salt CO2 upcycling to generate value-added materials, including graphene, graphite, microporous carbon, and transition metal oxide encapsulated graphite, with precise control over microstructure at a moderate temperature of 450°C. By carefully adjusting electrochemical parameters such as voltage, temperature, and cathode material, we successfully converted CO2 into various structural architectures, such as graphene and graphite, exhibiting customizable morphology and porosity at this relatively low temperature. The resulting electro-reduced carbon materials displayed impressive characteristics including high specific capacity, stable cycling performances, and exceptional rate capability when employed as anode materials in lithium-ion/sodium-ion batteries (LIBs/SIBs). Our innovative approach demonstrates efficient CO2 upcycling into diverse carbon architectures tailored for improved energy storage, thereby contributing to the advancement of clean and sustainable energy technologies by curbing carbon emissions towards achieving sustainable energy objectives.

Effect of Positive Active Material De-Agglomeration on 350Wh/Kg Class High Energy Density Lithium Sulfur Laminated Batteries

In recent years, lithium-sulfur (Li-S) batteries have been widely developed as next generation secondary batteries for aircraft applications such as drones and HAPS (High Altitude Platform Station), which are requires high gravimetric energy density. In order to achieve the cell design of 350 Wh/kg class Li-S batteries, we should focus on these three steps.First, we need to develop elemental and process technologies to achieve the capacity close to the theoretical sulfur capacity. Second, we need to use an electrolyte that is sparsely soluble or insoluble in polysulfide. Thirdly, we have to minimize the components other than the active material. The cathode is conventionally composed sulfur in Ketjen black (KB) on aluminum foil current collector. However, this limits the capacity of about 1250 mAh/g. Additionally, increasing the thickness of the cathode is an effective method for minimizing the number of cathode substrates, however, it is difficult to balance the high sulfur loading amounts and the high-rate performances, due to a difficulty to make adequate Li ion and electron paths.1) Micro-porous carbon has been reported as a supporting material that can exhibit a capacity close to the theoretical sulfur capacity2), In this study, we focused on activated carbon (AC) manufactured by Kuraray, which is commercially available and has a proven track record of mass synthesis. We used it in combination with ultra-thin aluminum sheet, successfully achieving a 350 Wh/kg class Li-S laminated battery.S/AC composite was obtained by mixing sulfur and AC (YP-80F, Kuraray) with weight ratio of 60 : 40, followed by heating at 155 °C for 12 h. Afterward the of S/AC were de-agglomerated by using the energy ball milling (MM500nano, Retsch). S/AC cathode was fabricated by coating S/AC slurry (S/AC: carbon nanofiber (CNF) : binder = 92.5 :4 :3.5 by weight) on Al sheet. To assemble the cell, the cathode (S loading: 4.7 mg/cm2) was pressed to reduce its thickness by 34%. 5 Ah class laminated cell was prepared by stacking 10 sheets of the S/AC cathodes, 11 sheets of Li anodes, 20 sheets of a separator, and the electrolyte lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/lithium bis(fluorosulfonyl)imide (LiFSI) : sulfolane (SL) : hydrofluoroether (HFE) = 0.8/0.2: 1: 1.7 (molar ratio)). Electrochemical performances were tested with voltage range between 1.0 V – 3.3 V after activation process.Focusing on the de-agglomeration of the positive electrode active material, we investigated a dispersion process of S/AC composite to achieve a capacity close to the theoretical sulfur capacity. After preparing S/AC composite, the A/AC was de-agglomerated using the ball milling. Figure 1 shows the comparison of the capacity of dispersion phase A and B at each cycle. It was found that the dispersion treatment increases the initial capacity close to the theoretical capacity of 1672 mAh/g. Also, the dispersion treatment (phase B) increased the capacities up to the 15th cycle, compared with those without the treatment (phase A). This suggest that the well dispersed S/ACimproved the diffusion of Li ions.Furthermore, in order to increase the energy density of the battery, we adopted an ultra-thin Al current collector of 7 μm in thickness instead of the conventional 20 μm thick Al sheet, and using the above dispersion process, we fabricated a large 70 mm x 70mm Li-S laminated battery.Fig.2 shows its charge-discharge curve of a new designed Li-S battery. The first plateau, which is generally observed around 2.3 V in a conventional S/KB system, is not confirmed. This is a feature of micro-porous carbon system. The Li-S battery delivered a discharge capacity of 6.7 Ah, which is equal to 1632 mAh/g-S.Fig. 3 shows a comparison of battery weights by employing KB and AC. The capacity of S/KB is approximately 1150 mAh/g-S, which is smaller than that of the AC (1632 mAh/g-S). Therefore, the loading amount of the active material can be reduced by employing the AC instead of KB, resulting in reduction of the carbon constituting the complex at the same time. Consequently, a laminate-type battery with high capacity of 6.7 Ah, and energy density (351 Wh/kg, laminate film and tabs are excluded in this calculation) was achieved.In the presentation, I would like to discuss the effect of de-agglomeration of the S/AC composite. [References] [1]. H. Nara, et.al., J. Electrochem. Soc., 164, A5026–A5030 (2017).[2] S. Usuki, et. al., J. Electrochem. Soc., 85, 650–655 (2017). [Acknowledgement] This work was partly supported by Advanced Low Carbon Technology Research, Development Program Special Priority Research Area “Next-Generation Rechargeable Battery” (ALCA-Spring) from the Japan Science and Technology Agency (JST) (Grant Number JPMJAL1301). Figure 1

