Ultrahigh Specific Surface Area Research Articles

The honeysuckle stem derived porous carbon with an ultra-high specific surface area and ultra-long cycle life

The honeysuckle stem derived porous carbon with an ultra-high specific surface area and ultra-long cycle life

Lignin-derived carbon aerogels with high surface area for supercapacitor applications

Carbon materials are attracting increasing interest in the field of supercapacitors because of their well-developed porous structures, large specific surface areas, long cycle life, good conductivity, and environmental friendliness. In this study, Kraft lignin extracted from black liquor was used to synthesize a lignin precursor via the sol–gel method. Under well-controlled pyrolysis conditions, this precursor produces lignin-based carbon aerogels (LECAs) with well-developed textural structures that exhibit excellent supercapacitor performance. A LECA with a specific surface area of 3742 m2 g−1 exhibits a saturated adsorption capacity of up to 3442 mg g−1 for methylene blue. As a supercapacitor electrode material, the LECA shows an excellent specific capacitance (504.7F g−1 at 0.2 A g−1) and a high stability (87.7% capacity retention after 10,000 cycles). In addition, a symmetric LECA-based supercapacitor exhibits high energy and power densities with maximum values of 18.1 Wh kg−1 and 16000 W kg−1, respectively. This excellent energy-storage ability may be attributable to the LECA electrode, which has an ultrahigh specific surface area, suitable pore size distribution, and trace amounts of heteroatoms such as O and S. Thus, this study provides a simple, scalable approach for improving the performance of lignin-based energy-storage materials and offers a route for the high-quality utilization of lignin derived from the pulp and paper industry toward the alleviation of environmental pollution.

A novel MoP2@Ni2P nanosheet and an individual kelp-based porous carbon for assembly a unique high performance asymmetric supercapacitor

In order to improve the specific capacity and energy density of the asymmetric supercapacitors, it is necessary to design positive and negative electrode materials with special structure and good electrochemical properties. Herein, a novel MoP2@Ni2P nanosheet material is prepared by one-step simple hydrothermal synthesis and low temperature phosphating method, which exhibits excellent specific capacity of 133.6 mAh g−1 at 0.5 A g−1. In addition, a kelp based porous carbon nanosheet material (AKPC) is prepared via swollen the kelp in a sodium chloride solution and then subjected to an activation and carbonization. Because of its biomaterial unique morphology, the carbon material shows ultra-high specific surface area (1197 m2 g−1) and large pore volume, thus possess a high specific capacitance of 180 F g−1 at 0.5 A g−1. Moreover, the above two materials are assembled into a unique asymmetric supercapacitor with operating voltage of 1.65 V, which has demonstrated a high energy density of 31.5 Wh kg−1 and excellent cycling stability with 81 % capacitance retention after 1500 cycles in aqueous electrolyte. The successful preparation of the asymmetric device provides a new idea for the development of high performance electronic devices.

High specific surface area γ-Al2O3 nanoparticles synthesized by facile and low-cost co-precipitation method

Alumina (Al2O3) nanoparticles (NPs) are particularly adsorbent NPs with a high specific surface area (SSA) that may well be utilized to clean water. In this study, pure γ-alumina NPs are successfully synthesized by the co-precipitation method, and the effect of ammonium bicarbonate concentration on the synthesized NPs is studied to find the optimum concentration to provide the highest capacity of copper ions removal from water. The results declare that spherical alumina NPs with average diameters in the range of 19–23 nm are formed with different concentrations of precipitation agent, and the concentration has no significant effect on the morphology of NPs. Furthermore, the precipitating agent concentration influences the optical characteristics of the produced alumina NPs, and the bandgap energies of the samples vary between 4.24 and 5.05 eV. The most important impact of precipitating agent concentrations reflects in their SSA and capacity for copper ion removal Ultra-high SSA = 317 m2/g, and the highest copper removal at the adsorbate concentration of 184 mg/L is achieved in an alkalis solution followed by a neutral solution. However, admirable copper removal of 98.2% is even achieved in acidic solutions with 0.9 g/L of the alumina NPs synthesized at a given concentration of ammonium bicarbonate, so this sample can be a good candidate for Cu ions removal from acidic wastewater.

