Graphitic Carbon Nanocages Research Articles

A sulfur-rich copolymer hybrid cathode for anchoring polysulfides and accelerating redox reaction in lithium sulfur batteries

In lithium-sulfur batteries (LSBs), sulfur-rich copolymers have attracted wide attention due to the reduced dissolution of active material and alleviated self-discharge problem through the efficient chemical interaction between polysulfide and carbon. Herein, we present an effective strategy to encapsulate sulfur-rich copolymer into NiCo2S4 encapsulated hierarchical porous N/O dual-doped graphitic carbon nanocages (GCNs), named S-DIB@NiCo2S4@PDA@rGO-GCNs. The host NiCo2S4@PDA@rGO-GCNs matrix can not only provide the “lithiophilic”-rich polar sites and tight anchored LiPSnon the N/O dual-doped GCNs surface, and “sulfphilic” NiCo2S4 electrocatalyst for accelerated sulfur electrochemistry, but also offer abundant hierarchical pores for accommodating sulfur and cushioning its volume expansion. Both of the experimental and theoretical analyses reveal the S-DIB@NiCo2S4@PDA@rGO-GCNs possesses the strong chemisorptions and catalytic ability with the synergetic mechanism, suppressing the self-discharge problem. As a proof-of-concept study, the assembled LSBs cells show excellent discharge capacities of 486 and 324 mA h g−1 at 5C and 10C after 1000 cycles, respectively. The corresponding capacity loss rate is as low as 0.032 % and 0.030 % per cycle, respectively. Thanks to the exceptional lithiophilic and sulfiphilic characteristic, the LSBs pouch cell also demonstrates high cycling stability. The proposed hierarchical encapsulation strategy with synergetic chemisorptions and catalytic ability shows great potential for developing advanced electrodes for next-generation high-performance rechargeable batteries.

Metallic cobalt/cobalt sulfide hetero-nanostructures embedded within N-doped graphitic carbon nanocages for the hydrogen evolution reaction

Metallic cobalt/cobalt sulfide embedded within N-doped graphitic carbon nanocages synthesized through a pyrolysis of ZIF-67 under H2 and S show morphological uniformity beneficial for maintaining electrochemical long-term durability.

Edge defect protection of graphitic carbon nanocages for stable potassium storage at low voltage

Graphitic nanocarbon possesses fast potassium storage capability at low voltage. However, a significant abundance of exposed edge surfaces and defects of graphitic nanocarbon would lead to a substantial number of irreversible reactions, thereby reducing the cyclic stability. Here, the edge defects of graphitic carbon nanocages (GCC) were protected by pitch-based disordered carbon shell to enhance the long-term cyclic stability. The mixture of GCC and pitch was compressed to ensure the full contact of the two components followed by carbonization at 1100 °C. The composite structure can protect the edge and defect of GCC to reduce the irreversible reactions. Moreover, the developed three-dimensional network can form interconnected paths to enhance the electron transfer. Benefiting from this structure, the composite anode achieves high reversible capacity below 1 V (214.1 mAh g−1 at 0.1 C) and high-rate (138.9 mAh g−1 at 1 C). Additionally, the composite anode exhibits higher cyclic stability (96.2% capacity retention from the first to the 80th cycle) than that of GCC (29.8%). This work presents a rational strategy to achieve the edge defect protection of graphitic nanocarbon, thereby facilitate the application of graphitic nanocarbon materials in potassium-ion batteries.

