Carbon Nanocages Research Articles

Titanium nitride@nitrogen-doped carbon nanocage composites as high-performance cathodes for aqueous Zn-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) pertain to a new type of electrochemical energy storage device that has received considerable attention. They integrate the advantages of high-energy Zn-ion batteries and high-power supercapacitors to meet the demand for low-cost, long-term durability, and high safety. Nevertheless, the challenge caused by the finite ion adsorption/desorption capacity of carbon electrodes gravely limits their energy densities. This work describes titanium nitride@nitrogen-doped carbon nanocage (TiN@NCNC) composite cathodes for AZHSCs to achieve a greatly improved energy density, and the composites can be facilely synthesized based on the calcination of a mixture of tetrabutyl titanate and zeolitic imidazolate framework-8 in argon atmosphere. The resulting composites are featured by the ultra-fine TiN particles dispersed uniformly on the NCNC surfaces, enhancing the Zn2+ storage capabilities. Using TiN@NCNC cathodes, the AZHSCs can operate stably with a high energy density of 154 Wh kg−1 at a specific power of 270 W kg−1 and achieve a remarkable capacity retention of 88.9 % after 104 cycles at 5 A g−1. At an extreme specific power of 8.7 kW kg−1, the AZHSCs can retain an energy density of 97.2 Wh kg−1. With these results, we stress that the TiN@NCNC cathodes render high-performance AZHSCs and the facile one-pot method can easily be scaled up, which enables AZHSCs a new energy-storage component for managing intermitted renewable energy sources.

Bimetallic nanoalloys planted on super-hydrophilic carbon nanocages featuring tip-intensified hydrogen evolution electrocatalysis

The insufficient availability and activity of interfacial water remain a major challenge for alkaline hydrogen evolution reaction (HER). Here, we propose an “on-site disruption and near-site compensation” strategy to reform the interfacial water hydrogen bonding network via deliberate cation penetration and catalyst support engineering. This concept is validated using tip-like bimetallic RuNi nanoalloys planted on super-hydrophilic and high-curvature carbon nanocages (RuNi/NC). Theoretical simulations suggest that tip-induced localized concentration of hydrated K+ facilitates optimization of interfacial water dynamics and intermediate adsorption. In situ synchrotron X-ray spectroscopy endorses an H* spillover-bridged Volmer‒Tafel mechanism synergistically relayed between Ru and Ni. Consequently, RuNi/NC exhibits low overpotential of 12 mV and high durability of 1600 h at 10 mA cm‒2 for alkaline HER, and demonstrates high performance in both water electrolysis and chlor-alkali electrolysis. This strategy offers a microscopic perspective on catalyst design for manipulation of the local interfacial water structure toward enhanced HER kinetics.

3D printing of customized Li-S microbatteries

Microbatteries serve as essential energy supply components in microelectronic, wearable and implantable devices. Despite recent efforts, developing lithium metal microbatteries with high energy densities and mechanical flexibility in structural design is still challenging, because of the poor interfacial stability and poor processability of lithium foil. Herein, we developed lithium-sulfur (Li-S) microbatteries with customized configurations using 3D printing techniques, which consist of a printable Li anode hosted within a graphene aerogel framework and a printable S cathode based on a carbon nanocages framework, featuring abundant porous structures and large specific surface areas. Consequently, the 3D-printed Li anode achieves over 900 hours of cycling with low overpotentials at an ultrahigh current density of 10 mA cm−2, and the 3D-printed S cathode delivers an ultrahigh capacity of 21.9 mAh cm−2 at the high thickness of 2.3 mm. Furthermore, the 3D-printed Li-S cell delivers an ultrahigh areal energy density of 48.4 mWh cm−2 at a high power density of 3.5 mW cm−2. The application potential of the 3D-printed customized Li-S microbatteries with arbitrary form factors is demonstrated by LED lighting and powering wearable sensor integration system, paving the way for their applications in miniaturized devices.