Activated Carbon with Ultrahigh Specific Surface Derived from Bamboo Shoot Shell through K2FeO4 Oxidative Pyrolysis for Adsorption of Methylene Blue.

To effectively remove methylene blue (MB) from dye wastewater, a novel activated carbon (BAC) was manufactured through co-pyrolysis of bamboo shoot shell and K2FeO4. The activation process was optimized to a temperature of 750 °C and an activation time of 90 min based on its excellent adsorption capacity of 560.94 mg/g with a yield of 10.03%. The physicochemical and adsorption properties of BACs were investigated. The BAC had an ultrahigh specific surface area of 2327.7 cm2/g and abundant active functional groups. The adsorption mechanisms included chemisorption and physisorption. The Freundlich model could be used to describe the isothermal adsorption of MB. The kinetics confirmed that the adsorption of MB belonged to the pseudo-second-order model. Intra-particle diffusion was the main rate-limiting step. The thermodynamic study showed that the adsorption process was endothermic and temperature was beneficial for the improvement of adsorption property. Furthermore, the removal rate of MB was 63.5% after three cycles. The BAC will have great potential for commercial development for purifying dye wastewater.

Sustainable Porous Carbons with Ultrahigh Specific Surface Areas for High-performance Supercapacitors

Waste biomass residues are prospective precursors for the preparation of sustainable porous carbons. In this work, we used the residues from Lonicera japonica Thunb and Ligusticum chuanxiong Hort to prepare porous carbons with ultra-high specific surface area (> 3000 m2 g−1), which deliver excellent capacitive performance for electrochemical double-layer capacitor. Porous carbon derived from Ligusticum chuanxiong Hort displays a specific capacitance of 314.4 F g−1 (1 A g−1) in three electrode system. The energy density of Ligusticum chuanxiong Hort-based symmetric supercapacitor reaches 8.4 Wh kg−1 at the power density of 519 W kg−1 in 6 M KOH. The cell remains a high energy density of 5.1 Wh kg−1 at an increased power density of 10.8 kW kg−1. Our work indicates that the waste biomass residues are promising and competitive precursors for the preparation of ultrahigh specific surface area porous carbons for supercapacitor application.

Synthesis of Graphdiyne Hollow Spheres and Multiwalled Nanotubes and Applications in Water Purification and Raman Sensing.

Controlling the structure of graphdiyne (GDY) is crucial for the discovery of new properties and the development of new applications. Herein, the microemulsion synthesis of GDY hollow spheres (HSs) and multiwalled nanotubes composed of ultrathin nanosheets is reported for the first time. The formation of an oil-in-water (O/W) microemulsion is found to be a key factor controlling the growth of GDY. These GDY HSs have fully exposed surfaces because of the avoidance of overlapping between nanosheets, thereby showing an ultrahigh specific surface area of 1246 m2 g-1 and potential applications in the fields of water purification and Raman sensing.

One-step synthesis of readily recyclable poplar sawdust-based porous carbon for the adsorption of tetracycline

To solve the problem of a large amount of poplar sawdust (Populus L.) in urgent need of disposal and widespread contamination by tetracycline (TC), a new and simple method of simultaneous activation, magnetization, and carbonization was used to prepare a magnetic porous carbon adsorbent (MPC). This agroforestry waste was successfully turned into a treasure. The magnetic properties make MPC easy to be separated from water. The activation of KHCO3 and FeCl3·6H2O and high-temperature carbonization significantly caused a significant increase in the pore volume of the MPC. The MPC has an ultra-high specific surface area (1002.48 m2 g−1) and well-developed microporous/mesoporous structures. The adsorption process of the MPC on tetracycline was a chemisorption-based monolayer adsorption process with an adsorption capacity of 288.2 mg g−1. π-π-EDA interactions and van der Waals forces were probably the most important driving forces for the adsorption of TC. The adsorption of TC by the MPC performed well at a wide range of pH and had significant resistance to interference. At the same time, the excellent adsorption effect was maintained after four cycles of experiments. The simple and unique preparation, magnetic properties, and excellent pore structures of the MPC make it a promising candidate for engineering applications.

