Nitrogen-doped Porous Carbon Research Articles

Work-function-prompted interfacial charge kinetics in hierarchical heterojunction flexible electrode for efficient capacitive deionization

The growing challenge of water scarcity has spurred extensive research into the development of advanced freestanding pseudocapacitive electrode materials. These electrodes, characterized by their controlled morphology, mechanical complexity, and enhanced desalination capabilities, are advancing water treatment technologies. Additionally, electrodes with interfacially influenced heterostructures demonstrate substantial potential to enhance electrochemical kinetics. However, their widespread adoption is hindered by intricate synthesis procedures and the necessity for multiple discrete components. Herein, the report introduces a cohesive approach that utilizes electrospinning and carbonization to create a freestanding, hierarchically porous nitrogen-doped carbon nanofiber network encapsulating FeNi3 alloy (FeNi3@CNFs) for desalination applications. The method enhances the interfacial effect, mitigates volume changes during sodium ion adsorption and desorption, and improves interfacial stability. By capitalizing on structural and compositional advantages, the novel FeNi3@CNFs electrode delivers outstanding electrochemical properties, including a high desalination capacity (46.47 mg g−1 at 1.2 V), rapid desalination rate (0.77 mg g−1 min−1), and enhanced cyclic durability. Computational analysis via Density Functional Theory shows that the work function prompts a surface charge redistribution at the FeNi3@CNFs heterojunction, optimizing the surface electronic structure and reducing the energy barrier for adsorption. The modification significantly boosts the diffusion kinetics of sodium adsorption. The study delineates a comprehensive methodology for fabricating high-performance heterostructured electrode materials that are effective for capacitive deionization.

Antibacterial and anti-inflammatory polyethyleneimine/polyacrylic acid hydrogel loaded with CeO2 quantum dots for wet tissue wound dressings

Searching for an antibacterial and anti-inflammatory dressing that can stably adhere to wet tissues remains a momentous clinical challenge, especially in the context of treatment failure due to multi-drug-resistant bacteria. Using a hard template method in combination with an in situ chelating strategy, three-dimensional nitrogen-doped graded porous carbon anchored 1.5–2.5 nm CeO2 quantum dots (CeO2-QDs) were tailor-designed in this study. Using the size effect, CeO2-QDs have a higher percentage of Ce3+ and oxygen vacancies that could amplify their antibacterial effects. Polyethyleneimine/polyacrylic acid (PEA) powder could self-gel and be adhesive due to its strong physical interactions, which make it an ideal carrier for CeO2-QDs. PEA@50 (mg/mL) CeO2-QDs hydrogel and PEA@75 (mg/mL) CeO2-QDs hydrogel with moderate doses of CeO2-QDs show a superior antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. Furthermore, PEA@50CeO2-QDs hydrogels possess excellent anti-inflammatory capacity through their antioxidant activity, which could promote macrophage M2 phenotype polarization. More importantly, cytotoxicity assays on L929 fibroblasts show that PEA@CeO2-QDs hydrogels have no significant toxicity, and a significant proliferative effect could be observed. Overall, PEA@50CeO2-QDs hydrogels have the potential to become a multifunctional wet tissue dressing with anti-inflammatory and antiseptic properties to promote the healing of infected wounds.

Mn-modulated Co–N–C oxygen electrocatalysts for robust and temperature-adaptative zinc-air batteries

Flexible zinc-air batteries (FZABs) are featured with safety and high theoretical capacity and become one of the ideal energy supply devices for flexible electronics. However, the lack of cost-effective electrocatalysts remains a major obstacle to their commercialization. Herein, we synthesized a porous dodecahedral nitrogen-doped carbon (NC) material with Co and Mn bimetallic co-embedding (CoxMn1−x@NC) as a highly efficient oxygen reduction reaction (ORR) catalyst for ZABs. The incorporation of Mn effectively modulates the electronic structure of Co sites, which may lead to optimized energetics with oxygen-containing intermediates thereby significantly enhancing catalytic performance. Notably, the optimized Co4Mn1@NC catalyst exhibits superior E1/2 (0.86 V) and jL (limiting current density, 5.96 mA cm−2) compared to Pt/C and other recent reports. Moreover, aqueous ZAB using Co4Mn1@NC as a cathodic catalyst demonstrates a high peak power density of 163.9 mW cm−2 and maintains stable charging and discharging for over 650 h. Furthermore, FZAB based on Co4Mn1@NC can steadily operate within the temperature range of −10 to 40 °C, demonstrating the potential for practical applications in complex climatic conditions.

