Large Mesopore Volume Research Articles

Synthesis and scale-up of ZSM-5 aggregates with hierarchical structure

ZSM-5 aggregates with hierarchical structure have been synthesized and scaled up by using colloidal S-1 as seed, without employing any organic templates. All the synthesized samples show ball-like aggregated morphologies, and the aggregates were composed of primary zeolite crystals. The seed plays an important role to the formation of ZSM-5 aggregates consisting of primary crystals, and changing the amount of seeds can adjust the crystal size of the ZSM-5 aggregates and primary crystals. The obtained ZSM-5 aggregates are nanosized, possessing a large mesopore volume and external surface area. After modification without calcination, the prepared ZSM-5 aggregates were used for the hydration of cyclohexene to cyclohexanol, exhibiting high catalytic performances, and the highest yield of cyclohexanol reaches 9.13%. When scaled-up from 100 mL to 2 and 5 L, the catalytic performance of ZSM-5 has a good reproducibility, and has great potential feasibility of scaling-up in industrial processes. The hierarchical ZSM-5 aggregates exhibit an excellent catalytic performance to the hydration of cyclohexene to cyclohexanol, which have great potential feasibility of scaling up in industrial processes.

Hierarchical zeolite mazzite: Physicochemical properties and α-pinene isomerization

Dealuminated mazzite shows very high acid strength of SiOHAl groups. The aim of our study was to produce hierarchical mazzite, containing mesopore system, but preserving strong acidity. This was done by desilication of dealuminated mazzite (Si/Al = 30), carried out using NaOH/TBAOH solutions. Desilication of zeolite as strongly acidic as mazzite was not done before. During desilication ca. 50% of silicon was extracted, the structural microporosity was indeed preserved, and large volume of mesopores was formed too. IR studies evidenced that very high acid strength of SiOHAl groups was preserved. According to NMR results five types of Al species were present in the desilicated material. Distribution of aluminium between two tetrahedral sites was non-random, with high preference toward occupying T2 positions located in the six-membered rings. The desilicated sample showed very high Brønsted acidity and high catalytic activity in the liquid-phase isomerization of α-pinene. Retention of the sample crystallinity, increased amount of Brønsted acid sites, their high acid strength and formation of large volume of 3D mesopores improving transport of reactants, all contributed to the enhanced catalytic activity of the desilicated mazzite.

Dendritic mesoporous carbon nanoparticles for ultrahigh and fast adsorption of anthracene

Developing highly effective adsorbents for efficient decontamination of organic pollutants from water is an evasive aim for community well-being and environmental protection. Here, we report the successful fabrication of dendritic mesoporous carbon nanoparticles (DMCNs) as an advantageous adsorbent for ultrahigh and fast adsorption of anthracene. Dendritic mesoporous organosilica nanoparticles with an octadecyl-rich framework were utilized to synthesize DMCNs through carbonization and removal of silica. The DMCNs show a high carbon content, large mesopore volume of 1.484 cm3 g−1 and high surface area of 1218 m2 g−1. It is revealed that both the high carbon content and highly accessible large surface area contribute to the excellent adsorption capacity towards anthracene (947.9 mg g−1), which is significantly higher than those in previous reports. Furthermore, the large radial pores of DMCNs with bimodal pore size distributions (2.1 and 18.4 nm) and open pore channels allow fast adsorption kinetics. The developed materials hold promise as effective adsorbents for efficient remediation of organic pollutants.

Spherical hollow mesoporous silica supported phosphotungstic acid as a promising catalyst for α-arylstyrenes synthesis via Friedel-Crafts alkenylation

In this work, a spherical hollow mesoporous silica (SHMS) with high surface area (902 m2/g) and large mesopore volume (1.31 cm3/g) was prepared via a facile and scalable two-step soft-hard dual template-assisted sol-gel approach (OSDSG) by using glucose-derived carbon nano/micro particles (NMCP) as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template, respectively, in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane (C18TMS). Supported phosphotungstic acid (PTA) catalysts on SHMS (PTA/SHMS) and on previously reported spherical mesoporous silica (PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), and NH3 temperature-programmed desorption (NH3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse α-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.

