Nitrogen-doped Carbon Foam Research Articles

Synergy of pore confinement and co-catalytic effects in Peroxymonosulfate activation for persistent and selective removal of contaminants

The activation of peroxymonosulfate (PMS) through nanoconfinement and co-catalytic effects has demonstrated considerable promise in environmental remediation. Nevertheless, the attainment of persistent efficiency and specificity for pollutant degradation remains a formidable obstacle. Herein, we proposed a solvent-free molten approach to convert a mixture of zeolitic imidazolate frameworks (ZIFs) and MoS2 into 3D integrated cobalt-molybdenum bimetallic nitrogen-doped porous carbon foam with catalytic/co-catalytic performance (MC@NCF). The integrated materials exhibited exceptional efficiency in degrading contaminants based on the synergy of pore confinement and co-catalytic effects, achieving almost 100 % tetracycline degradation in 10 min with a k-value as high as 112.44 min−1·M−1, which was superior to the existing catalysts reported so far. The experimental findings revealed that the structural adjustment of MC@NCF significant accelerated the mass transfer through the formation of interfacial Mo-S/O-Co and Mo-N-Co/C bonds electron-tuning bridges between pore-confined micro-units, leading to the increased singlet oxygen (1O2) yield. Therefore, the MC@NCF exhibited more remarkable stability without interference from coexisting inorganic ions and cations, humic acid, and water matrices. Moreover, a flow-through nanoreactor was constructed and acquired efficient reactivity with negligible biotoxicity, and easy nanocatalyst recycling after continuous operation. The possible reactivity mechanism was identified by Frontier molecular orbital theory HOMO-LUMO, Fukui function, LC-MS, EPR, in-situ ATR-FTIR, and Raman analyses. Our results will guide integrated “catalytic/co-catalytic” nanoconfined MOF derivatives design to further enhance deep water purification technology.

Degradation and mechanism of PFOA by peroxymonosulfate activated by nitrogen-doped carbon foam-anchored nZVI in aqueous solutions

Perfluorooctanoic acid (PFOA) is an emerging pollutant that is non-biodegradable and presents severe environmental and human health risks. In this study, we present an effective and mild approach for PFOA degradation that involves the use of nitrogen-doped carbon foam anchored with nanoscale zero-valent iron (nZVI@NCF) to activate low concentration peroxymonosulfate (PMS) for the treatment. The nZVI@NCF/PMS system efficiently removed 84.4% of PFOA (2.4 μM). The active sites of nZVI@NCF including Fe0 (110) and graphitic nitrogen played crucial roles in the degradation. Electrochemical analyses and density functional theory calculations revealed that nZVI@NCF acted as an electronic donor, transferring electrons to both PMS and PFOA during the reaction. By further analyzing the electron paramagnetic resonance and byproducts, it was determined that electron transfer and singlet oxygen were responsible for PFOA degradation. Three degradation pathways involving decarboxylation and surface reduction of PFOA in the nZVI@NCF/PMS system were determined. Finding from this study indicate that nZVI@NCF/PMS systems are effective in degrading PFOA and thus present a promising persulfate-advanced oxidation process technology for PFAS treatment.

