Nitrogen-doped Carbon Nanospheres Research Articles

A dual-template synergistic assembly strategy towards the synthesis of extra-small nitrogen-doped mesoporous carbon nanospheres with large pores.

Functional mesoporous carbon nanomaterials with large pores and small particle sizes have broad accessibility, but remain challenging to achieve. This study proposed a dual-template synergistic assembly strategy to facilely synthesize extra-small nitrogen-doped mesoporous carbon nanospheres with large pores in a low-cost manner. Directed by the synergistic effect of the combination of surfactants, sodium oleate (anionic surfactant) and triblock copolymer-P123 (nonionic surfactant) were selected as templates to construct nanomicelles (nanoemulsions), which were co-assembled with melamine-based oligomers to form composite nanomicelles, thus obtaining nitrogen-doped mesoporous polymer nanospheres (NMePS) and then nitrogen-doped mesoporous carbon nanospheres (NMeCS). Based on Schiff base chemistry, the melamine-based oligomers with self-assembly capability were synthesized as precursors, which is different from the conventional synthetic route of melamine-formaldehyde resin. The key parameters involved in the route were investigated comprehensively and correlated with the characterization results. Furthermore, the 50 nm-scale particle size and the large mesoporous size of 5.5 nm of NMeCS can facilitate effective mass transport, coupled with their high nitrogen content (15.7 wt%), contributing to their excellent performance in lithium-ion batteries.

Coal-based catalytic carbon membrane functionalized with nitrogen-doped carbon nanospheres for efficient bisphenol a removal

Catalytic membrane process, which combines membrane filtration and advanced oxidation, has promising application prospects in water decontamination. In this work, a novel metal-free coal-based catalytic carbon membrane (PPy/CCM-800) was developed and applied for the typical EDC-bisphenol A (BPA) removal from water via activating peroxymonosulfate (PMS). Morphology investigation manifested that the N-doped carbon nanospheres derived from the pyrolytic PPy particles distributed evenly on the surface of coal-based carbon membrane (CCM). In contrast to bare CCM, catalytic performance of PPy/CCM-800 was significantly enhanced by the anchoring of N-doped carbon nanospheres, and 97.89 % of BPA and 60.83 % of total organic carbon (TOC) can be removed by PPy/CCM-800 during catalytic filtration treatment. Catalytic mechanism investigations confirmed that the excellent decontamination performance of PPy/CCM-800 was attributed to the synergistic effects of radical and non-radical oxidation pathway, and the non-radical pathway (1O2 and direct electron transfer) played the dominant role. Moreover, the possible BPA degradation pathways were proposed based on the density functional theory (DFT) calculations and HPLC-MS results.

Nanosheets-assembled hollow N-doped carbon nanospheres encapsulated with ultrasmall NiSe nanoparticles for electrocatalytic hydrogen evolution

Developing highly active and stably non-precious metal electrocatalysts for hydrogen production in alkaline conditions is of paramount importance to hydrogen economy. Herein, nanosheet-assembled hollow nitrogen-doped carbon nanospheres confined with ultrasmall NiSe nanoparticles (NiSe@NC) are synthesized by employing a SiO2 template-assisted approach. As expected, the as-prepared NiSe@NC electrocatalyst delivers an overpotential of 169 mV at the current density of 10 mA/cm2 without iR-correction, and sustains at least 80 h for continuous operation, far outperforming the NiSe-p catalyst in 1 M KOH medium toward hydrogen evolution reaction (HER). The appealing HER performance is mainly ascribed to the synergy effect between hollow nitrogen-doped carbon and highly active NiSe nanoparticles, which improves catalytically active sites, expedites electron transfer rate and optimizes the electronic structure of NiSe@NC nanomaterial. More strikingly, this study presents the feasible insights for constructing robust cost-effective electrocatalysts towards efficient HER in harsh alkaline media.

