Tailoring the Li+ Intercalation Energy of Carbon Nanocage Anodes Via Atomic Al-Doping for High-Performance Lithium-Ion Batteries.

Graphitic carbon materials are widely used in lithium-ion batteries (LIBs) due to their stability and high conductivity. However, graphite anodes have low specific capacity and degrade over time, limiting their application. To meet advanced energy storage needs, high-performance graphitic carbon materials are required. Enhancing the electrochemical performance of carbon materials can be achieved through boron and nitrogen doping and incorporating 3D structures such as carbon nanocages (CNCs). In this study, aluminum (Al) is introduced into CNC lattices via chemical vapor deposition (CVD). The hollow structure of CNCs enables fast electrolyte penetration. Density functional theory (DFT) calculations show that Al doping lowers the intercalation energy of Li+. The Al-boron (B)-nitrogen (N-doped CNC (AlBN-CNC) anode demonstrates an ultrahigh rate capacity (≈300 mAh g-1 at 10 A g-1) and a prolonged fast-charging lifespan (862.82 mAh g-1 at 5 A g-1 after 1000 cycles), surpassing the N-doped or BN-doped CNCs. Al doping improves charging kinetics and structural stability. Surprisingly, AlBN-CNCs exhibit increased capacity upon cycling due to enlarged graphitic interlayer spacing. Characterization of graphitic nanostructures confirms that Al doping effectively tailors and enhances their electrochemical properties, providing a new strategy for high-capacity, fast-charging graphitic carbon anode materials for next-generation LIBs.

Unveiling Intrinsic Potassium Storage Behaviors of Hierarchical Nano Bi@N-Doped Carbon Nanocages Framework via In Situ Characterizations.

Metallic bismuth has drawn attention as a promising alloying anode for advanced potassium ion batteries (PIBs). However, serious volume expansion/electrode pulverization and sluggish kinetics always lead to its inferior cycling and rate properties for practical applications. Therefore, advanced Bi-based anodes via structural/compositional optimization and sur-/interface design are needed. Herein, we develop a bottom-up avenue to fabricate nanoscale Bi encapsulated in a 3D N-doped carbon nanocages (Bi@N-CNCs) framework with a void space by using a novel Bi-based metal-organic framework as the precursor. With elaborate regulation in annealing temperatures, the optimized Bi@N-CNCs electrode exhibits large reversible capacities and long-duration cyclic stability at high rates when evaluated as competitive anodes for PIBs. Insights into the intrinsic K+ -storage processes of the Bi@N-CNCs anode are put forward from comprehensive in situ characterizations.

Self-supported porous wood carbon electrode with a MoC/carbon nanocage composite for application in a high-performance supercapacitor.

The rational design and synthesis of carbon nanocages with highly complex porous structures are continuously facing challenges in the development of high-performance supercapacitors (SCs). The electrochemical performance characteristics of electrodes rely on their compositions and fabrication methods. Here, we propose a universal and efficient approach for the in-situ synthesis of zeolitic imidazolate framework-8 (ZIF-8) on porous carbonized wood, where the selective utilization of hexacarbonyl molybdenum protects the structural integrity of the ZIF-8 precursor, preventing collapse during thermal treatment. The subsequent pyrolysis process leads to the formation of small-sized molybdenum carbide (MoC) which are embedded in carbon nanocages (CN). The composite electrode consists of MoC/CN embedded in a porous carbonized wood (PCW), and it shows area-specific capacity of 9.7F cm-2 and 9.4 F cm-2 at 5 mA cm-2 and 30 mA cm-2, respectively. Subsequently, the symmetric supercapacitor, with two MoC/CN@PCW electrodes exhibits a areal specific capacitance of 2.7 F cm-2 at 5 mA cm-2. Moreover, this supercapacitor maintains an capacitance retention rate of 98.5 % after 12,000 discharge cycles. The supercapacitor exhibits a power density of 6.5 mW cm-2, resulting in an energy density of 0.864 mWh cm-2. Therefore, the utilization of wood-based electrodes holds promise for energy storage systems.

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.

Composition-adjustable Mo6Co6C2/Co@carbon nanocage for enhanced oxygen reduction and evolution reactions.

