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High entropy alloys (HEAs) are encapsulated in graphitized hollow carbon tubes to confine the growth of alloy particles during the formation process. Zinc–air batteries with HEAs as air electrodes exhibit long-lasting durability and high efficiency.

Lithium-sulfur battery is one of the most promising batteries, but it suffers from the low conductivity of sulfur and the dissolution/loss of lithium polysulfide. The dissolution/loss of lithium polysulfide is more serious at low rates, because there is enough time for lithium polysulfide to diffuse to the negative electrode, which leads to poorer cycle stability at low rates than at high rates. Here, a network of carbon nanofibers (NCNFs) is prepared by carbonizing the composite nanofibers of polyacrylonitrile and ZIF-8, which can be used to form composite with sulfur. However, due to poor conductivity and large pore size of NCNFs, the composite delivers low specific capacity and shows poor cycle stability. After coating with a layer of PEDOT:PSS, the conductivity and the dissolution/loss of lithium polysulfide are effectively addressed. As a result, the composite electrode with a sulfur loading up to 3.4 mg exhibits a maximum specific capacity of 793 mAh/g at 0.1 C, which remains to be 623 mAh/g even after 200 cycles. The PEDOT:PSS coating effectively improves the low current rate cyclability, which is a challenge for lithium-sulfur batteries.

Background: Metastasis of renal cell carcinoma most commonly occurs in the lungs, lymph nodes, bones, liver, and brain. It is rare for CCRCC to metastasize to the sigmoid colon after radical nephrectomy, which often signifies systemic metastasis and poor prognosis. Case Presentation: A 65-year-old woman was hospitalized for bloody stools, and she had a radical nephrectomy eight years ago after being diagnosed with CCRCC. The preoperative colonoscopic biopsy failed to clarify the nature of the mass, and the imaging examination suggested that the mass may be malignant. Following surgery to remove the mass, it was diagnosed as sigmoid metastatic CCRCC according to histopathology and immunohistochemistry. At present, she was in good health, and no clinical or radiological evidence of metastasis was found in her 11-month follow-up after surgery. Conclusion: Metastasis may take a long time to appear after radical nephrectomy, so it is essential to actively follow up and review patients who have undergone renal cancer surgery, and early detection and treatment of metastases remain crucial.

Efficient oxygen reduction reaction (ORR) electrocatalysts are critical for fuel cells. Herein, we report a facile synthetic method to prepare Co–N–C porous nanofibers (Co–N-CNFs) for high performance ORR electrocatalyst. Specifically, Polyacrylonitrile/Bimetallic (Cobalt and Zinc) ZIFs (PAN@BZIFs) hybrid is obtained by electrospinning and finally resulting in Co, N doped carbon nanofibers after pyrolysis. Electrochemical measurements demonstrate that it possesses remarkable ORR performance, superior stability and methanol tolerance under alkaline condition compared to commercial Pt/C catalyst. In this Co–N–C system, the ratio of Co/Zn in BZIFs and temperature of pyrolysis are confirmed as the important factors of specific surface area, graphitization and even ORR property. Thereby, through changing them, the best electrocatalytic activity was acquired with the ratio equals to 0.2 and pyrolyzing at 800 ℃. In addition, the excellent catalytic property can be attributed to the synergic coupling pores and hierarchical pore structure.

Developing robust oxygen evolution reaction (OER) electrocatalysts with excellent performance is essential for the conversion of renewable electricity to clean fuel. Herein, we present a facile concept for the synthesis of efficient high-entropy metal-organic frameworks (HEMOFs) as electrocatalysts in a one-step solvothermal synthesis. This strategy allows control of the microstructure and corresponding lattice distortion by tuning the metal ion composition. As a result, the OER activity was improved by optimizing the coordination environment of the metal catalytic center. The optimized Co-rich HEMOFs exhibited a low overpotential of 310 mV at a current density of 10 mA cm

