Nitrogen-doped Hierarchical Porous Carbon Research Articles

Nitrogen‐Doped Hierarchically Porous Carbon Materials with Enhanced Performance for Supercapacitor

AbstractHierarchical porous carbon (HPC) with a high specific surface area is a promising material for supercapacitors, owing to its effective ion diffusion paths and low transport resistance. Herein, a nitrogen‐doped hierarchical porous carbon (NHPC) material was successfully synthesized from a gelatin and graphene oxide composite through a combined solvation volatilization/nano‐CaCO3 template/KOH activation method. The obtained NHPC exhibits a large surface area (SBET=1091 m2 g−1) as well as a combination of electrical double layer capacitance and pseudocapacitance behavior. Benefiting from the advanced synergistic effect of the nitrogen‐doped property and the hierarchically porous structure, NHPC shows a specific capacitance of 234 F g−1 at 0.5 A g−1 in a three‐electrode system. Moreover, a supercapacitor based on NHPC exhibits an excellent cycle life (retaining>98 % after 5000 cycles) and a high energy density up to 9.43 Wh kg−1.

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional (3D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein, nitrogen doped hierarchical 3D porous carbons (NHPC) were prepared via a novel metal–organic aerogel (MOA), using hexamethylenetetramine (HMT), 1,3,5-benzenetricarboxylic acid and copper (II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 mA h/g at rate of 0.5 C (1 C = 1675 mA h/g) and high-rate capability of 354 mA h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.

Templated and Catalytic Fabrication of N-Doped Hierarchical Porous Carbon-Carbon Nanotube Hybrids as Host for Lithium-Sulfur Batteries.

Nitrogen-doped hierarchical porous carbon and carbon nanotube hybrids (N-HPC-CNTs) are fabricated by simple pyrolysis of the N-rich raw material melamine-formaldehyde (MF) resin in the presence of nano-CaCO3 and a bimetallic combination of Fe-Co catalyst. During carbonization, nano-CaCO3 acts as a template for creating a hierarchical porous carbon, and the N atoms originated from MF resin are in situ doped into the carbon matrix simultaneously. Meanwhile, volatile gases generated by the thermal decomposition of MF resin could serve as carbon and nitrogen sources to grow nitrogen-doped CNTs on HPC. The growth mechanism is the same as that for conventional chemical vapor deposition (CVD) growth of CNTs on the metal catalysts, but the technological requirements are obviously not as harsh as those for the CVD method. Low-cost raw materials and simple equipment are sufficient for the growth. Moreover, the density and length of the CNTs are tunable, which can be simply adjusted via applying different amounts of Fe-Co catalysts. Such an N-doped hybrid structured carbon with mesopores can not only effectively prompt the physical and chemical adsorption of polysulfides but also ensures a fast electron transfer because of the incorporation of CNTs, which provides sufficient conducting pathways and effective connections between the CNTs and HPC. Furthermore, CNTs grown on HPC can act as physical barriers to block the large pores on HPC, thereby reducing the polysulfide loss. Benefiting from the advantages, the N-HPC-CNT hybrids are a desirable host prospect for Li-S batteries.

Efficient Catalytic Hydrodeoxygenation of Aromatic Carbonyls over a Nitrogen‐Doped Hierarchical Porous Carbon Supported Nickel Catalyst

AbstractHydrodeoxgenation of ketones or aldehydes allows for efficient transformation of oxygen containing raw materials into value‐added chemicals and biofuels, which calls for efficient but inexpensive alternative catalytic systems. In the present contribution, a nitrogen‐doped hierarchical porous carbon (NHPC) was fabricated in a “leavening” method, functioning as a superior support for the anchoring of highly dispersed Ni nanoparticles (Ni/NHPC with ∼ 6.5 nm Ni nanoparticles). When tested in hydrodeoxygenation of bio‐derived vanillin (4‐hydroxy‐3‐methoxybenzaldehyde), this catalyst demonstrated much enhanced catalytic activity as compared to Ni/HPC (HPC means hierarchical porous carbon without nitrogen doping). A direct hydrogenolysis or hydrogenation‐hydrogenolysis reaction mechanism was proposed, which allows the present Ni/NHPC to exert full oxygen removal of a broad set of aromatic substrates with carbonyl or ‐OH at benzylic position. The modified electronic state of nickel interacted with nitrogen dopant and enhanced mass transfer contributed by the hierarchical porous structure of NHPC may be reasons for high reactivity.