Co-assisted strategy of sacrificial salt-template and nitrogen-doping to promote lithium storage performance of NiO-Ni/N-C frameworks

Tailoring the omnidirectional conductivity networks in nickel oxide-based electrodes is important for ensuring their long lifespan, stability, high capacity, and high-rate capability. In this study, nickel metal nanoparticles and a three-dimensional nitrogen-doped carbon matrix were used to embellish the nickel oxide composite NiO–Ni/N–C via simplified hard templating. When a porous nitrogen-doped carbon matrix is present, a rapid pathway would be established for charging and discharging the electrons and lithium ions in a lithium-ion battery, thereby alleviating the volumetric expansion of the NiO nanoparticles during the operation of the battery. Moreover, the Ni0 ions added to serve as active sites to improve the capacity of the NiO-based electrodes and strengthen their conductivities. The multielement-effects of the optimal NiO–Ni/N–C electrode leads it to exhibit a capacity of 1310.8 mAh g-1 at 0.1 A g-1 for 120 loops and a rate capability of 441.5 mAh g-1 at 20.0 A g-1. Kinetic analysis of the prepared electrodes proved their ultrafast ionic and electronic conductivities. This strategy of hard templating reduces the number of routes required for preparing different types of electrodes, including NiO-based electrodes, and improves their electrochemical performance to enable their use in energy storage applications.

Accelerating lithium-sulfur battery reaction kinetics and inducing 3D deposition of Li2S using interactions between Fe3Se4 and lithium polysulfides

Although lithium-sulfur batteries (LSBs) exhibit high theoretical energy density, their practical application is hindered by poor conductivity of the sulfur cathode, the shuttle effect, and the irreversible deposition of Li2S. To address these issues, a novel composite, using electrospinning technology, consisting of Fe3Se4 and porous nitrogen-doped carbon nanofibers was designed for the interlayer of LSBs. The porous carbon nanofiber structure facilitates the transport of ions and electrons, while the Fe3Se4 material adsorbs lithium polysulfides (LiPSs) and accelerates its catalytic conversion process. Furthermore, the Fe3Se4 material interacts with soluble LiPSs to generate a new polysulfide intermediate, LixFeSy complex, which changes the electrochemical reaction pathway and facilitates the three-dimensional deposition of Li2S, enhancing the reversibility of LSBs. The designed LSB demonstrates a high specific capacity of 1529.6 mA h g−1 in the first cycle at 0.2 C. The rate performance is also excellent, maintaining an ultra-high specific capacity of 779.7 mA h g−1 at a high rate of 8 C. This investigation explores the mechanism of the interaction between the interlayer and LiPSs, and provides a new strategy to regulate the reaction kinetics and Li2S deposition in LSBs.

Geometric and electronic engineering of cobalt, manganese oxide sites in porous nitrogen-doped carbon for boosted oxygen reduction activity in microbial fuel cell

The development microbial fuel cell relies heavily on cathodic catalysts to provide excellent activity and fast electron rotor transfer rates. However, the design of such electrocatalysts is extremely challenging. Here, a strategy is proposed to regulate the electrocatalyst comprised of cobalt and manganese oxides embedded the porous nitrogen-doped carbon (Co3O4-MnO2/NC) with dominant crystal surface by geometric and electronic engineering. Experimental results and theoretical calculations show that the coordination of bimetallic oxides with N atoms induces an asymmetric distribution of charge of central metal sites, which promotes the adsorption/desorption of oxygen intermediates. This electrocatalyst exhibits excellent oxygen reduction reaction (ORR) activity, long-term stability and antitoxic tolerance. Importantly, microbial fuel cell equipped with Co3O4-MnO2/NC generates excellent performance in power density, chemical oxygen demand (COD) removal rate and coulomb efficiency. This work demonstrates the importance of geometric and electronic engineering design of bimetallic oxide to expose more dominant crystal faces to improve electrocatalytic activity in electrochemical energy conversion systems.