A self-supporting graphitic carbon nanocage network confining high-loading sulfur for high performance potassium-sulfur batteries

Potassium-sulfur (K-S) battery is a promising candidate for high-energy and low-cost energy storage system. However, the development of K-S battery is challenged by the sluggish kinetics, low utilization of sulfur and serious shuttle effect. Herein, a novel self-supporting carbon/sulfur composite cathode (S@GCNs) was developed by infusing sulfur into an interconnected graphitic carbon nanocage (GCNs) network. Typically, the small GCNs (<10 nm) provide a large amount of space for sulfur storage, the sulfur content could reach more than 80 wt%. In addition, the interconnected GCNs network with high conductivity provide fast transport pathways for electrons/ions, and the strong confinement of GCNs on sulfur will buffer the volume expansion of sulfur and alleviate shuttle effect. The unique microstructure of S@GCNs boosts the rate capability and cycle stability of K-S battery, the initial capacity was 452.7 mAh/g, which remained 270.6 mAh/g and 205.9 mAh/g after 10 and 20 cycles, the capacity can reach 97.7 mA h g−1 even at 2000 mA g−1. Characterizations of the phase and structural evolution of S@GCNs revealed the reversible conversion mechanism of sulfur: S0↔ K2Sx (x = 5, 6)↔ K2Sx (x = 4)↔ K2S3.

Metal-organic framework derived magnetic phase change nanocage for fast-charging solar-thermal energy conversion

Efficient capture, conversion and storage of solar energy has been a long-term pursuit facing the green and low-carbon strategic goal. Nevertheless, fast-charging solar-thermal conversion and sustainable stable energy output are the key challenges in current solar-thermal energy storage systems. Herein, we rationally designed a sustainable stable and fast-charging solar-driven energy storage system that can simultaneously supply electricity and heat by integrating phase change materials (PCMs) and metal-organic framework (MOF) derived magnetic Co-decorated hybrid graphitic carbon and N-doped carbon (Co-GC@NC) nanocage. Benefiting from the synergistic effect between magnetic Co nanoparticles and GC@NC carbon hybrid, the resultant magnetic carbon nanocage demonstrates superior full-spectrum absorption and Co-GC@NC-based composite PCMs exhibit a high solar-thermal conversion efficiency of 90.7%. More attractively, the solar-thermal energy conversion and storage efficiency of Co-GC@NC-based composite PCMs is significantly enhanced by 115.8% due to the excellent magnetic manipulation ability of nanocage when a magnetic field was applied. Meanwhile, the designed solar-thermal energy conversion and storage system achieves a maximum output voltage of 290 mV and current of 92.6 mA. This magnetic nanocage-accelerated strategy provides constructive insights into the targeted construction of sustainable and stable fast-charging solar-driven energy storage systems.

WC and cobalt nanoparticles embedded in nitrogen-doped carbon 3D nanocage derived from H3PW12O40@ZIF-67 for photocatalytic nitrogen fixation

The 3D nanocages nitrogen-doped graphitic carbon (NGC) nanocages hybrid loaded with WC nanoparticles and Co nanoparticles (WC–Co/NGC) were first used for the nitrogen fixation.

In Situ Self-Polymerization to Form Hollow Graphitized Carbon Nanocages with Embedded Cobalt Nanoparticles for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur batteries, owing to the multi-electron participation in the redox reaction, possess enormous energy density, which has aroused much attention. Nevertheless, the detrimental shuttle effect, volume expansion, and electrical insulation of sulfur, have hindered their application. To improve the cyclability, a functional host, consisting of Co nanoparticles and N-doped hollow graphitized carbon (Co-NHGC) material, is elaborated, which has the advantages of: 1) the graphitized carbon material working as an electronic matrix to improve the utilization rate of sulfur; 2) the hollow structure relieving the stress change caused by volume expansion; 3) the rich active sites catalyze the electrochemical reaction of sulfur and entrap polysulfides. These advantages significantly improve the performance of the lithium-sulfur batteries. Accordingly, the S@Co-NHGC cathode exhibits excellent initial specific capacity, high coulombic efficiency, and excellent rate performance. This work utilizes a novel method of dopamine in situ etching of a metal-organic framework to synthetize the Co-NHGC host of sulfur, which will hopefully provide inspiration for other energy materials.