Reaction Transport Analysis and Parameter Identification for Designing Lithium–Sulfur Battery Electrodes

Electrical energy storage systems for renewable energy sources and the popularization of next-generation vehicles with low CO2 emissions and high energy efficiencies are required to realize a sustainable society. However, current cathode materials such as lithium–containing oxides used in lithium-ion batteries (LiBs) have limited storage capacities, and their energy density peaks at approximately 150–250 Wh/kg. To improve this, lithium–sulfur batteries (LiSBs) with high theoretical energy densities are currently being developed and expected to be deployed as the next-generation battery technology. In LiSBs, the complex dissolution and precipitation reactions of sulfur are the driving forces. However, the complex operating mechanisms of LiSBs are yet to be investigated. Ren et al. (1) modeled the precipitation mechanism of lithium sulfide by focusing on the characteristics of a two-step discharge reaction to clarify the relationship between the complex reaction mechanism and the battery characteristics of LiSBs. In addition to considering multistep polysulfide dissolution and reduction, they describe the rate-dependent Li2S precipitation phenomenon using electro-crystallization kinetics based on nucleation and growth theory. Thus far, research has been actively conducted on clarifying the complicated reaction mechanisms of LiSBs. These studies only simplify the reaction mechanisms and calculations using estimates of many dynamic parameters of intermediate products that are otherwise difficult to measure. However, if such a numerical analysis is applied to a new electrode system, it can lead to incorrect conclusions regarding the reaction mechanisms. In our previous study, we established a technique to identify parameters that are difficult to measure after cell assembly by fitting the measured and calculated values of the fully discharged characteristics of LiBs using a complex nonlinear optimization method (2). For LiSBs, combining actual measurements and calculations is useful to estimate the unknown parameters of a new electrode system. In LiSBs, the volume change of sulfur during charging and discharging is problematic. During discharge, the volume expands by approximately 1.8 times when sulfur combines with lithium and changes to lithium sulfide (3). Although the microstructure of the electrode is expected to be destroyed by volume expansion, which affects the battery performance, only a few studies have verified the volume change by numerical analysis with complicated mechanisms. In contrast, in our study, reaction transport analysis models that consider volume changes were established for LiBs (4). Therefore, we aimed to construct a lithium–sulfur battery design support system that combines a numerical analysis method for lithium–sulfur batteries considering volume changes with an optimization method.In this study, we examined the effect of sulfur-filled microporous activated carbon. Recently, it was reported that this microporous carbon with sulfur can be repeatedly cycled as a sulfur cathode exhibiting a high coulombic efficiency of almost 100% (5). Firstly, by using numerical simulation and optimization method, we evaluated mass transport and reaction properties with various parameters of pore structure. Next, we simulated the discharge performance with or without this activated pore. From this data, it was found that pore size strongly affects effective surface area and Li+ conduction and diffusion performance. As described above, it was suggested that an optimum pore structure exists from the viewpoint of the balance of reaction and mass transport, and the effect of different structures on transport properties was qualitatively evaluated. In the future, it is necessary to confirm the validity of the optimal structure through experiments and to quantitatively evaluate the effect of different CB.AcknowledgmentThis study was supported by JST GteX, Development of lithium-sulfur batteries with low environmental impact and high performance, Grant JPMJGX23S0, Japan.(1) M. Hagen et al., Adv. Energy Mater., 5(16), 1401986 (2015).(2) G. Inoue et al., J. Chem. Eng. JAPAN, 54(5), 207–212 (2021).(3) M. M. Islam et al., Phys. Chem. Chem. Phys., 17(5), 3383–3393 (2015).(4) G. Inoue et al., ECS Trans., 80(10), 275-282, (2017).(5) T. Tonoya et al., Electrochemistry Communications, 140, 107333 (2022).

Importance of the Interlayer Distance of Reduced Graphite Oxide for Reversible Redox Reaction of Quinone-Based Molecules

