Nitrogen-doped Porous Carbon Research Articles

Hollow Ni/NiO@N-doped porous carbon for lithium ion battery anode based on dual-buffering strategy

As a promising anode material of lithium-ion batteries (LIBs), the poor electrical conductivity and severe volume expansion during cycling of nickel oxide (NiO) greatly limit its practical application. Here, a hollow nitrogen-doped porous carbon-loaded hollow Ni/NiO nanocomposite (Ni/NiO@HNC) was obtained by introducing Ni2+ into hollow covalent organic framework (HCOF) and then calcining the Ni2+/HCOF. The as-prepared Ni/NiO is nanoscale and hollow, which effectively accommodates the expanded volume of NiO. Hollow nitrogen-doped porous carbon (HNC) obtained from HCOF can further accommodate the expanded volume of NiO. The residual Ni and HNC can improve the electrical conductivity of Ni/NiO@HNC greatly. The regular pores of HNC inherited from HCOF facilitate the Li+ transfer. Thus, the Ni/NiO@HNC-2 composites exhibited outstanding cycle stability and rate performance when utilized as anode materials in LIBs. Even after 200 cycles at 0.1 A g−1, the capacity was still kept at 695.1 mAh g−1. The work provides an idea to prepare LIBs anodes based on dual-buffering strategy.

Supermolecule-opitimized defect engineering of rich nitrogen-doped porous carbons for advanced zinc-ion hybrid capacitors.

Pitch-based porous carbons with adjustable surface chemical property and controllable pore structure are regarded as promising cathode materials for aqueous zinc-ion hybrid capacitors (ZIHCs), while its disordered carbon matrix and microstructure as well as insufficient surface defects often result in low Zn2+-storage capacity and poor rate capability of ZIHCs. Herein, a synergetic strategy of self-assembled supermolecule and enriched defective carbon engineering was developed to achieve ultrahigh edge-nitrogen doping for ZIHCs. The crystallite defects and surface structure of porous carbon could be effectively achieved through grafting electronegative oxygen-containing small molecules and high-level nitrogen-containing functional groups between modified polycyclic aromatic hydrocarbon and supermolecule framework. The optimized three-dimensional carbon structure delivered high capacity of 218 mAh g-1 at 0.2 A g-1, fast charge/discharge capability, enhanced energy density (165.4 Wh kg-1) and superior cycling stability (95% retention after 10000 cycles as cathode of ZIHCs). This provided new insight into the controllable synthesis of carbon cathodes for ZIHCs and expects to prepare functional porous carbon by supermolecules and special precursors.

Fluorine and sulfur atoms induced N-doped 3D porous carbon catalyzing oxygen reduction in the zinc-air battery

Introducing other heteroatom is considered to be a highly effective approach to improve the limited catalytic activity from single nitrogen element doping in nitrogen-doped porous carbon materials. In this work, F and S-modified nitrogen-doped porous carbon (F-S-N-C) is prepared by annealing the assembly material of poly3-fluoro aniline, hydroxyethyl sulfonic acid and g-C3N4, in which the g-C3N4 is employed as template agent and pore-forming agent. A series of characterization techniques indicate that simultaneous doping of F and the S atoms enhance the electron transfer and construct more defects for N-doped 3D porous carbon, resulting in improved electrocatalytic performance. The prepared F and S-cooperated nitrogen-doped porous carbon (F-S-N-C) exhibits significantly improved oxygen reduction reaction electrocatalytic activity in alkaline media with a half-wave potential of 0.808 V. The zinc-air battery (ZAB) with F-S-N-C as the air cathode catalyst demonstrates a peak power density of 167 mW cm−2, which is higher than that of commercial Pt/C (158 mW cm−2). Moreover, the specific capacity of the F-S-N-C-based ZAB reaches to 817 mAh·g−1.