Nanoribbon Superstructures of Graphene Nanocages for Efficient Electrocatalytic Hydrogen Evolution

Two-dimensional carbon architectures are attracting tremendous interests for various promising applications due to their outstanding electronic and mechanical properties, although it is a great challenge to rationally devise facile and operative methodologies to engineer their structural traits owing to complex synthetic processes. Herein, for the first time, we fabricate two-dimensional carbon nanoribbons via direct thermal exfoliation of one-dimensional Ni-based metal-organic framework (MOF) nanorods, in which interconnected graphitic carbon nanocages are self-assembled into a belt-like superstructure with carbon-encapsulated Ni nanoparticles immobilized on the surface. Due to the unparalleled structural superiority, the MOF-derived carbon nanobelts exhibit excellent catalytic performances in electrocatalytic hydrogen evolution. Importantly, the practical synthetic strategy may trigger the rapid development of carbon-based superstructures in many frontier fields.

Edge-Plane Exposed N-Doped Carbon Nanofibers Toward Fast K-Ion Adsorption/Diffusion Kinetics for K-Ion Capacitors

Sluggish kinetics severely limit the development of potassium-ion hybrid capacitors (PIHCs). Exposing active sites is recognized as an ideal strategy to resolve this issue, but the corresponding ma...

Superhierarchical Conductive Framework Implanted with Nickel/Graphitic Carbon Nanocages as Sulfur/Lithium Metal Dual-Role Hosts for Li-S Batteries.

High-energy-density Li-S batteries (LSBs) are considered as a promising next-generation energy-storage system. However, the sluggish redox kinetics and severe polysulfide shuttle effect in elemental sulfur cathodes, along with uncontrollable dendrite propagation in lithium metal anodes, inevitably depress the electrochemical performance of LSBs and impede their practical implementation. Motivated by a unique hierarchical geometry, specific chemical affinity, and nitrogen-enriched collagen component of natural skin fibers (SFs), here we proposed an effective structural engineering strategy for crafting an SF-derived superhierarchical N-doped porous carbon framework in situ implanted with nickel/graphitic carbon nanocages as a dual-role host to simultaneously address the challenges faced on the sulfur cathode and lithium anode in LSBs. The experimental results and theoretical calculation disclose that the implanted Ni nanoparticles and highly graphitic sp2 carbon nanocages together with doped N heteroatoms not only provide a synergetic trapping-catalytic-conversion effect for regulating soluble polysulfides with promoted redox kinetics in the cathode at both room and elevated (55 °C) temperatures but also yield Ni-enhanced lithiophilic N-heteroatom active sites in the host framework to control Li deposition and suppress Li dendrite growth in anodes. Combining the cathodic and anodic improvements further achieves a superb rate and cycling performance in full LSB cells with stable Coulombic efficiency, showing great potential in developing reliable LSBs.

Retraction of "Structurally Engineered Hollow Graphitized Carbon Nanocages as High-Performance Anodes for Potassium Ion Batteries".

Graphite is an attractive anode with high capacity and low cost for potassium ion batteries (PIBs), but suffers from poor cycle performance due to the large interlayer expansion during potassiation/depotassiation process. Here, we propose structurally engineered hollow graphitized carbon nanocages (HGCNs) as efficient anode materials for PIBs. The HGCNs were synthesized using a one-pot, self-template and self-graphitization approach where direct pyrolysis of nickel citrate converts citrate chains into carbon-shell and simultaneously reduces Ni2+ to form Ni metal core. This nickel core serves as not only a hard-template to create hollow-cage structure but also a catalyst to facilitate the graphitization of carbon-shell. The HGCNs synthesized at 1000 ºC (HGCN-1000), with its highly graphitized carbon-cage and developed porosity, exhibited an impressive K-storage capacity of 402.2 mAh g-1 at a current density of 30 mA g-1. The synergic combination of hollow morphology with graphitized carbon layers configured a stable structure capable of enduring extreme deformation, endowing HGCN-1000 a robust cyclic stability with a capacity retention of 95.9% over 2000 cycles at 1 A g-1. The proposed strategy provides an efficient route to combat the bottleneck cycling instability issue of graphitic carbon with hollow-graphitized carbon nanocages as promising anode materials for PIBs.

