Ultrahigh Specific Surface Area Research Articles

Biochar with enhanced performance prepared based on "graphite-structure regulation" conjecture designed to effectively control water pollution.

In this work, corn straw was used as raw material, Hummers method and activation were used to adjust the graphite structure in biochar, and preparing straw based biochar (H-BCS) with ultra-high specific surface area (3441.80 m2/g), highly total pore volume (1.9859 cm3/g), and further enhanced physicochemical properties. Compared with untreated straw biochar (BCS), the specific surface area and total pore volume of H-BCS were increased by 47.24 % and 55.85 %, respectively. H-BCS showed good removal ability in subsequent experiments by using chloramphenicol (CP), hexavalent chromium (Cr6+), and crystal violet (CV) as adsorption models. In addition, the adsorption capacities of H-BCS (CP: 1396.30 mg/g, Cr6+: 218.40 mg/g, and CV: 1246.24 mg/g) are not only higher than most adsorbents, even after undergoing 5 cycles of regeneration, its adsorption capacity remains above 80 %, indicating significant potential for practical applications. In addition, we also speculated and analyzed the conjecture about the "graphite-structure regulation" during the preparation process, and finally discussed the possible mechanism during the adsorption processes. We hope this work could provide a new strategy to solve the restriction of biochar performance by further exploring the regulation of graphite structure in carbon materials.

Shuttle-free zinc–iodine batteries enabled by a cobalt single atom anchored on N-doped porous carbon host with ultra-high specific surface area

Aqueous zinc‑iodine batteries are favorable solutions for grid-level energy storage owing to their cost-effective components and intrinsic safety. Nevertheless, the sluggish conversion kinetics and polyiodide shuttle effect have significantly hindered their practical applications. Herein, a Co single atom anchored on N-doped porous carbon nanosheets (Co-SAs@NPC) was produced through an efficient molten-salt engaged pyrolysis process and further utilized as the iodine host for aqueous zinc-iodine batteries. The large specific surface area (1741 m2 g−1) combined with abundant heteroatom-containing functional groups can afford a tight physical and chemical confinement towards iodine species. Meanwhile, the presence of Co single atoms exhibits high electrocatalytic activity towards I2 reduction reactions. According to the experimental results and DFT theoretical calculations, the resulting Co-SAs@NPC can simultaneously offer generous electrochemical active sites and electrocatalytic activity, which displays a high adsorption ability towards iodide species and boost the reversible redox reactions between iodine and iodides. Consequently, the as-assembled zinc-iodine batteries with Co-SAs@NPC/I2 cathodes can deliver a high specific capacity (295 mA h g−1 at 0.3 A g−1), good rate performance (199 mAh g−1 at 20 A g−1), and long cyclic stability over 10,000 cycles. Additionally, the absence of polyiodide shuttle was analyzed by a series of ex-situ spectrum analyses.

Multicomponent nickel-molybdenum-tungsten-based nanorods for stable and efficient alkaline seawater splitting

The electrolysis of seawater for hydrogen production holds promise as a sustainable technology for energy generation. Developing water-splitting catalysts with low overpotential and stable operation in seawater is essential. In this study, we employed a hydrothermal method to synthesize NiMoWOX microrods (NiMoWOX@NF). Subsequently, an annealing process yielded a composite N-doped carbon-coated Ni3N/MoO2/WO2 nanorods (NC@Ni3N/MoO2/WO2@NF), preserving the ultrahigh-specific surface area of the original structure. A two-electrode electrolytic cell was assembled using NC@Ni3N/MoO2/WO2@NF as the cathode and NiMoWOX@NF as the anode, demonstrating exceptional performance in seawater splitting. The cell operated at a voltage of 1.51 V with a current density of 100 mA·cm−2 in an alkaline seawater solution. Furthermore, the NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolytic cell exhibited remarkable stability, running continuously for over 120 h at a current of 1100 mA·cm−2 without any observable delay. These experimental results are corroborated by density functional theory calculations. The NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolyzer emerges as a promising option for industrial-scale hydrogen production through seawater electrolysis.

