Hierarchical porous carbon obtained from animal bone and evaluation in electric double-layer capacitors

Animal bone, an abundant biomass source and high volume food waste, had been converted into a hierarchical porous carbon in a simple two-step sustainable manner to yield a highly textured material. The structures were characterized by nitrogen sorption at 77 K, scanning electron microscopy and X-ray diffraction. The electrochemical measurement in 7 M KOH electrolyte showed that the porous carbon had excellent capacitive performances, which can be attributed to the unique hierarchical porous structure (abundant micropores with the size of 0.5–0.8 and 1–2 nm, mesopores and macropores with the size of 2–10 and 10–100 nm), high surface area (S_BET = 2157 m²/g) and high total pore volume (V_t = 2.26 cm³/g). Its specific capacitance was 185 F/g at a current density of 0.05 A/g. Of special interest was the fact that the porous carbon still maintained 130 F/g even at a high current density of 100 A/g.     

Synthesis of carbon-coated graphene electrodes and their electrochemical performance

In this work, C-graphene composed of core graphene and carbon shells was prepared to obtain a new type of carbon electrode materials. Carbon shells containing nitrogen groups were prepared by coating polyaniline (PANI) onto graphene by in situ polymerization and subsequent carbonization at 850 °C. After carbonization, the C-graphene contained 6.5% nitrogen and showed a 2D plate structure and crystallinity like that of pristine graphene. In addition, the C-graphene exhibited electrochemical performance superior to that of pristine graphene, and the highest specific capacitance (170 F/g) of the C-graphene was obtained at a scan rate of 0.1 A/g, as compared to 138 F/g for pristine graphene. This superior performance was attributed to the synergistic effect of porous carbon layer and the graphene and the pseudocapacitive effect by the nitrogen groups formed on the carbon electrode after carbonization.     

Fabrication and electrochemical characterization of polyimide-derived carbon nanofibers for self-standing supercapacitor electrode materials

We report the electrochemical performance of aromatic polyimide (PI)-based carbon nanofibers (CNFs), which were fabricated by electrospinning, imidization, and carbonization process of poly(amic acid) (PAA) as an aromatic PI precursor. For the purpose, PAA solution was electrospun into nanofibers, which were then converted into CNFs via one-step (PAA-CNFs) or two-step heat treatment (PI-CNFs) of imidization and carbonization. The FTIR and Raman spectra demonstrated a successful structural evolution from PAA nanofibers to PI nanofibers to CNFs at the molecular level. The SEM images revealed that the average diameter of the nanofibers decreased noticeably via imidization and carbonization, while it decreased slightly with increasing the carbonization temperature from 800 °C to 1000 °C. In case of PI-CNF carbonized at 1000 °C, a porous structure was developed on the surface of nanofibers. The electrical conductivity of PI-CNFs, which was even higher than that of PAA-CNFs, increased significantly from 0.41 to 2.50 S/cm with increasing the carbonization temperature. From cyclic voltammetry and galvanostatic charge/discharge tests, PI-CNF carbonized at 1000 °C was evaluated to have a maximum electrochemical performance of specific capacitance of ~126.3 F/g, energy density of ~12.2 Wh/kg, and power density of ~160 W/kg, in addition to an excellent operational stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47846.     

One-pot hydrothermal synthesis and supercapacitive performance of nitrogen and MnO co-doped hierarchical porous carbon monoliths

Nitrogen and MnO co-doped hierarchical porous carbon monolith (N-MnO-HPCM) materials were synthesized through a facile one-pot hydrothermal method. The resulting N-MnO-HPCM materials had hierarchical porous structure, high BET surface area (606 m²/g), large pore volume (0.33 cm³/g), and contained evenly dispersed MnO nanoparticles of about 6 nm in the carbon matrix. Their electrochemical performances as electrodes for supercapacitors were investigated. N-MnO-HPCM material exhibited an excellent electrochemical performance with a specific capacitance of 261.7 F/g at a current density of 1 A/g. It also showed a good rate capability with 74% capacity retention at high current density (5 A/g), indicating its potential applications in supercapacitors.     