Low-cost pyrolysis of biomass-derived nitrogen-doped porous carbon: Chlorella vulgaris replaces melamine as a nitrogen source.

Porous carbon generated from biomass has a rich pore structure, is inexpensive, and has a lot of promise for use as a carbon material for energy storage devices. In this work, nitrogen-doped porous carbon was prepared by co-pyrolysis using bagasse as the precursor and chlorella as the nitrogen source. ZnCl2 acts as both an activator and a nitrogen fixer during activation to generate pores and reduce nitrogen loss. The thermal weight loss experiments showed that the pyrolysis temperatures of bagasse and chlorella overlap, which created the possibility for the synthesis of nitrogen-rich biochar. The optimum sample (ZBC@C-5) possessed a surface area of 1508 m2g-1 with abundant nitrogen-containing functional groups. ZBC@C-5 in the three-electrode system exhibited 244.1F/g at 0.5A/g, which was extremely close to ZBC@M made with melamine as the nitrogen source. This provides new opportunities for the use of low-cost nitrogen sources. Furthermore, the devices exhibit better voltage retention (39%) and capacitance retention (96.3%). The goal of this research is to find a low cost, and effective method for creating nitrogen-doped porous carbon materials with better electrochemical performance for highly valuable applications using bagasse and chlorella.

Dendritic boron and nitrogen doped high-entropy alloy porous carbon fibers for high-efficiency hydrogen evolution reaction

Among various electrocatalysts, high-entropy alloys (HEAs) have gained significant attention for their unique properties and excellent catalytic activity in the hydrogen evolution reaction (HER). However, the precise synthesis of HEA catalysts in small sizes remains challenging, which limits further improvement in their catalytic performance. In this study, boron- and nitrogen-doped HEA porous carbon nanofibers (HE-BN/PCNF) with an in situ-grown dendritic structure were successfully prepared, inspired by the germination and growth of tree branches. Furthermore, the dendritic fibers constrained the growth of HEA particles, leading to the synthesis of quantum dot-sized (1.67nm) HEA particles, which also provide a pathway for designing HEA quantum dots in the future. This work provides design ideas and guiding suggestions for the preparation of borated HEA fibers with different elemental combinations and for the application of dendritic nanofibers in various fields.

Nitrogen-doped porous carbon hosted sulfur-rich polymer for room temperature Na-S batteries with superior cycle performances

Room temperature sodium-sulfur (RT Na-S) batteries are one of the most promising energy storage systems with high energy density due to the abundant reserves of sodium and sulfur elements on Earth. As a potential cathode material, sulfur-rich polymers are rarely reported in RT Na-S batteries compared with other metal-sulfur batteries. The unusual occurrence is a result of sulfur-rich polymer cathodes failing in Na-S batteries. To reverse the process, herein, we first illuminate the failure mechanism of sulfur-rich polymer cathodes (S-DIB as an example) in Na-S batteries, which root from the chemical reaction between the polysulfide and the sodium anode. To address this issue, we incorporate nitrogen-doped carbon (NC) into composites with S-DIB to establish ion diffusion pathways and limit polysulfide diffusion. The resulting S-DIB@NC composite demonstrates exceptional cycling performance, achieving a high capacity of 457 mA h g-1 after 1300 cycles. This research constitutes a significant step towards enhancing the viability of sulfur-rich polymers in Na-S batteries and paves the way for their widespread application.