Synthesis of Nitrogen-Doped Hierarchical Porous Carbons By a Phase-Transition-Assisted Method

Herein, we report a novel and facile strategy for the construction of nitrogen-doped hierarchically porous carbons (NHPCs) derived from citrate salts and ammonium chloride (NH4Cl) by a phase-transition-assisted method. During pyrolysis, NH4Cl decomposed into gas and citrate salts transformed into liquid at nearly the same temperature interval, such a phase transition of precursor leads to the formation of NHPCs. The decomposed NH3 gas contributes by enriching the N-dopant concentration to fabricate nitrogen-doped carbons, and HCl gas promotes the dispersion of the cation of citrate salts to facilitate the formation of NHPCs. Altering the cation of citrate salts, we can tune the pore structure of NHPCs from macroporous rich to microporous rich pore structure. Benefiting from the large specific surface area and hierarchical porous structure, the NHPCs exhibited excellent catalytic activity for ORR, and also served as a highly stable electrode material for supercapacitors. Figure 1

Hydrothermal Synthesis of Highly Dispersed Co3O4 Nanoparticles on Biomass-Derived Nitrogen-Doped Hierarchically Porous Carbon Networks as an Efficient Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions.

Developing high-performance bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of vital importance in energy storage and conversion systems. Herein, we demonstrate a facile hydrothermal synthesis of highly dispersed Co3O4 nanoparticles (NPs) anchored on cattle-bone-derived nitrogen-doped hierarchically porous carbon (NHPC) networks as an efficient ORR/OER bifunctional electrocatalyst. The as-prepared Co3O4/NHPC exhibits a remarkable catalytic activity toward both ORR (outperforming the commercial Pt/C) and OER (comparable with the commercial RuO2 catalyst) in alkaline electrolyte. The superior bifunctional catalytic activity can be ascribed to the large specific surface area (1070 m2 g-1), the well-defined hierarchically porous structure, and the high content of nitrogen doping (4.93 wt %), which synergistically contribute to the homogeneous dispersion of Co3O4 NPs and the enhanced mass transport capability. Moreover, the primary Zn-air battery using the Co3O4/NHPC cathode demonstrates a superior performance with an open-circuit potential of 1.39 V, a specific capacity of 795 mA h gZn-1 (at 2 mA cm-2), and a peak power density of 80 mW cm-2. This work delivers a new insight into the design and synthesis of high-performance bifunctional nonprecious metal electrocatalysts for Zn-air battery and other electrochemical devices.

A novel hierarchical porous nitrogen-doped carbon derived from bamboo shoot for high performance supercapacitor

Porous N-doped carbons hold good prospects for application in supercapacitor due to their low-cost, large surface area, good surface wettability, high electrical conductivity as well as extra pseudocapacitance. However, most synthetic methods required the tedious and multiple-step process with the assistance of hard/soft templates or the massive use of chemical reagents, and exogenous nitrogen sources, which made them difficult to realize industrial production and application. Here, we described a novel hierarchical porous N-doped carbons fabricated by a facile and sustainable approach via hydrothermal treatment and subsequent carbonization process by using renewable bamboo shoots as the starting material without any templates, additional chemical activation and nitrogen source. The obtained bamboo shoot-derived carbons possessed a large BET surface area (up to 972 m2 g−1), hierarchically interconnected porous framework, rich and uniform nitrogen incorporation (3.0 at%). Benefiting from these unique features, the novel carbon-based electrode materials displayed a high capacitance of 412 F g−1 in KOH electrolyte and long cycling life stability. Thus, an advanced electrode material for high-performance supercapacitor was successfully assembled by a simple and scalable synthesis route with abundant renewable resources freely available in nature.