The electrocatalytic activity of pomelo peel-derived nitrogen-doped carbon material for oxygen reduction reaction

Exploring the non-precious metal catalysts of oxygen reduction reaction (ORR) becomes the key to promote the industrialization of new energy devices such as fuel cells and metal-air batteries because of the sluggish kinetics of ORR. Three-dimensional N-doped carbon (NC-900) material was obtained using the high-temperature pyrolysis of pomelo peel waste. The prepared NC-900 catalyst possesses an ultra-high specific surface area of 1631.3 m2·g−1, high content of 57.7 ± 0.9% pyrrolic-N, and three-dimensional porous structure. As the ORR catalyst, NC-900 has a onset potential of 0.992 V and half-wave potential of 0.859 V, comparable to 0.988 and 0.872 V of Pt/C. The typical 4-electron pathway of ORR process is occupied by the surface of NC-900. The ORR catalytic activity of NC-900 was almost unaffected by methanol. After 8 h of continuous operation, the reduction current on the surface of NC-900 was decreased only 2.7% of the initial current. Based on these outstanding ORR performances, the pomelo peel-derived NC-900 can serve as a strong competitor for the substitute of Pt/C to promote the potential industrialization of new energy devices.

Amino functionalization of porous aromatic frameworks for efficient and stable iodine adsorption

In view of the excellent stability, ultra-high specific surface area, and structural versatility, porous aromatic frameworks (PAFs) have shown promising potential in gaseous iodine adsorption. Herein, PAF-1 and PAF-5 were synthesized with high specific surface areas. Amino groups as effective binding sites were introduced to these frameworks through post-modification, which facilitated a shift from simple physical adsorption of iodine vapor to a more robust chemical adsorption process. Meanwhile, PAF-6 was synthesized from nitrogen-rich monomers to demonstrate the role of N-binding site in iodine adsorption. PAF-6 exhibited the highest iodine adsorption capacity, verifying the critical role of N-adsorption active sites. The in situ synthesis of nitrogen-rich porous material show advantages over post-modification in creating effective iodine adsorbents. This work highlights the potential of PAFs as a promising material for the adsorption and fixation of radioactive iodine.

Porous nanofibers and micro-pyramid structures array for high-performance flexible pressure sensors

Flexible pressure sensors have attracted extensive research interest as smart wearable devices’ core components. However, developing flexible pressure sensors with high sensitivity and wide pressure detection range remains a great challenge. Utilizing electrospinning and mould transfer technology, this paper presents a novel ‘sandwich’ flexible pressure sensor composed of a sensitive layer of poly (lactic acid) (PLA) porous nanofiber network film and electrodes made of polydimethylsiloxane (PDMS) micro-pyramid structure array film. Through ultrasonic treatment, carbon black particles penetrate into the PLA porous nanofiber film, which effectively enhances the conductivity of the PLA film. Due to the complex conductive pathways formed by the ultra-high specific surface area of the PLA porous nanofibers and the three-dimensional amplification structure of the PDMS micro-pyramid arrays, the sensor has a high sensitivity of 54.06 kPa−1, a wide detection range of 0–56 kPa, an ultra-low detection limit of 2.5 Pa and excellent durability (10000 cycles). Impressively, the sensor is able to accurately monitor various physiological activities of the human body in real time, which is believed to be a strong impetus for the development of the next generation of wearable products.

One-pot synthesis of ultrahigh surface area porous carbon from coal tar residue: Characterization and application in phenol removal

Coal tar residue (CTR) is a hazardous industrial waste and its appropriate disposal evokes great concerns. In this work, superb surface area porous carbon was synthesized from extracted residue in CTR through one-pot KOH chemical activation and applied for phenol adsorption. Results revealed that micro-mesoporous porous carbon (MPC-3–850) with ultrahigh specific surface area of 5465 m2/g, and multiple oxygen-containing functional groups was synthesized at optimized conditions (mass proportion of KOH/MCTR was 1:3, pyrolysis temperature was 850℃). Adsorption results showed that the optimized absorbent dosage was 2 g/L, and adsorptive equilibrium time was 120 min. Maximum adsorption capacity of MPC-3–850 in experiment was reached higher than 360 mg/g and decreased at elevated temperatures. Near neutral conditions (pH=6–8) and lower co-existing ions (Mg2+, K+, Na+) strength had a slightly effect on adsorption performance. Adsorption process adhered to pseudo-second-order kinetic and Freundlich isotherm models, and was exothermic and spontaneous. The adsorption mechanism included pore filling, van der Waals forces, electron donor-acceptor interaction, hydrogen-bonding interaction, and π-π interaction. MPC-3–850 had a good ability to adsorb phenol in real coke wastewater and excellent adsorption capacity after 4 desorption-adsorption cycles.