Ultra-high specific surface area porous carbons derived from Chinese medicinal herbal residues with potential applications in supercapacitors and CO2 capture

Ultra-high specific surface area (SSA, > 3000 m2 g−1) porous carbons are promising materials for energy storage and gas selective adsorption and separation. In this work, we have synthesized porous carbons with ultra-high SSAs (up to 3410 m2 g−1) and large pore volumes (up to 2.095 cm3 g−1) from Chinese medicinal herbal residues (CHRs). The obtained ultra-high SSA porous carbons display good electrochemical performance as the electrode materials for supercapacitors with specific capacitances of up to 291.6 F g−1 at 1 A g−1 in 6 M KOH, as well as high rate retentions (72.0–82.1 %) at 50 A g−1. Moreover, as the CO2 capture materials, the ultra-high SSA porous carbons display high CO2 uptake capacities (up to 30.0 mmol g−1 at 298 K, 30 bar). Our work provides an effective strategy to fabricate ultra-high SSA CHRs derived porous carbons which simultaneously possess the great potential for energy storage and CO2 capture.

Functionalized MOF-Based Photocatalysts for CO2 Reduction.

Metal-organic frameworks (MOFs) materials have become a research forefront in the field of photocatalytic CO2 reduction attributed to their ultra-high specific surface area, adjustable structure, and abundant catalytic active sites. Particularly, MOFs can be facilely tuned to match CO2 photoreduction by utilizing post-modification of metal nodes, functionalization of organic linkers, and combination with other active materials. Herein, the recent advances in the construction strategy of MOF-based photocatalysts materials for CO2 reduction are highlighted. Some systematic modification strategies on MOF-based photocatalysts are also discussed, such as modification of metal sites and organic ligands, construction of heterojunction, introduction of single/dual-atom, and strain engineering. Finally, the future development directions of MOF-based photocatalysts in the field of CO2 reduction are presented.

Enhanced adsorption of 3,4-methylenedioxymethamphetamine by magnetic graphene oxide-polydopamine nanohybrid modified zeolitic imidazolate framework-67 and its micro-mechanism: Experiments and calculations

Exploring the structure-dependent adsorption mechanism of contaminants in wastewater is beneficial to high-efficiency adsorbents design and environmental remediation. In this study, emerging porous material of zeolitic imidazolate framework-67 (ZIF-67) has been modified by the magnetic graphene oxide-polydopamine nanohybrid (mGOP) to obtain three-dimensional ZIF-67/mGOP through an in-situ growth strategy, which was applied to adsorb 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”) in wastewater. A combination of characterizations, experiments (pH, humic acid and ion strength effect) and quantum chemical calculations revealed the microscopic adsorption mechanism involves each single component, of which the hydrogen bond (O/N…HO) and π–π electron donor acceptor (π–π EDA) interactions of mGOP endowed favourable adsorption of ZIF-67/mGOP, and mechanisms of the pore filling and Co-O chelation of ZIF-67 played synergistic effect. Such nanocomposite as a ZIFs-based adsorbent exhibited ultra-high porosity (total pore volume = 0.4033 cm3/g) and specific surface area (995.22 m2/g), revealed the heterogeneity and multilayer adsorption properties, and obtained a theoretical maximum adsorption capacity of 159.845 μg/g which higher than that of mZIF-67 alone. Overall, this work provided an effective strategy for rationally modulate ZIFs-based composites and exploration of adsorption mechanism.

Novel oral spherical activated carbon with ultrahigh specific surface area for adsorption of endogenous toxins

Oral adsorbents can treat chronic kidney disease by removing endogenous toxins from the gastrointestinal tract. Herein, a novel polystyrene-based spherical activated carbon adsorbent with an ultrahigh specific surface area (2125.18 m2·g−1) and a good particle strength (30 N) was successfully prepared via air-oxidation and steam activation. The spherical activated carbon adsorbent possessing hierarchically porous structure presented high creatinine adsorption capacity (up to 300.37 mg·g−1) and excellent adsorption selectivity for different molecular weight adsorbates. Moreover, the pH variation had little effect upon the adsorption capacity of creatinine on the adsorbents. Finally, the mechanism of creatinine adsorption on spherical activated carbon adsorbents was proposed. Van der Waals force and hydrogen bond were considered the driving forces of adsorption for creatinine.