Change in nonlinear optical response of C24 nanocage upon doping with lithium based superalkalis

Density functional theory (DFT) calculations are used to analyze the change in nonlinear optical (NLO) response, electronic and geometric properties of the Li based superalkalis doped C24 nanocage. It was observed that the adsorption of Li4N, Li3O and Li2F superalkalis on C24 nanocage results in thermodynamically stable isomers (A-F). The energy gap between the highest occupied and the lowest unoccupied molecular orbitals (GH-L) is reduced after superalkalis doping on carbon (C24) nanocage. Density of states spectra depict the strong contribution of superalkalis in HOMOs of the considered complexes. Natural bond orbital (NBO) charge analysis showed that the charge is being transferred from superalkali toward C24 nanocage. The values of polarizability (α o ) and hyperpolarizability (β o ) showed that doping of superalkalis on C24 has a significant effect on its NLO response, resulting in a considerable increase in values of α o and β o . Li4N@C24 isomer E showed the highest β o value of 6470.74 au. Time dependent density functional theory (TD-DFT) calculations are implemented to analyze the absorption spectra. This research provides unique and highly efficient superalkalis doped C24 isomers for their applications in future electronic devices.

Hierarchical Carbon Nanocages as Superior Supports for Photothermal CO2 Catalysis.

The exploitation of hierarchical carbon nanocages with superior light-to-heat conversion efficiency, together with their distinct structural, morphological, and electronic properties, in photothermal applications could provide effective solutions to long-standing challenges in diverse areas. Here, we demonstrate the discovery of pristine and nitrogen-doped hierarchical carbon nanocages as superior supports for highly loaded, small-sized Ru particles toward enhanced photothermal CO2 catalysis. A record CO production rate of 3.1 mol·gRu-1·h-1 with above 90% selectivity in flow reactors was reached for hierarchical nitrogen-doped carbon-nanocage-supported Ru clusters under 2.4 W·cm-2 illumination without external heating. Detailed studies reveal that the enhanced performance originates from the strong broadband sunlight absorption and efficient light-to-heat conversion of nanocage supports as well as the excellent intrinsic catalytic reactivity of sub-2 nm Ru particles. Our study reveals the great potential of hierarchical carbon nanocages in photothermal catalysis to reduce the fossil fuel consumption of various industrial chemical processes and stimulates interest in their exploitation for other demanding photothermal applications.

Self-enhanced localized alkalinity at the encapsulated Cu catalyst for superb electrocatalytic nitrate/nitrite reduction to NH3 in neutral electrolyte.

The electrocatalytic nitrate/nitrite reduction reaction (eNOx-RR) to ammonia (NH3) is thermodynamically more favorable than the eye-catching nitrogen (N2) electroreduction. To date, the high eNOx-RR-to-NH3 activity is limited to strong alkaline electrolytes but cannot be achieved in economic and sustainable neutral/near-neutral electrolytes. Here, we construct a copper (Cu) catalyst encapsulated inside the hydrophilic hierarchical nitrogen-doped carbon nanocages (Cu@hNCNC). During eNOx-RR, the hNCNC shell hinders the diffusion of generated OH- ions outward, thus creating a self-enhanced local high pH environment around the inside Cu nanoparticles. Consequently, the Cu@hNCNC catalyst exhibits an excellent eNOx-RR-to-NH3 activity in the neutral electrolyte, equivalent to the Cu catalyst immobilized on the outer surface of hNCNC (Cu/hNCNC) in strong alkaline electrolyte, with much better stability for the former. The optimal NH3 yield rate reaches 4.0 moles per hour per gram with a high Faradaic efficiency of 99.7%. The strong-alkalinity-free advantage facilitates the practicability of Cu@hNCNC catalyst as demonstrated in a coupled plasma-driven N2 oxidization with eNOx-RR-to-NH3.

