Porous Carbon Spheres Research Articles

Core-shell hierarchical porous carbon spheres with N/O doping for efficient energy storage

Cost-effective synthesis of core-shell carbon spheres for supercapacitor applications remains a challenge. N/O codoped hierarchical porous carbon spheres with the core-shell architecture (MPG2) are fabricated based on the dynamic Schiff-base chemistry free from any templates or complicated procedures. The nanoarchitectures of carbon materials are strongly determined by the addition of glyoxal which not only plays a key role in guiding the reassembly of dynamic imine intermediates to construct a stable core-shell architecture, but also endows carbon spheres with high mechanical strength/stability for the pyrolysis/hybrid modification due to the compact π-conjugated polymer shell. Benefiting from diffusion highways in hierarchical porous structure, a high ion-matching/adsorbing shell surface (1514 m2 g–1) with abundant micropores (0.5–0.8 nm) and N/O functionalities, the resultant MPG2-based symmetric supercapacitor using the lithium bis(trifluoromethane sulfonyl)imide electrolyte (the size of Li+/TFSI– is 0.069/0.79 nm) yields the large energy storage of 31.6 Wh kg–1 at 550 W kg–1 under the high aqueous voltage of 2.25 V, accompanied with a well-behaved cycling stability (capacitance retention of 86.2% over 10,000 rounds at 1 A g−1) and broad temperature applicability from 20 to 80 °C. Furthermore, MnO2 is further deposited on the robust MPG2 architecture to obtain the MPG2/MnO2 composite as a positive electrode in the asymmetric device, and the overlapped voltage window of the MPG2/MnO2 composite and the capacitive MPG2 paves another efficient avenue toward a high energy-power aqueous device of 43.74 Wh kg–1 at 450 W kg–1.

Sustainable Synthesis of N‐Doped Hollow Porous Carbon Spheres via a Spray‐Drying Method for Lithium‐Sulfur Storage with Ultralong Cycle Life

AbstractExploring high‐efficiency, long‐term cycling stability, and cost‐effective cathode materials for lithium‐sulfur (Li−S) batteries is hugely desirable and challenging. Herein, we have successfully developed a simple solution‐based spray‐drying method to fabricate nitrogen‐doped hollow porous carbon spheres (N‐HPCS) with biomass lignin as a carbon precursor and cyanuric acid as a N‐dopant and a porogen. The obtained N‐HPCS shows a specific surface area of 446.2 m2 g−1 and high‐level pyrrolic‐N doping of 64.13 %. The N‐HPCS/S cathode has a high initial discharge capacity of 1535.1 and 1104.0 mA h g−1 at 0.1 and 1 C, respectively. In addition, the N‐HPCS/S electrode exhibits outstanding cycle performance after 1000 cycles at 1 C, with a low capacity decay rate of only 0.041 % per cycle, which is superior to most of the recently reported carbon‐based S cathodes. N‐doping causes strong Li2Sx−N chemical adhesion in carbon spheres, effectively suppressing the dissolution and “shuttle effect” of the notorious polysulfide of Li−S batteries, in which pyrrolic‐N plays a leading role in the capture of polysulfides intermediates. This contribution is of great significance to the exploration of many other structure‐property design strategies for ultralong cycle life Li−S energy storage devices.

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...

Tailoring the Porous Structure of Mono‐dispersed Hierarchically Nitrogen‐doped Carbon Spheres for Highly Efficient Oxygen Reduction Reaction

The search for a low‐cost metal‐free cathode material with excellent mass transfer structure and catalytic activity in oxygen reduction reaction (ORR) is one of the most challenging issues in fuel cells. In this work, nitrogen‐rich m‐phenylenediamine is introduced into the synthesis of porous carbon spheres to tune the pore structure and nitrogen‐doped active sites. As a result, more pyridinic N and pyrrolic N functional species were observed at the interior and surface of the carbon spheres. The introduction of m‐phenylenediamine also regulated the nucleating of precursors, an urchin‐like mesoporous surface structure ensures point contact and less agglomeration between each particle was obtained. With optimized proportion of micropores/mesopores and improved nitrogen‐contained functional species, the ORR activity can be remarkably improved. The half‐wave potential of this catalyst could achieve to 0.81 V (versus RHE) which is only 42 mV lower than commercial Pt/C catalyst. Furthermore, the optimized cathode catalyst achieved a 69 mW cm−2 maximum power density when operated in direct methanol fuel cells at room temperature.