Hierarchical porous poly (L-lactic acid) fibrous vascular graft with controllable architectures and stable structure

Electrospun fibre has shown great potential in tissue engineering and regenerative medicine due to its high specific surface area and extracellular matrix-mimicking structure. However, fabricating an electrospun fibrous scaffold with controllable complex 3D macroscopic configuration remains a challenge. In the present study, a novel method was designed to transform 2D electrospun poly (L-lactic acid) (PLLA) fibrous membrane to tubular PLLA fibrous scaffolds with 3D complex but tailored configuration. The electrospun PLLA fibrous membrane was rolled around a designed mould and then treated with acetone. Treated vascular grafts’ length, diameter, and shape can be tailored by the mould parameters. Moreover, treated vascular grafts achieve favourable mechanical properties (Young’s modulus = 155 MPa, tensile stress = 8.79 MPa and radial force = 2.2 N) and the mechanical properties could be engineered on demand. In addition, treated vascular grafts kept their initial structure and size during long-term in vitro experiments once they were formed. In addition, with the acetone-induced recrystallization of PLLA, pristine solid PLLA fibres were changed to hierarchical porous PLLA fibres with ultra-high specific surface area (28.9 m2/g) and wettability (water contact angle = 101.32°), which has positive effects on cell adhesion and proliferation ability. A7r5 in vitro experiment shows that the proliferation rate of treated vascular grafts increased 153% at day 4 and 170.6% at day 7 compared with pristine vascular grafts.

Hierarchical rapeseed stalk-derived activated carbon porous structure with N and O codoping for symmetric supercapacitor

The high specific surface area, excellent electrical conductivity, and chemical stability of porous carbon have increasingly garnered attention in supercapacitors. Herein, rapeseed stalks were utilized as precursors to synthesize nitrogen (N) and oxygen (O) co-doped porous activated carbon (RSAC) through processes of high-temperature carbonization and KOH activation. The optimally synthesized RSAC-10 exhibits an ultra-high specific surface area of 3085 m2 g−1, a specific capacitance of 354.7 F g−1 at 1 A g−1, and remarkable cyclic stability (105% of its specific capacitance after 10,000 cycles). Moreover, a symmetric supercapacitor (SSC) fabricated with RSAC-10 electrodes and a 6 M KOH electrolyte demonstrates a high specific capacitance of 85.21 F g−1 at a current density of 0.25 A g−1, maintaining 89.8% of its initial capacitance after 10,000 cycles. Additionally, an SSC comprising RSAC-10 electrodes and [BMIM]BF4 electrolyte delivers an energy density of 52.6 Wh kg−1 at a power density of 375.1 W kg−1. This work presents an effective method for valorizing crop waste and successfully prepares electrode materials with high specific surface areas alongside substantial energy and power densities.

Sub‐1 nm Nanomaterials Applied in Energy Storage

AbstractSub‐1 nm nanomaterials (SNMs) present rapid electrons/ions transport and unique polymer‐analogue properties due to their ultrahigh specific surface area and nearly 100 % surface atomic exposure, which are very promising in the application of energy storage devices. However, there still lack of relative review about the SNMs applied in energy storage until now. This review focuses on the structural advantages of SNMs and their synthesis methods, and then discusses latest advances of employing SNMs for advanced battery systems. The superior functions of SNMs are emphasized for designing every single component in batteries, including electrode materials, separators and electrolytes, greatly improving the performance of batteries. Finally, the current challenges and future research directions of SNMs are proposed, aiming to provide a new insight into the design and manufacture of SNMs for the further development of high‐performance energy storage devices.