Hollow engineering of Co/N-doped C@carbon aerogel with hierarchical structure boosting interfacial polarization for ultra-thin microwave absorption and thermal insulation

Rational manipulation of the composition and microstructure design of aerogel materials is considered to be an effective method for achieving the dual functions of microwave absorption and thermal insulation. Herein, hollow Co/N-doped C@carbon aerogel with hierarchical structures was designed and constructed via a synergistic strategy including directed freeze-drying, ZIF-67 in situ growth, chemical etching and calcination treatment. Co/N-doped hollow carbon nanocages derived from ZIF-67 with uniform heterojunctions and layered micro-mesopores were constructed using tannic acid and heat treatment process. After that, abundant macroporous structure from the carbon aerogel itself was further introduced to upgrade the impedance matching property, light weight and interfacial polarization loss capability. Remarkably, as-fabricated Co/N-doped C@carbon aerogel (ZTA@A-900) displays optimal MA performance with a minimum reflection loss (RLmin) value of −54.0 dB at 15.32 GHz and a broad effective absorption bandwidth (EAB) of 4.04 GHz (13.44–17.48 GHz) at a thickness of only 1.4 mm. Furthermore, the ideal CST simulation results and excellent thermal insulation property of ZTA@A-900 make it an outstanding candidate for microwave absorbers under extreme conditions. Thus, our work opens up a new avenue for the design and fabrication of multifunctional lightweight microwave absorbers.

ZIF-8-derived ultrasmall ZnO nanoparticles embedded in porous carbon nanocage as anode material for lithium-ion batteries

ZIF-8-derived ultrasmall ZnO nanoparticles embedded in porous carbon nanocage as anode material for lithium-ion batteries

Healable and Conductive Two-Dimensional Sulfur Iodide for High-Rate Sodium Batteries.

Self-healing functional materials can repair cracks and damage inside the battery, ensuring the stability of the battery material structure. This feature minimizes performance degradation during the charging and discharging processes, improving the efficiency and stability of the battery. Here, we have developed a novel healing conductive two-dimensional sulfur iodide (SI4) composite cathode. This process integrates both sulfur and iodine compounds into carbon nanocages, forming a SI4@C core-shell structure. This cathode design improves electrical conductivity and repairability, facilitates rapid activation, and ensures structural integrity, resulting in a typical Na-SI4 battery with high capacity and an exceptionally long cycle life. At 10.0 A g-1, the capacity of the Na-SI4 battery can still reach 217.4 mAh g-1 after more than 500 cycles, and the capacity decay rate per cycle is only 0.06%. In addition, the cathode exhibits a cascade redox reaction involving S and I, contributing to its high capacity. The in situ growth of a carbon shell further enhances the conductivity and structural robustness of the entire cathode. The flexibility and bendability of SI4@C-carbon cloth make it applicable for flexible electronic devices, providing more possibilities for battery design. The strategy of engineering a two-dimensional self-healing structure to construct a superior cathode is expected to be widely applied to other electrode materials. This study provides a new pathway for designing novel binary-conversion-type sodium-ion batteries with excellent long-term cycling performance.

Heteroatom Sulfur-Modified ZIF-8 Derived Zn, N Co-Doped Carbon Nanocages as Highly Efficient ORR Catalysts for Zn-Air Batteries