Hierarchical Bi2O3 nanosheets and ZIF-8 derived porous nitrogen-doped carbon fibers as novel assembled nanocomposites for high-performance flexible supercapacitors

The unique design of the core–shell heterostructure is significant for obtaining electrode materials with excellent electrochemical properties. In this paper, porous carbon nanofibers (NPC@PPZ) embedded with N-doped porous carbon nanoparticles are used to construct flexible electrodes (NPC@PPZ@Bi2O3). Zeolite imidazole skeleton (ZIF)-8 and poly(methyl methacrylate) (PMMA) derived porous carbon fibers and Bi2O3 nanosheets, were utilized as the porous core and multilayer shell, respectively. The unique core and shell result in abundant pores and channels for fast ion transport and storage, high specific surface area, and additional electroactive sites. This perfect structural design enables the NPC@PPZ@Bi2O3 composite electrode to have excellent electrochemical performance. The results show that this electrode can obtain a high specific capacitance of 697 F g−1 at a current density of 1 A g−1 and a stable cycling performance at a high current density of 5 A g−1. The strategy developed in this study provides a new approach for the design and fabrication of flexible supercapacitors by electrostatic spinning combined with hierarchical porous structures.

Utilizing porous carbon composites based on biomass for lithium battery negative electrodes

This work used high-temperature calcination techniques along with basic chemical processing to produce a range of porous carbon compounds from biomass. After that, these substances were employed as anodes in lithium-ion batteries. The first hard carbon was produced via the dehydration reaction of strong sulfuric acid with sucrose (R-HC), then annealing in an NH3Ar environment was used to obtain the nitrogen-doped porous hard carbon (N-HC). Because N-HC has a high interlayer spacing (ca. 0.39 nm) and an abundant ultra-microporous structure (pore size < 0.75 nm), the lithium-ion diffusion coefficient in N-HC can reach up to 9.0 × 10−8 cm2.s−1. The obtained porous carbon compounds contain a rich pore structure, many functional groups, and a high specific surface area, according to the results. Following their application to the anode of lithium-ion batteries, they demonstrate favorable cycle stability and electrochemical performance. Furthermore, a detailed investigation into the kinetic characteristics of the lithium-ion diffusion behavior in the electrodes revealed that the porous carbon materials’ electrodes exhibited greater surface diffusion behavior for Li+.

"Fence" Effect Enabling a Metal-Organic Framework-Derived Single-Atom Co-N-C Catalyst for High-Performance Zn-Air Batteries.

It offers bright prospects to develop non-Pt group metal (non-PGM) electrocatalysts in the area of energy storage and conversion. Herein, we reported a simple spatial isolation strategy to synthesize Co-based electrocatalysts, using partially substituted Zn atoms in a ZnCo-ZIF precursor. The "fence" effect that originated from the partially substituted Zn atoms can yield a better isolation of Co atoms, achieving selective loading of Co species on nitrogen-doped porous carbon varying from nanoparticles to single atoms. The low boiling point of Zn enables abundant porous structures to the N-doped carbon substrate after pyrolysis. The best performing single-atom Co catalyst (Co-SAs/N-C) exhibits excellent oxygen reduction reaction activity in alkaline media. As an illustration, the rechargeable liquid Zn-air battery incorporating the Co-SAs/N-C catalyst demonstrates a substantial open circuit voltage of 1.49 V, a high specific capacity of 689.3 mAh g-1, and remarkable cycling stability over 200 h. This study paves the way for the strategic development of non-PGM electrocatalysts in battery applications.

Single Atom Catalyst Anchored on Nitrogen-Doped Porous Carbon As an Effective Sulfur Host for Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are considered highly promising for next-generation energy storage due to their high theoretical specific capacity and energy density. However, challenges such as the insulating nature of sulfur cathodes, the detrimental shuttle effect of lithium polysulfides (LiPSs), and sluggish conversion kinetics of LiPSs during charge/discharge cycles impede their commercial viability. In this study, we employed a facile ‘dissolution-carbonization’ approach to synthesize nitrogen-coordinated monometallic atomic catalysts anchored on mesoporous carbon to promote surface-mediated reactions of LiPSs. The hierarchical porous carbon support physically confines the sulfur species, while the introduction of single atoms efficiently captures polysulfide intermediates and facilitates their redox conversion kinetics with a lower activation energy barrier. The synergistic effect of the single atom and nitrogen-rich porous carbon (NC) significantly enhances reaction kinetics and sulfur species utilization. Consequently, LSBs incorporating single-atom catalysts (SACs) demonstrate remarkable performance metrics, including high-capacity retention (824.2 mAh g−1), superior Coulombic efficiency (>98.5%), low-capacity decay rate (0.042% per cycle) after 500 cycles at 1 C, and excellent rate capability (776 mA h g–1 at 3 C). This work presents an effective strategy that combines the functions of a nanoporous material host and SACs for lithium-sulfur batteries.