A nitrogen-doped hollow carbon nanospheres-based aptasensor for non-invasive salivary detection of progesterone

Developing an easy-to-use and non-invasive sensor for monitoring progesterone (P4) as a multi-functional hormone is highly demanded for point-of-care testing. In this study, an ultrasensitive electrochemical aptasensor is fabricated for monitoring P4 in human biofluids. The sensing interface was designed based on the porous nitrogen-doped hollow carbon spheres (N-HCSs). The N-HCSs covalently immobilized high-dense aptamer (Apt) sequences as the bioreceptor of P4. The electron transfer of the redox probe was hindered by incubating P4 on the aptasensor surface and forming the P4-Apt complexes. Meanwhile, the signaling was decreased under two wide linear dynamic ranges (LDRs) from 10 fM to 5.6 μM with a limit of detection (LOD) value of 3.33 fM. The aptasensor presented satisfactory selectivity in the presence of different off-target species with successful feasibility for P4 detection in some human urine and saliva samples. The aptasensor with high sensitivity, as an advantage for on-site and sensitive measurement of P4, can be considered a non-invasive tool for routine analysis of real-world clinical samples method.

Nitrogen-Doped Cellulose-Derived Porous Carbon Fibers for High Mass-Loading Aqueous Supercapacitors.

Biomass-based porous carbon with renewability and flexible structure tunability is a promising electrode material for supercapacitors. However, there is a huge gap between experimental research and practical applications. How to maintain good electrochemical performance of high mass-loading electrodes and suppress the self-discharge of supercapacitors is a key issue that urgently needs to be addressed. The structure regulation of electrode materials such as heteroatom doping is a promising optimization strategy for high mass-loading electrodes. In this work, nitrogen-doped cellulose-derived porous carbon fibers (N-CHPCs) were prepared by a facile bio-template method using cotton cellulose as raw material and urea as dopant. The prepared N-CHPCs have high specific surface area, excellent hierarchical porous structure, partial graphitization properties and suitable heteroatom content. The assembled high mass-loading (12.8 mg cm-2; 245 μm) aqueous supercapacitor has excellent electrochemical performance, i. e., low open-circuit voltage attenuation rate (21.39 mV h-1), high voltage retention rate (78.81 %), high specific capacitance (295.8 F g-1 at 0.1 A g-1), excellent area capacitance (3.79 F cm-2 at 0.1 A g-1), excellent cycling stability (97.28 % over 20,000 cycles at 1.0 A g-1). The excellent performance of high mass-loading N-CHPCs is of great significance for their practical applications in advanced aqueous supercapacitors.

Ribosome-inspired electrocatalysts inducing preferential nucleation and growth of three-dimensional lithium sulfide for high-performance lithium-sulfur batteries

Nucleation of lithium sulfide (Li2S) induced by electrocatalysts plays a crucial role in mitigating the shuttle effect. However, short-chain polysulfides on electrocatalysts surfaces tend to re-dissolve into electrolytes, delaying Li2S supersaturation and its nucleation. In this study, we draw inspiration from the ribosome-driven protein synthesis process in cells to prepare ultrasmall nitrogen-doped MoS2 nanocrystals anchored on porous nitrogen-doped carbon networks (N-MoS2-NC) electrocatalysts. Excitedly, the ex-situ SEM demonstrates that ribosome-inspired N-MoS2-NC electrocatalysts induce early nucleation and rapid growth of three-dimensional Li2S during discharge. Theoretical calculations reveal that the Li-S bond length in N-MoS2-Li2S(100) is shorter, and the corresponding interfacial formation energy is lower than in MoS2-Li2S(100). This accelerated conversion of lithium polysulfides to Li2S can enhance the utilization of active substances and inhibit the shuttle effect. This study highlights the potential of ribosome-inspired N-MoS2-NC in improving the electrochemical stability of Li-S batteries, providing valuable insights for future electrocatalyst design.