Bifunctional oxygen electrocatalysts that hold outstanding activity and stability are highly crucial for the development of efficient rechargeable Zn-air batteries. Herein, cobalt-molybdenum-based bimetallic carbide and cobalt nanoparticles embedded N-doped carbon nanocages are synthesized via the pyrolysis of functionalized zeolitic imidazolate framework precursor originated from zeolitic imidazolate framework sequentially coated with polydopamine and phosphomolybdic acid. Furthermore, we revealed the composition-performance relationship based on the exploration of bifunctional performance on the pyrolysis products. More importantly, the synergy of multiple active sites with hollow structure gives the prepared catalyst a low overpotential (284 mV) for oxygen evolution reaction and high half-wave potential (0.865 V) for oxygen reduction reaction, besides an excellent bifunctional durability. Furthermore, the prepared catalyst as a cathode electrocatalyst grants the assembled rechargeable Zn-air batteries a high open-circuit voltage, power density, specific capacity, and remarkable charge-discharge cycle stability. This work provides a strategy for the integration and active-adjustment of bifunctional catalyst and its potential applications in water splitting and other catalytic reactions.

Enhanced electron transfer and ion storage in phosphorus/nitrogen co-doped 3D interconnected carbon nanocage toward potassium-ion battery.

Heteroatoms doping strategies are often considered to be an effective approach to provide rich active sites for capacitive-controlled potassium storage, and enlarged interspacing for intercalation process. However, the excess doping level will form a large number of sp3 defects and thus severely damage π-conjugated system, which is unfavorable for electron transfer. Herein, a P/N co-doped three-dimensional (3D) interconnected carbon nanocage (denoted as PN-CNC) is prepared with the help of a template-assisted method. The use of template and P heteroatom can contribute to forming a 3D interconnected carbon nanocage to prevent conductive carbon matrix from being excessively damaged, favoring a high electronic conductivity. The co-existence of P/N doping configurations with suitable content not only generate abundant defects, edge-voids, and micropores for significant capacitive behaviors, but also supply adequate interlayer space for intercalation process, and all these together ensure enhanced ion storage. As a result, the optimized PN-CNC electrode exhibits an exceptional reversible capacity (262 mAh g-1) and a superior rate capability (214.2 mAh g-1). Besides, long-term cycling stability is easily fulfilled by delivering a high capacity of 188.7 mAh g-1 at 2 A g-1 after 3000 cycles.

Pseudocapacitive Vanadium Nitride Quantum Dots Modified One-Dimensional Carbon Cages Enable Highly Kinetics-Compatible Sodium Ion Capacitors.

The kinetics incompatibility between battery-type anode and capacitive-type cathode for sodium ion hybrid capacitors (SIHCs) seriously hinders their overall performance output. Herein, we construct a SIHCs device by coupling with quantum grade vanadium nitride (VN) nanodots anchored in one-dimensional N/F co-doped carbon nanofiber cages hybrids (VNQDs@PCNFs-N/F) as the freestanding anode and the corresponding activated N/F co-doped carbon nanofiber cages (APCNFs-N/F) as cathode. The strong coupling of VN quantum dots with N/F co-doped 1D conductive carbon cages effectively facilitates the ion/electron transport and intercalation-conversion-deintercalation reactions, ensuring fast sodium storage to surmount aforesaid kinetics incompatibility. Additionally, density functional theory calculations cogently manifest that the abundant active sites in the VNQDs@PCNFs-N/F configuration boost the Na+ adsorption/reaction activity well which will promote both "intrinsic" and "extrinsic" pseudocapacitance and further improve anode kinetics. Consequently, the assembled SIHCs device can achieve high energy densities of 157.1 and 95.0 Wh kg-1 at power densities of 198.8 and 9100.5 W kg-1, respectively, with an ultralong cycling life over 8000 cycles. This work further verified the feasibility of kinetics-compatible electrode design strategy toward metal ion hybrid capacitors.

Carbon Nanocage/Fe3O4/DNA-Based Magnetically Targeted Intracellular Imaging of Telomerase via Catalyzed Hairpin Assembly and Photodynamic-Photothermal Combination Therapy of Tumor Cells.