Biocompatible chitosan-carbon nanocage hybrids for sustained drug release and highly efficient laser and microwave co-irradiation induced cancer therapy

Graphitic carbon nanocages (GCNCs) are unique graphene-based nanomaterials that can be used for cancer photothermal therapy (PTT). However, low toxicity GCNC-based organic/inorganic hybrid biomaterials for microwave irradiation assisted PTT have not yet been reported. In the present study, chitosan (CS)-coated GCNCs (CS-GCNCs) loaded with 5-fluorouracil (5Fu) were used for cancer therapy when activated by 808-nm laser and microwave co-irradiation. The cytotoxicity of GCNCs was significantly reduced after coating with CS. For example, fewer cell-cycle defects were caused by CS-GCNCs in comparison with non-coated GCNCs. The release rate of 5Fu from CS-GCNCs was significantly slower than that of 5Fu from GCNCs, providing sustained release. The release rate could be accelerated by 808-nm laser and microwave co-irradiation. The 5Fu in CS-GCNCs retained high cancer cell killing bioactivity by enhancing the caspase-3 expression level. The cancer cell killing and tumor inhibition efficiencies of the 5Fu-loaded nanomaterials increased significantly under 808-nm laser and microwave co-irradiation. The strong cell killing and tumor ablation activities were due to the synergy of the enhanced GCNC thermal effect caused by laser and microwave co-irradiation and the chemotherapy of 5Fu. Our research opens a door for the development of drug-loaded GCNC-based nano-biomaterials for chemo-photothermal synergistic therapy with the assistance of microwave irradiation. Statement of SignificanceGraphitic carbon nanocages (GCNCs) are graphene-based nanomaterials that can be used for both drug loading and cancer photothermal therapy (PTT). Herein, we showed that chitosan (CS)-GCNCs hybrid biomaterials had very low cytotoxicity, high ability for loading drug, and exhibited sustained drug release. In particular, although low-power microwaves alone are unable to trigger cancer cell damage by GCNCs, the cell killing and mouse tumor inhibition efficiencies were significantly improved by near-infrared (NIR) laser and microwave co-irradiation compared with laser-triggered PTT alone. This combined use of laser and microwave co-irradiation promises essential therapeutic modality and opens a new avenue for PTT.

Photocatalysis: Supporting Ultrathin ZnIn2S4 Nanosheets on Co/N‐Doped Graphitic Carbon Nanocages for Efficient Photocatalytic H2 Generation (Adv. Mater. 41/2019)

In article number 1903404, Xiong Wen (David) Lou and co-workers demonstrate the growth of ultrathin ZnIn2S4 nanosheets on Co/N-doped graphitic carbon (NGC) nanocages, composed of ultrafine Co nanoparticles surrounded by a few-layered NGC shell, to construct hierarchical Co/NGC@ZnIn2S4 heterostructured cages. The Co/NGC@ZnIn2S4 hybrid shows outstanding photocatalytic H2 evolution performance under visible light without engaging any cocatalyst.

Supporting Ultrathin ZnIn2 S4 Nanosheets on Co/N-Doped Graphitic Carbon Nanocages for Efficient Photocatalytic H2 Generation.

Ultrathin ZnIn2 S4 nanosheets (NSs) are grown on Co/N-doped graphitic carbon (NGC) nanocages, composed of Co nanoparticles surrounded by few-layered NGC, to obtain hierarchical Co/NGC@ZnIn2 S4 hollow heterostructures for photocatalytic H2 generation with visible light. The photoredox functions of discrete Co, conductive NGC, and ZnIn2 S4 NSs are precisely combined into hierarchical composite cages possessing strongly hybridized shell and ultrathin layered substructures. Such structural and compositional virtues can expedite charge separation and mobility, offer large surface area and abundant reactive sites for water photosplitting. The Co/NGC@ZnIn2 S4 photocatalyst exhibits outstanding H2 evolution activity (e.g., 11270 µmol h-1 g-1 ) and high stability without engaging any cocatalyst.

