Nitrogen-doped Porous Carbon Microspheres Research Articles

Surface-coated AlF3 nanolayers enable polysulfide confinement within biomass-derived nitrogen-doped hierarchical porous carbon microspheres for improved lithium-sulfur batteries

The electrically insulating and volumetric deformation of sulfur and the shuttle effect of the intermediate lithium polysulfide (LiPSs) have severely hindered the development of lithium-sulfur batteries (LSBs). Herein, a synergistic strategy of hierarchical porous nitrogen-doped carbon microspheres (PNCM) derived from low-cost biomass with surface-coated AlF3 nanolayer as a multifunctional sulfur host (denoted as PNCM@S@AlF3) was developed. The PNCM not only possesses an abundant pore structure, large surface area, and high electrical conductivity but also features an intrinsic N-doped and fluorinated framework, which effectively enhances the physical adsorption and chemical anchoring to LiPSs. In addition, the AlF3 nanolayer protects the open surface of the porous carbon to isolate sulfur species from the electrolyte to reduce irreversible losses while accelerating the redox kinetics of LiPSs through strong polar adsorption and bonding. Hence, the PNCM@S@AlF3 cathode exhibits an initial capacity as high as 1176.2 mAh/g at 0.2C, and the cycling stability and rate capability are superior to that of PNCM@S without AlF3 coating. Impressively, the PNCM@S@AlF3 cathode delivers stable long-term cycling performance at a high rate of 2C, with 95.6% capacity retention after 500 cycles. This work presents a facile, sustainable, and efficient synergistic strategy for developing advanced LSBs.

Mechanisms and degradation pathways of doxycycline hydrochloride by Fe3O4 nanoparticles anchored nitrogen-doped porous carbon microspheres activated peroxymonosulfate

Peroxymonosulfate (PMS) based advanced oxidation processes have gained widespread attention in refractory antibiotics treatment. In this study, Fe3O4 nanoparticles anchored nitrogen-doped porous carbon microspheres (Fe3O4/NCMS) were synthesized and applied to PMS heterogeneous activation for doxycycline hydrochloride (DOX-H) degradation. Benefitting from synergy effects of porous carbon structure, nitrogen doping, and fine dispersion of Fe3O4 nanoparticles, Fe3O4/NCMS showed excellent DOX-H degradation efficiency within 20 min via PMS activation. Further reaction mechanisms revealed that the reactive oxygen species including hydroxyl radicals (•OH) and singlet oxygen (1O2) played the dominant role for DOX-H degradation. Moreover, Fe(II)/Fe(III) redox cycle also participated in the radical generation, and nitrogen-doped carbonaceous structures served as the highly active centers for non-radical pathways. The possible degradation pathways and intermediate products accompanying DOX-H degradation were also analyzed in detail. This study provides key insights into the further development of heterogeneous metallic oxides-carbon catalysts for antibiotic-containing wastewater treatment.

Hierarchical porous nitrogen-doped carbon microspheres after thermal rearrangement as high performance electrode materials for supercapacitors

Polyimides have been used as the precursor of carbon materials. Thermal rearrangement polymers with porous structure can be prepared by thermal treatment of hydroxyl-containing polyimides in the solid state. Herein, hydroxyl-containing polyimides with hierarchical microspheres were firstly prepared by solvothermal method. After thermal rearrangement at 450 °C and further carbonization, the hierarchical porous nitrogen-doped carbon microspheres were obtained, which showed good electrochemical characteristics. The effects of the concentration of polymer solution, thermal rearrangement time and final carbonization temperature on the structure and properties of final carbon materials were investigated. The hierarchical porous carbon materials were tested as an electrode for supercapacitors, and HPI-45–2-800 with high specific surface area of 877 m2 g−1 exhibited excellent electrochemical properties. The specific capacitance of HPI-45–2-800 was 211.3 F g−1 at the current density of 0.5 A g−1. When the current density was increased to 10 A g−1, the retention rate of specific capacitance was as high as 55%. After 10,000 cycles of charging and discharging, the specific capacitance of HPI-45–2-800 electrode was still retained 99.94% of the initial capacitance, showing excellent long-term charge–discharge cycling stability. The hierarchical porous nitrogen-doped carbon microspheres after thermal rearrangement are expected to be high performance electrode materials for supercapacitors.

Green Synthesis of Pyridyl Conjugated Microporous Polymers as Precursors for Porous Carbon Microspheres for Efficient Electrochemical Energy Storage

AbstractEfficient materials for electrochemical energy storage have received much attention. Herein we report a green metal‐free route to synthesize pyridyl conjugated microporous polymers (PCMPs) as precursors for nitrogen‐doped porous carbon microspheres (NCMs) with high surface areas up to 1232 m2 g−1 via a simple carbonization method. The resulting NCMs as supercapacitor electrodes exhibit high specific capacitance of 324 F g−1 at a current density of 0.1 A g−1, and high rate ability (182 F g−1 at 10 A g−1), and excellent cyclability (remained >97 % of initial capacitance at 2 A g−1 after 10000 cycles). This work also presents that molecular engineering of PCMP precursor, pyrolysis temperature and charge/discharge cycling allow the electrochemical energy storage properties of the NCMs to be controlled.