The release of microplastics (MPs) into the environment has engendered considerable ecosystem and human health concerns. Herein, we propose light-driven photocatalytic upcycling of MPs using heterojunction photocatalysts. A novel synthesis method was developed through in-situ conversion of unstable metal sites on bimetallic metal-organic frameworks (MOF), resulting in nanometer-sized particles with semiconductor properties which are confined into the framework of MOFs to prevent agglomeration. These modified MOF can be used for photocatalytic conversion of MPs along with hydrogen (H2) production. As a proof of concept, FeAg-MOF was selected as a precursor to fabricate Ag2O/Fe-MOF photocatalysts. Light illumination induced the formation of Ag2O with a particle size of ∼6 nm into MOF framework structure. The Ag2O/Fe-MOF displays a broad solar light-harvesting range with exposed active sites. Furthermore, band-matching the Ag2O/Fe-MOF heterojunction can enable the conversion of MPs into value-added chemicals, accompanied by H2 production. The present work provides an insight into designing advanced heterojunction photocatalysts and converting MPs into value-added chemicals, coupled with clean energy production.

Ferric sludge pollution and unsustainable utilization of Fe(II) reagent were tough nuts to crack for homogeneous Fenton treatment. Previous Fe(II) regeneration methods are still limited by high reagent consumption or low regeneration rate. In this work, granular sludge was introduced into the biocathode of microbial electrolysis cell (MEC), to improve Fe(II)-regeneration rate from actual ferric sludge at near neutral pH. Wastewater constituents in the bioanode of dual-chamber MEC were used as the reducing power to regenerate Fe(II). In the flow-through biocathode, 175 ± 16 mg/L of dissolved Fe(II) was efficiently regenerated from actual ferric sludge. The regeneration rate of dissolved Fe(II) was 7.2 times higher than that of the previously reported biocathode. Besides, the actual and synthetic ferric sludge had a similar Fe(II) regeneration performance. Interestingly, recalcitrant organics and 20 mg/L NO3–N in ferric sludge were removed by 96% and 100% during Fe(II) regeneration. The biomass in the granular sludge biocathode was 12 times that of the control biocathode, in which Clostridium sensu stricto dominated. These findings provide insights and theoretical support for developing a viable biotechnology platform, to close the gap for the efficient and sustainable iron cycle.

Two dimensional (2D) nanohetrostructures (NHS) composed of multimetal oxide nanoparticles (NPs) with site selective growth on either basal or lateral of the 2D multimetal oxide nanosheets (NSs) substrate are highly desirable due to their unique chemical and physical properties but extremely challenging in preparation. Herein, for the first time, we demonstrate the rational control growth of amorphous NiCoFeOx NPs on either lateral or basal of amorphous NiCoFeOx NSs by hydrothermal method. Owing to the lateral growth of amorphous NiCoFeOx NPs on the amorphous NiCoFeOx NSs, this unique architecture exhibits more electrocatalytic active sites and better stability due to higher In-plane conductivity than interlayer conductivity. Furthermore, density functional theory (DFT) calculation shows that due to the presence of low coordinated oxygen, it decreased the energy barrier of intermediates and enhanced the oxygen evolution reaction (OER) performance. While, NiCoFe oxide NHS with lateral growth of NiCoFeOx NPs lead to superior electrocatalytic activity toward oxygen evolution reaction (OER) with a low overpotential of 232 mV to reach a current density of 10 mAcm−2, due to the amorphous nature of NHS, synergistic effect, conductive support (like Nickel Foam) with metal oxide substrate. Furthermore, employing Lateral growth NHS as an anode and cathode for water splitting electrolyzer able to reach 10 mAcm−2 at a cell voltage of 1.49 V with robust durability. This work will provide a new dimension for the construction of other site selective 2D NHS with unique properties especially for OER.