Introduction Quinone-based molecules have attracted considerable attention as an electrode material. The electrochemical response of the molecules is typically quasi-reversible because the molecules are dissolved in electrolytes, a diffusion-controlled system. We reported that a flowable electrode composed of activated carbon (AC) and 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (BQDS) exhibits an adsorption-controlled system; peak-potential separation (ΔE p) was negligible.1 Herein, we report the dependence of interlayer distance of redox reaction using reduced graphite oxide (rGO) as a model electrode material. Experimental The cross-linking of diamine monomers tuned the interlayer distance of GO.2 A diamine monomer (0.1 mol) was added to a GO dispersion (0.4 g L−1). The dispersion was stirred for 1 h, and the powder was collected by suction filtration. This powder was dried at 353 K for 1 h to promote cross-linking between the carbon layer and the diamine, and then it was soaked in methanol for 24 h to remove the weakly adsorbed diamine monomers. The interlayer distance of GO was tuned by using diamine monomers with different chain lengths; the ethylenediamine (denoted as C2NH), hexamethylenediamine (C6NH), and dodecamethylenediamine (C12NH) were used as diamine monomers. Sodium anthraquinone-2-sulfonate monohydrate (AQS) was used as an electroactive molecule. AQS was introduced into the interlayer of GO, and the powder was collected through filtration and dried at 333 K. The GO powder was reduced under hydrogen flow at 473 K (denoted as AQS/C n NH-rGO: n = 2, 6, and 12). The working electrode was prepared by casting the electrode material ink onto a mirror-polished 3 mm-diameter glassy carbon rod. The deposited amount of electroactive material was 20 mg cm−2. A Pt mesh and Ag/AgCl (KCl sat.) were used as the counter and reference electrodes. Results and Discussion The cross-linkage was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and the presence or absence of GO nanosheet after exfoliation. The interlayer spacing of C n NH-rGO (n = 2, 6, 12) was investigated by X-ray diffraction. The d values of C2NH-GO, C6NH-GO, and C12NH-GO were 0.89, 1.00, and 1.45 nm, respectively. The interlayer distance of unmodified GO in the wet state increased compared to that in the dry state, which is attributable to the expansion due to the introduction of water molecules. In contrast, the interlayer space of C n NH-rGO (n = 2, 6, 12) was negligible. The interlayer distance did not change after H2 treatment. The current-potential response was rectangular, indicating that the double-layer capacitance is the primary charge storage mechanism. The specific capacitance increased with increasing the interlayer space; the values of C2NH-rGO, C6NH-rGO, and C12NH-rGO were 10.5, 38.4, and 101.2 F g- 1, respectively. The ΔE p values of AQS/C2NH-rGO, AQS/C6NH-rGO, and AQS/C12NH-rGO are 20, 85, and 110 mV, respectively. The reduced DE p could be attributed to the confinement effects.3 It is noted that the AQS/C2NH-rGO showed excellent reversibility even at a scan rate of 20 V s−1. In conclusion, we found that the interlayer distance of rGO directly affects the reversibility of the redox reaction of quinone-based molecules. Acknowledgments This work was partially supported by the Research Foundation for the Electrotechnology of Chubu, the Kondo Memorial Foundation, and the Tokyo Ohka Foundation for the Promotion of Science and Technology. References D. Takimoto, K. Suzuki, R. Futamura, T. Iiyama, S. Hideshima, and W. Sugimoto, Zero-Overpotential Redox Reactions of Quinone-Based Molecules Confined in Carbon Micropores, ACS Appl. Mater. Interfaces, 14, 31131 (2022). 10.1021/acsami.2c07429.W. S. Hung, C. H. Tsou, M. De Guzman, Q. F. An, Y. L. Liu, Y. M. Zhang, C. C. Hu, K. R. Lee, and J. Y. Lai, Cross-linking with diamine monomers to prepare composite graphene oxide-framework membranes with varying d-spacing, Chem. Mater., 26, 2983 (2014). 10.1021/cm5007873.K. Kaneko and K. Murata, An analytical method of micropore filling of a supercritical gas, 3, 197 (1997). 10.1007/BF01650131.

An Aqueous Organic Redox Supercapacitor Fabricated By Supercritical CO2 Impregnation of Quinones into Activated Carbon