Me-N-C Electrocatalyst Foams for the Oxygen Reduction Reaction in PEFCs

Polymer electrolyte fuel cells (PEFCs) will perform the crucial role of energy conversion when society shifts towards the hydrogen economy. However, to perform the the oxygen reduction reaction (ORR) efficiently, a finely dispersed platinum catalyst on a carbon black support is generally utilised. Platinum is an expensive critical raw material (CRM) and is thus susceptible to future shocks, such as bottlenecks in supply or volatile prices. As such it is imperative to investigate alternative platinum-free electrocatalysts.Over the past decade we have developed platinum-free Fe-N-C electrocatalysts with unique properties and microstructure. The basis for our catalysts is a nitrogen-doped carbon foam, which is obtained by thermal decomposition of metal alkoxides. The materials are exceptional in this field due to their unusually large macropores which aid gas diffusion, the very large surface area due to high microporosity, and the fact that the nitrogen content can be systematically varied.Using these electrocatalysts we have with achieved high activity and excellent durability in both acid and alkaline media. One of the advantages of this materials system is that it can be applied as a model catalyst to independently study the effect of different parameters on the catalytic activity. As such we have made important insights into the synthesis mechanisms of Fe-N-C electrocatalysts using techniques such as in situ X-ray absorption spectroscopy (XAS) and in situ X-ray photoelectron spectroscopy (XPS).Furthermore, whilst most research into platinum-free catalysts focusses on iron-containing materials, iron is known to cause degradation in the microporous layer and membrane due to the generation of peroxide-related radicals. As such, a new generation of Me-N-C electrocatalysts are being developed, in which Fe is replaced with e.g., Co or Sn. Here we will discuss the performance of these interesting new Fe-free electrocatalysts.This work was supported by JSPS KAKENHI Grant Number 19H02558.1. Mufundirwa, M. Ismail, G. F. Harrington, B. Smid, K. Sasaki, M. Pourkashanian, A. Hayashi, S. M. Lyth, Nanotechnology 31 (22), 225401 (2020)2. Mufundirwa, B. Smid, G. Harrington, B. V. Cunning, K. Sasaki, and S. M. Lyth, Journal of Power Sources, 375, 244-254 (2018)3. Zitolo, N. Ranjbar-Sahraie, T. Mineva, J. Li, Q. Jia, S. Stamatin, P. Krtil, S. M. Lyth, G. Harrington, S. Mukerjee, E. Fonda, F. Jaouen, Nature Communications, 8, 959 (2017)4. Liu, T. Daio, A. Mufundirwa, B. Cunning, K. Sasaki, S. M. Lyth, Electrochimica Acta, 220, 554-561 (2016)5. Liu, S. Yu, T. Daio, M. Ismail, K. Sasaki, and S. M. Lyth, Journal of the Electrochemical Society, 163 (9), F1049-F1054 (2016)6. Liu, T. Daio, K. Sasaki, S. M. Lyth, Journal of the Electrochemical Society, 161 (9), F838-F844 (2014)7. Liu, T. Daio, D. Orejon, K. Sasaki, S. M. Lyth, Journal of the Electrochemical Society 161 (4), F544-F550 (2014)8. S. M. Lyth*, Y. Nabae, N. M. Islam, T. Hayakawa, S. Kuroki, M. Kakimoto, S. Miyata, eJournal of Surface Science and Nanotechnology, 10, 29-32 (2012)

Flame-retardant ammonium polyphosphate/MXene decorated carbon foam materials as polysulfide traps for fire-safe and stable lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are one of the most promising modern-day energy supply systems because of their high theoretical energy density and low cost. However, the development of high-energy density Li-S batteries with high loading of flammable sulfur faces the challenges of electrochemical performance degradation owing to the shuttle effect and safety issues related to fire or explosion accidents. In this work, we report a three-dimensional (3D) conductive nitrogen-doped carbon foam supported electrostatic self-assembled MXene-ammonium polyphosphate (NCF-MXene-APP) layer as a heat-resistant, thermally-insulated, flame-retardant, and freestanding host for Li-S batteries with a facile and cost-effective synthesis method. Consequently, through the use of NCF-MXene-APP hosts that strongly anchor polysulfides, the Li-S batteries demonstrate outstanding electrochemical properties, including a high initial discharge capacity of 1191.6 mA h g−1, excellent rate capacity of 755.0 mA h g−1 at 1 C, and long-term cycling stability with an extremely low-capacity decay rate of 0.12% per cycle at 2 C. More importantly, these batteries can continue to operate reliably under high temperature or flame attack conditions. Thus, this study provides valuable insights into the design of safe high-performance Li-S batteries.