Carbon-based electrocatalysts derived from zeolitic imidazolate framework-8 (ZIF-8) have garnered significant attention, owing to their structural advantages, high surface area, and tunable active sites. Herein, we report the synthesis of heteroatom sulfur (S) modified ZIF-8 derived carbon nanocages (ZnS@N/S-C) for oxygen electrocatalysis through self-assembly and two-step pyrolysis. The resultant ZnS@N/S-C exhibits catalytic activity towards oxygen reduction reaction (ORR) with high half-wave potential (0.86 V) and stability (91.4%), separately, which is comparable to or superior to Pt/C. Furthermore, the application of ZnS@N/S-C as a cathode for Zn-air batteries (ZABs) demonstrates performance metrics such as an open-circuit voltage of 1.407 V, a power density of 114.4 mW cm−2, and a specific capacity of 764.6 mAh gZn −1, etc surpassing Pt/C. The performance of ZnS@N/S-C can be attributed to the fact that the introduction of S significantly increases the specific surface area, pore volume, and defect extent of the catalyst, while optimizing the electronic structure and generating ZnS active nanocrystals. This work employs a simple sulfurization strategy to enhance the ORR activity of ZIF-8-derived Zn-based catalysts with fully filled 3d orbitals, providing guidance for the development of such materials.

Two-dimensional medium-entropy SeSI composite cathodes with cascaded redox reactions for advanced sodium batteries

Na−S/Se/I2 batteries represent a promising rechargeable Na battery system because of high theoretical energy density and low raw material cost. However, the inherent electrical insulation and poor structural stability of S/Se/I2 cathodes result in the unsatisfactory battery performance. Here we develop a new medium-entropy Se-S-I composite cathode via a straight chemical reaction of 2xSe+yI2+CS2=2SexSIy+C, simultaneously consolidating a ternary Se-S-I compound within carbon nanocage, forming a SeSI@C core-shell structure. In the composite, SeSI has a distinctive single crystal structure with homogeneous elemental composition, while carbon shell shows a uniform annular nanoscale that can completely envelop SeSI active mass. The cathode structural design bears high electrical conductivity, fast synergistic activation and excellent structural integrity, accordingly enabling a high capacity with an ultralong cycle life in a representative Na−Se-S-I battery (425.4 mAh g−1 at 10.0 A g−1, 91.6 % retention for 2000 cycles). Notably, a tertiary cascade of Se, S, and I redox has been demonstrated for providing high capacity, and an in-situ grown carbon shell ensures electrical conductivity and structural stability through the entire cathode. This SeSI@C cathode architecture significantly alleviates issues of traditional S/Se/I2-based cathodes, and makes the Na−Se-S-I battery more promising for application.

Electrochemical detection of carbendazim using molecularly imprinted poly(3,4-ethylenedioxythiophene) on Co,N co-doped hollow carbon nanocage@CNTs-modified electrode

Precisely detecting trace pesticides and their residues in food products is crucial for ensuring food safety. Herein, a high-performance electrochemical sensing platform was developed for the detection of carbendazim (CBZ) using Co,N co-doped hollow carbon nanocage@carbon nanotubes (Co,N-HC@CNTs) obtained from core–shell ZIF-8@ZIF-67 combined with a poly(3,4-ethylenedioxythiophene) (PEDOT) molecularly imprinted polymer (MIP). The Co,N-HC@CNTs exhibited excellent electrocatalytic performance, benefitting from the synergistic effect of CNTs that provide a large specific surface area and excellent electrical conductivity, Co,N co-doped carbon nanocages that offer high electrocatalytic activity and hollow nanocage structures that ensure rapid diffusion kinetics. The conductive PEDOT-MIP provided specific binding sites for CBZ detection and significantly amplified the detection signal. The sensor showed superior selectivity for CBZ with an extremely low detection limit of 1.67 pmol L−1. Moreover, the method was successfully applied to detect CBZ in tomato, orange and apple samples, achieving satisfactory recovery and accuracy, thus demonstrating its practical feasibility.