Defect engineering or lattice distortion is considered an efficient strategy to enhance the intrinsic activity of an electrocatalyst. Multishell, hollow NiCoFe alloy spheres were prepared with vacancies, gaps or defect, and tilting of an atomic plane with incorporated graphitic carbon derived from the surfactant. The extra gaps or defects in the lattice, which can be verified by high-resolution transmission electron microscope, provide additional active edge sites for the hydrogen evolution reaction. As a result, three-dimensional NiCoFe alloy poses a very low overpotential of 16 mV in 0.5 M H2SO4 for the hydrogen evolution reaction and an unexpectedly small Tafel slope of 38 mV dec−1. This work can therefore broaden horizons and provide a new dimension for the design of new, highly efficient electrocatalysts for hydrogen evolution in an acidic medium.

Hexavalent chromium (Cr(VI)) is one of the major concerns for water environment and human health due to its high toxicicity, while ferric sludge produced from Fenton processes is also a tough nut to crack. In this study, the synergetic impact of ferric sludge derived from the Fenton process on the bioreduction of Cr(VI) in biocathode microbial electrolysis cell was investigated for the first time. As a result, Cr(VI) reduction efficiency at biocathode increased by 1.1 ∼ 2.6 times with 50 mg/L ferric sludge under different operation conditions. Besides, the Cr(VI) reduction enhancement decreased with the increase of pH and initial Cr(VI) concentration or increased with the increase of ferric sludge dosage. Correspondingly, relatively higher power density (1.027 W/m3 with 100 mg/L ferric sludge while 0.827 W/m3 for control) and lower activation energy and resistance were also observed. Besides, the presence of ferric sludge increased biomass protein (1.7 times higher with 100 mg/L ferric sludge) and cytochrome c (1.4 times higher with 100 mg/L ferric sludge). The evolution of microbial community structure for a higher abundance of Cr(VI) and Fe(III)-reducing microorganisms were exhibited, implying the enhancement of Cr(VI) reduction was due to the formation of Fe(II) from the reduction of ferric sludge. These findings provide insights and theoretical support for developing a viable biotechnology platform to realize waste treatment using waste.

Zn-air battery technologies have received increasing attention, while the application is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). In order to explore an efficient method to fabricate a high-performance electrocatalyst via modification of advanced nanostructure, a coaxial electrospinning method with in-situ synthesis and subsequent carbonization to construct 3D flexible Janus-like electrocatalysts is developed. The resulting Janus nanofibers have a unique core-shell hollow fiber structure, where NiFe alloy electrocatalysts supported by N-doped carbon nanobelt are located on the inner wall of the carbon layer, and leaf-like Co-N nanosheets are anchored on the outer wall of the carbon layer. As a result, the electrocatalyst exhibits excellent bifunctional catalytic performance for ORR and OER, demonstrating the small potential gap value of 0.73 V between the ORR half-wave potential and the OER potential at 10 mA cm-2 , which is even comparable to the mixed commercial noble catalyst with 20% Pt/C and RuO2 . The rechargeable Zn-air battery is constructed and displays a large open-circuit voltage of 1.44 V, high power density (130 mW cm-2) and energy density (874 Wh kg-1). This study provides a concept to synthesize and construct high performance bifunctional electrocatalysts.

Transition metal selenide-based materials have been demonstrated as promising electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), yet the actual design of a highly efficient and stable electro-catalyst based on these materials still remains a long and arduous challenge. Herein, a predesigned hybrid Zn/Co zeolitic imidazole framework was used to fabricate CoSe2/Co nanoheteroparticles embedded within hierarchically porous Co, N co-doped carbonnanopolyhedra/nanotubes (CoSe2/Co@NC-CNTs) through a facile approach involving controlled carbonization and selenization procedures. As expected, the optimized CoSe2/Co@NC-CNT-1 displayed outstanding electrocatalytic performance for the ORR and OER, with an onset potential of 0.95 V vs. RHE, a half-wave potential of 0.84 V vs. RHE for ORR, and a potential of 1.69 V vs. RHE for OER at 10 mA cm−2. It also exhibited excellent long-term stability and methanol resistance ability, which were superior to commercial IrO2 and the commercial 20 wt% Pt/C catalyst. Notably, the assembled Zn–air battery with CoSe2/Co@NC-CNT-1 showed a low charge–discharge voltage gap (0.696 V at 10 mA cm−2) and a high peak power density (100.28 mW cm−2) with long-term cycling stability. These superior performances can be ascribed to the synergistic effects of the highly active CoSe2/Co nanoheterostructure, hierarchically porous structure with a large surface area, high electrical conductivity and uniform doping of the Co and N.