Preparation and Testing of a Palladium-Decorated Nitrogen-Doped Carbon Foam Catalyst for the Hydrogenation of Benzophenone.

Catalytic activity of a palladium catalyst with a porous carbon support was prepared and tested for benzophenone hydrogenation. The selectivity and yields toward the two possible reaction products (benzhydrol and diphenylmethane) can be directed by the applied solvent. It was found that in isopropanol, the prepared support was selective towards diphenylmethane with high conversion (99% selectivity and 99% benzophenone conversion on 323 K after 240 min). This selectivity might be explained by the presence of the incorporated structural nitrogens in the support.

Microporous carbon foams: The effect of nitrogen-doping on CO2 capture and separation via pressure swing adsorption

This work investigates the effect of nitrogen doping on the porous structure and CO2 adsorption properties of hierarchically porous carbon foams, at different temperatures and pressures. A series of carbon foams with nitrogen contents of ∼7 to 13 at % is prepared by reaction of sodium ethoxide with different amino alcohols (namely monoethanolamine, diethanolamine, and triethanolamine), followed by thermal decomposition of the reaction product. The structure, morphology, porosity and chemical composition are studied using appropriate methods. The resulting material comprises micron-scale macropores combined with unrestricted micropores and mesopores embedded in the carbon walls. It is found that both nitrogen species and ultra-micropores contribute positively to CO2 uptake. The carbon foam with a nitrogen content of ∼7 at % (as well as an ultra-micropore volume of 0.44 cm3 g−1 and a specific surface area of 1549 m2 g-1) displays the highest CO2 uptake, adsorbing 5.14 mmol g−1 at 273 K, 3.22 mmol g−1 at 298 K, or 1.93 mmol g−1 at 323 K. This nitrogen-doped carbon foam adsorbs more CO2 than the undoped carbon foam reference, despite having significantly lower ultra-micropore volume and higher specific surface area. This highlights the importance of nitrogen species in CO2 capture. However, increasing the nitrogen content leads to suppression of the micropore volume, resulting in poor CO2 uptake. High CO2/N2 selectivity with good separation of CO2 from the CO2-N2 gas mixture, fast adsorption via physisorption, and excellent cycling durability are also observed, pointing towards the high regenerative ability of these materials.

Controlled fabrication of nitrogen-doped porous carbon foam with refined hierarchical architectures for desalination via capacitive deionization

Porous carbon materials have been regarded as a promising alternative to activated carbon for desalination via capacitive deionization (CDI) due to refined architectures and functionalities. However, it is still challenging to obtain a controlled hierarchical pore structure and considerable nitrogen-doped content by convenient method. Herein, nitrogen-doped hierarchical porous carbon foams (NHCFs) with different microstructural features, nitrogen contents and nitrogen species were successfully fabricated via a stepwise pyrolysis carbonization strategy using easily available melamine foam. Due to the synergistic effect of hierarchical porous structure and doped nitrogen, the optimized NHCF sample carbonized at 800℃ (NHCF-800) exhibited a maximum desalination capacity of 30.1 mg g−1 at the optimal operating parameters (500 mg/L NaCl solution, 1.2 V) and an excellent regeneration performance after 50 continuous adsorption–desorption cycles. Furthermore, density functional theory (DFT) was also conducted to elaborate the disparity of sodium adsorption energy among the nitrogen species for in-depth understanding, and it mainly benefits from the ascendency of the pyrrolic-N and pyridinic-N over the graphitic-N dopant. This work paves the way of rational regulation of nitrogen-doped process and hierarchical porous structure carbon as CDI electrode materials for desalination.