Hierarchical AlPO4-5 and SAPO-5 microporous molecular sieves with mesoporous connectivity for water sorption applications

Herein, we report the synthesis of hierarchical AlPO4-5 and SAPO-5 molecular sieves that exhibit varying degrees of mesoporous interconnectivity by controlling the amount of triethylamine (TEA) (used as the structure directing agent) and the Si-to-Al ratio (Si/Al); the gel mixture had a composition of (1 − y) Al2O3:y SiO2:1.3 P2O5:x TEA:200 H2O. The molecular sieves were characterized by X-Ray powder Diffraction (XRD) and Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX), and their sorption properties were studied by N2 adsorption-desorption at 77 K and water adsorption at 316 K. In the synthesis gel with x = 1.6 ((1 − y) Al2O3:y SiO2:1.3 P2O5:1.6 TEA:200 H2O), SAPO-5 and AlPO4-5 exhibit high Brunauer-Emmett-Teller specific surface areas of ~380 m2 g−1 and 325 m2 g−1, respectively. SAPO-5, having a composition of Si0.46Al0.6P0.804, exhibits significant water uptake at low relative pressures (3.4 mmol/g at P/P0 = 0.03 vs. 0.2 mmol/g for pure AlPO4-5) attributed to the contribution of hydrophilic Brønsted acid sites, arising from the charge imbalance created by the isomorphic substitution of Si into the aluminophosphate structure predominantly via the SM2 mechanism. Furthermore, SAPO-5 exhibited a hierarchical pore structure having distinct pore size distributions centred on 0.7 nm and 15.8 nm, attributed to the AFI framework and the induced mesoporosity, respectively. At higher relative pressures, SAPO-5 exhibited the highest total water adsorption capacity of 14.1 mmol/g at a relative pressure of 0.38, compared to 11 mmol/g for AlPO4-5. The higher overall capacity of SAPO-5 is attributed to capillary condensation into the relatively large mesopore volume.

Water vapor sorption isotherms, pore structure, and moisture transport characteristics of alkali-activated and Portland cement-based binders

Moisture transport plays a key role in determining the different durability-related features of cementitious materials. In this paper, moisture sorption in a range of low-calcium (geopolymer-type) and calcium-rich alkali-activated binders are studied and compared with that of Portland cement-based binders. Through the analysis of water vapor sorption isotherms (WVSI) and mercury intrusion porosimetry (MIP) test results, two vastly different pore structures were observed. Fly ash-based geopolymer-type binders showed a very porous structure where a large volume of mesopores coexisted with a significant volume of macropores. Alkali-activated slag binders, however, had a very fine pore structure, with a relative lack of large macropores. The different pore structure of fly ash-based and slag-based binders led to amplification of pore blocking and cavitation in blended systems by the addition of slag. Analysis of the sorption kinetics showed the prominent effect of the presence of calcium in the matrix to reduce the permeability.

Activity and Stability of Carbide Derived Carbon Supports in PEMFC Application

Polymer electrolyte membrane fuel cells (PEMFCs) are regarded as a promising alternative energy conversion devices for both mobile and stationary applications. Main problems hindering the wide-scale commercialization of PEMFCs are high overpotential for oxygen electroreduction reaction (ORR) at the cathode decreasing the efficiency as well as the instability of porous carbon supports in fuel cell working conditions. Therefore, novel catalyst materials are being sought for PEMFC applications [1, 2]. Hierarchical microporous-mesoporous carbon supports were prepared from molybdenum carbide using the high temperature chlorination method. Prepared materials exhibited high specific surface area and large mesopore volume [3-4]. Thermogravimetric analysis, X-ray diffraction, low temperature nitrogen sorption and high resolution transmission electron microscopy methods were used to characterize the structure of the synthesized catalyst materials. Prepared catalysts were used in the single cell measurements. Catalyst coated membrane method was used to prepare the MEAs using ultrasonic spaying technique. The polarization curves and chronopotentiometric measurements were conducted to evaluate the activity and stability of the catalyst materials synthesized. From cyclic voltammetry the electrochemically active surface area values were calculated and used to estimate the contact surface of platinum nanoparticles and Nafion electrolyte. The series resistance of electrolyte, polarization resistance and activation energy values have been calculated from electrochemical impedance spectroscopy data. It was established that prepared carbon materials with well-defined properties are excellent objects to study the impact of the catalyst support properties on the performance of a PEM fuel cell. It was found that the novel synthesized catalyst materials are very stable and catalytically active towards ORR. Therefore, prepared materials are suitable for PEMFC applications. Acknowledgements. This work was supported by Estonian target research project IUT20-13, Personal Research Grant PUT1033, Estonian Centre of Excellence Project No. 2014-2020.4.01.15-0011. References S. Sepp, K. Vaarmets, J. Nerut, I. Tallo, E. Tee, H. Kurig, J. Aruväli, R. Kanarbik, E. Lust, Electrochim. Acta 2016, 203, 221−229.S. Sepp, K. Vaarmets, J. Nerut, I. Tallo, E. Tee, H. Kurig, J. Aruväli, R. Kanarbik, E. Lust, J. Solid State Electrochem. 2016, 21(4), 1035–1043.S. Sepp, E. Härk, P. Valk, K. Vaarmets, J. Nerut, R. Jäger, E. Lust, J. Solid State Electrochem. 2014, 18(5), 1223 – 1229.E. Lust, K. Vaarmets, J. Nerut, I. Tallo, P. Valk, S. Sepp, E. Härk, Electrochim. Acta 2014, 140, 294-303.