Synergistic vacancy engineering of Co/MnO@NC catalyst for superior oxygen reduction reaction in liquid/solid zinc-air batteries

The pursuit of efficient and economically viable catalysts for liquid/solid-state zinc-air batteries (ZABs) is of paramount importance yet presents formidable challenge. Herein, we synthesized a vacancy-rich cobalt/manganese oxide catalyst (Co/MnO@NC) stabilized on a nitrogen-doped mesoporous carbon (NC) nanosphere matrix by leveraging hydrothermal and high-temperature pyrolysis strategy. The optimized Co/MnO@NC demonstrates fast reaction kinetics and large limiting current densities comparable to commercial Pt/C in alkaline electrolyte for oxygen reduction reaction (ORR). Moreover, the Co/MnO@NC serves as an incredible cathode material for both liquid and flexible solid-state ZABs, delivering impressive peak power densities of 217.7 and 63.3 mW cm−2 and robust long-term stability (459 h), outperforming the state-of-the-art Pt/C and majority of the currently reported catalysts. Research indicates that the superior performance of the Co/MnO@NC catalyst primarily stems from the synergy between the heightened electrical conductivity of metallic Co and the regulatory capacity of MnO on adsorbed oxygen intermediates. In addition, the abundance of vacancies regulates the electronic configuration, and superhydrophilicity facilitates efficient electrolyte diffusion, thereby effectively ensuring optimal contact between the active site and reactants. Besides, the coexisting NC layer avoids the shedding of active sites, resulting in high stability. This work provides a viable approach for designing and advancing high-performance liquid/solid-state ZABs, highlighting the great potential of energy storage technology.

Enhanced lithium storage in pomegranate-like carbon via dual confinement of lithiophilic seeds and Li deposition

The uncontrollable dendrite growth and infinite volume expansion of Li during cycling lead to low Coulombic efficiency (CE) and short cycling life, severely impeding the commercial progress of lithium metal batteries (LMBs). In this work, nitrogen-doped carbon nanospheres (CSs) with ultrafine lithiophilic ZnO nanoparticles encapsulated by interconnected pomegranate-like carbon sheets (denoted as ZnO@NPCS) have been designed and constructed to serve as novel lithium hosts. The ultrafine ZnO nanoparticles uniformly distributed in the CSs can significantly reduce the Li nucleation barrier, while the well-designed pomegranate-like carbon sheets within the CSs can provide continuous and fast electron/ion transport channels, accelerating the Li+ transfer kinetics. Moreover, the internal interconnected carbon networks can confine the lithiophilic nanoparticles, preventing them from detaching or aggregating during cycling, and meanwhile offer individual voids to accommodate deposited Li. Thus, both lithiophilic seeds and deposited Li can be well confined in the pomegranate-like structure. Such a dual-confinement effect enables the ZnO@NPCS electrode to exhibit ultralong cycling life for more than 1000 cycles with ultrahigh CE (>99.5 %) without Li dendrites growth, which is further validated by in-situ transmission electron microscopy and phase-field simulations. Therefore, this dual-confinement strategy provides an inspiring insight to design superior Li hosts for developing superior LMBs and can be extended to other battery systems.

Atomically Dispersed Pd-N1C3 Sites on a Nitrogen-Doped Carbon Nanosphere for Semi-hydrogenation of Acetylene.

Rationally designing efficient catalysts for semi-hydrogenation of acetylene is significant but challenging. Herein, Pd isolated single-atom sites (ISAS) on a covalent-organic-framework (COF)-derived nanosphere (Pd-ISAS/CN) are synthesized by a COF-absorption-pyrolysis strategy. This synthetic strategy is also applicable for Pt and Ru ISAS catalysts, demonstrating that it is a general method to synthesize noble-metal ISAS on COF-derived carbon materials. Pd-ISAS/CN exhibits outstanding reactivity and high selectivity for semi-hydrogenation of acetylene, with 92% conversion of acetylene, 80% selectivity toward ethylene at 100 °C, and corresponding activity is as high as 712 molacetylene molmetal-1 h-1. Extended X-ray absorption fine structure (EXAFS) measurement and density functional theory (DFT) calculation reveal the Pd-N1C3 sites from Pd-ISAS/CN efficiently boost the reactivity for semi-hydrogenation of acetylene. This work will bring inspiration to rationally design noble-metal-based ISAS catalysts derived from COF materials and boost catalytic performance by optimizing the coordination environment of catalytic sites.