The aqueous organic redox supercapacitor (OSC) is a metal-free, safe, and cost-effective energy storage device.[1] It utilizes activated carbons (AC) impregnated with two types of quinones as electrodes and an aqueous solution as the electrolyte. The redox reaction of quinones serves as the electron carrier. Conventional liquid impregnation methods for loading quinones onto AC have been used but such methods are limited by low quinone loading ratios and low specific capacities. In this study, a supercritical fluid (SCF) impregnation method is proposed to improve the quinone loading and the energy density of OSC. All OSC fabricated via this method were evaluated, and the impregnation effects compared with those in liquid impregnation method through thermogravimetric analysis (TG) and X-ray absorption fine structure (NEXAFS) measurements.The cathodes were fabricated by placing AC and tetrachloro-1,4-benzoquinone (TCBQ) in a tube reactor, maintaining them at 105°C and 15 MPa for 24 hours, as per previous study.[2] The anodes were prepared by placing AC, 1, 5-dichloroanthraquinone and ethanol in a reactor and holding the mixture at 155°C and 25 MPa for 24 hours. For comparison, liquid impregnation method was used to fabricate respective electrodes.[1] The quinone loading in each sample was assessed through TG analysis while the electrochemical measurements were performed using a 0.5 mol/L sulfuric acid solution as the electrolyte. Specific capacities of half-cell (1A/g, -0.3-0.3V vs Ag/AgCl) and full cell (2A/g, 0-1.2V) configurations were determined via constant current measurements using a galvanostatic. Additionally, the quinone loading on AC surface of each sample was investigated using the NEXAFS method.In comparison with the liquid impregnation method, cathodes and anodes produced through SCF impregnation exhibited a 37% and 83% increase in specific capacity, respectively. This enhancement was attributed to the amplified impregnation and loading of redox molecules. The superior solubility of redox molecules in supercritical CO2, along with its high diffusion and low viscosity, facilitated the impregnation and loading of redox molecules into the micropores of the porous carbon. In fact, TG analysis results showed that the supercritical quinone loading was higher in the supercritical impregnation method than in the liquid impregnation method, and the correlation between quinone loading and electrode properties was confirmed. Overpotential suppression was also confirmed, suggesting a decrease in interfacial resistance due to improved adsorption morphology.[3] Full cell measurements showed an energy density of 21 Wh/kg, 1.4 times higher than previous studies.[1] In a durability test of 1000 cycles, the energy density retention rate was 95%, indicating excellent electrode properties with high capacity and long life. Comparing the OSC properties in this study to other energy storage devices, the OSC performed higher than nickel-cadmium and lead-acid batteries for energy density and power density, and higher than cobalt-based lithium-ion batteries in terms of power density.[4] In the K-edge NEXAFS spectra of carbon, the transition peak to the 1s→π* orbital derived from TCBQ[5] was observed at a higher energy in the SCF impregnation compared to the in liquid impregnation. In this case, the peak appeared at a higher energy level due to the strong interactions between the TCBQ supported by the SCF impregnation and AC resulting in the increase in the ratio of π-bonded components and hence an increase in the effective oxidation number. References Tomai et al., Sci. Rep.,4, 3501(2014)Nakayasu et al., Chem. Commun.,59, 3079(2023)N. Tisawat et al., Appl. Surf. Sci., 491, 784–791(2019)S. Sarmah et al., WIREs Energy Environ., 01, 461(2022)SC. Ray et al., Sci. Rep., 4, 3862(2014)

Development of Co-, Fe- and N-Doped Mesoporous Carbon Catalysts for Anion-Exchange Membrane Fuel Cell Cathode

Hydrogen has a lot of promise to be utilized in sustainable transportation and energy production using low-temperature polymer electrolyte membrane fuel cells. While proton-exchange membrane fuel cells are already commercialized, they still have issues with needed substantial amount of platinum as electrocatalyst. By switching to alkaline electrolyte, cheaper and more sustainable electrocatalysts can be used for cathodic oxygen reduction reaction (ORR). For instance, transition metal and nitrogen doped nanocarbons (M-N-C, M = Fe, Co, Mn, etc.) have shown very good ORR activity in alkaline media. Anion-exchange membrane fuel cell (AEMFC) technology, however, is still in research phase, and any further developments in electrocatalysts is necessary.1-3 Herein the focus is on developing mesoporous M-N-C electrocatalysts for the ORR and studying the effect of carbon support porous structure on the AEMFC performance. Mesoporous carbons (MCs) are prepared by combining phloroglucinol with glyoxal/glyoxylic acid. In the first part, soft-templating approach by Pluronic F127 is taken,4 in the second part of the work, effect of additional hard template (MgO) is investigated through dual-templating. We have limited the amount of harsh and environmentally unfriendly chemicals, offering more sustainable approaches beyond the silica-templating for synthesizing mesoporous carbons. The prepared MCs have high specific surface area (up to 900 m2 g-1) and have high content of mesopores in 5-8 nm range. To further study the effect of porous structure of carbon support on the AEMFC performance, nanocarbon composites with MC (prepared in first part) and either highly microporous carbide-derived carbon (CDC) or carbon nanotubes (CNTs) are also prepared (Figure 1a).Our previous works have shown that bimetallic materials, containing iron and cobalt, perform the best in AEMFC.5-6 Thus herein, all prepared nanocarbon supports are doped with nitrogen (1,10-phenanthroline as source), cobalt and iron (Co- and Fe-acetate) via high-temperature pyrolysis, which yields electrocatalyst with atomically dispersed metal centers (Figure 1b). Rotating disc electrode (RDE) method is employed for preliminary ORR-activity testing with the prepared CoFe-N-C materials showing high electrocatalytic activity in 0.1 M KOH (E 1/2 up to 0.84 V vs RHE) and good stability after 10,000 potential cycles. In the first part, using nanocarbon composites with varying porous structure yielded electrocatalysts with almost identical performance in the RDE test. However, the effect of porous structure came evident during AEMFC testing, wherein presence of more mesoporous structure was beneficial.4 In the second part using dual-templating approach, the most optimal ratio of two templates (F127 and MgO) was found, together with promising AEMFC performance.In conclusion, we have employed three different mesoporous carbon synthesis routes (soft- or dual-templating), optimized the conditions, and after doping obtained highly active ORR electrocatalysts with great promise for the AEMFC application.