Facile synthesis of a triptycene-based porous organic polymer with a high efficiency and recyclable adsorption for organic dyes

Water contamination resulting from organic dyes has had severe detrimental effects on human health and environmental tolerance. To address this issue, a delicate strategy for taking host–guest function in porous organic polymers via a facile Friedel–Crafts reaction of triptycene and post-modification was achieved. By means of this route, a sulfonic acid functionalized triptycene-based porous organic polymer (TPOP–SO₃H) with a hierarchical structure and a desirable Brunauer–Emmett–Teller value of 1002 m²/g was synthesized this study. The TPOP–SO₃H material demonstrated a maximum adsorption capacity for methylene blue of 97.1 mg/g. Remarkably, an absorption efficiency of more than 90% of TPOP–SO₃H was observed even after five cycles. Therefore, such a hierarchical porous organic polymer can be highly recommended as one type of promising material for the treatment of organic dye-polluted wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47987.     

Hierarchical porous nitrogen-doped carbon materials derived from one-step carbonization of polyimide for efficient CO<Subscript>2</Subscript> adsorption and separation

Hierarchical porous nitrogen-doped carbon (HPNC) materials are synthesized through one-step carbonization of polyimide using triblock copolymer P123 as mesoporous template. The microstructure, chemical composition and CO₂ adsorption behaviors are investigated in detail. The results show that HPNC materials have hierarchical micro-/mesopore structures, high specific surface area of 579 m²/g, large pore volume of 0.34 cm³/g, and nitrogen functional groups (5.2 %). HPNC materials exhibit high CO₂ uptake of 5.56 mmol/g at 25 °C and 1 bar, which is higher than those of previously reported nitrogen-doped porous carbon materials. After 5 cycles the value of CO₂ adsorption uptakes is 5.28 mmol/g, which is approximately 95 % of the original adsorption capacity. The estimated CO₂/N₂ selectivity of HPNC materials is 17, revealing great promise for practical CO₂ adsorption and separation applications. The efficient CO₂ uptake and enhanced CO₂/N₂ selectivity are due to the combination of nitrogen-doped and hierarchical porous structures of HPNC materials.     

A sustainable printed circuit board derived hierarchically porous carbon/polyaniline composites for supercapacitors

The hierarchically porous carbon/polyaniline electrodes derived from the nonmetallic part of waste printed circuit board have been synthesized by a convenient carbonization and activation method. A detailed analysis of the morphology, structure, and electrochemical performances of as-prepared composites is presented. As expected, the balanced specific surface area and porous structure manifest their remarkable electrochemical performances. Apparently, the multiple synergistic effects are crucial to simultaneously achieving high capacity and significantly increased stability. As a result, the electrodes display exceptional rate capability, superior cyclic stability, and high specific capacitance (520.0 F/g at 1 A/g). Furthermore, the asymmetrical device possesses an improved energy density of 9.3 Wh/kg with a power density of 62.4 W/kg in H₂SO₄ electrolyte. Moreover, a potential mechanism contributing to the superior performance of hierarchically porous carbon/polyaniline composites has been studied in detail. Noteworthy, this study provides a feasible strategy for recycling waste printed circuit boards. Importantly, this approach will provide a path toward the rational synthesis and design of electrode materials for supercapacitors that take both high-performance and cost-effective into account.     

纳米木质素基多孔炭的制备及其电化学性能

基于绿色低共熔溶剂（DES）高效分离麦草生物质组分以制备纳米木质素（LNP）,本文采用化学活化法并进一步热解炭化制备纳米木质素基多孔炭（LNPC）。借助SEM、Raman、BET-物理吸附等分析手段研究了锌系活化剂及热解炭化温度（600℃、700℃、800℃）对LNPC的结构特征及电化学性能的影响。研究结果表明,相对于LNP直接热解炭化后纳米碳粒子的极易团聚,经锌化物活化后所制备的LNPC表现出更好的分散性和多级孔道形貌结构。尤其,以ZnCO₃活化后制备的LNPC-ZnCO₃-800具有更突出的性能,较高石墨化程度（I_D/I_G为0.68）、较高BET比表面积（679m²/g）、高介孔率（86.7%）、均匀纳米碳粒子构成的介孔结构。此外,以LNPC-ZnCO₃-800制备的工作电极,在0.5A/g时的比电容可达179F/g,与直接热解炭化的LNPC-800（64F/g）相比,其比电容的容量提高了180%。     