In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

This study presents a nitrogen-doped microporous carbon nanospheres (N@MCNs) prepared by a facile polymerization–carbonization process using low-cost styrene. The N element in situ introduces polystyrene (PS) nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent, and then carbonization obtains N@MCNs. The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride. The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure. The results showed that N@MCNs exhibit superb reduction performance of friction and wear. When the addition of N@MCNs was 0.06 wt%, the friction coefficient of PAO-10 decreased from 0.188 to 0.105, and the wear volume reduced by 94.4%. The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%, respectively. The carrying capacity of load was rocketed from 100 to 400 N concurrently. Through the analysis of the lubrication mechanism, the result manifested that the prepared N@MCNs enter clearance of the friction pair, transform the sliding friction into the mixed friction of sliding and rolling, and repair the contact surface through the repair effect. Furthermore, the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides, which can avert direct contact with the matrix and improve the tribological properties. This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction. This preparing method can be ulteriorly expanded to multi-element co-permeable materials. Nitrogen and boron co-doped carbon nanospheres (B,N@MCNs) were prepared by mixed carbonization of N-enriched PS and boric acid, and exhibited high load carrying capacity and good tribological properties.

Size-controllable synthesis of monodispersed nitrogen-doped carbon nanospheres from polydopamine for high-rate supercapacitors

Size-controllable synthesis of monodispersed nitrogen-doped carbon nanospheres from polydopamine for high-rate supercapacitors

Core-Shell Tandem Catalysis Coupled with Interface Engineering For High-Performance Room-Temperature Na-S Batteries.

The sluggish redox kinetics and shuttle effect seriously impede the large application of room-temperature sodium-sulfur (RT Na-S) batteries. Designing effective catalysts into cathode material is a promising approach to overcome the above issues. However, considering the multistep and multiphase transformations of sulfur redox process, it is impractical to achieve the effective catalysis of the entire S8 →Na2 Sx →Na2 S conversion through applying a single catalyst. Herein, this work fabricates a nitrogen-doped core-shell carbon nanosphere integrated with two different catalysts (ZnS-NC@Ni-N4 ), where isolated Ni-N4 sites and ZnS nanocrystals are distributed in the shell and core, respectively. ZnS nanocrystals ensure the rapid reduction of S8 into Na2 Sx (4<x≤8), while Ni-N4 sites realize the efficient conversion of Na2 Sx into Na2 S, bridged by the diffusion of Na2 Sx from the core to shell. Besides, Ni-N4 sites on the shell can also induce an inorganic-rich cathode-electrolyte interface (CEI) on ZnS-NC@Ni-N4 to further inhibit the shuttle effect. As a result, ZnS-NC@Ni-N4 /S cathode exhibits an excellent rate-performance (650 mAh g-1 at 5 A g-1 ) and ultralong cycling stability for 2000 cycles with a low capacity-decay rate of 0.011% per cycle. This work will guide the rational design of multicatalysts for high-performance RT Na-S batteries.

Bismuth Metal–Organic Framework/Carbon Nanosphere Composites for Ultrasensitive Simultaneous Electrochemical Detection of Lead and Cadmium

An amino-functionalized bismuth metal–organic framework (Bi-BDC-NH2) composited with nitrogen-doped mesoporous carbon nanosphere (NMCS) was prepared to fabricate a Bi-BDC-NH2@NMCS electrochemical sensor for simultaneous determination of Pb(II) and Cd(II). The synthesized Bi-BDC-NH2 was granular, amorphous, and loosely aggregated to form a porous structural composition where NMCS was embedded. The large specific area and exposed sites of Bi-BDC-NH2@NMCS copromote the adsorption and electron transfer of metal ions on the electrode surface. Compared with the traditional bismuth film electrode, the Bi-BDC-NH2@NMCS electrode can improve the charge transfer, stability, and conductivity. The developed method exhibited superior stripping performance with a detection limit of 0.36 ng mL–1 for Pb(II) and 0.44 ng mL–1 for Cd(II), respectively, and a linear range of 1.0–1500 ng mL–1. It was applied to detect Pb(II) and Cd(II) in liver, fish, and shrimp samples with recoveries of 93.6–99.7% and 94.4–103.2%, respectively.