Nitrogen‐Doped Hierarchical Porous Carbon Architecture Incorporated with Cobalt Nanoparticles and Carbon Nanotubes as Efficient Electrocatalyst for Oxygen Reduction Reaction

AbstractHierarchical porous carbon has attracted great interest because of its distinctive structure and superior properties for designing electrochemical energy storage and conversion devices. In this work, a novel method to fabricate nitrogen‐doped hierarchical porous carbon (NHPC) is reported, which is incorporated with Co nanoparticles and carbon nanotubes (CNTs). The NHPC is prepared using a facile and scalable MgO–Co template method. Metal nitrate–glycine solution combustion synthesis, followed by a high temperature calcination, is used to prepare MgO–Co/N‐doped carbon precursor. CNTs are formed by the in situ Co‐catalytic growth during heat treatment; at the same time, localized graphitic layers are also formed around the Co nanoparticles. After acid washing, NHPC with hierarchical multipores and ultrafine Co nanoparticles is obtained. When applied as oxygen reduction reaction (ORR) catalyst, the NHPC displays high catalytic activity not only in terms of onset potential and current density, but also superior durability and tolerance to methanol crossover in alkaline electrolyte. The remarkable ORR activity is originated from the cooperative effects of high specific surface area, hierarchical pore structure, ultrasmall Co nanocrystals, localized graphitic layers, CNTs, and N‐doping.

CO2 capture in lignin-derived and nitrogen-doped hierarchical porous carbons

Nitrogen-doped and hierarchical porous carbons were synthesized from lignin precursor by KOH and NH3 activation with BET surface area of 1631–2922 m2/g. X-ray photoelectron spectroscopy (XPS) revealed 5.6–7.1 at.% nitrogen with predominantly pyridinic, amino and pyrrolic/pyridonic type of functionality. Maximum CO2 adsorption capacity at 298 K and 273 K and pressure upto 760 torr (1 bar) was found to be 5.48 and 8.6 mmol/g respectively, which is higher than that of majority of nitrogen-doped carbons, reported in literature. Ideal Adsorbed Solution Theory (IAST)-based selectivity for CO2/N2 revealed that selectivity increases with the increase in nitrogen content. IAST calculations were also employed to calculate the binary adsorption isotherms to simulate mixed gas adsorption for CO2 and N2 as a function of total pressure and mole fraction of CO2 in the gas mixture. Continuous CO2 adsorption-desorption studies for 10 cycles revealed that all the nitrogen-doped carbons retained its working capacity at the end of the cycles. Finally, a breakthrough study for (10/90) CO2/N2 mixture in a dynamic column experiment confirmed a physical separation of the two components. The overall results suggest that nitrogen-doped carbons from lignin can be used as potential adsorbents for CO2 capture purposes.

Pt electrocatalyst supported on metal ion-templated hierarchical porous nitrogen-doped carbon from chitosan for methanol electrooxidation

Hierarchical porous nitrogen-doped carbon (HPNC) derived from chitosan is synthesized through a novel metal ion-templated strategy. In this process, the absorbed Cu(II)-loaded chitosan was calcined at various temperatures which results in carbon/Cu composites. After removal of Cu particles with acid medium, hierarchical porous carbon forms which includes macropores, mesopores and micropores. The specific surface area of HPNC900 reaches 755 m2 g−1. The XPS results show that all the carbon materials contain nitrogen as the doped element due to the use of chitosan as a nitrogen-containing carbon source. Furthermore, highly dispersed Pt nanoparticles have been successfully deposited on the as-prepared HPNC through the in-situ reduction method. The average size of Pt nanoparticles anchored on HPNC900 is only 2.76 ± 0.33 nm. The synthesized products are characterized by TEM, SEM and XRD analysis techniques. Among the studied electrocatalysts, the as-prepared Pt/HPNC900 electrocatalyst (HPNC fabricated at 900 °C) shows superior electrocatalytic activity and stability towards methanol oxidation in comparison with Pt/Vulcan XC-72 catalyst. The current density of methanol oxidation on Pt/HPNC900 is ∼2.5 times higher than that of Pt/Vulcan XC-72 catalyst. The enhanced electrocatalytic activity is ascribed to hierarchical porous structures, nitrogen-doped surface characteristic and high BET specific surface area of HPNC. Therefore, the present method is very useful for fabrication of high-performance electrocatalyst for methanol oxidation.