Development of Bromine Adsorbing Carbon Felt Electrode by Coating of Nitrogen-Doped Mesoporous Carbon Layer for Highly Stable Flowless Zinc-Bromine Battery

Renewable energy is well known for the extreme volatility of power production, and secondary battery-based energy storage systems (BESS) are the key to the novel and safe energy industry to expand the supply of renewable energy. Currently, lithium-ion battery-based ESS is commonly used, but the frequent ignition accidents from these ESSs rather become an obstacle to the growth of the renewable energy field. Among the redox batteries, the flowless zinc-bromine battery (FLZBB) is studied as the alternative since it uses a non-flammable and cost-effective aqueous Zn- Br2 electrolyte. However, its main challenges are that bromine (Br2) and polybromide anions (), formed at the positive electrode during the charging process, cross over to the negative electrode due to the difference in chemical potential between the electrodes. The diffused Br2 oxidizes the zinc metal, electrodeposited on the negative electrode, and causes a self-discharge reaction that consumes the charging active material and Br2 the battery performance and life. Herein, we present a nitrogen-doped mesoporous carbon coated on the pristine graphite felt fibers (NMC/GF). By uniformly forming a nitrogen-doped porous carbon material on the GF fibers through the evaporation-induced self-assembly (EISA) method, it is a simple and cost-effective method to develop the structural and properties of the GF positive electrode to increase the ability of adsorption and storing the active materials, Br2 and polybromide anions (,, and ) generated during the charging process. In addition, it also improved the bromine redox reaction kinetics by having a strong affinity with the aqueous Zn-Br2 electrolyte. This facilitates long-term charge/discharge cycles, enabling high performance and improved durability for Coulombic efficiency over 95% for 5000 cycles in the FLZBB single-cell platform at a current density of 20 mA cm-2 and a high-rate areal capacity of 2 mAh cm-2.

Engineering rich defects in nitrogen-doped porous carbon to boost oxygen reduction reaction kinetics

Metal-free carbon-based materials offer a promising alternative to Pt-based catalysts for the oxygen reduction reaction (ORR). However, challenges persist due to its sluggish kinetics and poor acid ORR performance. Here, we introduce a novel nitrogen-doped porous carbon with rich defects sites (such as pentagons, edge and vacancy defects) (PV/HPC) via a simple etching strategy. The PV/HPC demonstrates long-term stability and exceptional catalytic activity with half-wave potential of 0.9 V and average electron transfer number of 3.98 in alkaline solution while 0.78 V and 3.78 in acidic solution, indicating its efficiency and robustness as an ORR catalyst. Additionally, it achieves a higher kinetic current density of 91.9 mA cm−2 at 0.8 V, which is 1.75 times that of Pt/C (52.5 mA cm−2). Furthemore, it enables Al-air battery to attain a maximum power density of 487 mW cm−2, compared to 477 mW cm−2 for the Pt/C catalyst. Density functional theory (DFT) calculations elucidate that the introduction of multifunctional defects in nitrogen-doped porous carbon collectively reduces the reaction energy barrier of the departure of OH* and boosts the oxygen reduction reaction kinetics. This work presents a simple method to design durable and effective carbon-based ORR catalysts.

Robust nitrogen-doped porous carbon encapsulated NiCo2S4 nanodecahedrons for enhanced lithium storage

Transition metal sulfides (TMSs) are attractive anode materials for lithium-ion batteries (LIBs) due to their cost effectiveness, impressive redox properties, and high specific capacity. Among them, NiCo2S4 stands out with a substantial theoretical capacity of 703 mAh g−1 and a high electronic conductivity of 1.25 × 106 S m−1, making it a strong candidate for LIBs. However, NiCo2S4 experiences volume changes and mechanical stress during long-term cycling, leading to structural degradation and rapid capacity decay, which hinders its application. To address these issues, we have developed dodecahedral NiCo2S4 embedded within a nitrogen-doped porous carbon structure (NiCo2S4/NC). The optimal NiCo2S4/NC-300 material exhibits minimum charge transfer resistance, maximum pseudo-capacitive contribution, and exceptional lithium storage performance. At 0.1 A g−1, NiCo2S4/NC-300 exhibits an initial discharge/charge specific capacity of 1730.1/949.4 mAh g−1 and retains a discharge capacity of 454.4 mAh g−1 after 100 cycles. Even at 0.5 A g−1, it delivers an initial discharge/charge capacity of 1301.1/540.1 mAh g−1 with a capacity retention of 81.2 % after 500 cycles. This study presents significant potential for NiCo2S4/NC as a high-performance anode material for LIBs, providing new strategies and insights into the mechanisms for enhancing the performance of TMS-based bimetallic anode materials.