Interfacial Si–O–Zr bonds induced well dispersed zirconia on magnetic mesoporous silicas for enhanced tetracycline removal

Constructing recoverable materials with both high adsorption capacity and excellent photocatalytic performance towards antibiotics elimination is very meaningful and challenging in wastewater remediation. In this work, we demonstrate a simple interface engineering strategy to design well dispersed zirconia on core–shell structured magnetic mesoporous silica microspheres (MMS) for efficient removal of tetracycline hydrochloride (TC). With ultrahigh specific surface area (682.0 m2/g) and interfacial Si-O-Zr serving as active sites, the optimal sample (MMS-Zr10) exhibits enhanced TC adsorption capacity of 266.5 mg/ZrO2 g, which is 19.2-fold than that of pure ZrO2. Simultaneously, the photocatalytic degradation rate constant of TC over MMS-Zr10 in the presence of peroxydisulfate (PDS) is 12.5 times that of ZrO2 under visible light irradiation, which may be attributed to the enhanced light harvest capability and high charge separation efficiency facilitated by interfacial Zr–O–Si charge transfer channels. Furthermore, in consecutive adsorption cycles in both deionized (DI) water solution and actual wastewater, no obvious decline in TC removal % is observed. The TC adsorption is mainly governed by pore filling, hydrogen bonding and electrostatic interactions; whilst O2•−, h+, SO4•−, •OH and 1O2 species are responsible for enhanced photocatalytic degradation of TC.

ZIF-8@CsPbBr3 Nanocrystals Formed by Conversion of Pb to CsPbBr3 in Bimetallic MOFs for Enhanced Photocatalytic CO2 Reduction.

Perovskite nanocrystals are embedded into metal-organic frameworks (MOFs) to create composites with high light absorption coefficients, tunable electronic properties, high specific surface area, and metal atom tunability for enhanced photocatalytic carban dioxide (CO2 ) reduction. However, existing perovskite-MOF structures with a large particle size are achieved based on Pb source adsorption into the pores of MOFs, which can significantly break down the porous structure, thereby resulting in a decreased specific surface area and impacting CO2 adsorption. Herein, a novel perovskite-MOF structure based on the synthesis of bimetallic Pb-containing MOFs and post-processing to convert Pb to CsPbBr3 nanocrystals (NCs) is proposed. It is discovered that the additional Pb is not introduced by adsorption, but instead engages in coordination and generates Pb-N. The produced ZIF-8@CsPbBr3 NCs are ≈40nm and have an ultra-high specific surface area of 1325.08 m2 g-1 , and excellent photovoltaic characteristics, which are beneficial for photocatalytic CO2 reduction. The electronic conversion rate of composites is 450mol g-1 h-1 , which is more than three times that of pure perovskites. Additionally, the superior reduction capacity is sustained after undergoing four cycles. Density Functional Thoery (DFT) simulations are used to explore the 3D charge density at the ZIF-8@CsPbBr3 NCs interface to better understand the electrical structure.

Efficient removal of chlortetracycline hydrochloride by MOF-5-derived metal-free carbon materials with ultra-high specific surface area

Metal-organic frameworks (MOFs) have drawn great interest in pollutant adsorption due to their large specific surface area, abundant active sites, and regular pore structure, while they suffer from serious secondary pollution by inevitable metal spillage during pollutant treatment. Herein, we reported a series of MOF-derived metal-free carbon materials (MC-X-Y) for chlortetracycline hydrochloride (CTC) adsorption. The outcome pointed out that the MC-1000–60 prepared under 1000 °C for 60 min exhibited highest specific surface area (2299 m2·g−1) and maximum adsorption capacity for CTC (1588 mg·g−1 within 90 min), which was sixfold higher than that of commercial activated carbon and original MOF-5. The adsorption kinetics and isotherms of MC-1000–60 on CTC conformed to pseudo-second-order kinetic model and Langmuir model, respectively, indicating that the CTC adsorption was inclined to monolayer adsorption and dominated by chemisorption. Impressively, the CTC adsorption capacity for MC-1000–60 after used for 4 adsorption cycles could still reach up to 1199 mg·g−1. The co-existing ion and humid acid exerted insignificant interfering effect on CTC adsorption. The ultra-high adsorption capacity, fast adsorption rate, excellent recyclability and metal-free nature highlighted its light application prospect in solving the CTC-related pollution issues, being expected to be next generation of advanced adsorbents for removing emerging pollutants.