(Invited) Novel Nitrogen and Sulfur Doped Colloid Imprinted Carbons (CICs) As Catalysts for Electrochemical CO2 Reduction

Electrochemical carbon dioxide (CO2) reduction represents a promising strategy for transforming this ubiquitous greenhouse gas into valuable commodities. Moreover, it offers a solution for storing intermittent renewable electricity by converting CO2 to chemical fuels. Unlike the formation of hydrocarbons, the reduction of CO2 to carbon monoxide (CO) involves only two electron/proton transfers, making it a less complex process. Also, CO is a very useful product as it can be used as a crucial feedstock for the production of fuels via the catalytic Fischer-Tropsch process. Nevertheless, the electrocatalytic conversion of CO2 to CO, carried out typically at metals, experiences significant challenges due to changing morphology with time, poor CO2RR product selectivity, and unavoidable competition with the hydrogen evolution reaction in aqueous environments.Therefore, attention has also been extended to CO2RR at carbon-based catalysts, as carbon possesses a plethora of inherent advantages, including its customizable and stable porous structures, high surface area, low cost, and environmental friendliness. While these properties make carbon highly favorable as a catalyst, it is inactive towards CO2 reduction in its pure state and must be doped or surface modified to achieve reasonable CO2RR kinetics. As an example, nitrogen-doped carbons (N-C) have shown acceptable activity towards the CO2RR,[1] attributed to the electronic modulation of conjugated sp2 carbon atoms by adjacent nitrogen dopants, disrupting electroneutrality by delocalizing π-orbital electrons within the carbon framework and creating active sites for CO2 activation. Even so, as N-C catalysts require significant overpotentials to attain satisfactory reaction rates and as the Faradaic efficiencies can be low and unstable, there is a pressing need to devise novel strategies to enhance the catalytic efficacy of N-C materials and achieve highly efficient CO2-to-CO conversion.To overcome these limitations, a dual-doping approach has been suggested, with the observed enhancement in activity of co-doped catalysts (e.g., N and sulfur) generally attributed to synergistic effects between nitrogen and the secondary atoms.[2] Computational simulations have predicted that the inclusion of sulfur into N-graphene could increase the asymmetrical spin density of the carbon system due to the higher polarizability of sulfur atoms compared to nitrogen and carbon atoms, thereby leading to improved catalytic performance. Moreover, sulfur modification can offer a potentially effective avenue for enhancing CO2RR performance over N-C materials by leveraging the electronic contribution from sulfur.[3] However, to the best of our knowledge, there are limited reports on the implementation of sulfur decoration strategies for electrocatalytic CO2RR.Our team has been working on a family of fully tunable monodisperse mesoporous carbon sheets, designated as nanoporous carbon scaffolds (NCS), along with colloid imprinted carbon (CIC) powders as carbon support materials. The CIC and NCS materials possess identical ordered monodisperse pore diameters, selected to be anywhere between 10 and 100 nm. These mesoporous carbons present numerous advantages compared to microporous carbons, notably their internal accessibility to solutions and gases, as well as their highly defective surfaces, making them easily modified. Specifically, the NCS offers additional benefits due to its self-supported nature and suitability for conducting fundamental CO2RR membrane electrode assembly (MEA) studies. To date, we have successfully N-doped both the CICs and the NCS and are now moving towards co-doping with S. N-doping has been achieved by subjecting the carbons to an NH3 atmosphere at 800 °C and S-doping is carried out by heat treatment of a mixture of the carbons and benzyl disulfide in Ar. We are also investigating a carbon precursor having intrinsic N and S content to simplify the preparation steps. In this case, the N,S-C catalysts were prepared by ball milling of dry silica particles (85 nm) and Alberta-sourced mesophase pitch. Subsequently, the mixture underwent carbonization at 900 °C for 2 hours, followed by removal of silica using a NaOH solution to yield the final product. CO2RR testing of these first generation of N,S doped catalysts has been carried out primarily in CO2-saturated bicarbonate solutions in an H-cell, giving an impressive CO Faradaic efficiency of 80% at overpotentials of only 390 mV and maintaining their stability for many hours of polarization. XPS studies are underway to establish a correlation between S, N content and speciation with the electrocatalytic activity and durability of these materials, with CO2RR testing also being carried out under flow conditions for comparison. Acknowledgements We would like to thank Momentum Materials Solution (Calgary) for providing the mesophase pitch. This work was supported by NSERC and CANSTOREnergy. References Wu, J., et al., ACS nano, 2015. 9(5).Duan, X., et al., Advanced Materials, 2017. 29(41).Pan, F., et al., Applied Catalysis B: Environmental, 2019. 252.