Hollow carbon nanospheres (HCNs) with specific surface areas up to 2949 m2 g-1 and pore volume up to 2.9 cm3 g-1 were successfully synthesized from polyaniline-co-polypyrrole hollow nanospheres by carbonization and CO2 activation. The cavity diameter and wall thickness of HCNs can be easily controlled by activation time. Owing to their large inner cavity and enclosed structure, HCNs are desirable carriers for encapsulating sulfur. To better understand the effects of pore characteristics and sulfur contents on the performances of lithium-sulfur batteries, three composites of HCNs and sulfur are prepared and studied in detail. The composites of HCNs with moderate specific surface areas and suitable sulfur content present a better performance. The first discharge capacity of this composite reaches 1401 mAh g-1 at 0.2 C. Even after 200 cycles, the discharge capacity remains at 626 mAh g-1 .

It is critical for nanoporous carbons to have a large surface area, and low cost and be readily available for challenging energy and environmental issues. The pursuit of all three characteristics, particularly large surface area, is a formidable challenge because traditional methods to produce porous carbon materials with a high surface area are complicated and expensive, frequently resulting in pollution (commonly from the activation process). Here we report a facile method to synthesize nanoporous carbon materials with a high surface area of up to 1234 m2 g−1 and an average pore diameter of 0.88 nm through a simple carbonization procedure with carefully selected carbon precursors (biomass material) and carbonization conditions. It is the high surface area that leads to a high capacitance (up to 213 F g−1 at 0.1 A g−1) and a stable cycle performance (6.6% loss over 12 000 cycles) as shown in a three-electrode cell. Furthermore, the high capacitance (107 F g−1 at 0.1 A g−1) can be obtained in a supercapacitor device. This facile approach may open a door for the preparation of high surface area porous carbons for energy storage.

Hierarchical FAU zeolites with house-of-card-like (HCL) structures were synthesized through a one-pot organotemplate-free route in the Na2O-Al2O3-SiO2-H2O system. The structure details and formation mechanism of HCL zeolites were determined by the combination of electron crystallography and synthesis chemistry. The results revealed that the unique HCL morphology was attributed to large solution viscosity, and the evolution process obeyed a skeleton crystal growth model due to the limited vortexing effect, which was different from those of the HCL zeolites obtained using organic templates.

Microbial electrosynthesis of hydrogen peroxide is receiving growing interest for a green substitute for anthraquinone process. However, poor oxygen transmission of electrode remains an obstacle to enhance H2O2 production rate without aeration. Here, a superhydrophobic natural air diffusion floating electrode (NADFE), which naturally and efficiently entraps O2 in the air, was proposed for the first time to improve microbial electrosynthesis of H2O2. Furthermore, a one-step calcined electrode preparation method was developed to reduce energy consumption further. In the microbial electrolysis cell with the NADFE, a high H2O2 production rate of 39 mg/L/h and current efficiency of 86% were achieved without aeration. The production rate of H2O2 was 2.2 times that of a gas diffusion electrode. Importantly, the energy consumption was 34.3 times lower than an electrochemical system. Therefore, the high H2O2 production rate and current efficiency, and low energy consumption of the process provide a superior alternative for environmental remediation.