Electrocatalytic performance of Ni-promoted Co nanoclusters supported by N-doped carbon foams for rechargeable Zn-air batteries

Ni/Co diatomic clusters supported on nitrogen-doped carbon foams are prepared via molten salt method to improve the density of surface active sites of zinc-air battery catalysts and further explore metal-modified carbon-based catalysts. The influence of Co and Ni atoms on the carbon foam structure is investigated by X-ray diffraction and high-resolution electron microscopy, and the presence of metal atoms in N-doped carbon foams is confirmed by X-ray spectroscopy. The left shift of the diffraction peak of Co doped graphitic carbon indicates an increase in the interlayer spacing and a reduced graphitization degree, while the introducton of Ni atoms promotes graphitization. For Ni–Co/NFC-2, Ni inhibits the insertion of Co in carbon layer by increasing graphitization, thus exposing more Co-active substances on the surface, which is important for improving the catalytic process of ORR and OER. According to electrochemical tests, Ni–Co co-doped carbons exhibited superior bi-functional electrocatalytic performance with oxygen reduction reaction (ORR) Eonset = 0.97 V and a Tafel slope of 49.5 mV dec−1, accompanied by oxygen evolution reaction (OER) Ej = 10 mA cm−2 = 1.46 V. Zinc-air battery (ZAB) cell, utilizing the developed material as a catalyst, exhibited a high discharge power density of 138 mW cm−2 with stable performance for up to 200 h.

Nitrogen-doped carbon foams with high Pd dispersion for efficient solid phase catalytic hydrogenation of 1,4-bis(phenylethynyl)benzene

Nitrogen-doped carbon foams with high Pd dispersion for efficient solid phase catalytic hydrogenation of 1,4-bis(phenylethynyl)benzene

Fe3C nanoparticles decorated 3D nitrogen-doped carbon foam as a highly efficient electrocatalyst for nitrate reduction to ammonia

Electrochemical nitrate (NO3−) reduction is considered as a promising strategy to remove NO3−-containing pollution with simultaneous production of ammonia (NH3) under ambient conditions. However, this reaction involves multi-electron transfer steps, which requires active electrocatalysts for high NH3 selectivity. Herein, we demonstrate the development of Fe3C nanoparticles decorated 3D nitrogen-doped carbon foam (Fe3C NPs@NCF) as an efficient electrocatalyst to reduce NO3− to NH3. Such Fe3C NPs@NCF attains a high Faradaic efficiency (96.9%) and a large NH3 yield (8391.8 μg h−1 cm−2). More importantly, Fe3C NPs@NCF also delivers high stability.

Carboxymethyl chitosan-derived carbon foam with hierarchical pores tuned by potassium tetraborate and potassium carbonate for supercapacitors

Porous carbons have been extensively concerned in energy-storage fields due to their good conductivity, stable chemical and physical properties, and large specific surface area. The fabrication of porous carbons possessing controlled structure and excellent capacitive performance by facile preparation methods is highly desirable. Herein, a nitrogen-doped carbon foam derived from carboxymethyl chitosan is fabricated via a gel-based method with potassium tetraborate tetrahydrate (K2B4O7·4H2O) as the template agent and potassium carbonate (K2CO3) as the activating agent. The as-prepared carbon foam (KBCF) owns hierarchical pores (i.e., macro-, meso-, and micropores) resulting from the synergy of K2B4O7 and K2CO3. Moreover, the doped nitrogen atoms in KBCF originating from the amino groups in carboxymethyl chitosan provide additional pseudocapacitance. As a result, KBCF possesses a large specific surface area (large to ~3231.0 m2 g−1), outstanding specific capacitance (317 F/g at 1 A g−1), and excellent cycle life (retaining 96.3 % of the initial capacitance after 10,000 consecutive charge-discharge cycles). The assembled symmetric quasi-solid supercapacitor (KBCF//KBCF) can deliver a high power density of 25 kW kg−1 at an energy density of 2.35 Wh kg−1 and an energy density of 6.84 Wh kg−1 at a power density of 500 W kg−1. The outstanding electrochemical performance demonstrates a promising prospect of KBCF in high-performance supercapacitor electrodes.