银耳菌糠衍生的三维多级孔炭及其电化学应用性能

食用菌菌糠富含疏松多孔的木质纤维基质和菌丝残体蛋白,将其用于高性能生物质基多孔炭的制备具有先天优势,亦能产生可观的生态和经济效益。本文以银耳菌糠为原料,利用NaOH/尿素（质量比为7∶12）水溶液体系进行冻融预处理后,经高温热解炭化制备获得高氮掺杂量（7.78%）的三维（3D）多级孔炭材料。孔结构分析结果显示样品BC-5-800的比表面积可达1568m²/g,孔容为1.53cm³/g且中孔率高达83%。以BC-5-800为工作电极,在三电极测试体系中,当电流密度为0.5A/g时,测得的比电容为278F/g,且在10A/g下仍能保持230F/g的比电容;在两电极装置中,当功率密度高达6990W/kg时,能量密度达到5.83Wh/kg,且经10000次循环充放电后的电容保持率为87%,呈现出优异的循环稳定性。本研究为食用菌菌糠的高值化回收再利用提供了新思路。     

Porous carbon nanosheet with high surface area derived from waste poly(ethylene terephthalate) for supercapacitor applications

Converting waste plastics into valuable carbon materials has obtained increasing attention. In addition, carbon materials have shown to be the ideal electrode materials for double-layer supercapacitors owing to their large specific surface area, high electrical conductivity, and stable physicochemical properties. Herein, an easily operated approach is established to efficiently convert waste poly(ethylene terephthalate) beverage bottles into porous carbon nanosheet (PCNS) through the combined processes of catalytic carbonization and KOH activation. PCNS features an ultrahigh specific surface area (2236 m² g⁻¹), hierarchically porous architecture, and a large pore volume (3.0 cm³ g⁻¹). Such excellent physicochemical properties conjointly contribute to the outstanding supercapacitive performance: 169 F g⁻¹ (6 M KOH) and 135 F g⁻¹ (1 M Na₂SO₄). Furthermore, PCNS shows a high capacitance of 121 F g⁻¹ and a corresponding energy density of 30.6 Wh kg⁻¹ at 0.2 A g⁻¹ in the electrolyte of 1 M TEATFB/PC. When the current density increases to 10 A g⁻¹, the capacitance remains at 95 F g⁻¹, indicating the extraordinary rate capability. This work not only proposes a facile approach to synthesize PCNS for supercapacitors, but also puts forward a potential sustainable way to recycle waste plastics and further hopefully mitigates the waste plastics-related environmental issues. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48338.     

Synthesis of mesoporous carbon spheres with a hierarchical pore structure for the electrochemical double-layer capacitor

Mesoporous carbon spheres with hierarchical foam-like pore structures have been synthesized by a dual-templating strategy using phenolic resol as a carbon source, Pluronic F127 and spherical silica mesocellular foams (Si-MCFs) as the soft and hard template, respectively. The results show that the morphology and mesostructure of the silica template are faithfully replicated. The obtained mesoporous carbon material with spherical diameter size of ca. 3–5 μm exhibits hierarchical pore sizes (from ca. 3.5 to 60 nm), high specific surface area (1320 m²/g) and large pore volume (3.5 cm³/g). The carbon surface contains plenty of oxygen-containing groups, resulting in hydrophilic property for an electrode material. In addition, Pluronic F127 plays an important role in the synthesis for maintaining the foam-like mesostructure of the silica templates and faithful replication of the spherical morphology. The electrochemical measurements show that the hierarchically mesoporous carbon spheres as an electrochemical double-layer capacitor (EDLC) electrode present a long cyclic life, excellent rate capability, and high specific capacitance as ca. 208 F/g at 0.5 A/g in (2.0 M) H₂SO₄ aqueous solution. Its specific capacitance can still remain ca. 146 F/g at a high loading current density of 30 A/g with the retention of ca. 70%. Furthermore, this material also exhibits excellent capacitive performance in (C₂H₅)₄NBF₄/propylene carbonate electrolyte, and its specific capacitance is 97 F/g at loading current density of 0.5 A/g.     