P-doped MoS2 nanosheets embedded in 3D porous carbon for electrocatalytic hydrogen evolution reaction

Due to its inherent electrochemical catalytic activity, molybdenum sulfide (MoS2) is a potential electrocatalyst for hydrogen evolution reaction (HER). However, the limited exposure of its active sites resulting from the easy stacking of nanosheets and inert basal plane hampered its optimal catalytic activity. Herein, we developed a novel facile hydrothermal method to prepare phosphorus-doped MoS2 nanosheets anchored on agar-derived 3D nitrogen-doped porous carbon (P-MoS2/NC). The synthesized P-MoS2/NC electrocatalyst possesses high HER catalytic activity with a low overpotential of 167 mV at 10 mA cm−2 and a small Tafel slope of 45 mV dec−1. The excellent performance is attributed to the unique 3D network carbon structure, which avoids the stacking of the MoS2 sheets resulting in more exposed active sites. Additionally, the P atom introduced on the surface of MoS2 sheets successfully activated the in-plane inertness. This work provides an efficient strategy for designing and preparing high-quality catalysts with enhanced electrocatalytic HER activity.

Systematic study of the N concentration effects on metal-free ORR electrocatalysts derived from corncob: Less is more

We report nitrogen-doped biomass-derived porous carbon materials with great performance for the Oxygen Reduction Reaction (ORR) in alkaline media. The level of nitrogen doping in a simple pyrolysis of corncob (CC) was varied systematically, a 1:1 CC:urea ratio (CC1U) gave the best performance in terms of onset potential (Eonset = 0.97 V vs. RHE), maximum current density (jmax = -3.22 mA cm−2), hydroperoxide ion yield (%HO2– = 1.18 % at 0.5 V), and electron transfer number (n = 3.86 at 0.5 V). Unexpectedly, for higher CC:urea ratios the doping decreases, instead of plateauing, with lower concentration of C-N sites and more sp2 sites as determined by XPS, as well as lower specific surface area (SSA), while increasing both porosity and carbon (002) interplanar distance (d(002)). These materials should be durable and robust, since their performance actually improved after accelerated degradation tests. This study proves that renewable “waste” can be upconverted into metal-free electrocatalysts for electrochemical energy conversion technologies and emphasizes the need for studying and controlling doping levels to enhance performance.

Synthesis and electrochemical performance of low cost nitrogen-doped carbon cryogel composites as supercapacitor electrodes

Developing cost-effective methods for synthesizing Nitrogen-doped carbon cryogels is crucial for advancing supercapacitor technology due to their enhanced electrochemical properties. Nitrogen-doped porous carbon cryogels are synthesized through the freeze-drying method by substituting resorcinol with phenol and using urea/melamine as nitrogen sources. The effect of nitrogen sources on the structure and electrochemical performance is investigated. In the case of carbon cryogel composites samples, using melamine as the nitrogen source (PMF) is more favorable than using urea (PUF), while both nitrogen-doped samples significantly outperform the undoped samples (PF). The PMF sample displays a specific surface area of 1119.00 m2 g−1, and a nitrogen content of 2.19 wt%. In the three-electrode system, the specific capacitance of the PMF sample reaches up to 247.9 F g−1 at a current density of 0.5 A g−1, and its rate performance is 85.52 %. By comparison, the PF sample exhibits specific capacitance and rate performance of 85.4 F g−1 and 33.44 % under the same parameters. The assembled symmetric supercapacitor in a buckle type system also demonstrates exceptional energy density (14.41 Wh kg−1), long-term cycle stability, and a favorable capacitance retention rate (72.2 %). These excellent electrochemical performances can be attributed to the synergistic effects of the hierarchical pore structures and heteroatoms doping.