Nanoporous Hollow Carbon Spheres Derived from Fullerene Assembly as Electrode Materials for High-Performance Supercapacitors

The energy storage performances of supercapacitors are expected to be enhanced by the use of nanostructured hierarchically micro/mesoporous hollow carbon materials based on their ultra-high specific surface areas and rapid diffusion of electrolyte ions through the interconnected channels of their mesoporous structures. In this work, we report the electrochemical supercapacitance properties of hollow carbon spheres prepared by high-temperature carbonization of self-assembled fullerene-ethylenediamine hollow spheres (FE-HS). FE-HS, having an average external diameter of 290 nm, an internal diameter of 65 nm, and a wall thickness of 225 nm, were prepared by using the dynamic liquid-liquid interfacial precipitation (DLLIP) method at ambient conditions of temperature and pressure. High temperature carbonization (at 700, 900, and 1100 °C) of the FE-HS yielded nanoporous (micro/mesoporous) hollow carbon spheres with large surface areas (612 to 1616 m2 g-1) and large pore volumes (0.925 to 1.346 cm3 g-1) dependent on the temperature applied. The sample obtained by carbonization of FE-HS at 900 °C (FE-HS_900) displayed optimum surface area and exhibited remarkable electrochemical electrical double-layer capacitance properties in aq. 1 M sulfuric acid due to its well-developed porosity, interconnected pore structure, and large surface area. For a three-electrode cell setup, a specific capacitance of 293 F g-1 at a 1 A g-1 current density, which is approximately 4 times greater than the specific capacitance of the starting material, FE-HS. The symmetric supercapacitor cell was assembled using FE-HS_900 and attained 164 F g-1 at 1 A g-1 with sustained 50% capacitance at 10 A g-1 accompanied by 96% cycle life and 98% coulombic efficiency after 10,000 consecutive charge/discharge cycles. The results demonstrate the excellent potential of these fullerene assemblies in the fabrication of nanoporous carbon materials with the extensive surface areas required for high-performance energy storage supercapacitor applications.

Fabrication and Application of Ag, Black TiO2 and Nitrogen-Doped 3D Reduced Graphene Oxide (3D Black TiO2/Ag/N@rGO) Evaporator for Efficient Steam Generation

The scarcity of fresh water, which is aggravated by rapid economic development and population growth, is a major threat to the modern world. Solar-driven interfacial desalination and steam generation is a promising strategy that localizes heat at the air-water interface through appropriate thermal management and demonstrates efficient photothermal performance. In the current study, Ag, black TiO2, and nitrogen-doped 3D reduced graphene oxide (3D black TiO2/Ag/N@rGO) hierarchical evaporator was fabricated, and its morphology, elemental composition, porosity, broadband solar absorption potential, photothermal performance, and interfacial desalination potential were assessed. The 3D solar evaporator showed efficient solar absorption over the entire broadband UV-visible near-infrared (UV-Vis NIR) region and demonstrated 99% photothermal conversion efficiency and potential freshwater generation of 1.43 kg·m−2 h−1. The specific surface area and porosity analyses demonstrated an ultrahigh specific surface area, high pore volume, and a mesoporous structure, with a predominant pore diameter of 4 nm. The strong photothermal performance can be attributed to the nitrogen doping of the rGO, which boosted the electrocatalytic and photothermal activity of the graphene through the activation of the excess free-flowing π electrons of the sp2 configuration of the graphene; the broadband solar absorption potential of the black TiO2; and the localized surface plasmon resonance effect of the AgNPs, which induced hot electron generation and enhanced photothermal conversion. Hence, the high photothermal conversion efficiency attained can be attributed to the synergistic photothermal performances of the individual components and the high interfacial surface area, abundant heat, and mass transfer microcavities of the 3D hierarchical porous solar absorber, offering multiple reflections of light and enhanced solar absorption. The study highlights the promising potential of the 3D evaporator for real-word interfacial desalination of seawater, helping to solve the water shortage problem sustainably.