Magnetically-separable hierarchically porous carbon monoliths with partially graphitized structures as excellent adsorbents for dyes

Magnetically-separable hierarchically porous carbon monoliths with partially graphitized structures were synthesized through confinement self-assembly in polyurethane (PU) foam associated with a direct carbonization process from triblock copolymer F127, phenolic resol and ferric nitrate. It was observed that the magnetic Fe nanoparticles were embedded in the walls of graphitic porous carbon matrix, and the resulting materials exhibited hierarchically porous structure with macropores of 100–450 μm, mesopore size of 4.8 nm, BET surface area of 723 m²/g, pore volume of 0.46 cm³/g, and saturation magnetization of 3.1 emu/g. Using methylene blue as model dye pollutant in water, the carbon monolith materials showed high adsorption capacity of 190 mg/g, exhibiting excellent adsorption characteristics desirable for the application in adsorption of dyes and easy separation under an external magnetic field.     

葡萄柚皮多孔碳高性能对称性超级电容器电极材料的制备及性能

以柚子皮为碳源(GC),高温氧化碳化(GCO)处理后采用K₂CO₃活化制得GCO600,最佳优化产物GCO600-14具有丰富的网状孔隙,其比表面积达661.7 m²/g。三电极体系中,在1 A/g时,GCO600-14的比电容为413 F/g,电流密度扩大30倍后仍可达到2 896 F/g,为原先的70%;循环5 000圈后比电容仍未原来值的96%。构建的对称性电容器GCO600-14//GCO600-14能量密度为26、20.2 (W·h)/kg时,相应的功率密度分别为720、20 800 W/kg。说明GCO600-14作为新型的、环境友好的储能材料具有潜在的应用前景。     

Preparation and electrochemical performances of porous polypyrrole film by interfacial polymerization

In this study, porous polypyrrole (PPy) film was synthesized by facile interfacial polymerization using ionic liquid as oxidant. The morphology of PPys changed from dense microspherical/nanospherical agglomerated structure to porous structure with the increasing concentration of the oxidant. The magnetic ionic liquid, 1‐butyl‐3‐methylimidazolium tetrachloroferrate (Bmim[FeCl₄]), played a major role of oxidant when the concentration was lower than 0.075M. As the concentration increased to 0.075M, the π–π interactions between pyrrole cations and iminazole ring of Bmim[FeCl₄], as evidenced by Fourier transform infrared spectrometer results, may affect the packing of PPy chains and subsequently cause the formation of porous structure of PPys. Electrochemical performances showed that PPy with porous structure displayed the highest specific capacitance of 170 F/g at a current density of 2 A/g in 1M H₂SO₄ solution and a good capacitive behavior, which has potential application as supercapacitor materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

One-pot hydrothermal synthesis of nitrogen-doped hierarchically porous carbon monoliths for supercapacitors

The nitrogen-doped hierarchically porous carbon monoliths (N-HPCMs) were successfully synthesized by using dicyandiamide (DCDA) as nitrogen source, phenolic resol as carbon precursor and mixed triblock copolymers as templates via a one-pot hydrothermal approach. The obtained carbon monoliths possess tunable mesopore size (4.3–11.4 nm), large surface area (552–660 m²/g), and high nitrogen content (up to 12.1 wt%). Ascribed to the nitrogen-doped frameworks and hierarchical porosity, N-HPCMs exhibit good electrochemical performance as the supercapacitor electrode with specific capacitance of 268.9 F/g (in 6 M KOH) at a current density of 1 A/g, and a 4.1 % loss of the specific capacitance after 5,000 charge–discharge cycles, indicating a long-term cycling stability. Such unique features make N-HPCMs promising electrode materials for high performance supercapacitors.     

Synthesis of bamboo-derived porous carbon: exploring structure change,pore formation and supercapacitor application

Biomass porous carbon possessing hierarchical pores and abundant heteroatoms has emerged as a sustainable and cost-effective functional material. Herein, a green cellulose solvent was employed as the activation agent and nitrogen source to obtain this distinctive structure from bamboo cellulose fibers. With the assistance of thermal treatment, the solvent could fully infiltrate into cellulose structure of raw material and result in the cellulosic structure damage, forming ultimately the three-dimensional conductive network, hierarchical pores, as well as high heteroatom doping (8.43 at%). Benefited from the unique structure, the obtained porous carbon as the supercapacitor electrode showed excellent capacitive performance (280 F/g at 0.3 A/g), good rate capability and cyclic stability. Moreover, influences of hydrothermal temperature on cellulose structure, pore formation, and the resultant supercapacitor performance were demonstrated. This green strategy shows potential for producing hierarchical porous carbon with high heteroatoms from biomass resources.