Convenient and large-scale synthesis of nitrogen-rich hierarchical porous carbon spheres for supercapacitors and CO2 capture

Herein, considering the great potential of nitrogen-doped hierarchical porous carbons in energy storage and CO2 capture, we designed a convenient and easily large-scale production strategy for preparing nitrogen-doped hierarchical porous carbon sphere (NHPCS) materials. In this synthesis route, spherical resorcinol-formaldehyde (RF) resins were selected as carbon precursor, and then the ZnCl2-impregnated RF resin spheres were carbonized in a NH3 atmosphere at a temperature range of 600–800°C. During the one-step heat-treatment process, nitrogen atom could be efficiently incorporated into the carbon skeleton, and the interconnected and hierarchical pore structure with different micro/mesopore proportion could be generated and tuned by adjusting the activating agent ZnCl2 dosage and carbonization temperature. The resultant nitrogen-doped hierarchical porous carbon sphere materials exhibited a satisfactory charge storage capacity, and the optimal sample of NHPCS-2-8 with a high mesopore proportion obtained at 800°C with a ZnCl2/RF mass ratio of 2:1 presented a specific capacitance of 273.8Fg−1 at a current density of 0.5Ag−1. More importantly, the assembled NHPCS-2-8-based symmetric capacitor displayed a high energy density of 17.2 Wh kg−1 at a power density of 178.9Wkg−1 within a voltage window of 0∼1.8V in 0.5M Na2SO4 aqueous electrolyte. In addition, the CO2 capture application of these NHPCS materials was also explored, and the optimal sample of NHPCS-0-8 with a large micropore proportion prepared at 800°C exhibited an exceptional CO2 uptake capacity at ambient pressures of up to 4.23mmolg−1 at 0°C.

Flower-like hierarchical porous nitrogen-doped carbon spheres from a facile one-step carbonization method for supercapacitors

A facile one-step carbonization method was developed to fabricate flower-like hierarchical porous nitrogen-doped carbon sphere (FHPNCS) from polyimide using polyurethane foam as macroporous scaffold. The FHPNCS possessed flower-like spherical morphology, well-developed hierarchical porous structure, high specific surface area and nitrogen-containing functional groups. These advantages led to excellent electrochemical performance. The FHPNCS electrode exhibited a high specific capacitance of 251.6 F g−1 at 1 A g−1, a high rate capability of 76% capacitance retention at 5 A g−1, and an outstanding cycling stability of only 4.4% loss in specific capacitance after 2000 cycles. Compared with previously reported multi-step templating methods, the present method only involves a facile thermal treatment procedure and avoids the use of hard templates and toxic raw materials, thus exhibiting great potential for large scale production of nitrogen-doped carbon materials for practical applications in supercapacitors.

Hierarchical porous nitrogen-doped partial graphitized carbon monoliths for supercapacitor

Porous carbon monoliths have attracted great interest in many fields due to their easy availability, large specific surface area, desirable electronic conductivity, and tunable pore structure. In this work, hierarchical porous nitrogen-doped partial graphitized carbon monoliths (N–MC–Fe) with ordered mesoporous have been successfully synthesized by using resorcinol-formaldehyde as precursors, iron salts as catalyst, and mixed triblock copolymers as templates via a one-step hydrothermal method. In the reactant system, hexamethylenetetramine (HMT) is used as nitrogen source and one of the carbon precursors under hydrothermal conditions instead of using toxic formaldehyde. The N–MC–Fe show hierarchically porous structures, with interconnected macroporous and ordered hexagonally arranged mesoporous. Nitrogen element is in situ doped into carbon through decomposition of HMT. Iron catalyst is helpful to improve the graphitization degree and pore volume of N–MC–Fe. The synthesis strategy is user-friendly, cost-effective, and can be easily scaled up for production. As supercapacitors, the N–MC–Fe show good capacity with high specific capacitance and good electrochemical stability.