Preparation of nitrogen-doped carbon pyrolyzed from ZIF-8 and its performance in electrocatalytic oxygen reduction to hydrogen peroxide

As an environment-friendly strategy, electrocatalytic hydrogen peroxide (H2O2) generation via two-electron oxygen reduction reaction (2e– ORR) has attracted significant scientific and technological attention. Nevertheless, limited to the low catalytic activity and high cost of noble metal-containing catalysts, forging desired electrocatalysts with high catalytic activity, low cost, and sustainability is still challenging. In this work, nitrogen doped porous carbon materials named p-ZIF-800 and p-ZIF-950 were obtained by pyrolysis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals at 800 °C and 950 °C, respectively. Then, they were employed as a catalytic layer in the gas diffusion electrodes p-ZIF-n/Ni/CB (n = 800 °C or 950 °C, CB = acetylene black). The production rates of H2O2 are up to 1.18 mg h−1 cm−2 and 1.25 mg h−1 cm−2 for p-ZIF-800/Ni/CB and p-ZIF-950/Ni/CB, respectively. Noticeably, although p-ZIF-800 had a lower degree of graphitization the difference in catalytic activity between p-ZIF-800 and p-ZIF-950 is negligible. This can be construed as a higher total nitrogen and richer mesoporous structure in p-ZIF-800 than in p-ZIF-950. Under optimized conditions of an electrode spacing of 3 cm, a pH value of 6.5, and a current density of 7.5 mA cm−2, the H2O2 production rate of p-ZIF-800/Ni/CB in the “floating-cathode” cell is up to as high as 2.09 mg h−1 cm−2, which is about 3.3 times higher than that of the cell with the “submerged-cathode” under aeration and stirring. Also, the p-ZIF-800/Ni/CB cathode demonstrates remarkable stability, it maintains its structure without losing catalytic activity after 5 catalytic cycle experiments. These results indicate that the state-of-the-art pyrolysis-based nitrogen-doped porous carbon materials exhibit a high potential for the advanced electrocatalyst of H2O2 electrogeneration.

Flexible and crosslinking electrospun porous carbon nanofiber membranes as freestanding binder-free anodes for lithium-ion batteries

Electrospinning carbon nanofibers with one-dimensional nanostructures have enormous potential for electronic applications owing to their flexibility, electrical conductivity, high surface area and attractive structure. In this paper, porous nitrogen-doped carbon nanofiber membranes with chemical crosslinking structure (PNCNMs-CC) were prepared for lithium-ion batteries anodes by crosslinking treatment and carbonization process using polyimide as precursor, melamine as nitrogen source and ethyl orthosilicate as pore-forming agent. The heightened nitrogen content synergizes with the augmented specific surface area, engendering a striking electrochemical enhancement. Rich pore structure provides more active sites. When utilized as a binder-free, current collector-free anode, PNCNMs-CC shows an excellent rate performance and long cycle stability. The first discharge specific capacity of PNCNMs-CC delivered 710 mAh g−1 at 50 mA g−1. After 1000 cycles at a high current density of 1 A g−1, PNCNMs-CC shows 88 % capacity retention, demonstrating a promising candidate as the flexible anodes for high-performance energy storage devices.

In-situ approach to porous nitrogen-doped carbon nanosheets functionalized by Brønsted acidic ionic liquids for microwave-assisted upgrading fructose to 5-hydroxymethylfurfural