Nanostructure-modified in-situ synthesis of nitrogen-doped porous carbon microspheres (NPCM) loaded with FeTe2 nanocrystals and NPCM as superior anodes to construct high-performance lithium-ion capacitors

Lithium-ion capacitors (LICs) are the new generation of hybrid energy storage devices because they combine the advantages of both lithium-ion batteries and supercapacitors. This paper reports a three-dimensional N-doped porous carbon microspheres (NPCM) prepared from polymers with aromatic skeletons, and in-situ growth of FeTe2 nanocrystals in carbon microspheres to form 3D network nano-hybrid FeTe2@NPCM-2 composite. This porous microsphere structure facilitates the provision of sufficient room to buffer the large volume expansion effects of the FeTe2 cycle, the unique carbon matrix NPCM has numerous active sites, excellent electrical conductivity and stable tap density. Simultaneously, using biomass mung-bean shells as precursor to prepare hierarchical porous carbon (HPC) as cathode material of LIC, it exhibits a huge specific surface area (SSA) (2103.31 m2 g−1), abundant micro-mesopores and possible oxygen-containing functional groups. The constructed LIC FeTe2@NPCM-2//HPC and NPCM//HPC have ultrahigh energy density (228.29 and 192.96 W h kg−1) and superior power density (10 and 10 kW kg−1) and good cycle retention rate. Hence, we hope that lithium-ion capacitors with transition metal tellurides as anodes have broad application prospects in the fields of new energy 3C electronic products and hybrid vehicles.

Nitrogen-doped porous carbon microspheres for high-rate anode material in lithium-ion batteries

Developing high-capacity anode materials is urgent for next-generation lithium-ion batteries (LIBs) with the increasing need of larger scale applications. In order to obtain suitable anode materials, nitrogen-doped porous carbon microspheres (NPCMs) were prepared via spray drying followed by carbonization using chitosan as both carbon and nitrogen sources. The structure and properties of NPCMs were characterized by thermogravimetric, Raman spectroscopic, x-ray diffraction, scanning electron microscopic, transmission electron microscopic as well as x-ray photoelectron spectroscopic analysis, and the electrochemical performance of NPCM electrodes were also evaluated. The results show that the diameter of the obtained microspheres is 1–7 μm. When used as the anode material, the NPCMs display a reversible capacity of 443 mAh g−1 at 100 mA g−1 after 120 cycles and maintain a high capacity of 377 mAh g−1 at 1 A g−1 after 500 cycles. Even at a high current density of 4 A g−1, a discharge capacity of 256 mAh g−1 can also be obtained. The excellent rate performance and long cycle life of the electrode might be ascribed to the nitrogen-doping, porous and amorphous structure of NPCMs. The results suggest that the prepared NPCMs have the potential to be used as a promising anode material for high-capacity LIBs.

Strongly Cooperative Nano-CoO/Co Active Phase in Hierarchically Porous Nitrogen-Doped Carbon Microspheres for Efficient Bifunctional Oxygen Electrocatalysis

The development of highly efficient, non-noble-metal-based bifunctional oxygen electrocatalysts with low cost for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the key...

Hierarchical Nitrogen-Doped Porous Carbon Microspheres as Anode for High Performance Sodium Ion Batteries.

Sodium ion batteries (SIBs) have been considered as a promising alternative to lithium ion batteries (LIBs) for large scale energy storage in the future. However, the commercial graphite anode is not suitable for SIBs because of its low Na+ ions storage capability and poor cycling stability. Recently, another alternative as anode for SIBs, amorphous carbon materials, have attracted tremendous attention because of their abundant resource, nontoxicity, and most importantly, stability. Here, N-doped hierarchical porous carbon microspheres (NHPCS) derived from Ni-MOF have been prepared and used as anode for SIBs. Benefiting from the open porous structure and expanded interlayer distance, the diffusion of Na+ is greatly facilitated and the Na+ storage capacity is significantly enhanced concurrently. The NHPCS exhibit high reversible capacity (291 mA h g−1 at current of 200 mA g−1), excellent rate performance (256 mA h g−1 at high current of 1,000 mA g−1), and outstanding cycling stability (204 mA h g−1 after 200 cycles).

Prussian blue analogues derived porous nitrogen-doped carbon microspheres as high-performance metal-free peroxymonosulfate activators for non-radical-dominated degradation of organic pollutants

Herein, Zn–Co Prussian blue analogues derived porous nitrogen-doped carbon are applied for the degradation of organic pollutantsviaa non-radical pathway.