Pyrolytic conversion of Mesua ferrea testa to nitrogen-doped porous carbon for supercapacitor applications

Developing a high energy density supercapacitor is of great challenge due to the low surface area of commercial activated carbon. The present work aims at developing highly porous nitrogen-doped porous carbon from biomass for supercapacitors. Herein, Mesua ferrea (Nahor) shells, a widely available biomass in northeast India, was used to prepare porous carbon. The effect of activation temperature on structural, textural properties, and electrochemical performance is studied. The carbonization temperature highly influenced the pore structure, porosity, surface area, and thereby influencing the electrochemical performance. The porous carbon pyrolyzed at 700 °C delivered a high specific capacitance of 210 F g-1 at 1 A g-1, higher than porous carbon made at higher temperature (27.5 F g-1 at 1 A g-1 for carbon pyrolyzed at 800 °C). The results provide insights that will be of use in the development of high-energy-density capacitors employing biomass-derived porous carbon.

Controlled incorporation of Zn into nitrogen-doped porous carbon boosts the alcohol dehydrogenation to carboxylic acids

The dehydrogenation of primary alcohols to carboxylic acids is a crucial process in chemical industries such as fibers and plastics. Carboxylic acids, the resulting products, are not only important chemical raw materials but also fundamental pharmaceutical intermediates. Zn-based catalysts have gained attention as a promising option for this transformation owing to their economic cost and abundant reserves. However, stability issues, including structure collapse and morphological changes, have plagued the reported Zn-based catalysts during this transformation. In response to these challenges, this study focused on the design and development of Zn-based catalysts via controlled incorporation of Zn into nitrogen-doped porous carbon to modulate the numbers of defects and Lewis acid-base site pairs. Through extensive screening of various parameters, the best-performing catalyst, namely Zn@NC-800, exhibited high activity and remarkable stability, surpassing all the reported Zn-based catalysts. Moreover, this catalyst demonstrated great recyclability since it could maintain approximately 90 % yields after 9 cycles. Notably, the product formation rate of this catalyst could reach 3833 μmol·gcat.−1·h−1, exceeding that of most reported non-noble metal heterogeneous catalysts. Consequently, this study offers a promising approach for efficiently and stably catalyzing alcohol dehydrogenation reactions using non-noble metals.

Cobalt-copper bimetallic selenides embedded in nitrogen-doped porous carbon nanocubes for diclofenac electrochemical sensing

Diclofenac (DCF) is a non-steroidal anti-inflammatory drug (NSAID), and its overuse poses a potential threat to human health and the aquatic environment, designing high-efficiency electrocatalysts for DCF detection is urgent. Herein, cobalt-copper bimetallic selenides embedded in nitrogen-doped porous carbon nanocubes (CoCuSe@NC) were elaborately designed via one-step in situ selenization of bimetallic CoCu-MOF. The chemical constituents and micromorphology of CoCuSe@NC composites can be further optimized by precisely regulating the selenization process and the doping ratio of bimetal in MOF precursor. As an electrocatalyst, CoCuSe@NC was proved to be highly efficient in electrochemical sensing of DCF with a broad linear range of 0.1–400 µmol/L and a detection limit of 0.024 µmol/L. This was attributed to the synergistic advantages between the heterogeneous structures, which produced more electrochemically active sites, effectively shortened the electron transport path, and improved electrocatalytic performance. Consequently, the constructed sensor exhibits high sensitivity, remarkable stability and applicability, and in particular can selectively detect DCF from other structurally similar coexisting analogs, resulting from the unique metal chelation ability. This work paves the way for designing effective bimetallic selenide electrocatalysts and exploring their applications in DCF electrochemical sensing.