Hydrogen and carbon dioxide uptake on scalable and inexpensive microporous carbon foams

Hierarchically porous carbon foam (CF) and microporous nitrogen doped carbon foam (NCF) were synthesized at gram scale via the one-step thermal decomposition of metal alkoxides. The total hydrogen uptake of CF reached a maximum of 11.0 wt% at 77 K and 9.5 MPa (or 5.2 wt% excess at 3.9 MPa). This large uptake is attributed to large surface area (3452 m2/g) and pore volume (2.19 cm3/g). Even at room temperature, the total hydrogen uptake reached 2.50 wt% (or 0.94 wt% excess). Nitrogen doping resulted in lower hydrogen uptake at higher pressure, due to the lower surface area. Interestingly however, slightly improved hydrogen uptake was obtained in NCF at lower pressure compared to CF, and we attribute this to the narrower pore size. Meanwhile, the CO2 uptake of CF was 15.2 mmol/g at 273 K and 0.5 MPa. The CO2 uptake of NCF was slightly lower, but the CO2/N2 and CO2/H2 selectivity were higher. This was attributed to increased isosteric heat of adsorption between CO2 and the nitrogen-doped carbon surface. This work shows the potential of bulk-synthesized low-cost metal alkoxide-derived carbon foams to be used in gas storage and separation applications.

Core-shell structural nitrogen-doped carbon foam loaded with nano zero-valent iron for simultaneous remediation of Cd (II) and NAP in water and soil: Kinetics, mechanism, and environmental evaluation

An economical, efficient, and environmentally friendly technology was developed for simultaneous remediation of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in soil and water. In this study, using pinecones powder as the precursor, the core-shell structural nitrogen-doped carbon foam loaded with nano zero-valent iron (nZVI@NCF) was synthesized through Mannich reaction and high-temperature carbon reduction. The nZVI@NCF was applied as the adsorbent and catalyst to simultaneously remediate the composite pollutants of Cd (II) and naphthalene (NAP). Under the optimal conditions, the adsorption capacity of Cd (II) in water and soil were 13.9 mg·g−1 and 1.97 mg·g−1, respectively, and the adsorption process conformed to the pseudo-second-order kinetic model. The degradation rates of NAP in water (10 mg·L−1) reached almost 100% as well as it could reach 59.12% in soil (10 mg·kg−1). In addition, it was proved that the presence of NAP could compete with Cd (II) for the active sites on the surface of the material to inhibit the adsorption of Cd (II), while the co-existence of Cd (II) could improve the degradation of NAP by the nZVI@NCF/PMS system due to the nZVI-Cd bimetallic effect and the pro-oxidant effect of Cd (II) promoting the generation of ROS. The free radical quenching experiment revealed that the generated ·O2− was the main substance that mediated the redox of nZVI/Fe2+/Fe3+ to oxidative NAP during the degradation process. Furthermore, the results of the phytotoxicity test demonstrated that the nZVI@NCF/PMS system could effectively remediate the soil co-contaminated with Cd (II) and NAP as well as improve the soil environment quality. This research will provide new materials and potential technologies for the efficient treatment of the composite pollutants in the environment.

A highly compressible, nitrogen doped carbon foam based all pseudo-capacitance asymmetric supercapacitors

Compressible supercapacitors are playing an increasingly significant role in sensors and wearable electronic devices. However, compressible supercapacitors have a limited specific capacity as well as lower working voltage. In this work, three-dimensional (3D) N-doped carbon foam is being explored for fabrication of a compressible supercapacitor with pseudocapacitive spinel. The fact that self-growing ZnFe2O4 on highly compressible nitrogen doped carbon foam composite electrodes can deliver significant pseudo-capacitance at negative potentials, an all-pseudocapacitive asymmetric supercapacitor device is fabricated by combining it with NiCo2O4 cathode. The composite electrodes combine the superior electrochemical and mechanical performances with maximum compressive strain of 80% and durability (cyclic strains up to 500 times under the strain of 60%). The asymmetric supercapacitor demonstrates an energy density of 11.84 Wh kg−1 (0.39 mWh cm−3) at 300 W kg−1 (10 mW cm−3), with 96.5% capacitance retention after 15 000 charge-discharge cycles at the compressive strain of 60%. Our work provides new insights for the design of compressible supercapacitors with high performance and accelerates the development of a new generation in energy storage devices with compressibility.