Developing non-noble metal-based electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is highly desirable, while still facing challenges. Herein, a self-sacrifice template engineering strategy that feasible carbonization of the copolymer of melamine-trithiocyanurim wrapped by polydopamine was developed to fabricate N, S hollow co-doped carbon tube (NSCHCT) based trifunctional electrocatalyst. Owing to the hierarchical structure, including hollow and porous structure, the obtained catalyst exhibits rich active sites and favourable mass transfer advantage, boosting the kinetic of the catalytic process. Moreover, multiple heteroatoms-doping provides various active sites. Notably, the thiophene sulfur combining with pyridinic N(p-N/S) and thiophene sulfur combined with graphitic N (g-N/S) shows the lowest activation energy barrier for OER/ORR and HER, respectively. As a result, the NSCHCT assembled Zinc-air battery shows excellent performance with a power density of 109 mW cm−2 and a high open-circuit voltage of 1.44 V, comparable with the Pt/C + RuO2 system.

The utilization of solar energy for CO2 reduction reaction (CO2RR) into valuable hydrocarbons offers attractive solution towards low-carbon future, but their performance is affected by the competing hydrogen evolution reaction (HER) that occurs simultaneously. Herein, we proposed maximizing interface integration and surface reconstructing engineer strategy to improve the CO2RR activity and selectivity of heterojunction photocatalyst. A surface-reconstructed ZnO/CuOx catalysts are uniformly anchored on the porous carbon nanosheet arrays that are supported by carbon nanofibers (ZnO/CuOx-C CNFs). Downsizing ZnO/CuOx maximizes the interface integration of components to promote electron-hole pairs separation and increase surface active site density. Moreover, the surface reconstruction (the formation of the hydroxyl groups on ZnO via facile light irradiation) promotes the kinetic of CO2RR to CH4 and oxygen evolution reaction (OER), while depressing the competing HER and CO generation. All these advantages contribute to the excellent catalytic performance: a high CH4 generation rate of 241.6 μmol h−1 g−1 with the selectivity of ∼96 % for ZnO/CuOx-C CNFs under full light irradiation. The insight into the modification of photocatalyst structure and mechanism investigation pave the way for a new design strategy to advance solar photocatalytic technology for CO2 reduction.

Nitrogen-enriched hierarchical porous carbon nanofibers (NHCFs) are promising candidates for supercapacitors. However, the synthesis of these carbons with high N content and large specific surface area is still great challenging. Here, a flexible NHCF paper is fabricated by electrospinning zeolitic imidazolate framework-8 (ZIF-8) suspended in polyacrylonitrile (PAN) solution, followed by a combined heating and acid treatment. The specific surface area and N content of the prepared NHCFs can be controlled by varying the amounts of ZIF-8 and calcination temperature. The highest specific surface area (559 m2 g−1), ultrahigh N content (15.59 wt%) and best electrochemical performance can be obtained from the calcination of PAN/ZIF-8 (66.7 wt%) at 800 °C, with a maximum specific capacitance of 302 F g−1 at a current density of 0.5 A g−1. In addition, the specific capacitance up to 146.7 F g−1 can still be obtained at high current density of 40 A g−1. The excellent electrochemical performance can be attributed to the synergetic effect of high nitrogen content, hierarchical porous structure and high specific surface area.

Lithium-sulfur batteries are the most promising candidates for future high-energy applications because of the unparalleled capacity of sulfur (1675 mAh g −1 ). However, lithium-sulfur batteries have limited cycle life and rate capability due to the dissolution of polysulfides and the extremely low electronic conductivity of sulfur. To solve these issues, various porous carbons including hollow carbon nanospheres (HCNs) have been used for improving the conductivity. However, these methods still suffer from polysulfides dissolution/loss owing to their weak physical adsorption to polysulfides. Herein, we introduced a covalent grafting route to composite the HCNs and the vulcanized trithiocyanuric acid (TTCA). The composite exhibits a high loading of the vulcanized TTCA by the HCNs with high surface area and large pore volume, and covalent bonds to sulfur, effectively depressing the dissolution of polysulfides. The first discharge capacity of the composite reaches 1430 mAh g −1 at 0.1 C and 1227 mAh g −1 at 0.2 C.