Human telomerase has been identified as a potential tumor biomarker for early cancer diagnosis and cancer progression monitoring. We construct a novel magnetic targeting carbon nanocage/Fe3O4/DNA (CNC/Fe3O4/DNA) nanoprobe for intracellular imaging of telomerase via the signal amplification strategy catalyzed hairpin assembly (CHA) and for photodynamic-photothermal therapy of tumor cells. Telomerase primer DNA, trigger DNA, hairpin DNA1 (H1), and hairpin DNA2 (H2) were adsorbed to the surface of CNC/Fe3O4 nanoparticles (CNC/Fe3O4 NPs), and the fluorescence of (chlorin e6) Ce6 was quenched by CNC/Fe3O4 NPs. After entering the living cell through magnetic targeting, the telomerase primer DNA can be extended in the presence of highly activated telomerase, leading to the issue of trigger DNA, which can initiate the CHA cycling process followed by the amplification of the fluorescence intensity. The in vitro detection results justified that the proposed nanoprobe showed good sensitivity and selectivity for telomerase. Confocal microscopy studies indicated that such a nanoprobe can be used to detect the activity of telomerase in living cells and the fluorescence signal was stronger under the guidance of a magnetic field. We successfully employed this nanoprobe to monitor the dynamic activity of telomerase in various types of tumor cells and normal cells and to damage tumor cells by photodynamic-photothermal combination therapy, which evidenced that this is a promising biological method for early cancer diagnosis and tumor cell therapy.

Enhanced Electrosorption Ability of Carbon Nanocages as an Advanced Electrode Material for Capacitive Deionization.

The structure of an electrode material has an important impact on the performance of a capacitive deionization (CDI) device. However, it is still a challenge to design and synthesize electrode materials with a rational structure based on deep understanding of their structure-dependent CDI performance. Herein, we report the preparation of carbon nanocages (CNCs) with regulated shell thickness and a rich pore structure as an advanced material for high-performance CDI electrodes. The as-prepared CNC has a considerable specific capacitance of 149 F g-1 at a scan rate of 5 mV s-1. When used as CDI electrodes, the CNC shows an outstanding electrosorption ability of 17.5 mg g-1 at 1.4 V at an initial concentration of 250 mg L-1 NaCl solution. Furthermore, the CNC electrode displays high salt adsorption rate and good cyclic stability. Finite element simulations reveal that the superior structure of the CNC substantially promotes the ion transfer rate by shortening ion diffusion paths in the cavity of the electrode material. Also, both inner and outer walls of the CNC provide sufficient active sites for fast adsorption and desorption of salty ions. This work not only demonstrates that the CNC is a potential electrode material for CDI applications but also paves a way to design and prepare high-performance electrode materials based on a new perspective on their structure-performance relationship.

Enhanced Metabolic Activity of Cytochrome P450 via Carbon Nanocage-Based Photochemical Bionanoreactor.

Recently, the early screening of the genotoxicity of new chemicals and drugs calls for the envelope of micro-/nanoreactors for metabolic study. Herein, a novel light-driven enzymatic bionanoreactor is designed with the gold nanoparticle (NP)-modified carbon nanocage (Au@CNC) as a nanoreactor and meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) as a photosensitizer for cytochrome P450-mediated drug metabolism. By confining the cytochrome P450 3A4 (CYP3A4) enzyme and TCPP inside the pores of Au@CNC, a high metabolic activity is achieved by using 7-ethoxytrifluoromethyl coumarin as the substrate because of the three-dimensional hierarchical porous structure, large surface area, and fast electron transfer capacity of Au@CNC. It is noted that owing to the presence of AuNPs inside CNC, the surface hydrophilicity of CNC is much improved, which further promotes the catalytic activity of the CYP3A4 enzyme. To our knowledge, this is the first attempt to apply CNC as a bionanoreactor for NADPH-free and light-driven in vitro drug metabolism. In addition, the presented bionanoreactor exhibits a variety of advantages in terms of fast response, short assay time (10 min), high sensitivity, and good selectivity, which are expected to expedite drug screening and render potential advances in drug discovery and development.