Fe3C/Fe nanoparticles decorated three-dimensional nitrogen-doped carbon foams for highly efficient bisphenol A removal through peroxymonosulfate activation

The design of heterogeneous catalysts has become one of the most important steps in the popularization of advanced oxidation processes for wastewater remediation. With a nitrate-assisted polymer-bubbling strategy, we prepared three-dimensional carbon foams decorated by commensal Fe3C/Fe nanoparticles through a direct pyrolysis of the mixture of polyvinyl pyrrolidone and ferric nitrate nonahydrate. The as-obtained composites, Fe3C/Fe@NCFs, are employed as heterogeneous peroxymonosulfate (PMS) activators to remove bisphenol A (BPA) in aquatic environments with a predetermined concentration. It is found that both Fe3C/Fe nanoparticles and N-doped carbon frameworks can activate PMS to release powerful oxidative species for BPA removal. The effect of pyrolysis temperature on the catalytic performance of Fe3C/Fe@NCFs is studied in detail. The results reveal that high pyrolysis temperature induces the agglomeration of Fe3C/Fe nanoparticles and the loss of N content, and low pyrolysis temperature only generates low-crystallinity carbon frameworks and small proportion of graphitic N configuration. Therefore, Fe3C/Fe@NCFs from moderate temperature (700 °C) can produce the highest BPA removal efficiency. The synergy of Fe3C/Fe nanoparticles and N-doped carbon frameworks, as well as the structure advantages is clearly established in comparison with some control samples. Quenching experiments and electron paramagnetic resonance (EPR) tests indicate that BPA can be degraded in both radical pathway and non-radical pathway, where SO4−, O2−, and 1O2 are primary reactive species. In addition, the influences of some routine factors and actual water backgrounds were also investigated and analyzed comprehensively.

Tunable surface pseudocapacitance assisted fast and flexible lithium storage of graphene wrapped NiO nano-arrays on nitrogen-doped carbon foams

Advanced materials incorporating battery-like high capacity and capacitor-like high rate capability hold promise for achieving both high energy and power density lithium ion batteries (LIBs). However, capacitive behavior for high capacity NiO anode has seldom been reported because the surface or near-surface fast faradic surface redox reactions highly depends on specific structure design. Herein, a flexible electrode that graphene wrapped NiO nanosheet arrays anchor on three-dimensional porous nitrogen-doped carbon foam (rGO@NiONCF) is fabricated. The rGO@NiONCF composite possesses a unique sandwich structure with 3D porous NCF as the inner conductive scaffold, ultrathin NiO nanosheet arrays as a middle layer, and rGO as the outer conductive buffer layer. The elaborated structure design endows rGO@NiONCF with enhanced electronic conductivity, sufficient electrolyte infiltration and restricted volume variation. As a result, the rGO@NiONCF electrode delivers high reversible capacity (1583 mAh g−1 at 0.1 A g−1) and superior cycling stability (maintains 607 mA h g−1 at 1 A g−1 after 500 cycles). Moreover, the enhanced surface capacitance adroitly facilitates an impressive fast charge and slow discharge performance. These results reveal that rational material design to encourage pseudocapacitance effect is a valuable roadmap for NiO-based battery towards more practical applications.