Synthesis of Porous Metal Oxides Utilizing Nanosheet Colloid with Liquid Crystallinity

Activated carbon, a high specific surface area microporous carbon(>2000 m2 g–1), has been used as the electrode material for electrochemical double layer capacitors.1 The structure of activated carbon is characterized by a three-dimensional network consisting of graphene-like layers. Preparation of metal oxides with a similar porous structure is anticipated to behave as pseudocapacitive electrode materials with high energy density. However, the hierarchical porous structure of activated carbon is obtained by gas-phase or chemical activation treatment and is applicable only to carbonaceous materials. Thus, an alternative strategy is necessary to prepare metal oxides with porous architectures similar to activated carbon.Assembly of inorganic oxide nanosheets is one of the promising methods to prepare hierarchical porous metal oxides. Here, we focus on the phenomenon where inorganic oxide nanosheets form liquid crystal structures in colloids and align macroscopically under an electric field. A highly concentrated hexaniobate nanosheet ([Nb6O17]4 –(ns)) colloid is known to exhibit liquid crystalline behavior.2 Additionally, the orientation of nanosheet with micro-mesoscale sheet spacing (< tens of nm) forms a hierarchical macroscopic structure (< several hundred µm) under an electric field.3 Therefore, the liquid crystalline structure and its responsiveness to electric fields in nanosheet colloids are effective for controlling the hierarchically nanosheet-assembled structure. In this study, we applied the freeze-drying method of nanosheet liquid crystals (NLC) to transfer the structure within the fluid nanosheet colloid to the dried aggregates (Figure 1).[Nb6O17]4 –(ns) colloids with developed liquid crystal domains form stripe-shaped macrostructures by applying an alternating current (AC) electric field (10 Vp–p, 50 kHz) perpendicular to the direction of gravity.3 Figure 1(a) shows the polarized optical microscopy (POM) image of the stripe-shaped macrostructures with a width of 100 µm and intervals of 200 µm composed of [Nb6O17]4 –(ns). In the birefringent regions, NLC oriented perpendicular to the direction of the AC electric field and parallel to the direction of the gravity. After applying an electric field to the cell, the cell was immersed in liquid nitrogen with applying the electric field and then dried in vacuum, resulting in the formation of a sponge-like nanosheet aggregate between the electrodes. The bright-field optical microscope image of the freeze-dried aggregates shows the similar stripe-shaped macrostructures to that of NLC under the electric field (Figure 1(b)). Therefore, the macrostructure of NLC oriented in an electric field can be transferred into the porous nanosheet aggregates by freeze-drying method. These results indicate that the liquid crystalline and electric field responsive properties of nanosheet colloids are useful for structural design of nanosheet-assembled materials. References P. Simon and Y. Gogotsi, Nat. Mater., 7, 845 (2008).N. Miyamoto and T. Nakato, Adv. Mater., 14, 1267 (2002).T. Nakato, Y. Nono, E. Mouri and M. Nakata, Phys. Chem. Chem. Phys., 16, 955 (2014). Figure 1

Upcycling PET Bottles into P-Doped Hard Carbon Anode Materials for Li-Ion Batteries

Introduction The urgent need to address environmental concerns, particularly the escalating plastic waste crisis, has underscored the importance of exploring innovative methods for enhancing plastic bottle recycling [1]. Among these methods, upcycling—transforming plastic waste into products of greater intrinsic value—has gained significant attention [2, 3].This study focuses on applying upcycling methods to plastic bottles, with a specific emphasis on Polyethylene terephthalate (PET) materials sourced from the Coca-Cola corporation as a case study. PET bottles are chosen due to their widespread use in consumer markets and their prevalence in plastic waste streams.The primary objective of this research is to systematically investigate processes for repurposing PET bottles into hard carbon materials. Such materials hold promise for various applications, notably in energy storage systems like lithium-ion batteries (LIBs). By examining PET dissolution in various solvents, this study aims to identify efficient and sustainable pathways for producing high-quality carbon materials.Additionally, this study integrates phosphorus (P) doping into the synthesis process. P-doping has been demonstrated to enhance the electrochemical performance of carbon materials by altering their electronic and structural properties. The authors successfully synthesized P-doped hard carbon and conducted comprehensive characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. These analyses provide insights into the effects of doping on the structure and morphology of the resulting hard carbon materials, shedding light on mechanisms behind their improved electrochemical performance.This research aims to contribute to the development of environmentally sustainable solutions for plastic waste management. Through the application of upcycling methods to PET bottles and the integration of P-doping strategies, this study seeks to address the environmental challenges posed by plastic waste while exploring avenues for value-added product creation in advanced technological domains.2. Experimental A novel approach is presented for the synthesis of hard carbon material for lithium-ion batteries (LIBs) utilizing recycled PET bottles from Coca-Cola Classic. The bottles underwent thorough washing with water and ethanol, followed by air drying and cutting into small 3-4 mm square pieces prior to dissolution. Solvents for PET dissolution were prepared by mixing dichloromethane (DCM) with trifluoroacetic acid (TFA) in a volume ratio of 3:7. The PET pieces were dissolved in the solvent mixture at a rate of 2 grams per 10 ml of solvent using a stirrer at 100 rpm for 4 hours. P-doping was achieved by adding phosphoric acid (H3PO4) to the plastic solution in various concentrations (1 mol, 2 mol, 3 mol H3PO4 per 10 ml of solution). The resulting solution was applied as a thin layer (50 μm thick) onto a glass surface and dried in air for 24 hours. Subsequently, the resulting film was annealed in an argon atmosphere at 750°C for 2 hours with a heating rate of 5 degrees/min. The resulting carbon materials were characterized and utilized as anodes for lithium-ion half-cells. Electrochemical properties of the batteries were evaluated using cyclic voltammetry (CV) and galvanostatic charge/discharge methods. This study demonstrates a sustainable and efficient method for the synthesis of carbon materials for LIBs from recycled plastic waste, with promising electrochemical performance. Results and Discussion The XRD analysis presented in Figure 1 demonstrate that the obtained carbon sample possessed the high-quality attributes required for battery-grade hard carbon which is substantiated by the distinct peaks observed. Moreover, the initial discharge capacity stands at an 758.53 mAh/g, accompanied by an initial Coloumbic efficiency of 49.75%. After the 10th cycle the Coulombic efficiency reached 97.98%. The corresponding capacitance values after the 10th and 50th cycle are 338,35 and 304,71 mA.Fig. 1 X-ray diffraction pattern of obtained powder References Olazabal, I., Goujon, N., Mantione, D., Alvarez-Tirado, M., Jehanno, C., Mecerreyes, D., & Sardon, H. (2022). From plastic waste to new materials for energy storage. <i>Polymer Chemistry</i>, <i>13</i>(29), 4222–4229. https://doi.org/10.1039/d2py00592aMirjalili, A., Dong, B., Pena, P., Ozkan, C. S., & Ozkan, M. (2020). Upcycling of polyethylene terephthalate plastic waste to microporous carbon structure for energy storage. <i>Energy Storage</i>, <i>2</i>(6). https://doi.org/10.1002/est2.201Nagmani, & Puravankara, S. (2023). Utilization of PET derived hard carbon as a battery-type, higher plateau capacity anode for sodium-ion and potassium-ion batteries. <i>Journal of Electroanalytical Chemistry</i>, <i>946</i>. https://doi.org/10.1016/j.jelechem.2023.117731 Figure 1