Dual-metal zeolitic imidazolate frameworks and their derived nanoporous carbons for multiple environmental and electrochemical applications

Nanoporous carbons were prepared by thermal conversion of zinc/cobalt-based zeolitic imidazolate frameworks (ZIF-8/ZIF-67) and their bimetallic ZIFs, and used for environmental remediation, energy storage and conversion. For wastewater treatment by adsorption, pristine ZIFs presented high adsorption capacities of phenol while the carbon derivatives showed a negligible capacity, due to the collapse of frameworks during the pyrolysis, resulting in a sharp decrease in specific surface area and micropore fraction. However, the as-derived carbons exhibited excellent catalytic performances in degradation of phenol and p-hydroxybenzoic acid by advanced oxidation using peroxymonosulfate. Moreover, ZIF-67 derived carbons also produced the best performances in electrochemical oxygen reduction and evolution reactions due to a high graphitic degree, while ZIF-8 derived carbons showed the highest specific supercapacitance, attributing to the large mesopore volume and specific surface area. This study illustrated that the structures of ZIFs-derived carbon materials are determined by the metal species and constituents of the parental ZIFs as well as the pyrolysis conditions, making the carbons varying performances in environmental and electrochemical applications.

Preparation of chabazite with mesopores templated from a cationic polymer

Mesoporous chabazite zeolites were prepared by using the cationic polymer polydiallyldimethylammonium chloride (PDADMAC) as template for mesopores and N,N,N-trimethyl-1-adamantammonium hydroxide as structure directing agent for the chabazite framework. The prepared zeolites had large surface areas and significant mesopore volumes that increased with high PDADMAC loading. Nitrogen sorption isotherms of chabazite zeolites with low loadings of PDADMAC (0.8–2.3 wt.%) displayed a composite of Type I and II with a broad H4 hysteresis loop at p/po=0.8–1.0. At a high polymer loading (3.1 wt.%) the resulting zeolite displayed the Type IV sorption isotherm and H3 hysteresis. The chabazite zeolites prepared with 0.8–2.3 wt.% polymer had exponentially decaying mesopore size distribution curves ranging from 2 to 30 nm centred around 4–5 nm. A polymer loading of 3.1 wt.% gave a zeolite with a multimodal meso- and macropore size distribution curve ranging from 2 to 140 nm. Adjusting the synthesis gel composition made it possible to prepare mesoporous chabazite zeolites with PDADMAC loadings up to 3.1 wt.% at Si/Al = 20–70.

Nitrogen-doped biomass-based hierarchical porous carbon with large mesoporous volume for application in energy storage

N-doped biomass-derived carbon with high specific surface area, suitable N atom doping ratio and superior hierarchical porous structure has been prepared by one-step carbonization activation method. Benefiting from the mesoporous structure formed by fragments of nanowires PPy anchoring to each other during the carbonization process, the product possesses large pore volume (1.53 cm3 g−1) and mesoporous volume (1.01 cm3 g−1). Owing to the synergistic effect of the superior pore structure and suitable N atom doping ratio, the product exhibits excellent performance for energy storage. Typically, the product exhibits high specific capacitance (330 F g−1) and rate capability (71.5% of capacitance retention at 20 A g−1) in three-electrode systems. A coin-type symmetric supercapacitor has been assembled based on the product, and an energy density as high as 37.5 W h kg−1 is verified in this cell. Furthermore, the product is also applied to the area of lithium-ion battery, where a high reversible capacity of 1662 mA h g−1 at 0.1 A g−1 is confirmed, indicating the superior Li+ storage capability.