A metal-free nanozyme-activated prodrug strategy for targeted tumor catalytic therapy

Abstract Enzyme-mediated activation of prodrug in tumor cells is an attractive strategy for targeted cancer therapy. Of note, natural peroxidase and indole-3-acetic acid (IAA) have been shown as a promising enzyme-prodrug combination. However, insufficient endogenous peroxidase activity and the difficulty in selectively expressing exogenous peroxidase in tumor cells have severely limited its antitumor efficiency. The discovery of nanomaterials with peroxidase-like activity (nanozyme), particularly the metal-free nanozymes that possesses high stability and good biocompatibility, bring a new opportunity to overcome these challenges. Here, under the guidance of theoretical calculations, we developed a metal-free phosphorous and nitrogen dual-doped porous hollow carbon sphere nanozyme (PNCNzyme) with robust peroxidase-like activity in acidic environment. Based on this metal-free nanozyme, we developed a nanozyme-IAA activation strategy that activated IAA to produce abundant ROS and trigger tumor cell apoptosis. We also introduced folate (FA) onto the nanozyme to enhance its tumor targeting and endocytosis efficacy by tumor cells. Upon administrated to mice, the FA-PNCNzymes@IAA effectively accumulated in the xenografts derived from cervical cancer cells, catalyzed the production of ROS, and induced apoptosis. Taken together, these data demonstrate that the nanozyme-IAA combination is an effective enzyme-prodrug activation strategy for tumor targeted catalytic therapy.

Tailoring Polymer Colloids Derived Porous Carbon Spheres Based on Specific Chemical Reactions.

Porous carbon spheres derived from polymer colloids with regular geometry, monodispersed morphology, well-controlled contents and structures play important roles in many areas of application, such as energy storage/conversion, gas adsorption/separation, catalysis, and chemo-photothermal therapy. Suitable polymerization reaction and synthetic strategy are both critical for the obtainment of stable polymer colloids as carbon precursors. Basic polymerization reactions are the cornerstones of synthetic strategies, which directly provides the direct molecular-based design of functionalized polymer/carbon spheres. Thus, this progress report mainly focuses on the summary of suitable polymerization reactions for colloidal polymer derived porous carbon spheres. Recent advances in the synthetic strategies and applications are also discussed, including their corresponding polymerization reactions. Finally, the perspectives for the development of polymer derived porous carbon spheres are provided based on the controlled synthesis of polymer colloids and optimization over the carbonization process to achieve highly functionalized carbon spheres for practical applications.

NiS nanoparticles assembled on biological cell walls-derived porous hollow carbon spheres as a novel battery-type electrode for hybrid supercapacitor

Designing a battery-type electrode material with high electrochemical performance based on eco-friendly and sustainable strategy has great significance for the development of supercapacitors. Herein, NiS nanoparticles are deposited on the surface of the porous hollow carbon spheres (PHCSs) derived from inexpensive and pollution-free yeast cells wall by an in situ hydrothermal process, forming a litchi shell-like three-dimensional (3D) double-shell structure. The PHCSs as a carbon substrate can effectively suppress the aggregation of NiS nanoparticles and ensure more ground storage sites to enhance the performance of the electrode material. More notably, the reaction concentration of nickel ion has a remarkable effect on the electrochemical performance of composites. The optimized sample shows a high specific capacity of 531.5 C g−1 at 1 A g−1, excellent rate capability of 412.1 C g−1 at 10 A g−1 and outstanding cycling life span of 83.3% after 5000 cycles. Furthermore, the assembled hybrid device delivers a high energy density of 24.4 Wh kg−1 at a power density of 767 W kg−1 and an excellent cycle stability by delivering 89.3% capacitance retention after 5000 ultralong cycles. This work offers a feasible strategy to synthesize economical and efficient electrode materials and demonstrates its enormous potential in energy storage. A novel NiS/porous hollow carbon sphere composite with double-shell structure was synthesized by a green and available self-template method, which exhibits superior supercapacitor performance.