Biomimetic Fe-Cu Dual-atomic-site catalysts enable efficient H2O2 activation for tumor lymphatic metastasis inhibition

Achieving efficient activation of H2O2 in the tumor microenvironment (TME) and further improving the therapeutic efficiency is a great challenge in chemodynamic therapy against cancer. Herein, inspired by natural enzymes, atomically dispersed catalysts with Fe-Cu hetero-binuclear active sites on hollow nitrogen-doped carbon nanospheres (FeCuNC) are synthesized as catalytic nanomedicines for cancer therapy. We found that Fe-Cu hetero-binuclear sites in FeCuNC can catalytically dissociate the O–O bonds in H2O2 molecules more easily than those of single-Fe sites. Besides, the intrinsic photothermal effect of FeCuNC not only further accelerates H2O2 decomposition to produce abundant reactive oxygen species but also achieves synergistically chemodynamic therapy and photothermal therapy to induce cancer cell apoptosis and restrain tumor growth. Moreover, FeCuNC can accurately identify sentinel lymph node metastasis and effectively suppress tumor metastasis and recurrence. This work will provide an advanced strategy for the design of advanced catalysts for H2O2 activation in TME, which holds great promise for practical clinical applications.

Fe-Decorated Nitrogen-Doped Carbon Nanospheres as an Electrochemical Sensing Platform for the Detection of Acetaminophen.

In this work, Fe-decorated nitrogen-doped carbon nanospheres are prepared for electrochemical monitoring of acetaminophen. Via a direct pyrolysis of the melamine-formaldehyde resin spheres, the well-distributed Fe-NC spheres were obtained. The as-prepared Fe-NC possesses enhanced catalysis towards the redox of acetaminophen for abundant active sites and high-speed charge transfer. The effect of loading Fe species on the electrochemical sensing of acetaminophen is investigated in detail. The synergistic effect of nitrogen doping along with the above-mentioned properties is taken advantage of in the fabrication of electrochemical sensors for the acetaminophen determination. Based on the calibration plot, the limits of detection (LOD) were calculated to be 0.026 μM with a linear range from 0-100 μM. Additionally satisfactory repeatability, stability, and selectivity are obtained.

EDTA-Assisted Synthesis of Nitrogen-Doped Carbon Nanospheres with Uniform Sizes for Photonic and Electrocatalytic Applications.

We report a robust method for the facile synthesis of N-doped carbon nanospheres with uniform and tunable sizes. Instead of involving a surfactant or other templates, this synthesis relies on the incorporation of ethylenediaminetetraacetic acid (EDTA) into the emulsion droplets of phenolic resin oligomers. The EDTA provides a high density of surface charges to effectively increase the electrostatic repulsion between the droplets and thereby prevent them from coalescing into irregular structures during polymerization-induced hardening. The EDTA-loaded polymer nanospheres are highly uniform in terms of both size and shape for easy crystallization into opaline structures. While maintaining good uniformity, the diameters of the resultant N-doped carbon nanospheres can be readily tuned from 100 to 375 nm, allowing for the fabrication of opaline lattices with brilliant structural colors. The EDTA also serves as an additional nitrogen source to promote the formation of graphitic-N, making the N-doped carbon nanospheres highly active, metal-free bifunctional electrocatalysts toward oxygen reduction and oxygen evolution reactions.

Electrocatalytic reduction of carbon dioxide in confined microspace utilizing single nickel atom decorated nitrogen-doped carbon nanospheres