Synthesis of mesopore-dominated porous carbon with ultra-high surface area via urea-assisted KOH activation

A mesoporous porous carbon (PC-KOH + Urea) with ultra-high specific surface area (SSA) was prepared from steam exploded poplar through urea-assisted KOH activation. The obtained PC-KOH + Urea had an ultra-high SSA of 3316 m2 g−1 and a total pore volume (VT) of 1.96 cm3 g−1, much higher than that of PC-KOH and PC-Urea, produced by KOH and urea activation alone, respectively. Meanwhile, PC-KOH + Urea possessed extremely high mesopores surface area (Smeso) (2183 m2 g−1) and mesopore volume (Vmeso) (1.46 cm3 g−1). In addition, urea can also serve as nitrogen source to dope nitrogen into PC-KOH + Urea, resulting in nitrogen content of 3.29%. To study the effects of urea on pore-forming, thermogravimetric analysis (TG) and thermogravimetric infrared technology (TG-IR) were adopted. It can be assumed that the ultra-high SSA of PC-KOH + Urea was mainly attributed to the reactions between pyrolysis products of urea and carbon. With ultra-high SSA, mesopore-dominated structure, and nitrogen doping, PC-KOH + Urea exhibited a high specific capacitance of 335.3 F g−1 at current density of 0.5 A g−1 in 6 M KOH aqueous electrolyte. In cyclic stability measurement, the capacitance retentions of PC-KOH + Urea were 99.6% after 4000 cycles. Thus, urea-assisted KOH activation was a feasible method to produce porous carbon with excellent performance.

The efficient removal of congo red and ciprofloxacin by peony seeds shell activated carbon with ultra-high specific surface area.

Preparation of high-performance activated carbon from agroforestry waste biomass can effectively improve the shortcomings of traditional biomass carbon performance. Using the waste biomass peony seeds shell (PSS) as the precursors in this study, high performance activated carbon was prepared by the KOH two-step activation method and used to remove congo red (CR) and ciprofloxacin (CIP) in water pollution. The obtained PSS-based activated carbons (PSACs) were characterized by SEM, EDS, N2 adsorption-desorption isotherm, FTIR, and XRD methods. The results showed that the activated carbon at 700°C (PSAC-700) had an ultra-high specific surface area (2980.96m2/g), excellent micropore volume (1.12cm3/g), and abundant surface functional groups. The results of adsorption performance revealed that PSAC-700 exhibited excellent adsorption capacity for CR (qmax = 2003.2mg/g) and CIP (qmax = 782.3mg/g), which was superior to the carbon-based adsorbents reported reviously in the literature. Langmuir model could well describe the adsorption process of PSACs for CR and CIP, indicating that the pollutant molecules were uniformly adsorbed on the surface monolayer. The regeneration experiment suggested that after three cycles, the adsorption capacities of PSAC-700 for CR and CIP reached 1814mg/g and 697mg/g, respectively, with good repeatability. The preparation of PSAC-700 in this study has high adsorption capacity and strong application, which is an ideal material for wastewater purification adsorbent and has broad application prospect.

A third-order plate model with surface effect based on the Gurtin–Murdoch surface elasticity

Thin films with micro/nano scale thickness possessing ultra-high specific surface area have been widely used in opto-, thermo-, and electro-mechanical actuators for ultra-sensitive detection of physical signal change and few molecular absorptions. However, there still lacks a rigorous plate model capable of describing the large deflection and, in the meanwhile, the complex surface effects of those films, especially the coupling between surface shear stress and bulk shear deformation. In this paper, via the satisfaction of the surface balance relation in the Gurtin–Murdoch theory, we refine Reddy’s third-order plate theory to accurately characterize the size-dependent deformation and uncover the influences of the surface layer on the second and third order shear deformations of micro/nano plates. It is revealed that the modified displacement field of our plate model can engender changes in local behaviors including the through-thickness distributions of bulk shear strain and shear stress, which bring about the change in global stiffness and stability of the plates, especially those with smaller length-to-thickness ratio. When the magnitude of residual surface stress increases, the stiffness and stability of the plate are enhanced, due to the amplification of bulk shear stress. Our model also indicates that miniature structures do not share entirely the same displacement field with macroscopic ones, and the method of deriving size-dependent displacement field incorporating surface effect can be extended to more complex cases. This work provides a strategy for tuning the static and dynamic behaviors of thin film devices by modifying the surface elastic constants and residual stress.