Porous silicon (PSi) has been widely investigated for use in many applications. PSi is usually prepared through the selective etching of silicon. Recently, PSi has been prepared by reducing dense silicon monoxide (SiO) with magnesium. Although the porosity has been confirmed to be a result of the selective acid dissolution of MgO, the formation mechanisms of the composite of MgO and PSi are not very clear. To better understand the formation mechanisms, we synthesized two types of PSi by reducing compact SiO and disproportionate SiO (d-SiO) with different magnesium content. The BET surface area and pore volume of these PSi samples first increased and then decreased. The highest BET surface area was 304 and 328 m2 g−1 for PSi prepared from SiO and d-SiO, respectively. These BET surface areas are among the highest for PSi prepared from dense SiO or silica. An inductive effect of the preformed silicon network in d-SiO was found by contrasting the pore characteristics of the two types of PSi derived from SiO and d-SiO. Accordingly, we suggested two models for the formation mechanisms of PSi from SiO and d-SiO.

Hierarchical clews of carbon nanobelts (CsCNBs) with surface area up to 3445 m2 g−1 have been synthesized by a template-free method from low cost raw materials. The composite of CsCNBs/sulfur displays high initial capacities of 1476, 1021 and 838 mA h g−1 at 1, 3 and 5C, respectively, and ultraslow capacity decay rate of 0.052% per cycle during 300 cycles.

Two dimensional (2D) porous carbon nanosheets (CNS) have attracted tremendous research interests in energy storage and conversion, such as supercapacitors (SCs) and lithium-sulfur batteries, because of their unique micromorphology, chemical stability and high specific surface area (SSA). Rational design and facile scalable synthesis of CNS with high SSA, low cost and ultrathin nanosheet structure is highly desired but hitherto remains a big challenge. Here, we report a novel synthesis method of 2D hierarchical porous CNS with ultrahigh SSA (2687 m2 g−1) and ultrathin structure by directly pyrolysing and activating a unique and abundant biomass sheet. The electrochemical characterisations show that the prepared CNS-4-1 materials as electrodes creates a good energy-storage capability, with the energy density being 91 Wh kg−1 for symmetric SCs in ionic liquids, which is the highest in the reported biomass-derived CNS materials for SCs applications so far. Besides, the CNS-5-1 also exhibits a high initial capacity of 1078 mAh g−1 at 0.1 C when it acted as a sulfur hosting material for lithium-sulfur batteries. More importantly, it also shows a 586 mAh g−1 reversible capacity and an approaching 100% coulombic efficiency after 500 cycles at a high rate of 1 C. These superior electrochemical properties of the CNS are mainly attributed to their unique 2D ultrathin nanosheet structure, large SSA, and reasonable hierarchical porous structure. This work not only provides a new strategy to fabricate the ultrathin CNS in large scale and low cost but also enlarges CNS materials potential applications in energy storage.

Clews of polymer nanobelts (CsPNBs) have the advantages of inexpensive raw materials, simple synthesis and large output. Novel clews of carbon nanobelts (CsCNBs) have been successfully prepared by carbonizing CsPNBs and by KOH activation subsequently. From the optimized process, CsCNBs*4, with a specific surface area of 2291 m2 g−1 and a pore volume of up to 1.29 cm3 g−1, has been obtained. Fundamentally, the CsCNBs possess a three-dimensional conductive network structure, a hierarchically porous framework, and excellent hydrophilicity, which enable fast ion diffusion through channels and a large enough ion adsorption/desorption surface to improve electrochemical performance of supercapacitors. The product exhibits a high specific capacitance of 327.5 F g−1 at a current density of 0.5 A g−1 in a three-electrode system. The results also reveal a high-rate capacitance (72.2% capacitance retention at 500 mV s−1) and stable cycling lifetime (95% of initial capacitance after 15 000 cycles). Moreover, CsCNBs*4 provides a high energy density of 29.8 W h kg−1 at a power density of 345.4 W kg−1 in 1 M tetraethylammonium tetrafluoroborate/acetonitrile (TEABF4/AN) electrolyte. These inspiring results imply that this carbon material with a three-dimensional conductive network structure possesses excellent potential for energy storage.