Controllable preparation of nitrogen-doped graphitized carbon from molecular precursor as non-metal oxygen evolution reaction electrocatalyst

Abstract Nitrogen-doped graphitized carbon materials have been proposed as promising catalytic materials for oxygen evolution reaction in alkaline water-electrolysis hydrogen production. In this study, newly graphene-like graphitized carbon nanocages and nitrogen-doped graphitized carbon nanotubes are controllably prepared by using Tween-20 as molecular precursor, Ni as graphitization catalyst and urea as nitrogen source. The as-prepared materials are characterized by X-Ray Diffraction, scanning electron microscope, transmission electron microscopy and Raman spectroscopy X-ray photoelectron spectroscopy. The OER electrochemical performances are evaluated by linear sweep voltammetry and chronoamperometry. It is found that the nitrogen-doped graphitized carbon nanotubes have higher oxygen evolution activity, lower oxygen evolution overpotential and desirable electrochemical stability relative to graphitized carbon nanocages, demonstrating it is a promising catalytic material for OER in alkaline water-electrolysis hydrogen production.

Graphitized carbon nanocages/palladium nanoparticles: Sustainable preparation and electrocatalytic performances towards ethanol oxidation reaction

Graphitized carbon (GC) nanocages have been successfully prepared via a sustainable carbon powder buried-type Ni catalysis-growth technology from Tween-80 molecule precursor. The GC nanocages are used as support for the further construction of GC/Pd electrocatalyst towards ethanol oxidation reaction. The material structures and surface morphologies are studied by XRD, SEM and TEM techniques. The electrochemical properties are investigated by CV, LSV, EIS and CP techniques. The results showed that GC nanocages have good graphited structure and plentiful opening gaps, and the Pd nanoparticles were evenly distributed on the inner and outer surfaces of GC nanocages. The GC/Pd electrocatalyst exhibits excellent electrocatalytic performance towards ethanol oxidation. The positive scanning peak current density of GC/Pd electrode is up to 1612 A/g Pd in 1.0 mol/L NaOH +1.0 mol/L ethanol electrolyte, which is much higher than those (500–1100 A/g Pd) of traditional Pd electrodes supported with carbon nanotubes or graphene nanosheets.

Well-defined carbon nanoframes containing bimetal-N-C active sites as efficient bi-functional electrocatalysts for Li-O2 batteries

Design and fabrication of framework-structured porous precursors have been regarded as a prospective albeit challenging strategy to obtain bimetal/NC-enriched bifunctional elecrocatalysts. In this work, an effective bottom-up approach involving solution-based self-assembly and a post-annealing process was developed to confine (Co, Zn)-N-C active sites into N-enriched graphitic carbon nanocages. This novel architecture containing N-doped-C stabilized bimetallic nanoparticles derived from ZIF precursors was well-studied by a series of characterization and analysis techniques. Details were given that these well-dispersed (Co, Zn) nanoparticles were encapsulated into the pyridinic-N-dominated graphitic carbon nanocage with a total metal loading of approximately 7.4 at.%. This favorable hierarchical structure not only enhances the electron conductivity, but also owns a sufficient BET surface area facilitating the gas-liquid-solid triphase reaction and producing more space to store discharge products. Importantly, results infer that the interesting nanoframes manifests a satisfying ORR/OER activity and enhanced cell performance whether liquid or solid-state electrolytes are used. As such, our work rationalizes that this type of cage-shaped bimetal-N-C material is promising for high-performance Li-O2 batteries.

In-Situ Template Formation Strategy for the Preparation of Nitrogen Doped Carbon Nanocage with Graphitic Shell as Electrode Material for Supercapacitor.