Carbon dioxide electroreduction reaction (CO2RR), as a rational regulation of CO2 resource utilization, demands effectively selective catalysts for converting CO2 into high-value-added chemicals. Carbon-based nanoreactors featuring rationally designed porous framework structures might provide a unique chemical environment for confining and stabilizing the active metal species, consequently improving the CO2RR activity. Herein, nitrogen-doped porous carbon nanospheres decorated by single Ni atom (Ni-NCN) featuring a Ni-N4 structure were synthesized using the modified sol-gel method for the reduction of CO2 to CO. The synergistic effect of the Ni-N4 active sites homogenously distributed in the interconnected pore structure and the favorable chemical confined microspace of carbon nanospheres endows it with excellent CO2RR activity. In the H- type cell, Ni-NCN displays a CO Faradaic efficiency up to 96.6 % and a CO current density of 9.8 mA cm−2 at − 0.83 V (vs. RHE), as well as a high turnover frequency (TOF) of 10658 h−1 at − 1.33 V (vs. RHE). In the flow cell, the mass transfer can be further facilitated by the formation of three-phase interface. The Faradaic efficiency and current density of CO2RR catalyzed by Ni-NCN is enhanced to 97.9 % and 102.4 mA cm−2 at − 1.13 V (vs. RHE), and the wide potential window ranges from − 0.53 V to − 1.33 V (vs. RHE) with the Faradaic efficiency more than 95 %. Density functional theory (DFT) calculations reveal that the high selectivity of Ni-N4 sites is mainly ascribed to the high energy barrier that restrains the hydrogen evolution reaction (HER). Meanwhile, the lower CO binding energy on Ni-N4 site helps the escape of CO to increase the TOF of active sites. The in-situ Fourier transform infrared (FTIR) spectroscopy verifies that the intermediate *COOH can be more stable in the confined environment of Ni-NCN to promote the selectivity of CO2RR. The strategy of constructing confined microspace paves a new path for the rational design of high-efficient single atom catalysts for CO2 reduction.

Activating redox kinetics of polysulfides within edge-rich nitrogen doped porous interconnected carbon nanosphere

Theoretically, lithium-sulfur batteries (LSBs) are highly competitive in achieving high energy density storage systems. However, the shuttle effect of polysulfides (LiPSs) and sluggish redox kinetics have severely hampered the commercialization of LSBs. Although a number of catalysts have been applied to solve these problems, their preparation processes and costs are hardly compatible with universalization. Herein, we presented an edge-rich nitrogen-doped porous carbon nanospheres with an interconnection structure (N-PCS) as sulfur redox host, of which mesoporous voids accommodated sulfur to achieve homogenization of sulfur, microporous spaces acted as physical confinement to bind the LiPSs. The interconnected carbon nanosphere could be regarded as penetrated conductive network, which greatly shorten the diffusion distance of Li+ and accelerated carrier diffusion. Moreover, abundant edge doped-nitrogen substances introduced a large number of chemisorption centers and catalytic active sites, realizing the strong adsorption and rapid conversion of LiPSs within the N-PCS skeleton. As a result, the S/N-PCS cathode had a first discharge specific capacity of 755 mAh g−1 at 1.0 C and operated enduringly with an ultra-low capacity decay rate (0.04% per cycle) up to 1000 cycles. Not to be outdone, the S/N-PCS cathode provided area specific capacities of up to 4.76 and 5.27 mAh cm−2 at elevated sulfur loadings of 4.31 and 5.49 mg cm−2. This work not only provides a low-cost improvement strategy, but also expands new research ideas for the development of high-performance LSBs cathodes.

Facile and scalable construction of nitrogen-doped lignin-based carbon nanospheres for high-performance supercapacitors

Lignin-based carbon nanospheres have a high specific surface area, large porosity, and excellent stability, while being used in potential applications such as catalyst carriers, adsorbents, and energy storage materials. However, the low hydrophilicity and poor chemical activity of pure carbon nanospheres make it challenging for those materials to meet the needs of various functions. The introduction of nitrogen atoms can increase the active site of the materials, thereby improving the performance. In this study, lignin nanospheres (LNS) with a solid content of 5.8 mg mL−1 in the suspension and an actual yield of 85% were prepared using a γ-valerolactone/water binary system. Based on that, nitrogen-doped lignin-based carbon nanospheres (NCS) were successfully constructed. The doping ratio of urea and carbonization temperature significantly affected the physicochemical properties of the carbon materials. By varying the urea doping ratio and temperature, the nitrogen atom content of the NCS varied from 5.0 to 10.9 at.%. After assembling them into electrochemical capacitors, NCS-15–700 exhibited excellent capacitance of 232 F g−1 at 0.5 A g−1 and 10,000 cycles long cycling stability (retention of 97.2%). The specific capacitance was enhanced by approximately 40% compared to undoped lignin-based carbon nanospheres (LCS). It is evident that nitrogen-doped lignin-based carbon nanospheres have promising applicability in supercapacitors.