Hierarchically yolk-shell porous carbon sphere as an electrode material for high-performance capacitive deionization

The yolk-shell porous carbon spheres (YS-PCSs) with hierarchically nanoarchitecture were fabricated via a gradient sol-gel process combined with surfactant-directed co-assembly at different carbonized temperature of 600 °C, 700 °C, and 800 °C. The samples were used as electrode materials in capacitive deionization (CDI) process to measure their desalination performances. The results demonstrated that YS-PCS700 electrode displayed the best capacitive behavior and the lowest ions transfer resistance among all YS-PCS samples, and the electrosorption capacity reached up to 19.77 mg g−1 with 1.2 V applied voltage when the initial concentration of NaCl solution was 1000 mg L−1. The enhanced CDI performance was presumably attributed to the high specific surface area (1058 m2 g−1), the large pore volume (1.77 cm3 g−1) and the good wettability. Moreover, YS-PCS700 electrode still maintained excellent electrosorption capacity after 20 cycles CDI experiments under the same experimental conditions, indicating wonderful regeneration ability. It was desirable to develop the YS-PCS700 as a promising and alternative electrode material in CDI application.

Dual taming of polysufides by phosphorus-doped carbon for improving electrochemical performances of lithium–sulfur battery

Lithium–sulfur (Li–S) batteries are promising energy-storage technology, but a major technical issue is the shuttling of soluble polysulfides between electrodes, resulting in rapid capacity fading. In such case, phosphorus doped porous carbon spheres (P–C) material are designed and applied as both sulfur host material and separator modifier to mitigate the shuttling problem in Li–S batteries. The porous structure can physically intake polysulfides, and the same time, the phosphorus element can chemically interact with polysulfides. Based on the favourable combination of both physical adsorption and chemical anchoring, the assembled battery with as-prepared P–C materials acting as both sulfur host and separator modifier can achieve high utilization of active species and realize good cycling stability. Specifically, an initial capacity of 1430 mAh g−1 at 0.1 C and 650 mAh g−1 at 5 C is achieved, with outstanding cyclability and negligible capacity fading rate of 0.06% per cycle at 2 C even for 1000 cycles.

Aerosol-assisted preparation of N-doped hierarchical porous carbon spheres cathodes toward high-stable lithium-ion capacitors

Lithium-ion capacitors (LICs) are gradually emerging as one of the most indispensable hybrid energy storage devices. However, it is one main challenge to evade the mismatch of electrochemical kinetics and specific capacity between cathode and anode in LICs. Herein, we have proposed an efficient strategy to prepare the nitrogen-doped hierarchical porous carbon spheres (NHPCS) as cathode, which is synthesized by a simple aerosol-spraying pyrolysis using the low-cost phenolic resin as carbon source without any other catalyst or hard template. The NHPCS exhibits porous nanospheres structure with an appropriate nitrogen doping level (3.65 at.%). Benefitting from the two-pronged strategy of N-doped feature and nanostructure engineering, NHPCS achieves a high specific capacity of 74 mAh g−1 at a current density of 0.1 A g−1 and remains 86.5% of initial capacity even being subjected to a high rate of 50-fold. Furthermore, a high-performance LIC has been developed by coupling NHPCS cathode and hard carbon anode, which delivers a maximum energy density of 151 Wh kg−1 and excellent cycle stability (96.3% capacity retention after 3000 cycles). Significantly, such designed porous carbon could not only be convenient for scalable production, but also be served for many other energy storage devices. We have presented a larger-scale spray pyrolysis strategy to prepare nitrogen-doped hierarchical porous carbon spheres (NHPCS). A high-stable lithium-ion capacitor has been constructed by coupling NHPCS cathode with hard carbon anode, which exhibits a maximum energy density of 151 Wh kg−1 and capacity retention of 96.3% over 3000 cycles, showing great potential for the next-generation energy storage application.

Preparation and adsorption property of novel inverse-opal hierarchical porous N-doped carbon microspheres

The design of pore structure is the key factor for the performance of porous carbon spheres. In this work, novel micron-sized colloidal crystal microspheres consisting of fibrous silica (F-SiO2) nanoparticles are firstly prepared by water-evaporation-induced self-assembly of F-SiO2 nanoparticles in the droplets of an inverse emulsion system to be used as sacrificial templates. Acrylonitrile (AN) was infiltrated in the voids of the F-SiO2 colloidal crystal microspheres, and in-situ induced by 60Co γ-ray to polymerize into polyacrylonitrile (PAN). After the PAN-infiltrated F-SiO2 colloidal crystal microspheres were carbonized and etched with HF solution, novel micron-sized inverse-opal N-doped carbon (IO-NC) microspheres consisting of hollow carbon nanoparticles with a hierarchical macro/meso-porous inner surface were obtained. The IO-NC microspheres have a specific surface area as high as 266.4 m2/g and a molar ratio of C/N of 5. They have a good dispersibility in water, and show a high adsorption capacity towards rhodamine B (RhB) up to 137.28 mg/(g microsphere). This work offers a way to obtain novel micron-sized hierarchical macro/meso-porous N-doped carbon microspheres, which opens a new idea to prepare high-performance hierarchical porous carbon materials.