     

Ethanol-based synthesis of hierarchically porous carbon using nanocrystalline beta zeolite template for high-rate electrical double layer capacitor

A porous carbon with a mesopore–micropore hierarchy has been synthesized using ethanol as a carbon source within a beta zeolite template, which possesses mesopores and micropores in a hierarchical manner. Various compounds have been evaluated as the carbon source in the carbon synthesis. The result indicates that ethanol vapor is suitable for the hierarchical carbon synthesis, as compared with propylene or acetylene gas. The advantage of ethanol is attributed to the formation of water from the ethanol decomposition during carbonization process. The water seems to assist in delaying the deposition of carbons at the exterior (or the mesopore walls). The resultant carbon after removal of the template is composed of regular micropores of 1-nm diameter and irregular mesopores of 10–30 nm arranged in a hierarchical manner. The hierarchical carbon exhibits a very high electrical double-layer capacitance both at low and high discharge current densities in galvanostatic measurements, as compared to solely microporous or solely mesoporous carbons. The high performance is attributed to facile transport of electrolytes in the hierarchically porous structure.     

煤基富氮层级多孔碳制备及其催化脱硫性能

以煤加工副产物煤焦油中蒽油馏分为碳源、多巴胺为氮源，基于纳米碳酸钙球模板在碳化过程中发生的诱导自活化作用，一步共碳化制得氮掺杂多孔碳（NPCs）材料。通过元素分析、低温氮气吸附-脱附测试、扫描及透射电镜表征，结果表明，NPCs材料的氮元素掺杂量高，且具有发达的微孔-介孔梯级孔道结构。结合室温下催化硫化氢选择性氧化为单质硫的反应性能评价，发现改变模板剂用量、碳/氮源投料比和碳化温度，可调控NPCs材料的氮掺杂量（质量分数6.4%~21.3%）、比表面积、孔道结构发达程度及相应的定向转化硫容，最佳工艺条件下合成样品的饱和硫容高达5.8 g H₂S/(g催化剂)。     

Development of novel porous carbon frameworks through hydrogen-bonding interaction and its ethylene adsorption activity

Porous carbon materials are widely used in separation, catalysis and energy storage/conversion. We have synthesized a new porous carbon material by solvent evaporation induced self assembly method using hydroquinone/formaldehyde as a precursor which can help self assembly with template triblock copolymer PEO-PPO-PEO (F127). The template removal have resulted the porous carbon material (PCM) framework upon carbonization. We have also prepared porous carbon fibers (PCF) using kapok fibers along with hydroquinone/formaldehyde/F127 and observed its ethylene adsorption capacity. Kapok fibers were obtained from the plant species Ceiba pentandra. The characterization of PCM and PCF were accomplished by microanalysis, powder X-ray diffraction, FTIR, scanning electron microscopy, transmission electron microscopy, thermo-gravimetric analysis, elemental analysis and N₂ adsorption?Cdesorption isotherm. The prepared carbon materials (PCM and PCF) showed excellent gas absorption ability towards ethylene gas at room temperature as well as at 50?°C.     

Porous carbon-silica composites and carbon materials from rice husk: Production technology, texture, and dispersity

A method based on carbonization in a fluidized-bed catalytic reactor is suggested for utilization of rice husks, which are hard-to-recycle waste from paddy production. The bottom ash resulting from carbonization at 465–600°C is a carbon-silica nanocomposite (C/SiO₂) with a SiO₂ content of 58.7–81.8 wt % and a specific surface area of S _BET = 152–232 m²/g. Leaching of SiO₂ with hydrofluoric acid yields porous carbon materials with a specific surface area of 165–494 m²/g and a SiO₂ content of <1%. These materials have been characterized by small-angle X-ray scattering (SAXS), transmission electron microscopy, and X-ray diffraction. Particle size data for SiO₂ in the carbon-silica nanocomposite have been obtained for the first time. As the carbonization temperature is raised from 465 to 600°C, the average particle size of silica increases from 5.5 to 8.1 nm. Development of the SAXS procedure for determining the size of silica particles in the carbon matrix would provide a promising tool for knowingly designing porous carbon materials with preset properties. The carbonization of rice husks in a fluidized catalyst bed is among the most promising methods of their conversion into C/SiO₂ nanocomposites and porous carbon materials with the use of template synthesis approaches.