Hierarchically porous carbon derived from waste acrylic fibers for super-high capacity lithium ion battery anodes

Acrylic fiber is one of three important synthetic fibers in the world. The disposal and reuse of large number of waste acrylic fibers from fabric manufacturers or waste recovery is an urgent economic and environmental issue. Here, a porous carbon was derived from waste acrylic fibers via pre-oxidized, carbonization and KOH activation. Furthermore, we adopted melamine as nitrogen source to dope the porous carbon materials. When used as the anode of lithium ion batteries, this nitrogen-doped porous carbon shows high reversible capacity of ca. 1200 mA h g−1 after 50 cycles at 0.1 A g−1. Reversible capacities of 550 and 370 mA h g−1 are obtained at higher current densities of 1 and 5 A g−1 after 500 cycles, respectively. The outstanding electrochemical performance are a result of its large mesopore volume, high-level N-doping (especially, pyridinic-N), large quantity of edge defects, and three-dimensional hierarchical porous architecture. This paper demonstrates that the reuse of waste industrial acrylic fibers as energy storage materials is a promising method for both energy and environmental fields.

Nitrogen-doped hierarchically porous carbon nanopolyhedras derived from core-shell ZIF-8@ZIF-8 single crystals for enhanced oxygen reduction reaction

It’s significant to develop efficient and durable metal-free electrocatalysts for oxygen reduction reaction (ORR). The ORR performance of metal-free electrocatalysts are known to be limited by insufficient activity compared with platinum catalysts. Optimizing the configuration of porous texture or electronic structure can create and expose more active sites as well as facilitate mass transfer, which are effective ways to improve ORR activity. Here we fabricated a core-shell N-doped hierarchically porous carbon nanopolyhedras (CS-HPCNs) derived from core-shell ZIF-8@ZIF-8 single crystals. The pore characteristics and doped N species of catalysts were tuned by controlling the carbonization process for higher ORR activity. CS-HPCNs exhibited increased mesopore volume and surface area, higher contents of pyridinic and graphitic N compared with carbon nanocubes (HPCNs) without core-shell structure. Compared to commercial Pt/C catalyst, CS-HPCN1000-5 (carbonized at 1000 °C for 5 h) showed comparable onset potential, higher limiting current density and kinetic current density in an approximate four-electron ORR process. The large mesopore volume and surface area of such core-shell hierarchically porous structures, together with high contents of pyridinic and graphitic N, contributed to its good ORR activity. The construction of hierarchically porous structures with enhanced mesopore volume and surface area in metal-free N-doped carbon catalyst is proved to be an efficient approach to boost ORR activity.

A dual-templating synthesis strategy to hierarchical ZSM-5 zeolites as efficient catalysts for the methanol-to-hydrocarbons reaction

A novel dual-templating synthesis strategy is presented to obtain hierarchical ZSM-5 zeolite using a combination of known structure-directing agents for ZSM-5 synthesis and C16H33-[N+-methylpiperidine] (C16MP) as mesoporogen. C16MP is a cheap surfactant, which can be obtained in a single step by alkylation of N-methylpiperidine. The zeolite materials were extensively characterized for their textural and acidic properties and evaluated on the basis of their ability to convert methanol to hydrocarbons. Bulk and nanosheet (di-quaternary ammonium surfactant) ZSM-5 zeolites served as reference materials. Hierarchical ZSM-5 zeolite can be obtained in this way with diethylamine, n-propylamine, 1,4-diaminobutane, 1,6-diaminohexane. In particular, the combination with diethylamine afforded a material that displayed similar performance in the methanol-to-hydrocarbons reaction as nanosheet ZSM-5. The optimum ZSM-5 zeolite is highly crystalline, contains a large mesopore volume and few silanol groups and external Brønsted acid sites, which contributes to the low rate of deactivation.