Efficiency of Ni Nanoparticles Supported on Hierarchical Porous Nitrogen-Doped Carbon for Hydrogenolysis of Kraft Lignin in Flow and Batch Systems

Ni nanoparticles supported on nitrogen-doped carbon (NDC) prepared via salt-melt synthesis with a hierarchical porosity were successfully applied as the catalyst for the degradation of Kraft lignin. It is shown that Ni-NDC is more efficient when compared to Ni nanoparticles deposited on an N-free carbon support, prepared with similar porosity features (Ni–C) and to Ni nanoparticles deposited on a commercial carbon (Ni-Cref). The efficiency of these materials was compared for reactions performed both in batch and flow reactors, highlighting the effect of the reactor setup on the stability of the recovered catalysts.

Removal of Cr6+ from wastewater via adsorption with high-specific-surface-area nitrogen-doped hierarchical porous carbon derived from silkworm cocoon

The development of highly efficient adsorbents is an effective way to remove Cr6+ from wastewater for environment protection. Herein, a high-specific-surface-area nitrogen-doped hierarchical porous carbon (NHPC) derived from silkworm cocoon was synthesized and applied as an efficient adsorbent for the removal of Cr6+ from wastewater. The resultant NHPC possesses a specific surface area as high as 3134m2g−1 and a unique hierarchical porous structure with a large number of small mesopores (2–4nm) and micropores (0.8–2nm) embedded in the sidewall of bowl-like macropores (200–300nm), in which sufficient exposure of adsorption sites and high-flow transfer of Cr6+ ions can be achieved. As a result, the NHPC exhibits a remarkable adsorption performance with a larger adsorption capacity (366.3mgg−1), a higher adsorption rate (4×10−2gmg−1min−1) and a superior recyclability in comparison with the commercial adsorbent (Norit CGP). Thermodynamic and kinetic analyses indicate that the adsorption process is spontaneous and endothermic, which fits well with the pseudo-second-order kinetic model and Langmuir isotherm model. This biomass-based porous carbon with well-defined hierarchical porous structure can be applied as a promising adsorbent for the removal of Cr6+ from wastewater.

A high-power lithium-ion hybrid electrochemical capacitor based on citrate-derived electrodes

Achieving high-power lithium-ion hybrid electrochemical capacitor (Li-HEC) through facile and low-cost synthesis procedures is still quite challenging. In this work, starting from daily used food additives, nitrogen-doped hierarchical porous carbon (N-HPC) was prepared through facile pyrolysis of magnesium citrate and subsequent NH3 treatment, and carbon-coated Fe2O3 (Fe2O3@C) was synthesized by thermal decomposition of ferric citrate and following heat treatment in air, respectively. As-prepared N-HPC and Fe2O3@C were separately employed as cathode and anode materials to fabricate a high-power, which delivers a high energy density of 65Whkg−1 at 368Wkg−1, and 31Whkg−1 at a high power density of 9.2kWkg−1. And it remains 84.1% capacity over 1000 galvanostatic charge-discharge cycles at 1Ag−1.

Macroalgae-derived nitrogen-doped hierarchical porous carbons with high performance for H2 storage and supercapacitors

Enteromorpha prolifera was converted into hierarchical carbons through the carbonization and activation with surface area and pore volume up to 3345 m2 g−1 and 1.94 cm3 g−1, showing excellent performance for H2 storage and supercapacitors.

A facile template approach to nitrogen-doped hierarchical porous carbon nanospheres from polydopamine for high-performance supercapacitors

A facile polydopamine-templated approach to nitrogen-doped hierarchical porous carbon nanospheres for high-performance supercapacitors.

Hierarchical design of nitrogen-doped porous carbon nanorods for use in high efficiency capacitive energy storage

We report a novel synthesis route for creating 3D interconnected hierarchical porous nitrogen-doped carbon nanorods (3D-IPCRs) using 1D polyaniline nanorods as a precursor and SiO2 as a porogen.

Hierarchical nitrogen-doped porous carbon derived from lecithin for high-performance supercapacitors

The development of renewable carbon sources for sustainable energy storage applications is of significance importance.