Fe3O4 nanoparticles encapsulated in graphitized and in-plane porous carbon nanocages derived from emulsified asphalt for a high-performance lithium-ion battery anode

Fe3O4 nanoparticles encapsulated in graphitized and in-plane porous carbon nanocages derived from emulsified asphalt for a high-performance lithium-ion battery anode

Heterostructure CoSe2/Sb2Se3 nanocrystals embedded into nanocage-in-nanofiber carbon framework for ultralong-life sodium-ion batteries

Transition metal selenides are considered as one of the most promising anode materials for sodium-ion batteries (SIBs) on account of their high theoretical specific capacity. However, the poor conductivity, sluggish kinetics and volume expansion during the (de)sodiation process hinder its application. Herein, a novel heterostructure of CoSe2/Sb2Se3 nanocrystals embedded into nanocage-in-nanofiber carbon framework is designed and constructed via electrospinning, carbonization, ion exchange and selenization processes. In this structure, bimetallic selenide heterostructure accelerates electron/ion transfer kinetics and Na+ adsorption capacity, carbon nanocages structure alleviates the volume expansion and maintains structural integrity during the (de)sodiation process, and carbon nanofibers connect the nanocages in series to shorten the electron transmission path and enhance electrical conductivity. As a self-supporting anode for SIBs, as-synthesized CoSe2/Sb2Se3@C@CNF shows a high reversible capacity of 406 mAh g-1 at 0.2 A g-1 after 200 cycles and displays excellent rate capability. More remarkably, the CoSe2/Sb2Se3@C@CNF anode manifests an outstanding cycling stability for over 2000 and 12,000 cycles at 1 and 5 A g-1, with the capacity retention being 97 % and 103 % respectively. Meanwhile, the excellent sodium storage performance is revealed by kinetic analysis, energy level analysis and density functional theory calculations.

Highly Dispersed Quasi-1 nm Ruthenium Nanoclusters on Hierarchical Nitrogen-Doped Carbon Nanocages Constructed by Surface-Constrained Sintering for Alkaline Hydrogen Evolution

Highly Dispersed Quasi-1 nm Ruthenium Nanoclusters on Hierarchical Nitrogen-Doped Carbon Nanocages Constructed by Surface-Constrained Sintering for Alkaline Hydrogen Evolution

Pyrolysis fuel oil-derived hollow carbon nanocages as high-stability anode materials for potassium ion storage

The use of graphite to make anode materials for potassium-ion batteries (KIBs) results in diminished electrochemical performance, largely due to significant interlayer expansion caused by potassation/depotassiation. To address this limitation, novel hollow carbon nanocages (HCNCs) are prepared from pyrolysis fuel oil (PFO), a cost-effective byproduct. The HCNCs heat-treated at 1500 °C has a graphitic structure with high porosities and numerous closed pores and exhibits a notable potassium-ion storage capacity of 307.2 mAh/g at a current density of 50 mA g−1. Moreover, structurally stable HCNCs withstand the substantial volume expansion associated with potassium-ion intercalation. The stability of the material is attributed to a hybrid adsorption/insertion mechanism, which results from synergistic interplay between the unique morphologies of the HCNCs and the developed carbon layers. This configuration delivers a specific capacity of 131.6 mAh/g and 98.9 % capacity retention over 1000 cycles at a high current density of 2000 mA g−1. Consequently, these proposed HCNCs present a significant advance in developing efficient carbon materials for KIBs, and addressing the critical challenges of graphite such as unstable cycling stability.

WC nanoparticles and NiFe alloy co-encapsulated in N-doped carbon nanocage for exceptional OER and ORR bifunctional electrocatalysis

Developing earth-abundant electrocatalysts with optimized intrinsic active sites is crucial for enhancing bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance. In this study, we fabricated a hollow structured carbon framework utilizing NiFe Prussian Blue analogs (PBAs) as templates, while polypyrrole (PPy) and phosphotungstic acid (PW12). Pyrrole monomer underwent polymerization on the nanocubic PBA surface in the presence of PW12 (PBA@PPy-PW12). Subsequent carbothermal reduction created an N-doped carbon shell with embedded NiFe alloy and tungsten carbide (WC) nanoparticles. The polymeric PPy-PW12 nature can not only prevent the aggregation of PBA and WC structures but also enhance electrical conductivity by connecting neighboring nanospheres. Moreover, the introduction of WC can significantly enhance the bifunctional electrocatalytic activity of the carbon-based catalyst, which is attributed to synergism between the WC and NiFe materials within the NC layer. Consequently, NiFe/W0.3C@NC exhibited outstanding OER (overpotential = 290 mV for 10 mA/cm2; Tafel slope = 57 mV/dec) and ORR (half wave potential = 0.81 V; Tafel slope = 61 mV/dec) performances. This work presents a promising avenue for developing high-performance electrocatalysts for energy conversion systems that showcase remarkable efficiency, stability, and potential practicability.