Baking-inspired pore regulation strategy towards a hierarchically porous carbon for ultra-high efficiency cationic/anionic dyes adsorption

Converting waste resource into porous carbon toward contaminant capturing is a crucial strategy for realizing “treating waste with waste”. Inspired by bread baking process, the soybean meal activated carbon (SAC) with multimodal pore structures was developed via thermally remodeling the pores of waste soybean meal. The obtained SAC-3-800 has ultra-high specific surface area (3536.952 m2/g), as well as a hierarchically porous structure. SAC-3-800 exhibits extremely high adsorption capacity for methylene blue (MB) (3015.59 mg/g), methyl orange (MO) (6486.30 mg/g), and mixed dyes (8475.09 mg/g). The hierarchically porous structure enabled fast adsorption kinetics of SAC-3-800 for MB and MO (∼30 min). Additionally, SAC-3-800 shows excellent dynamic adsorption and regeneration performance, exhibiting great potential for industrial applications. This work showcases a feasible method for synthesizing hierarchically porous carbon with outstanding adsorption performance that can simultaneously achieve efficient treatment of dye-wastewater and value-added utilization of waste resources.

Hydrothermal synthesis of LDO/vinasse biochar composites with ultra-high specific surface areas for phosphate remediation and fertilizer utilization

In this work, CaMgAl-layered double oxide/biochar (LDO@BC) composites were elaborated by hydrothermal coprecipitation and calcination for the efficient recovery of phosphate as well as the further application of the reclaimed composites as fertilizers. On the one hand, the appropriate selection of biochar derived from vinasses as the substrates could solve the limitations of LDO like low specific surface areas as well as poor dispersion. The obtained composites possess the ultrahigh specific surface area as high as 508.97 m2/g. Therefore, a maximum adsorption capacity of 153.64 mg/g is achieved. In addition, our composites are with fast adsorption rates that nearly 100 % phosphate could be removed within 60 s at a trace concentration owing to the large specific surface areas. On the other hand, the recovered adsorbents could be used as fertilizers because of the high contents of P, Ca and Mg elements. The phosphate-adsorbed LDO@BC (P-LDO@BC) demonstrated a positive fertilization effect, significantly accelerating plant growth with length increment by 0.75 times and mass increment by 2.09 times compared with the control groups. Thus, this work not only provides a new approach for waste vinasse utilization, but also presents a promising adsorbing material for phosphate recovery and reuse.

Preparation and characterization of polyvinyl chloride based carbon materials with high specific surface area

Using PVC as raw material and KOH as activator, the carbon adsorption material with ultra-high specific surface area up to 5677.2 m2/g was prepared by chemical activation method, and its structure was characterized to study its adsorption performance on methylene blue solution; the activated mixture was analyzed for chlorine element and the recovery of chlorine element was calculated. The results show that the surface of the obtained activated carbon material is in the shape of smooth lotus root flakes with well-developed pore structure; the adsorption value of methylene blue adsorption can reach 765.0 mg/g, which can adsorb methylene blue solution quickly and efficiently; the elemental chlorine can be recovered efficiently with a recovery rate of 95.33 %, which can effectively reduce the toxic hydrogen chloride gas produced in the process of PVC pyrolysis. Excellent adsorption capacity of H2, CO2 and CH4. This experiment can provide an effective method for the harmless treatment of PVC.

Scalable synthesis of N, O co-doped hierarchical porous carbon for high energy density supercapacitors

Rational design of hierarchical porous architecture with abundant pseudocapacitive sites is highly desirable for carbon electrode materials. However, the lengthy production process and high economic input limit its broader application. Herein, we successfully prepared N, O co-doped hierarchical porous carbon (NOHC) through hydrothermal carbonization (HTC) of chitin biomass with the assist of NH4Cl and subsequent carbonization with NaNH2. The optimal NOHC600 exhibits a remarkable hierarchical porous structure and an ultrahigh specific surface area (SSA) of 2555 m2 g−1. Furthermore, it showcases a significant content of N, O co-doping, thereby providing abundant defects and additional active sites for ion adsorption. The aforementioned characteristics ensure outstanding capacitance performance of NOHC600. In the three-electrode system, NOHC600 exhibits a remarkable specific capacitance of up to 455 F g−1 at a current density of 0.5 A g-1. The symmetric supercapacitors (SCs) based on NOHC600 achieve an impressive energy density of 30.4 Wh kg−1 at a power density of 180 W kg−1. Moreover, the all-solid-state NOHC600 microsupercapacitors (MSCs) demonstrate an exceptional areal capacitance of 78.2 mF cm−2 and an areal energy density of up to 10.8 μWh cm−2. Accordingly, this facile and scalable strategy shows a great potential for producing high-heteroatom-doped porous carbon materials from chitin biomass, which can be applied in practical energy-related applications.