A hydrophilic surface molecularly imprinted polymer on a spherical porous carbon support for selective phenol removal from coking wastewater

A novel hydrophilic surface molecularly imprinted polymer from bi-functional monomers on a porous carbon nanosphere support (AMPS-Am-MIP) was prepared to improve the selective adsorption capacity towards phenol from coking wastewater using hydrophilic 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylamide (Am) as the monomers, and phenol as the imprinting molecule. The surface morphology, functional groups, thermal stability and hydrophilicity of AMPS-Am-MIP were investigated, and the adsorption properties including kinetics, isotherms, selectivity and regeneration were tested. Results showed that the adsorption of AMPS-Am-MIP towards phenol in water reaches equilibrium in 180 min and the highest adsorption capacity was 96.59 mg g-1. Its selection factor for phenol is as high as 1.67 in the presence of structural analogs, quinoline and hydroquinone. The adsorption capacity remained above 80% of the initial adsorption value after five adsorption−regeneration cycles. When the pH value of the phenol-containing water was around 8, close to that of coking wastewater, the adsorption capacity reached 46.84 mg g-1, indicating the applicability and high efficiency of AMPS-Am-MIP for phenol adsorption in alkaline coking wastewater.

A Honeycomb-Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage.

Superstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter-sized porous superstructure of carbon nanosheets (SCNS) by using metal-organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb-like morphology with wall-sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two-electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra-large geometric size, and the Fe-immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn-air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.

A Honeycomb‐Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage

AbstractSuperstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter‐sized porous superstructure of carbon nanosheets (SCNS) by using metal–organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb‐like morphology with wall‐sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two‐electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra‐large geometric size, and the Fe‐immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn–air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.

Nitrogen-doped hierarchically porous carbon spheres for low concentration CO2 capture

Synthesis of spherical carbon beads with effective CO2 capture capability is highly desirable for large scale application of CO2 sorption, but remains challenging. Herein, a facile and efficient strategy to prepare nitrogen-doped hierarchically porous carbon spheres was developed via co-pyrolyzation of poly(vinylidene chloride) and melamine in alginate gel beads. In this approach, melamine not only serves as the nitrogen precursor, but also acts as a template for the macropores structures. The nitrogen contents in the hierarchically porous carbon spheres reach a high level, ranging from 11.8 wt% to 14.7 wt%, as the melamine amount increases. Owing to the enriched nitrogen functionalities and the special hierarchical porous structure, the carbon spheres exhibit an outstanding CO2 capture performance, with the dynamic capacity of as much as about 7 wt% and a separation factor about 49 at 25 °C in a gas mixture of CO2/N2 (0.5:99.5, v/v).

Lithium–Sulfur Batteries: Molecular‐Level Design of Pyrrhotite Electrocatalyst Decorated Hierarchical Porous Carbon Spheres as Nanoreactors for Lithium–Sulfur Batteries (Adv. Energy Mater. 20/2020)

In article number 2000651, Zhong-Shuai Wu, Jian Liu and co-workers develop Fe1−xS-decorated mesoporous carbon spheres as a nanoreactor, which can be applied as a lithium–sulfur battery cathode. The nanoreactor shows excellent polysulfide catalytic activity and cyclic stability. This nanoreactor design strategy not only provides a new protocol for building high-capacity and long-cycle rechargeable batteries, but also opens an avenue for design of safer and high-energy-density lithium-metal batteries.

Porous Carbon Spheres Derived from Waste Ion-Exchange Resins and Research on Adsorption of Methylene Blue

A kind of porous carbon spherical material with high specific surface (SBET=1,292 m2/g) was synthesized from deactivated methyl tert butyl ether (MTBE) resins with KOH as the activator (KAC). This synthesized material was characterized by Brunner Emmet Teller (BET) measurements, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and X-ray fluorescence (XRF). Additionally, the mechanism of adsorbing methylene blue (MB) on this porous carbon sphere was studied and interpreted from kinetics, adsorption equilibrium and thermodynamic properties. Results showed that the kinetics data fitted the pseudo-second-order model well; the adsorption equilibrium data followed Langmuir model with a maximum adsorption capacity of 478.5 mg/g; and the thermodynamic parameters displayed an endothermic and spontaneous adsorption process of MB on carbon spheres.