Polyacrylamide Gel-Derived Nitrogen-Doped Carbon Foam Yields High Performance in Supercapacitor Electrodes

Polyacrylamide Gel-Derived Nitrogen-Doped Carbon Foam Yields High Performance in Supercapacitor Electrodes

Flexible non-enzymatic glucose biosensor based on CoNi2S4 nanosheets grown on nitrogen-doped carbon foam substrate

A flexible non-enzymatic glucose sensing material which consists of the CoNi2S4 nanosheets grown on the reticular Nitrogen-doped Carbon Foam substrate (CoNi2S4@NCF) has been successfully fabricated by a simple two-step synthesis process. The micromorphology, composition and valence of the CoNi2S4@NCF are researched by means of FESEM, TEM, XPS and XRD. Subsequently, the glucose sensing characteristics of the CoNi2S4@NCF are studied by Cyclic Voltammetry and Amperometry, and the detection performance of CoNi2S4@NCF synthesized by different processes is compared. Through a series of tests, it is found that when the volume ratio of deionized water to anhydrous ethanol is 30 ml: 30 ml, the prepared CoNi2S4@NCF has excellent glucose sensing properties. The sensitivity is 6.675 μA mM−1 cm−2 and 54.82 μA mM−1 cm−2 over the linear detection range of 0.5–12.5 mM and 12.5–30 mM, respectively. At the same time, the CoNi2S4@NCF has outstanding anti-interference, stability, repeatability and shows good performance in the detection of actual samples. In addition, the synthesized CoNi2S4@NCF has good flexibility and compressibility. Compared with general sensing materials, this flexible material is more conducive to storage and use. It provides a new idea for wearable instruments. All these fully indicate that the fabricated CoNi2S4@NCF have a good prospect in the field of non-enzymatic glucose sensing.

Uniformly growing Co9S8 nanoparticles on flexible carbon foam as a free-standing anode for lithium-ion storage devices

Lithium-ion capacitor (LIC) possesses multiple merits of Faradaic and capacitive behaviors and shows excellent energy and power densities. Herein, Co9S8 nanoparticles embedded on melamine foam derived three-dimensional (3D) carbon foam (M-Co9S8@NCF) was successfully constructed by an in-situ anchoring and annealing method. When the composite was used as a free-standing anode electrode of lithium-ion battery, volume expansion effect is relieved and reaction kinetic is significantly improved benefitting from the synergistic effect of unique 3D carbon network and ultrafine nanoparticles. Therefore, the M-Co9S8@NCF free-standing electrode delivers superior rate performance (1024 mAh g−1 at 0.1 A g−1 and 468 mAh g−1 at 2 A g−1) and stable cycling performance (617 mAh g−1 at 1 A g−1 for 500 cycles). Moreover, porous nitrogen-doped carbon foam (PNCF) was synthesized as the cathode of LIC. M-Co9S8@NCF//PNCF LIC device was then fabricated to combine the advantages of battery-type anode and supercapacitor-type cathode, which achieves a high energy density (166 Wh kg−1 at 182 W kg−1), high power density (83 Wh kg−1 at 7674 W kg−1) as well as satisfactory capacitance retention (83.5% at 5 A g−1 after 5000 cycles). This work offers a convenient method to construct metal sulfide-based free-standing electrode for the advanced lithium-ion storage devices.

Hierarchically porous nitrogen-doped carbon foams decorated with zinc nanodots as high-performance sulfur hosts for lithium-sulfur battery

To prevent polysulfides from dissolution into electrolyte, we propose a novel and simple approach to nitrogen-doped carbon foams which contain hierarchically porous structure and are decorated with zinc nanodots through one-pot carbonization and activation process. These carbon foams, which serve as hosts for sulfur in lithium battery, can provide a conducting network and shorter diffusion length for Li-ions. Specially, the zinc nanodots derived from the carbothermal reaction of ZnCl2 at high temperature can interact with sulfur/polysulfides by strong chemisorption. In addition, the zinc nanodots can also facilitate the conversion reaction between Li2Sx (2 < x < 8) and Li2S/Li2S2. Therefore, Zn@NCFs/S cathode presents high sulfur utility and large capacity.