Three-dimensional Hierarchical Porous Carbon Research Articles

Hierarchical porous carbon from hazardous waste oily sludge for all-solid-state flexible supercapacitor

Rationally packed porous carbon with high ion-accessible surface area and low ion-transport resistance is proved to be an excellent candidate as electrode materials in high performance supercapacitors. However, its cost-effective fabrication still remains a significant challenge. Here, we report on a novel three-dimensional hierarchical porous carbon (HPC) synthesized via a facile and low-cost approach from hazardous waste oily sludge for the first time. Both the smart “self-template” effect and appropriate activation effect are crucial for the rational hierarchical porous structure. The “self-template” procedure is the key point for creating the skeleton of carbon, and the KOH activation process is able to regulate pore size distribution and increase specific surface area. The as-fabricated HPC possesses favorable features for supercapacitor, such as outstanding specific surface area (2561m2g−1), large pore volume (2.25cm3g−1), tunable and large range of pore size distribution. The HPC-based electrode can deliver an admirable capacitance of 348.1Fg−1 at 0.5Ag−1 and 94.3% capacitance retention at 5Ag−1 after 10,000 cycles in aqueous electrolyte. Remarkably, the all-solid-state HPC//HPC symmetric supercapacitor displays outstanding capacitance of 81.3Fg−1 at 0.5Ag−1 with high energy density of 7.22W h kg−1. It is demonstrated that the strategy developed here would provide cost-effective production of HPC electrode material for high performance supercapacitors and offer a promising avenue of large-scale fabrication of HPC from other hazardous industrial waste.

A polyacrylonitrile copolymer-silica template for three-dimensional hierarchical porous carbon as a Pt catalyst support for the oxygen reduction reaction.

Herein, we report a novel route to construct a hierarchical three-dimensional porous carbon (3DC) through a copolymer-silica assembly. In the synthesis, silica acts as a hard template and leads to the formation of an interconnected 3D macropore, whereas styrene-co-acrylonitrile polymer has been used as both a carbon source and a soft template for micro- and meso-pores. The obtained 3DC materials possess a large surface area (∼550.5 m2 g-1), which facilitates high dispersion of Pt nanoparticles on the carbon support. The 3DC-supported Pt electrocatalyst shows excellent performance in the oxygen reduction reaction (ORR). The easy processing ability along with the characteristics of hierarchical porosity offers a new strategy for the preparation of carbon nanomaterials for energy application.

Biomass-derived dendritic-like porous carbon aerogels for supercapacitors

Three-dimensional (3D) dendritic-like hierarchical porous carbon areogels (PCAs) have been fabricated via a simple and efficient solvent exchange method followed by an activation process. The natural and renewable biomass material, leonardite fulvic acid (LFA) is used as the carbon source. The hierarchical porous structures are composed of numerous nanospheres with interconnected 3D carbon architectures which are in favor of enhancing the electrical conductivity and facilitating ion transport by providing small resistances and short diffusion pathways. The resultant PCAs are advantageous as electrodes for electrochemical energy storage. For example, the PCAs2 sample exhibits a superior high specific capacitance of 368Fg−1 at a current density of 0.05Ag−1 in 6M KOH electrolyte, which can still remain 228Fg−1 when the current density increases to 100Ag−1. The sample also has outstanding cycling stability with capacitance retention of 98.4% after 10,000 cycles. Remarkably, it is shown that the PCAs2 sample exhibits outstanding electrochemical performance in an organic electrolyte as well. It has an energy density of 43.50Whkg−1 at a power density of 33.85Wkg−1 and still maintains 23.25Whkg−1 at a power density of 5.89kWkg−1. This suggests that the 3D hierarchical PCAs should be a competitive and promising supercapacitor electrode material.

Lithium battery using sulfur infiltrated in three-dimensional flower-like hierarchical porous carbon electrode

Three dimensional, flower-like hierarchical porous carbon (FPC) and its CO2-activation (AFPC) are reported as sulfur-hosting matrixes in Li/S battery. The composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherms as well as by galvanostatic cycling and electrochemical impedance spectroscopy (EIS) in lithium-cell. Both samples show well defined micrometric morphology and a sulfur content as high as 66% expected to reflect into rather high practical energy density of the electrode in lithium-sulfur battery. The lithium sulfur cell using the FPC-S composite exhibits at 25 °C a moderate cycling stability with delivered capacity ranging from 1000 to about 610 mAh g−1 upon 50 cycles at 100 mA g−1. The AFPC-S composite reveals increased cycling stability and delivers a capacity ranging from 1000 to 680 mAh g−1. Improved capacity is achieved by slightly increasing the temperature, as demonstrated by cycling the FPC-S at 35 °C using a current as high as 500 mA g−1. The excellent rate capability of the electrode is associated to the carbon texture and morphology that significantly lower the cell resistance, as indeed demonstrated by EIS measurement upon cycling.