Catalytic cracking of n-hexane to light alkene over ZSM-5 zeolite: Influence of hierarchical porosity and acid property

ZSM-5 is active in n-hexane cracking to light alkenes, but with the disadvantage of fast deactivation. A long lifetime ZSM-5 with high activity and anti-carbon deposition performance was of great concern for industrial application. The hierarchical ZSM-5 zeolites (xHF-ZSM5) were obtained by chemical etching with fluoride ions and characterized by XRD, FTIR, NH3-TPD, SEM, TEM, N2 adsorption-desorption. They showed higher BET surface area, larger mesoporous volume, less defect zones, commensurable microporous structure and acid property compared with that of the parent ZSM-5. The defects were dissolved resulting in higher crystallinity zeolite. They showed better catalytic performance with less carbon deposition in catalytic cracking of n-hexane due to superior channel structure, large mesoporous and macroporous structure. In order to reduce the amount of carbon deposition further, 0.5HF-ZSM5 was selected and made phosphorus modification. After phosphorus modification, the catalytic activity and stability was maintained at a high level, and the carbon deposition of n-hexane cracking was restrained due to the gradual decreasing of acid amount with the increase of phosphorus content. The amount of carbon deposition decreased and reached the minimum of 23 mg g−1 for 0.5HF-ZSM5-1P, which was four times less than that of the parent ZSM-5.

Morphologically Cross‐Shaped Ru/HZSM‐5 Catalyzes Tandem Hydrogenolysis of Guaiacol to Benzene in Water

AbstractHydrogenolysis of C−O bonds is an important tool for synthesis of valuable fuels and chemicals from biomass. In this contribution, we report that morphologically cross‐shaped HZSM‐5‐loaded Ru nanoparticles have demonstrated high activity in the selective hydrogenolysis of guaiacol to benzene in water with 97 % yield and a rate of 7.8 g g−1 h−1 accompanied with high durability. N2 sorption analysis showed that Ru/HZSM‐5 (cross‐shaped) had a large mesoporous surface area and pore volume for loading small and uniform Ru nanoparticles, as confirmed by TEM images. The stronger interaction of Ru and cross‐shaped HZSM‐5 was simultaneously confirmed by a higher hydrogen reduction temperature of RuO2 on calcined Ru/HZSM‐5, a blueshift of Ruδ+‐(CO)n, Ruδ+‐(CO), and Ru0‐(CO) species in the IR spectra of adsorbed CO, and a higher Ru 3d5/2 binding energy in X‐ray photoelectron spectroscopy measurements. The reaction constant in guaiacol hydrogenolysis to phenol over cross‐shaped Ru/HZSM‐5 (0.051 min−1) was 3–4 times higher than that on spherical and cuboid Ru/HZSM‐5 (0.012–0.029 min−1) at identical conditions, attributed to the remarkable hydrogenolysis catalytic capability of Ru nanoparticles on cross‐shaped HZSM‐5. In addition, adsorption of guaiacol and hydrogen was more substantial on cross‐shaped Ru/HZSM‐5, as evidenced by of IR and mass spectroscopy, respectively. The higher adsorption of guaiacol is attributed to the abundant Lewis acid sites on cross‐shaped Ru/HZSM‐5, as the Al−OH enriched Lewis acid sites favor the adsorption of oxygen‐containing guaiacol. The higher rate constant in the primary step, together with the adsorbed high concentrated reactant and hydrogen (with nearly first‐order reaction kinetics) on cross‐shaped Ru/HZSM‐5, facilitates the overall tandem reaction, leading to an excellent hydrogenolysis catalyst working at hydrothermal conditions for biomass conversion.

Ordered mesoporous carbons as highly efficient absorbent for coal gasification wastewater – A real case study based on the Inner Mongolia Autonomous coal gasification wastewater

Coal gasification wastewater (CGW) possess a high phenolics content, how to remove phenols is the crux of the environmental problems. In this work, we report the design and synthesis of a several highly graphitized ordered mesoporous carbons (OMCs) by carbonization of precursors from phenol and formalin. The obtained porous OMCs have uniform structures with the pore size, order degree, and surface areas being controllable by varying the synthesis conditions. In depth study of the prepared materials reveals that the OMCs carbonized at 923.15 K exhibit ordered 2D hexagonal mesoporous structures with high degree of graphitization, high surface area (590.6 m2·g−1), appropriate pore size (mean diameter about 10 nm) and large mesoporous pore volume (0.512 cm3·g−1). The prepared OMCs are applied as adsorbent for treatment of the CGW collected directly from the biochemical effluent of coal chemical enterprise in Inner Mongolia Autonomous region, China. The OMCs show excellent adsorption properties for phenol effluent with the removal efficiency of phenols being up to 92.3%. The adsorption experiment data demonstrates that the adsorption is a multi-molecular layer adsorption process, during which the physical adsorption takes place. In addition, the study of adsorption thermodynamics indicates that the adsorption process is spontaneous and endothermic. The adsorption of samples on phenol from CGW has reached an ideal level.