A Nano-Rattle SnO2@carbon Composite Anode Material for High-Energy Li-ion Batteries by Melt Diffusion Impregnation.

The huge volume expansion in Sn-based alloy anode materials (up to 360%) leads to a dramatic mechanical stress and breaking of particles, resulting in the loss of conductivity and thereby capacity fading. To overcome this issue, SnO2@C nano-rattle composites based on <10 nm SnO2 nanoparticles in and on porous amorphous carbon spheres were synthesized using a silica template and tin melting diffusion method. Such SnO2@C nano-rattle composite electrodes provided two electrochemical processes: a partially reversible process of the SnO2 reduction to metallic Sn at 0.8 V vs. Li+/Li and a reversible process of alloying/dealloying of LixSny at 0.5 V vs. Li+/Li. Good performance could be achieved by controlling the particle sizes of SnO2 and carbon, the pore size of carbon, and the distribution of SnO2 nanoparticles on the carbon shells. Finally, the areal capacity of SnO2@C prepared by the melt diffusion process was increased due to the higher loading of SnO2 nanoparticles into the hollow carbon spheres, as compared with Sn impregnation by a reducing agent.

Atomically dispersed Fe-N-S-C anchored on pomegranate-shaped carbon spheres for oxygen reduction reaction and all-solid-state zinc-air battery

Flexible Zn-air battery (ZAB) plays a pivotal role in the eventual realization of wearable/portable electronic devices such as hearing aids and electronic wristwatches owing to its high energy density and stable working voltage. However, the efficiency and long-term durability are still inevitably limited by the sluggish kinetics of oxygen reduction reaction (ORR) in air electrode. Herein, we fabricated a planar all-solid-state rechargeable ZAB with excellent scalability by integrating atomically dispersed FeNx anchored on nitrogen-sulfur dual-doped porous carbon spheres and a highly conductive poly (acrylamide-co-acrylic acid) solid polymer alkaline electrolyte. Owing to the introduction of sulfur in carbon substrate, the catalyst exhibits superior ORR performance over 20% commercial Pt/C. Specially, it also displays outstanding all-solid-state ZAB capacity with a maximum power density of 85.5 mW/cm2, as well as ultralong cycle life for more than 40 h, which outperforms that of most conventional polyvinyl alcohol alkaline gel electrolyte-based flexible quasi-solid-state or all-solid-state ZAB. Density functional theory results reveal that the dopants N and S play a synergetic interplay in modulating the electronic structure of atomically dispersed FeNx species and provide a fast electron transfer path for ORR.

Molecular‐Level Design of Pyrrhotite Electrocatalyst Decorated Hierarchical Porous Carbon Spheres as Nanoreactors for Lithium–Sulfur Batteries

AbstractLithium–sulfur batteries (LSBs) are a class of new‐generation rechargeable high‐energy‐density batteries. However, the persisting issue of lithium polysulfides (LiPs) dissolution and the shuttling effect that impedes the efficiency of LSBs are challenging to resolve. Herein a general synthesis of highly dispersed pyrrhotite Fe1−xS nanoparticles embedded in hierarchically porous nitrogen‐doped carbon spheres (Fe1−xS‐NC) is proposed. Fe1−xS‐NC has a high specific surface area (627 m2 g−1), large pore volume (0.41 cm3 g−1), and enhanced adsorption and electrocatalytic transition toward LiPs. Furthermore, in situ generated large mesoporous pores within carbon spheres can accommodate high sulfur loading of up to 75%, and sustain volume variations during charge/discharge cycles as well as improve ionic/mass transfer. The exceptional adsorption properties of Fe1−xS‐NC for LiPs are predicted theoretically and confirmed experimentally. Subsequently, the electrocatalytic activity of Fe1−xS‐NC is thoroughly verified. The results confirm Fe1−xS‐NC is a highly efficient nanoreactor for sulfur loading. Consequently, the Fe1−xS‐NC nanoreactor performs extremely well as a cathodic material for LSBs, exhibiting a high initial capacity of 1070 mAh g−1 with nearly no capacity loss after 200 cycles at 0.5 C. Furthermore, the resulting LSBs display remarkably enhanced rate capability and cyclability even at a high sulfur loading of 8.14 mg cm−2.