Preparation of multistage microporous and mesoporous nitrogen-doped carbon nanospheres and study on electrocatalytic oxygen reduction

Non-metallic carbon-based catalysts are one of the most promising catalysts for electrocatalytic oxygen reduction (ORR). However, the controlled synthesis of the pore structures of carbon-based catalysts and the determination of catalytic sites still remains to be further explored. Based on this, two nitrogen-doped carbon-based catalysts with microporous and mesoporous structures were prepared in this paper. The two catalysts had different pore structures and nitrogen-doped species. The experimental results showed that the carbon-based catalyst (PC-NH3) rich in microporous structure and pyridine nitrogen doping had better catalytic performance, the electrocatalytic oxygen reduction performance of the catalyst was comparable to that of the platinum catalyst, and it had excellent methanol resistance and stability. This study provided important guidance for the application of porous carbon materials in oxygen reduction.

N-doped carbon nanospheres as selective fluorescent probes for mercury detection in contaminated aqueous media: chemistry, fluorescence probing, cell line patterning, and liver tissue interaction.

A precise nano-scale biosensor was developed here to detect Hg2+ in aqueous media. Nitrogen-doped carbon nanospheres (NCS) created from the pyrolysis of melamine-formaldehyde resin were characterized by FESEM, XRD, Raman spectra, EDS, PL, UV-vis spectra, and N2 adsorption-desorption, and were used as a highly selective and sensitive probe for detecting Hg2+ in aqueous media. The sensitivity of NCS to Hg2+ was evaluated by photoluminescence intensity fluctuations under fluorescence emission in the vicinity of 390nm with a λexc of 350nm. The fluorescence intensity of the NCS probe weakened in the presence of Hg2+ owing to the effective fluorescence quenching by that, which is not corresponding to the special covalent liking between the ligand and the metal. The effects of the fluorescence nanoprobe concentration, pH, and sensing time were monitored to acquire the best conditions for determining Hg2+. Surprisingly, NCS revealed excellent selectivity and sensitivity towards Hg2+ in the samples containing Co2+, Na+, K+, Fe2+, Mn2+, Al3+, Pb2+, Ni2+, Ca2+, Cu2+, Mg2+, Cd2+, Cr3+, Li+, Cs+, and Ba2+. The fluorescence response was linearly proportional to Hg2+ concentration in 0.013-0.046µM with a limit of detection of 9.58nM. The in vitro and in vivo toxicological analyses confirmed the completely safe and biocompatible features of NCS, which provides promise for use for water, fruit, vegetable, and/or other forms of natural-connected materials exposed to Hg2+, with no significant toxicity noticed toward different cells/organs/tissues.

Polyindole-Derived Nitrogen-Doped Carbon Nanosphere/Al2O3 Composites with High-Performance Microwave Absorption

In this study, polyindole-derived nitrogen-doped carbon nanosphere/Al2O3 (PINNC/Al2O3) composites are fabricated by hydrothermal, in situ aggregation and high-temperature pyrolysis using potassium aluminum sulfate dodecahydrate, urea, and indole as raw materials. The results show that the introduction of alumina modulates the impedance matching and results in the formation of a great deal of interfaces with polyindole-derived nitrogen-doped carbon nanospheres, which promotes the reinforcement of interfacial polarization. Moreover, the unique semicircular spherical structure of alumina and the pleated structure of carbon nanospheres facilitate multiple microwave attenuation. The abundance of in situ nitrogen atom doping in the carbon material and the defects that formed after pyrolysis can supply a great deal of polarization sites for dipole polarization, thus enhancing dipole polarization loss. As the matching thickness reached 2.5 mm, the minimum reflection loss (RL) of the PINNC/Al2O3 composites is −46.08 dB at 16.72 GHz (fill ratio of 0.5). And as the matching thickness is merely 3.0 mm, the effective absorption bandwidth (EAB) is 7.04 GHz. This study can serve as a good guide for the devising of polyindole-derived nitrogen-doped carbon-based electromagnetic microwave absorbents.

Dendritic hollow nitrogen-doped carbon nanospheres for oxygen reduction at primary zinc–air batteries

Role of pore size in the N-doped porous carbon in the mechanism of oxygen reduction reaction at electrochemical energy storage and conversion systems.