In the search for robust and recoverable supported Brønsted acidic ionic liquids (BAILs) catalysts for efficient upgrading bio-sugars to value-added chemicals, an in-situ strategy of supramolecular preorganization-thermal polycondensation is designed to fabricate porous ultrathin nitrogen-doped carbon nanosheets (NCNSs), and then BAILs-functionalized NCNSs catalysts are prepared via successive quaternary ammonization by sultones and anion exchange with Brønsted acids. By adjusting the molar composition of the starting monomers, the textural properties of NCNSs supports are tuned; and by functionalization with different sultones (1,3-propanesultone and 1,4-butanesultone) and organic (trifluoromethanesulfonic acid and p-toluenesulfonic acid) or inorganic (H2SO4 and H3PO4) acids, the surface hydrophobicity and Brønsted acid strength of the catalysts are regulated. The catalysts are applied in microwave-assisted upgrading fructose to 5-hydroxymethylfurfural, and influences of Brønsted acid nature, surface hydrophobicity and textural properties on the catalytic performance are explored. For the most active [C4SO3HN][OTf]-NCNSs-MA-3 catalyst with the advantages of superstrong Brønsted acidity, higher surface hydrophobicity and perfect porous ultrathin sheet-like nanostructure, the conversion of fructose and the yield of 5-hydroxymethylfurfural of 100% and 87.7% are achieved after microwave irradiation for 15 min, outperforming Amberlyst-15 resin and HY zeolite. The catalysts also demonstrate the robust catalytic reusability, and after five consecutive catalytic runs, the obvious activity loss hardly occurs, along with little acid sites leaching.

High Peroxidase-like Activity of Single Iron Atoms Anchored on N-doped Porous Carbon for the Colorimetric Detection of Biothiols

In this report, single iron atoms anchored on nitrogen-doped porous carbon (Fe-ISAs/CN) was prepared and shown to possess high peroxidase-like activity. Fe-ISAs/CN could effi ciently catalyze the oxidation of the peroxidase substrate 3,3?,5,5?-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue color. In terms of the excellent peroxidase-like activity, single iron atoms anchored on nitrogen-doped porous carbon playing a critical role. Besides, an inhibition effect on the oxidation of TMB catalyzed by Fe-ISAs/CN was induced by biothiols in the presence of H2O2. Taking these advantages together, a simple colorimetric method for rapid and sensitive detection of biothiols was established.

Defective nitrogen doped carbon material derived from nano-ZIF-8 for enhanced in-situ H2O2 generation and tetracycline hydrochloride degradation in electro-Fenton system

Tetracycline hydrochloride (TC) accumulates in large quantities in the water environment, causing a serious threat to human health and ecological environment safety. This research focused on developing cost-effective catalysts with high 2e- selectivity for electro-Fenton (EF) technology, a green pollution treatment method. Defective nitrogen-doped porous carbon (d-NPC) was prepared using the metal-organic framework as the precursor to achieve in-situ H2O2 production and self-decomposition into high activity ·OH for degradation of TC combined with Co2+/Co3+. The d-NPC produced 172.1 mg L−1 H2O2 within 120 min, and could degrade 96.4% of TC in EF system. The self-doped defects and graphite-nitrogen in d-NPC improved the oxygen reduction performance and increased the H2O2 yield, while pyridine nitrogen could catalyze H2O2 to generate ·OH. The possible pathway of TC degradation was also proposed. In this study, defective carbon materials were prepared by ball milling, which provided a new strategy for efficient in-situ H2O2 production and the degradation of pollutants.

ZIF-67-derived Co@NC as an efficient catalyst for magnesium sulfite oxidation in the flue gas desulfurization process

Magnesium desulfurization is a wet flue gas desulfurization (WFGD) technology widely used in China, however, the low oxidation rate of magnesium sulfite (MgSO3), a byproduct of WFGD, causes the subsequent oxidation and crystallization process to require amount energy. Here, we prepared a cobalt-based nitrogen-doped porous carbon catalyst (Co@NC) using ZIF-67 as a precursor for the efficient catalytic oxidation of MgSO3 generated during magnesium desulfurization. The performance of Co@NC catalysts obtained at an optimal calcination temperature of 650 °C showed that the catalysts with oxidation rates up to 0.1332 mmol·L−1·s−1 of MgSO3 were considerably better than those previously studied, which outperformed the catalysts described in earlier research by a considerable margin. Further studies revealed that the Co@NC’s exceptional catalytic activity was attributed to both its special porous structure and the exposed active Co sites in the organic skeleton. The uniformly dispersed Co species act as the active sites of the Co@NC that can be fully contacted with the reactant. The presence of 0.5 g·L−1 Co@NC increases the MgSO3 oxidation rate by about 14 times compared to the noncatalytic benchmark. A practical tactic is furnished by this research for energy saving and emission reduction in the WFGD process, especially for the efficient oxidation and resource conversion of the by-product MgSO3.