Facile One-Pot Synthesis of ZSM-5 Aggregates with Inter- and Intra-Crystalline Mesopores for Methanol to Gasoline Conversion

ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals (combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide (APAM). The resultant zeolites (AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH3-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline (MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter- and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM.

Hierarchical Micro-/Mesoporous Carbon Derived from Rice Husk by Hydrothermal Pre-Treatment for High Performance Supercapacitor

The exploration of highly abundant and available biomass wastes as sustainable precursors through a scalable and cost-effective synthesis strategy is extremely important for novel materials development in energy storage and conversion technologies. Herein, we have successfully fabricated hierarchical micro-/mesoporous carbons (HMMC) from low-cost and eco-friendly agricultural residues via an easy method. The highly hierarchical porous carbons were obtained from rice husk via NaOH-assisted hydrothermal pre-treatment followed by carbonization/activation process. The NaOH-assisted hydrothermal treatment removed ash content and facilitated the development of pores, especially the mesopores, resulting in hierarchical porous carbons with high specific surface area, large pore volume and high ratio (49.3%) of mesopores. These hierarchically structural advantages guarantee the excellent performances of the resultant porous carbons as electrodes for supercapacitors. The rice husk-derived HMMC electrode exhibit a maximum capacitance of 302.2 F g−1 at a current density of 1 A g−1 in a three-electrode system with 6 M KOH as electrolyte, which is significantly better than 193.7 F g−1 at 1 A g−1 obtained on rice husk-derived microporous carbons via direct carbonization and activation. Moreover, the NaOH-assisted HMMC electrodes also show good cycle stability. These results demonstrated that NaOH-assisted hydrothermal pre-treatment is a facile and effective way to produce hierarchical porous carbons from natural biomass wastes with improved electrochemical performances for supercapacitors.

Mesopore-dominant nitrogen-doped carbon with a large defect degree and high conductivity via inherent hydroxyapatite-induced self-activation for lithium-ion batteries.

In this study, N-doped mesopore-dominant carbon (NMC) materials were prepared using bio-waste tortoise shells as a carbon source via a one-step self-activation process. With intrinsic hydroxyapatites (HAPs) as natural templates to fulfill the synchronous carbonization and activation of the precursor, this highly efficient and time-saving method provides N-doped carbon materials that represent a large mesopore volume proportion of 74.59%, a high conductivity of 4382 m S−1, as well as larger defects, as demonstrated by Raman and XRD studies. These features make the NMC exhibit a high reversible lithium-storage capacity of 970 mA h g−1 at 0.1 A g−1, a strong rate capability of 818 mA h g−1 at 2 A g−1, and a good capacity of 831 mA h g−1 after 500 cycles at 1 A g−1. This study provides a highly efficient and feasible method to prepare renewable biomass-derived carbons as advanced electrode materials for the application of energy storage.

Facile Synthesis of Corn Silk Derived Nanoporous Carbon for an Improved Supercapacitor Performance

Efforts made in this current study focus on the development of a novel, simple, cost-effective yet efficient approach to synthesize nanoporous carbon material from corn silk biomass for supercapacitor applications. We have employed different activation approaches in order to obtain a higher surface area and large mesoporous volume fraction. The performance of corn silks derived nanoporous activated carbon materials for supercapacitor applications was evaluated in a symmetric two electrode configuration using aqueous/non-aqueous electrolytes at various current densities and scan rates. Electrochemical results indicated that the as-synthesized nanoporous carbon prepared by single step activation exhibits ideal supercapacitor performance ∼160 F/g (at 1 A/g current density) with excellent rate capability and cyclic stability. Further, it displayed a promising amount of energy that can be stored in a given mass ∼32.28 Wh/kg at the power density of 870.68 W/kg. Benchmark studies revealed that the nanoporous carbon developed in the current study is at par with the performance of the commercial carbon electrode. The superior performance of corn silks derived nanoporous carbon is attributed to high surface area pertaining to its unique mesoporous fiber-like morphology, which facilitates fast ionic and electronic diffusion of the electrolyte into and out of the pores during charging and discharging.