Ultra-high specific surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

Biomass-based activated carbon (CBACs) was successfully prepared by pyrolysis-activation of Taihu cyanobacteria. When the impregnation ratio and activated temperature were 2 and 800 oC, respectively, the optimal CBACs possessed an ultra-high specific surface (2178.90 m2·g−1) and plenty of micro-and meso-pores, as well as a high pore volume (1.01 cm3·g−1). Ascribed to ultra-high surface area, π-π interaction, electrostatic interaction, as well as hydrogen bonding interactions, the CBACs displayed huge superiority in efficient dye removal. The saturated methylene blue (MB) adsorption capacity by CBACs could be as high as 1143.4 mg·g−1, superior to other reported biomass-activated carbons. The adsorption was endothermic and modelled well by the pseudo-second-order kinetic, intra-particle diffusion, and Langmuir models. This work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.

High-performance supercapacitors based on compact graphene composite hydrogels

Because of its ultra-high specific surface area and outstanding electrochemical performance, graphene has become a study focus of electrode materials for supercapacitors. However, severe agglomeration and poor volumetric electrochemical properties greatly reduce its potential for practical applications. Here, we proposed a simple hydrothermal strategy to synthesize L-glutamic acid functionalized nanocellulose/reduced graphene oxide composite hydrogels (GNGHs) with compact porous structures and plentiful heteroatom functional groups. In the hydrothermal process, a high concentration of graphene oxide solution (GO) was employed to boost the packing density of the samples. Nanocellulose (NC) and the molecular chains of L-glutamic acid were used as spacers to modulate the porous structure of GNGHs. At the same time, NC and heteroatomic groups can also boost the surface wettability of GNGHs, thereby increasing their ion-available specific surface area. The GNGH-15 based symmetric aqueous supercapacitors (SASC) deliver high gravimetric (282.0 F g−1) and volumetric (329.9 F cm−3) specific capacitance, remarkable rate capacity, and good cycling durability. Moreover, the all-solid-state flexible supercapacitors (ASSC) assembled by GNGH-15 also exhibit prominent specific capacitance (154.7 F g−1) and good rate performance. These brilliant electrochemical properties make GNGHs a strong contender for electrode materials of energy storage devices.

UiO-type MOFs catalyzed ring-opening copolymerization of epoxides and cyclic anhydrides

Ring-opening copolymerization (ROCOP) of epoxide with cyclic anhydride plays critical role in the preparation of polyesters. Herein, the UiO-type MOFs including UiO-66, UiO-66-NH2, UiO-66-NO2, UiO-66-Br and UiO-67 with octahedral morphology were synthesized by different ligands and used as heterogeneous catalysts for ROCOP of epoxide with cyclic anhydride. It was shown that the UiO-67 with ultra-high specific surface area and large pore size endows it with abundant of catalytic active sites and the highest catalytic activity, which makes UiO-67 present seven times higher turnover frequency (192.6 h−1) than that of UiO-66 (23.6 h−1) under the same conditions. Besides, the strong electron-absorbing group enhances the catalytic activity of UiO-type MOFs. The cycling test proves that the UiO-67 has good recoverability and there was no significant loss of catalytic activity after been reused for three times. The kinetic study showed that the ROCOP of epoxide with cyclic anhydride catalyzed by UiO-67 was a first-order kinetic reaction, and its apparent activation energy (Ea) was about 71.75 kJ∙mol−1 calculated by the Arrhenius equation, which was 27.5% lower than that of UiO-66 (98.94 kJ∙mol−1).