Three-dimensional beehive-like hierarchical porous polyacrylonitrile-based carbons as a high performance supercapacitor electrodes

Three-dimensional beehive-like hierarchical porous carbons (HPCs) have been prepared by a facile carbonization of polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN) core-shell polymer particle followed by KOH activation. The all-organic porogenic core-shell precursor was synthesized by a simple and green surfactant-free emulsion polymerization. The as-obtained HPCs show favorable features for electrochemical energy storage such as high specific surface area of up to 2085 m2 g−1, high volume of pores up to 1.89 cm3 g−1, hierarchical porosity consisting of micro, meso, and macropores, turbostratic carbon structure, uniform pore size and rich oxygen-doping (21.20%). The supercapacitor performance of HPCs exhibit a high specific capacitance 314 F g−1 at a current density of 0.5 A g−1 and 237 F g−1 at a current density of 20 A g−1, ultra-high rate capability with 83% retention rate from 1 to 20 A g−1 and outstanding cycling stability with 96% capacitance retention after 2000 cycles. The facile, efficient and green synthesis strategy for novel HPCs from polymer sources could find use in supercapacitors, lithium ion batteries, fuel cells and sorbents.

Nickel Cobalt Hydroxide @Reduced Graphene Oxide Hybrid Nanolayers for High Performance Asymmetric Supercapacitors with Remarkable Cycling Stability.

Nanolayered structures present significantly enhanced electrochemical performance by facilitating the surface-dependent electrochemical reaction processes for supercapacitors, which, however, causes capacitance fade upon cycling due to their poor chemical stability. In this work, we report a simple and effective approach to develop a stable, high performance electrode material by integrating 2D transition metal hydroxide and reduced graphene oxide sheets at nanometer scale. Specifically, a hybrid nanolayer of Ni-Co hydroxide @reduced graphene oxide (Ni,Co-OH/rGO) with an average thickness of 1.37 nm is synthesized through an easy one-pot hydrothermal method. Benefiting from the face to face contact model between Ni-Co hydroxide and rGO sheets, such unique structure presents superior specific capacitance and cycling performance as compared to the pure Ni-Co hydroxide nanolayers. An asymmetric supercapacitor based on Ni,Co-OH/rGO and three-dimensional (3D) hierarchical porous carbon is developed, exhibiting a high energy density of 56.1 Wh kg(-1) along with remarkable cycling stability (80% retention after 17 000 cycles), which holds great promise for practical applications in energy storage devices.

Facile synthesis of nitrogen-doped hierarchical porous lamellar carbon for high-performance supercapacitors

Three-dimensional interconnected N-enriched hierarchical porous lamellar carbon with a multilevel pore structure has been fabricated using waste nitrogen-containing mantis shrimp shell as a carbon precursor and KOH as an impregnation solution.

Three-Dimensional Nitrogen-Doped Hierarchical Porous Carbon as an Electrode for High-Performance Supercapacitors.

A facile and sustainable procedure for the synthesis of nitrogen-doped hierarchical porous carbons with a three-dimensional interconnected framework (NHPC-3D) was developed. The strategy, based on a colloidal crystal-templating method, utilizes nitrogenous dopamine as the precursor due to its unique properties, including self-polymerization under mild alkaline conditions, coating onto various surfaces, a high carbonization yield, and well-preserved nitrogen doping after heat treatment. The obtained NHPC-3D possesses a high surface area of 1056 m(2) g(-1) , a large pore volume of 2.56 cm(3) g(-1) , and a high nitrogen content of 8.2 wt %. The NHPC-3D is implemented as the electrode material of a supercapacitor and exhibits a specific capacitance as high as 252 F g(-1) at a current density of 2 A g(-1) . The device also shows a high capacitance retention of 75.7 % at a higher current density of 20 A g(-1) in aqueous electrolyte due to a sufficient surface area for charge accommodation, reversible pseudocapacitance, and minimized ion-transport resistance, as a result of the advantageous interconnected hierarchical porous texture. These results showcase NHPC-3D as a promising candidate for electrode materials in supercapacitors.

Oxygen-Rich Hierarchical Porous Carbon Derived from Artemia Cyst Shells with Superior Electrochemical Performance

In this study, three-dimensional (3D) hierarchical porous carbon with abundant functional groups is produced through a very simple low-cost carbonization of Artemia cyst shells. The unique hierarchical porous structure of this material, combining large numbers of micropores and macropores, as well as reasonable amount of mesopores, is proven favorable to capacitive behavior. The abundant oxygen functional groups from the natural carbon precursor contribute stable pseudocapacitance. As-prepared sample exhibits high specific capacitance (369 F g(-1) in 1 M H2SO4 and 349 F g(-1) in 6 M KOH), excellent cycling stability with capacitance retention of 100% over 10 000 cycles, and promising rate performance. This work not only describes a simple way to produce high-performance carbon electrode materials for practical application, but also inspires an idea for future structure design of porous carbon.