Highly Interconnected Macroporous Carbon Spheres for Ionogel-Based Stretchable Supercapacitors

Due to their exceptional properties such as lightweight, high electrical conductivity, specific surface area (SSA), adjustable pore structures, and desired surface characteristics, carbonaceous materials have substantial interest as electrode materials for supercapacitors (SCs). In attempts to achieve high energy density, ionic liquid (IL) electrolyte is has attracted great attention Because it can be used in a wide voltage range. However, initial attempts to incorporate IL into SCs encountered challenges, as the large and sluggish ions struggled to effectively access the narrow pores of conventional microporous carbons. In addressing these issues, we have synthesized interconnected meso/macroporous carbon spheres (MCSs) that were produced via co-assembly of polymer and silica sphere (20-70 nm). The interconnected large meso/macropores facilitated ion mass-transport and thereby efficient utilization of the carbon electrode's surface for capacitive energy storage. The MCS-based SCs demonstrated a high capacitance (328.93 F g-1) and ultrahigh energy density (182.7 Wh kg-1), and MCS/IL-based inogel SCs exhibited a remarkably high energy density of 0.111 mWh cm⁻ 2 and a high-power density 8.89 m Wcm-2 demonstrated excellent mechanical durability 0% and 100% strain, with notable capacitive retention of 95.3% observed at 100% strain. Comparable to the best results reported to date. Therefore, the results obtained in this study provide morphological insights into the differences in electrochemical performance based on pore size and particle size. Additionally, these findings contribute to the design of carbon-based materials suitable for electrochemically robust yet dynamically sluggish ionic liquid electrolytes, aiming for high-performance deformable energy supply devices.

Sulfur vacancy-rich ZnS on ordered microporous carbon frameworks for efficient photocatalytic CO2 reduction

ZnS has garnered significant attention as a versatile photocatalyst in the field of CO2 reduction. However, its photocatalytic efficiency has been hindered by its high charge recombination rates and sluggish reaction kinetics. Herein, we demonstrate a highly efficient CO2 photoreduction on well-designed S-deficient ZnS nanoparticles within an ordered mesoporous N-doped carbon framework (Vs-ZnS/OMNC) through an in situ thermal treatment strategy. The fs-TA spectrum elucidated that introducing sulfur vacancy (Vs) effectively promoted the separation of photogenerated charges in ZnS/OMNC and significantly improved its reaction kinetics. In situ DRIFTS spectroscopy and DFT calculations revealed that these S vacancies led to charge accumulation on neighboring Zn atoms, enabling effective adsorption and activation of CO2 molecules. Particularly, the vacancy strategy also effectively lowered the energy barrier for forming the key intermediate *COOH. Therefore, the CO evolution rate of Vs-ZnS/OMNC reached 712.1 μmol·g−1·h−1, which is 2.84 times higher than that without sulfur vacancy (250.74 μmol·g−1·h−1). Its CO2 reduction performance surpassed most ZnS-based photocatalysts reported previously. Additionally, the Vs-ZnS/OMNC exhibited outstanding stability without obvious degradation after five reaction cycles. This study provides insights into developing advanced photocatalysts through vacancy defect engineering combined with ordered mesoporous carbon structures.