Construction of Bimetallic Co/Fe-Incorporated PTA/FDA Nanoclusters for Boosting Electrocatalytic Oxygen Evolution

Summary. Electrochemical water decomposition as a crucial approach for the gradual growth of renewable energy has attracted extensive attention. Metal-organic frameworks (MOFs) which benefit from ultra-high specific surface area, controllable nanostructures, and excellent porosity have been widely used as high activity catalyst for the decomposition of water by electrochemical means. Herein, the composition and morphology of metal–organic framework nanoclusters with bimetallic Co/Fe-incorporated PTA/FDA nanoclusters is designed for efficient and durable OER electrocatalysts, including CoFe-BTC/PTA, CoFe-BTC/FDA, and CoFe-PTA/FDA. The crystal structure of MOF materials is composed of alternating organic hydrocarbon BTC, PTA, or FDA and inorganic metal oxide layer. Co and Fe interact as central atoms, joining BTC, PTA, or FDA ligands to form a highly symmetric MOF structure. The electronic structures and active sites of various metals are different, and the insertion of iron atoms plays a certain role in the regulation of their electronic structures. CoFe-PTA/FDA shows significant OER overpotential η 10 = 295 mV (1.525 V vs. RHE) reached 10 mA cm-2, with 62.85 mV dec-1 for Tafel slope and pretty conspicuous stability (72 hours of continuous testing). The DFT calculation results show coordination unsaturated metal atom is the primary active center of these electrocatalytic reaction, and the coupling effect caused by adding Fe is the key to adjust the electrocatalytic activity.

Defect engineering on zeolitic imidazolate framework membrane via thermal annealing for organic solvent nanofiltration

Zeolitic imidazolate frameworks (ZIFs) have been attracting intensive attention in membrane separation fields because of their ultrahigh specific surface areas, well-defined apertures, and variable topological characteristics. However, the aperture sizes of ZIFs are smaller than the kinetic diameters of most organic solvent molecules, which impedes their applications in organic solvent separation. Herein, we develop a thermal annealing-derived methodology for defect engineering on the ZIF-67 membrane. This post-synthetic modification not only expanded the aperture size of ZIF-67 but also repaired intercrystalline cracks in the polycrystalline ZIF-67 layer. By controlling the thermal annealing conditions, the permeability of the polycrystalline ZIF-67 membrane toward organic solvent nanofiltration was enhanced by two times. Moreover, the annealed ZIF-67 membrane showed a high rejection of more than 99.6% for dyes (Evans blue) and pharmaceutical molecules (tetracycline, vitamin B12). This work provides an avenue for the controllable modification of ZIFs membranes to broaden their applications.

Nature-inspired self-activation method for the controllable synthesis of highly porous carbons for high-performance supercapacitors

The specific surface area (SSA) and pore structure are two critical factors that determine the energy storage performance of carbon-based supercapacitors. However, for biobased carbon electrodes, it is difficult to simultaneously control the pore structures and achieve high SSA. Herein, highly porous carbons (HPCs) with ultrahigh SSA and controllable pore structures are produced through hydrogel-controlled carbonization and activation process for glucose. Polyacrylamide (PAM) is used as the pore-forming agent, and pore structures can be regulated by controlling the content of PAM. The highest SSA of the HPCs reaches 3381 m2 g−1 with a 60% PAM content. Compared with the sample without PAM, the specific capacitance of HPCs-60 shows a 63% increase, reaching 441 F g−1 at a current density of 0.25 A g−1. Moreover, a KOH/PVA symmetric supercapacitor assembled from HPCs-60 not only exhibits an excellent energy density (10.9 Wh kg−1 at a power density of 125 W kg−1) but also has high cycling stability (∼10% loss over 20,000 cycles) and good flexibility. The as-prepared supercapacitors can provide stable power supplies for multiple electronic devices, indicating that the HPCs have enormous potential for use in high-performance electrochemical energy storage devices.