Soluble salt self-assembly-assisted synthesis of three-dimensional hierarchical porous carbon networks for supercapacitors

Three-dimensional hierarchical porous carbons are synthesized via a simple one-pot method using the self-assembly of various water-soluble salts as structure-directing templates, which exhibit excellent capacitive performance.

Embedding NiCo2O4 nanoparticles into a 3DHPC assisted by CO2-expanded ethanol: a potential lithium-ion battery anode with high performance.

A high-performance anode material, NiCo2O4/3DHPC composite, for lithium-ion batteries was developed through direct nanoparticles nucleation on a three-dimensional hierarchical porous carbon (3DHPC) matrix and cation substitution of spinel Co3O4 nanoparticles. It was synthesized via a supercritical carbon dioxide (scCO2) expanded ethanol solution-assisted deposition method combined with a subsequent heat-treatment process. The NiCo2O4 nanoparticles were uniformly embedded into the porous carbon matrix and efficiently avoided free-growth in solution or aggregation in the pores even at a high content of 55.0 wt %. In particular, the 3DHPC was directly used without pretreatment or surfactant assistance. As an anode material for lithium-ion batteries, the NiCo2O4/3DHPC composite showed high reversible capacity and improved rate capability that outperformed those composites formed with single metal oxides (NiO/3DHPC, Co3O4/3DHPC), their physical mixture, and the composite prepared in pure ethanol (NiCo2O4/3DHPC-E). The superior performance is mainly contributed to the unique advantages of the scCO2-expanded ethanol medium, and the combination of high utilization efficiency and improved electrical conductivity of NiCo2O4 as well as the electronic and ionic transport advantages of 3DHPC.

KOH self-templating synthesis of three-dimensional hierarchical porous carbon materials for high performance supercapacitors

We report a KOH self-templating synthesis of three-dimensional hierarchical porous carbon using resol as the precursor and KOH as both the template and activating agent. The resulting resol-derived porous carbon (RPC) exhibits a high surface area (up to 2700 m2 g−1) and well-interconnected macropores with micropores and mesopores decorated on the carbon walls. Consequently, the RPC shows low internal resistance, high specific capacitance, good rate capability and excellent cycling stability in 6 M KOH as a supercapacitor electrode. Because of its easy fabrication and low cost, it offers a good alternative method for synthesis of carbon electrodes for energy-storage devices such as Li-ion batteries, fuel cells and supercapacitors.

Supercritical Carbon Dioxide Assisted Deposition of Fe3O4Nanoparticles on Hierarchical Porous Carbon and Their Lithium-Storage Performance

A composite of highly dispersed Fe3 O4 nanoparticles (NPs) anchored in three-dimensional hierarchical porous carbon networks (Fe3 O4 /3DHPC) as an anode material for lithium-ion batteries (LIBs) was prepared by means of a deposition technique assisted by a supercritical carbon dioxide (scCO2 )-expanded ethanol solution. The as-synthesized Fe3 O4 /3DHPC composite exhibits a bimodal porous 3D architecture with mutually connected 3.7 nm mesopores defined in the macroporous wall on which a layer of small and uniform Fe3 O4 NPs was closely coated. As an anode material for LIBs, the Fe3 O4 /3DHPC composite with 79 wt % Fe3 O4 (Fe3 O4 /3DHPC-79) delivered a high reversible capacity of 1462 mA h g(-1) after 100 cycles at a current density of 100 mA g(-1) , and maintained good high-rate performance (728, 507, and 239 mA h g(-1) at 1, 2, and 5 C, respectively). Moreover, it showed excellent long-term cycling performance at high current densities, 1 and 2 A g(-1) . The enhanced lithium-storage behavior can be attributed to the synergistic effect of the porous support and the homogeneous Fe3 O4 NPs. More importantly, this straightforward, highly efficient, and green synthetic route will definitely enrich the methodologies for the fabrication of carbon-based transition-metal oxide composites, and provide great potential materials for additional applications in supercapacitors, sensors, and catalyses.