Production and characterization of biochar and modified biochars by carbonization process of bearberry (Arctostaphylos uva-ursi. L.): Adsorption capacities and kinetic studies of Pb2+, Cd2+ and rhodamine B removal from aqueous solutions

In this work, Bearberry (Arctostaphylos uva-ursi L.) leaves and twigs were used as novel biomass source for production of biochar and modified biochars (manufacturing of microporous and mesoporous carbons by physical and chemical activations, using CO2 and H3PO4) via one-step carbonization (800 °C) with excellent physicochemical properties, for effective removal of Pb2+ and Cd2+ ions, and synthetic dye (Rhodamine B - RhB) from aqueous solutions. Results showed that carbonized (BL-C) and physically activated carbons (BL-CO2) as microporous adsorbents (specific surface areas 219.0 m2/g and 305.5 m2/g) show remarkable removal efficiency of Pb2+ (99.8 % and 99.9 %, for BL-C and BL-CO2), while these adsorbents showed moderate affinity for Cd2+ elimination (53.5 % and 48.5 %). BL-H3PO4 as mesoporous adsorbent with lower specific surface and larger pores (90.2 m2/g with Dmax = 33.6 nm), shows very good removal efficiency of PhB (~ 87 %). It was found that physical adsorption occurs during RhB removal onto BL-H3PO4, where dominant mechanism represents film diffusion, with reduced boundary layer effect. Adsorption process takes place over π–π, hydrogen bonding and electrostatic interactions. Adsorption processes of Pb2+ and Cd2+ onto BL-CO2 and BL-C take place via physical and chemical adsorption, but with different type of mechanism, including combination of diffusion and chemisorption (increased effect of boundary layer) and intra-particle diffusion (greatly reduced boundary layer effect), respectively. A very interesting fact found in this study, is that metal oxide surfaces (as Cu2O, SiO2, ZnO present in activated carbons) exhibit an efficient binding towards cadmium, providing physisorption capability onto non-metallic graphene features.

Conjugated Microporous Polymer-Derived Nitrogen-Doped Carbon Nanocomposites with Multiple Magnetic Components for Broadband Microwave Absorption

Conjugated Microporous Polymer-Derived Nitrogen-Doped Carbon Nanocomposites with Multiple Magnetic Components for Broadband Microwave Absorption

A metallic lithium anode for solid-state batteries with low volume change by utilizing a modified porous carbon host

Lithium metal is a promising negative electrode material for solid-state batteries (SSBs). However, uncontrolled lithium deposition and stripping cause several issues during cycling. Herein, the microporous carbon YP-50F and its modifications obtained by thermal ethene-based chemical vapor deposition (CVD) are investigated as 3D host to accommodate and control the deposition of metallic lithium. In half-cells vs. lithium, the CVD-YP composite electrode with Li6PS5Cl electrolyte shows significantly higher initial coulombic efficiency (79.5 %) than the pristine carbon (55.3 %) due to the reduction of side reactions. The metallic character of the deposited lithium is evidenced by 7Li Nuclear Magnetic Resonance spectroscopy. However, full cells with nickel-rich NCM (LiNi0.9Co0.05Mn0.05O2) positive electrode and CVD-YP composite negative electrode show reasonable performance over 50 cycles without occurrence of (micro-) short-circuits (in contrast to 2D reference electrodes). In addition, small prototype pouch cells are investigated and the thickness change during (dis)charging is less than one third compared to a bare lithium metal electrode. This demonstrates low breathing behavior of the CVD-YP electrode and confirms the reversible storage of metallic lithium within the 3D carbon-based composite electrode.

From Green to Black Gold: Highly Microporous Carbons from Pistachio Shells by a Controlled Physical Activation Process.

Highly microporous carbons with BET surface areas of up to ca. 3300 m2 g-1 and pore volumes of up to 1.6 cm3 g-1 have been successfully synthesized from pistachio shells, a waste whose generation is growing on account of the nutritive value of pistachios and the resilience of this crop to climate change. Such a high pore development has been achieved by a simple and benign CO2 physical activation process assisted by a custom pre-treatment of the biomass. Different approaches have been explored in this work for the transformation of pistachio shells into carbon materials with diverse microstructures, mineral matter content and particle size/morphology, tuning thereby their reactivities towards CO2 and diffusion kinetics and, in this way, pore development. In particular, the most efficient route for the production of highly microporous carbons from pistachio shells involves a hydrothermal carbonization process which increases the degree of aromatization and effectively removes the mineral matter, enhancing thereby the efficiency of both carbon production and porosity generation. By increasing the activation temperature, substantial shortening of the operation time can be achieved without compromising pore development. This work provides new integral strategies towards the production of biomass-based, CO2-activated carbons with a focus on optimizing pore structure, minimizing energy consumption and maximizing product yield.