Unveiling the Synergy of Architecture and Anion Vacancy on Bi2Te3-x@NPCNFs for Fast and Stable Potassium Ion Storage.

Large volume strain and slow kinetics are the main obstacles to the application of high-specific-capacity alloy-type metal tellurides in potassium-ion storage systems. Herein, Bi2Te3-x nanocrystals with abundant Te-vacancies embedded in nitrogen-doped porous carbon nanofibers (Bi2Te3-x@NPCNFs) are proposed to address these challenges. In particular, a hierarchical porous fiber structure can be achieved by the polyvinylpyrrolidone-etching method and is conducive to increasing the Te-vacancy concentration. The unique porous structure together with defect engineering modulates the potassium storage mechanism of Bi2Te3, suppresses structural distortion, and accelerates K+ diffusion capacity. The meticulously designed Bi2Te3-x@NPCNFs electrode exhibits ultrastable cycling stability (over 3500 stable cycles at 1.0 A g-1 with a capacity degradation of only 0.01% per cycle) and outstanding rate capability (109.5 mAh g-1 at 2.0 A g-1). Furthermore, the systematic ex situ characterization confirms that the Bi2Te3-x@NPCNFs electrode undergoes an "intercalation-conversion-step alloying" mechanism for potassium storage. Kinetic analysis and density functional theory calculations reveal the excellent pseudocapacitive performance, attractive K+ adsorption, and fast K+ diffusion ability of the Bi2Te3-x@NPCNFs electrode, which is essential for fast potassium-ion storage. Impressively, the assembled Bi2Te3-x@NPCNFs//activated-carbon potassium-ion hybrid capacitors achieve considerable energy/power density (energy density up to 112 Wh kg-1 at a power density of 1000 W kg-1) and excellent cycling stability (1600 cycles at 10.0 A g-1), indicating their potential practical applications.

Engineering single-atom Mn on nitrogen-doped carbon to regulate lithium-peroxide reaction kinetics for rechargeable lithium-oxygen batteries

Precision engineering of catalytic sites to guide more favorable pathways for Li2O2 nucleation and decomposition represents an enticing kinetic strategy for mitigating overpotential, enhancing discharge capacity, and improving recycling stability of Li-O2 batteries. In this work, we employ metal–organic frameworks (MOFs) derivation and ion substitution strategies to construct atomically dispersed Mn-N4 moieties on hierarchical porous nitrogen-doped carbon (Mn SAs-NC) with the aim of reducing the overpotential and improving the cycling stability of Li-O2 batteries. The porous structure provides more channels for mass transfer and exposes more highly active sites for electrocatalytic reactions, thus promoting the formation and decomposition of Li2O2. The Li-O2 batteries with Mn SAs-NC cathode achieve lower overpotential, higher specific capacity (14290 mA h g−1 at 100 mA g−1), and superior cycle stability (>100 cycles at 200 mA g−1) compared with the Mn NPs-NC and NC. Density functional theory (DFT) calculations reveal that the construction of Mn-N4 moiety tunes the charge distribution of the pyridinic N-rich vacancy and balances the affinity of the intermediates (LiO2 and Li2O2). The initial nucleation of Li2O2 on Mn SAs-NC favors the O2 → LiO2 → Li2O2 surface-adsorption pathway, which mitigates the overpotentials of the oxygen reduction (ORR) and oxygen evolution reaction (OER). As a result, Mn SAs-NC with Mn-N4 moiety effectively facilitates the Li2O2 nucleation and enables its reversible decomposition. This work establishes a methodology for constructing carbon-based electrocatalysts with high activity and selectivity for Li-O2 batteries.