Nitrogen doped carbon nanocage with graphitic shell (NGCS) was fabricated through in-situ solid reaction between calcium acetate and dicyandiamide in an inert atmosphere followed by acid etching. The role played by the calcium acetate (Ca(Ac)2) and dicyandiamide (DCD) during the synthesis process is one-stone-two-birds. Calcium acetate plays multiple functions: template agent, graphitization catalyst, and carbon source. Dicyandiamide can be considered as the nitrogen sources and the chemical reaction agent that can be reacted with calcium acetate to form it into CaCN2. The NGCS obtained at 800 °C has a specific surface area of 420 m2/g and nitrogen content of 8.87 at%. The excellent electrochemical performance can be attributed to the combination effects of porous structure, nitrogen doping and graphitized nanocage shell of NGCS electrode. The hollow structure serves as the reservoir for fast electrolyte ion supplement. Nitrogen groups not only improve the wettability of interfaces between carbon surface and electrolyte, but also generate extra pseudocapacitance through redox reaction. The graphitic carbon nanocage shell can enhance the conductivity and facilitates the fast charge transfer. At a current density of 0.5 A/g, the specific capacitance of the NGCS-800 electrode is 215 F/g. Furthermore, the NGCS-800 electrode exhibits excellent rate capability (80% capacitance retention at 10 A/g) and outstanding cycling stability (96.89% capacitance retention after 5000 cycles). These intriguing results demonstrate that nitrogen doped carbon with graphitic shell will be highly promising as electrode materials for supercapacitors and other energy storage and conversation applications.

Drug-Loaded Polymer-Coated Graphitic Carbon Nanocages for Highly Efficient in Vivo Near-Infrared Laser-Induced Synergistic Therapy through Enhancing Initial Temperature

Graphitic carbon nanocages (GCNCs) have unique geometric structures and physical properties, which have been extensively investigated for various applications. However, no reports focusing on using GCNCs and polymer-coated GCNCs for solid tumor ablation induced by near-infrared laser irradiation under enhanced initial body temperature, or on the biosafety of GCNCs in vivo, have been published. Here, we developed chitosan (CS)-coated GCNCs and showed that both GCNCs and GCNCs/CS in mouse tumors can rapidly convert an 808 nm laser light energy into heat, which efficiently kill nasopharyngeal carcinoma cells and inhibit tumor growth. The tumors are further damaged by the phototoxicity of GCNCs/CS after loading with 5-Fluorouracil (5FU). Tumors are no longer detected after 6 days of 5FU-GCNCs/CS treatment under irradiation, which is due to the synergistic effect of the photothermal response of GCNCs and the chemotherapy of 5FU. None of the tumors reappeared during the following 12 days of no irradiation. Interestingly, increasing the initial body temperature of the mice significantly improved the photothermal effect of GCNCs in vivo and the synergistic effect of photothermal therapy and chemotherapy, thus accelerating the shrinking of tumors. To the best of our knowledge, this is the first study to improve the photothermal ablation of GCNCs and synergetic photothermal-chemotherapy of drug-loaded GCNCs through enhancing the initial body temperature. As the results show that GCNCs, GCNCs/CS, and 5FU-GCNCs/CS are safe in mice after intratumoral injection both with and without laser irradiation, our technique may have great potential for future clinical translation.

Graphitic Carbon Nanocage as a Stable and High Power Anode for Potassium‐Ion Batteries

AbstractAs an emerging electrochemical energy storage device, potassium‐ion batteries (PIBs) have drawn growing interest due to the resource‐abundance and low cost of potassium. Graphite‐based materials, as the most common anodes for commercial Li‐ion batteries, have a very low capacity when used an anode for Na‐ion batteries, but they show reasonable capacities as anodes for PIBs. The practical application of graphitic materials in PIBs suffers from poor cyclability, however, due to the large interlayer expansion/shrinkage caused by the intercalation/deintercalation of potassium ions. Here, a highly graphitic carbon nanocage (CNC) is reported as a PIBs anode, which exhibits excellent cyclability and superior depotassiation capacity of 175 mAh g−1 at 35 C. The potassium storage mechanism in CNC is revealed by cyclic voltammetry as due to redox reactions (intercalation/deintercalation) and double‐layer capacitance (surface adsorption/desorption). The present results give new insights into structural design for graphitic anode materials in PIBs and understanding the double‐layer capacitance effect in alkali metal ion batteries.