Porous carbon-MnO2 heterostructures for high energy density aqueous ammonium-ion asymmetric supercapacitors

Aqueous ammonium-ion (NH4+) is gaining attention as a viable energy storage option due to the use of NH4+ as the charge carrier, offering advantages of resource abundance, safety, fast diffusion, and a unique storage mechanism. Despite these benefits, the development of storage devices with NH4+ as the charge carrier are still in the early stages, highlighting the crucial need to explore suitable electrode materials for the production of high-performance devices. In this study, broken porous carbon nanocages (BPCs) serve as the support structure to form a heterostructure with δ-MnO2 nanosheets (MnO2-BPCs) grown onto them, building aqueous NH4+ asymmetric supercapacitors (ASCs). Both MnO2-BPCs and BPCs act as host materials for storing aqueous NH4+, exhibiting high specific capacitance and long cycling durability. The assembled NH4+ ASCs present good capacitive performance, with a large specific capacitance of 223 F g−1 and capacitance preservation of 91.4 % over 10,000 cycles. The high energy density achieved by NH4+ ASCs is crucial for advanced energy storage thanks to their elevated specific capacitance and broad operating voltage. The balanced capacitive performance of the positive and negative electrodes is essential in enhancing the energy storage capabilities of NH4+ ASCs. This work provides a straightforward method for creating porous carbon-MnO2 heterostructures for NH4+ storage and paves the way for designing aqueous NH4+-based sustainable energy storage systems (SESSs) for capacitive energy storage.

ZIF67-derived ultrafine Co9S8 nanoparticles embedded in nitrogen-doped hollow carbon nanocages for enhanced performances of trifunctional ORR/OER/HER and overall water splitting

ZIF67-derived ultrafine Co9S8 nanoparticles embedded in nitrogen-doped hollow carbon nanocages for enhanced performances of trifunctional ORR/OER/HER and overall water splitting

Synergistic multi-functional N-doped carbon Nanocage@CNT/ZnMn2O4/Ti3C2 MXene: Powering battery, supercapacitor, and catalyzing hydrogen evolution

This study presents a novel approach to enhance the electrochemical capabilities of 3D pyrolytic carbon for energy applications. Using a chemical blowing technique, highly conductive carbon nanotubes (CNTs) are embedded within a 3D N-doped carbon nanocage (NCN). This integration involves an additional carbon source during Ni(NO3)2 induced polymer blowing, leveraging the dual role of Ni(NO3)2 in polymer expansion and catalyzing CNT growth. Our research merges ZnMnO4/Ti3C2 with high-capacity N-Doped Carbon Nanocage@CNT (NCN/CNT@ZnMnO4/Ti3C2) to amplify electrochemical performance. The NCN/CNT@ZnMnO4/Ti3C2 showed specific capacitance of 1843 Cg-1 at 1.0 Ag-1, attributed to augmented electrical conductivity and charge storage characteristics. The supercapattery configuration maintains a specific capacitance of 195 Cg-1 at 1.0 Ag-1, cyclic stability of 95% over 18,000 cycles, and a power density of 1145 W-kg−1 at an energy density of 67 Wh-kg−1. In HER applications, NCN/CNT@ZnMnO4/Ti3C2 demonstrates a lower Tafel slope of 56.41 mV-dec−1, signifying a significant advance in high-performance supercapacitors.