Nitrogen-doped micropores-contained carbon nanofibres (NMCNFs) were prepared by carbonizing ZIF-8 grown in liquid-phase along with electrospinning. When NMCNFs act as sulphur host materials in lithium–sulphur batteries, NMCNFs can retard the shuttle effect and dissolution of polysulfides through the synergic action of effective physical confinement to micropores and nitrogen surface chemical absorption. NMCNFs show a capacity up to 636 mAh g−1 after 500 cycles against Li anode.

Lithium–sulfur (Li–S) batteries are probably the most promising candidates for the next-generation batteries owing to their high energy density. However, Li–S batteries face severe technical problems where the dissolution of intermediate polysulfides is the biggest problem because it leads to the degradation of the cathode and the lithium anode, and finally the fast capacity decay. Compared with the composites of elemental sulfur and other matrices, sulfur-containing polymers (SCPs) have strong chemical bonds to sulfur and therefore show low dissolution of polysulfides. Unfortunately, most SCPs have very low electron conductivity and their morphologies can hardly be controlled, which undoubtedly depress the battery performances of SCPs. To overcome these two weaknesses of SCPs, a new strategy was developed for preparing SCP composites with enhanced conductivity and desired morphologies. With this strategy, macroporous SCP composites were successfully prepared from hierarchical porous carbon. The composites displayed discharge/charge capacities up to 1218/1139, 949/922, and 796/785 mA h g–1 at the current rates of 5, 10, and 15 C, respectively. Considering the universality of this strategy and the numerous morphologies of carbon materials, this strategy opens many opportunities for making carbon/SCP composites with novel morphologies.

Herein, N-doped graphitic hierarchically porous carbon nanofibers (NGHPCF) were prepared by electrospinning the composite of bimetallic-coordination metal–organic frameworks and polyacrylonitrile, followed by a pyrolysis and acid wash process. Control over the N content, specific surface area, and degree of graphitization of NGHPCF materials has been realized by adjusting the Co/Zn metal coordination content as well as the pyrolysis temperature. The obtained NGHPCF with a high specific surface area (623 m2 g−1) and nitrogen content (13.83 wt%) exhibit a high capacitance of 326 F g−1 at 0.5 A g−1. In addition, the capacitance of 170 F g−1 is still maintained at a high current density (40 A g−1); this indicates a high capacitance retention capability. Furthermore, a superb energy density (9.61 W h kg−1) is obtained with a high power density (62.4 W kg−1) using an organic electrolyte. These results fully illustrate that the prepared NGHPCF binder-free electrodes are promising candidates for high-performance supercapacitors.

Facile synthesis of carbon materials with high heteroatom content, large specific surface area (SSA) and hierarchical porous structure is critical for energy storage applications. In this study, nitrogen and oxygen co-doped clews of carbon nanobelts (NCNBs) with hierarchical porous structures are successfully prepared by a carbonization and subsequent activation by using ladder polymer of hydroquinone and formaldehyde (LPHF) as the precursor and ammonia as the activating agent. The hierarchical porous structures and ultra-high SSA (up to 2994 m2 g−1) can effectively facilitate the exchange and transportation of electrons and ions. Moreover, suitable heteroatom content is believed to modify the wettability of the carbon material. The as-prepared activated NCNBs-60 (the NCNBs activated by ammonia at 950 °C for 60 min) possess a high capacitance of 282 F g−1 at the current density of 0.25 A g−1, NCNBs-45 (the NCNBs are activated by ammonia at 950 °C for 45 min) and show an excellent capacity retention of 50.2% when the current density increase from 0.25 to 150 A g−1. Moreover, the NCNBs-45 electrode exhibits superior electrochemical stability with 96.2% capacity retention after 10,000 cycles at 5.0 A g−1. The newly prepared NCNBs thus show great potential in the field of energy storage.