Facile synthesis of CoxP decorated porous carbon microspheres for ultrasensitive detection of 4-nitrophenol

A novel cobalt phosphide (CoxP, a mixture of CoP and Co2P) embedded within nitrogen-doped porous carbon microspheres was facilely prepared by pyrolysis of a composite precursor. The composite precursor was achieved by in-situ growth of Co-based zeolitic imidazolate framework (ZIF-67) on the Zn(PO4)x microspheres. The as-prepared CoxP decorated nitrogen-doped porous carbon microspheres (CoxP/NC) possess uniform distribution of graphite-encapsulated CoxP, a large surface area (826m2g−1) and abundant mesopores. It was found the CoxP/NC exhibited excellent electrocatalytic performances toward 4-nitrophenol (4-NP). Therefore, CoxP/NC was developed to fabricate an ultrasensitive electrochemical sensor for 4-NP by using differential pulse voltammetry (DPV). In comparison with glassy carbon electrode (GCE) and nitrogen-doped carbon (NC) modified GCE, the CoxP/NC modified GCE (CoxP/NC/GCE) showed a remarkable increase in DPV current toward 4-NP. Under optimized condition, an ultrahigh sensitivity of 20.9 (μA μmol−1 L) and a low detection limit of 2 × 10−9molL−1 (at a signal-to-noise ratio of 3, S/N = 3) for 4-NP were achieved. Additionally, the CoxP/NC/GCE was successfully applied to detect 4-NP in tap water with good recoveries for its attractive selectivity and repeatability, which indicated that CoxP/NC could be a promising candidate for analyzing 4-NP.

Frontispiece: Porous Nitrogen-Doped Carbon Microspheres Derived from Microporous Polymeric Organic Frameworks for High Performance Electric Double-Layer Capacitors

Frontispiece: Porous Nitrogen-Doped Carbon Microspheres Derived from Microporous Polymeric Organic Frameworks for High Performance Electric Double-Layer Capacitors

Porous nitrogen-doped carbon microspheres derived from microporous polymeric organic frameworks for high performance electric double-layer capacitors.

This research presents a simple and efficient method to synthesize porous nitrogen-doped carbon microspheres (PNCM) by the carbonization of microporous poly(terephthalaldehyde-pyrrole) organic frameworks (PtpOF). The common KOH activation process is used to tune the porous texture of the PNCM and produce an activated-PNCM (A-PNCM). The PNCM and A-PNCM with specific surface area of 921 and 1303 m(2) g(-1) , respectively, are demonstrated as promising candidates for EDLCs. At a current density of 0.5 A g(-1) , the specific capacitances of the PNCM and A-PNCM are 248 and 282 F g(-1) , respectively. At the relatively high current density of 20 A g(-1) , the capacitance remaining is 95 and 154 F g(-1) , respectively. Capacity retention of the A-PNCM is more than 92% after 10000 charge/discharge cycles at a current density of 2 A g(-1) .

Porous nitrogen-doped carbon microspheres as anode materials for lithium ion batteries.

Nitrogen-doped carbon microspheres (NCSs) were fabricated via a simple, fast and energy-saving microwave-assisted method followed by thermal treatment under an ammonia atmosphere. NCSs thermally treated at different temperatures were investigated as anode materials for lithium ion batteries (LIBs). The results show that NCSs treated at 900 °C exhibit a maximum reversible capacity of 816 mA h g(-1) at a current density of 50 mA g(-1) and preserve a capacity of 660 mA h g(-1) after 50 cycles, and even at a high current density of 1000 mA g(-1), a capacity of 255 mA h g(-1) is maintained. The excellent electrochemical performance of NCSs is due to their porous structure and nitrogen-doping. The present NCSs should be promising low-cost anode materials with a high capacity and good cycle stability for LIBs.

Ultrahigh oxygen reduction activity of Pt/nitrogen-doped porous carbon microspheres prepared via spray-drying

Pt nanoparticles supported on nitrogen-doped porous carbon microspheres (Pt/CN) were synthesized via an in-situ spray-drying technique followed by calcination. The addition of ammonium hydroxide had a remarkable influence on the solution chemistry, which promoted the simultaneous formation of metallic Pt and nitrogen doping onto carbon support material. Furthermore, the precursor pH influenced the subsequent oxygen reduction activity of the product. Ultrahigh oxygen reduction reaction (ORR) activity was recorded for a catalyst prepared at a precursor pH of 8.4 with mass activity and specific activity were 564 mA mg−1 Pt and 834 μA cm−2 Pt, respectively. This investigation resulted in an effective strategy to escalate the catalyst ORR during limited catalyst surface area enhancement.