Three-dimensional flower-like and hierarchical porous carbon materials as high-rate performance electrodes for supercapacitors

Three-dimensional flower-like and hierarchical porous carbon material (FHPC) has been fabricated through a simple and efficient carbonization method followed by chemical activation with flower-like ZnO as template and pitch as carbon precursor. The hierarchical porous structure is composed of numerous micropores and well-defined mesopores in the interconnected macroporous walls. The FHPC electrode can achieve a relatively high capacitance of 294Fg−1 at a scan rate of 2mVs−1 and excellent rate capability (71% retention at 500mVs−1) with superior cycle stability (only 2% loss after 5000 cycles) in 6molL−1 KOH electrolyte. The symmetric supercapacitor fabricated with FHPC electrodes delivers a high energy density of 15.9Whkg−1 at a power density of 317.5Wkg−1 operated in the voltage range of 0–1.8V in 1molL−1 Na2SO4 aqueous electrolyte.

Synthesis of functionalized 3D hierarchical porous carbon for high-performance supercapacitors

Functionalized three-dimensional hierarchical porous carbon (THPC) is prepared via a facile modified chemical activation route with polypyrrole microsheets as precursor and KOH as activating agent. The as-obtained THPC presents a large specific surface area (2870 m2 g−1), high-level heteroatom doping (N: 7.7 wt%, O: 12.4 wt%), excellent electrical conductivity (5.6 S cm−1), and hierarchical porous nano-architecture containing macroporous frameworks, mesoporous walls and microporous textures. Such unique features make the THPC an ideal electrode material for electrochemical energy storage. As the electrode material for a supercapacitor, the THPC exhibits a high capacitance, excellent rate performance and long-term stability in both aqueous and organic electrolytes.

Hierarchical interconnected macro-/mesoporous Co-containing N-doped carbon for efficient oxygen reduction reactions

Three-dimensional (3D) hierarchical porous Co-containing N-doped carbon materials (HP-Co-CNs) have been successfully prepared for the first time by using cyanamide as a nitrogen source and poly(vinyl alcohol) (PVA) hydrogel-based composites as in situ templates. Remarkably, the resulting HP-Co-CNs possess controllable nitrogen content, high surface area, hierarchical interconnected macro-/mesoporous structure, and a certain amount of Co-Nx moieties which could act as active sites in the oxygen reduction reaction (ORR). In studying the application of HP-Co-CNs for the ORR, the HP-Co-CNs showed excellent electrocatalytic performance for a four-electron ORR, and longer-term stability and higher methanol tolerance then the commercial Pt/C electrocatalyst in alkaline medium, highlighting the importance of macropores for diffusion and a sufficient amount of active sites related to high specific surface area for improving the ORR performance.

Three-dimensional hierarchical porous carbon with a bimodal pore arrangement for capacitive deionization

In this work, three-dimensional hierarchical porous carbon (3DHPC) has been prepared via a double-template strategy with a colloidal crystal SiO2 as the hard template as well as a triblock copolymer as the soft template and its capacitive deionization (CDI) behavior in a NaCl aqueous solution was investigated for the first time. The resultant 3DHPC exhibits a bimodal porous structure with numerous mesopores defined in the well-interconnected macroporous walls. The unique pore architecture, resulting from an effective combination of the mesopores and macropores, presents a higher surface area as well as an improved electronic conductivity, which are quite beneficial for a high CDI performance. The electrochemical behaviors of the prepared electrodes were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements and 3DHPC shows great superiority when used as the CDI electrode. Moreover, the dependence of the CDI performance on the ion size and valence were also investigated in salt solutions with various cations and anions. Briefly, ions with a smaller hydrated radius and higher valence ensure a stronger electrostatic force onto the 3DHPC electrode, associated with an improved electrosorption behavior. Also, the desalination performance and regeneration behavior of the electrodes were evaluated by batch mode CDI apparatus. The high desalination capacity and excellent regeneration performance render the 3DHPC electrode a great potential in the CDI process.

Electrochemical capacitance and ionic transport in the mesoporous shell of a hierarchical porous core–shell carbon structure

A three-dimensional (3D) hierarchical porous carbon structure was prepared with possible variations in porosity at three levels of length scales. The carbon structure was template-synthesized from a core–shell silica sphere assembly. The as-synthesized carbon featured a semi-ordered porous structure with hollow macro-cores (330 nm) surrounded by a mesoporous shell containing uniform pores of 3.9 nm and distinct interstitial space between the core–shell domains. The mesoporous shell thickness was stepwise increased from 0, 25, 50 to 100 nm while keeping an identical core size to create a family of hierarchical porous structures for a systematic investigation of electrochemical capacitance and ionic transport. The shell thickness affected the overall porosity and relative porosities of the shell, core, and interstitial regions. A thicker mesoporous shell possessed a higher surface area which led to a proportional increase in electrochemical capacitance which can be fully realised at low scan rates. For the carbon structure with the maximum shell thickness of 100 nm, electrochemical capacitance per unit area and power density declined at high scan rates and high currents when ionic transport through long mesopores became limiting. The power density of the better as-synthesized porous carbon was up to 11.7 kW kg−1 when the corresponding energy density was 5.9 W h kg−1.