LiF modified hard carbon from date seeds as an anode material for enhanced low-temperature lithium-ion batteries

The performance of traditional Li-ion batteries deteriorates when operating at sub-zero temperatures mainly due to the slow diffusion of Li-ions in commercial negative electrode materials. Various alternative anodes have been explored, but complex fabrication methods hinder practical implementation. This work proposes a cost-effective anode material, a porous structured nitrogen-doped hard carbon synthesized from date seeds with further LiF modification to achieve an artificial LiF-rich solid electrolyte interphase (SEI) layer. The resulting anode material showcases promising characteristics, achieving a specific capacity of 525 mAh g−1 after 50 cycles at room temperature. Furthermore, it maintains a substantial capacity of 280 mAh g−1 after 100 cycles at −20 °C. Notably, even when subjected to a high current of 2C at −20 °C, the electrode still provides a remarkable capacity of 72 mAh g−1 after 500 cycles. The outstanding charge storage performance at low temperatures is attributed to the predominance of capacitance-controlled charge storage mechanisms in the prepared anode. Post-mortem analysis confirms structural stability and formation of a uniform LiF-rich SEI layer. This novel approach presents a practical solution to the difficulties encountered by LIBs in cold environments, paving the way for improved battery performance and longevity.

Synergy of pore confinement and co-catalytic effects in Peroxymonosulfate activation for persistent and selective removal of contaminants

The activation of peroxymonosulfate (PMS) through nanoconfinement and co-catalytic effects has demonstrated considerable promise in environmental remediation. Nevertheless, the attainment of persistent efficiency and specificity for pollutant degradation remains a formidable obstacle. Herein, we proposed a solvent-free molten approach to convert a mixture of zeolitic imidazolate frameworks (ZIFs) and MoS2 into 3D integrated cobalt-molybdenum bimetallic nitrogen-doped porous carbon foam with catalytic/co-catalytic performance (MC@NCF). The integrated materials exhibited exceptional efficiency in degrading contaminants based on the synergy of pore confinement and co-catalytic effects, achieving almost 100 % tetracycline degradation in 10 min with a k-value as high as 112.44 min−1·M−1, which was superior to the existing catalysts reported so far. The experimental findings revealed that the structural adjustment of MC@NCF significant accelerated the mass transfer through the formation of interfacial Mo-S/O-Co and Mo-N-Co/C bonds electron-tuning bridges between pore-confined micro-units, leading to the increased singlet oxygen (1O2) yield. Therefore, the MC@NCF exhibited more remarkable stability without interference from coexisting inorganic ions and cations, humic acid, and water matrices. Moreover, a flow-through nanoreactor was constructed and acquired efficient reactivity with negligible biotoxicity, and easy nanocatalyst recycling after continuous operation. The possible reactivity mechanism was identified by Frontier molecular orbital theory HOMO-LUMO, Fukui function, LC-MS, EPR, in-situ ATR-FTIR, and Raman analyses. Our results will guide integrated “catalytic/co-catalytic” nanoconfined MOF derivatives design to further enhance deep water purification technology.

Jujube shell-derived organic/inorganic nitrogen-doped porous carbon: electrochemical properties and contribution of nitrogen-doped forms to ion adsorption and storage

Jujube shell-derived organic/inorganic nitrogen-doped porous carbon: electrochemical properties and contribution of nitrogen-doped forms to ion adsorption and storage

Nitrogen-Doped Porous Carbons Derived from Peanut Shells as Efficient Electrodes for High-Performance Supercapacitors.

The doping of porous carbon materials with nitrogen is an effective approach to enhance the electrochemical performance of electrode materials. In this study, nitrogen-doped porous carbon derived from peanut shells was prepared as an electrode for supercapacitors. Melamine, urea, urea phosphate, and ammonium dihydrogen phosphate were employed as different nitrogen dopants. The optimized electrode material PA-1-1 prepared by peanut shells, with ammonium dihydrogen phosphate as a nitrogen dopant, exhibited a N content of 3.11% and a specific surface area of 602.7 m2/g. In 6 M KOH, the PA-1-1 electrode delivered a high specific capacitance of 208.3 F/g at a current density of 1 A/g. Furthermore, the PA-1-1 electrode demonstrated an excellent rate performance with a specific capacitance of 170.0 F/g (retention rate of 81.6%) maintained at 20 A/g. It delivered a capacitance of PA-1-1 with a specific capacitance retention of 98.8% at 20 A/g after 5000 cycles, indicating excellent cycling stability. The PA-1-1//PA-1-1 symmetric supercapacitor exhibited an energy density of 17.7 Wh/kg at a power density of 2467.0 W/kg. This work not only presents attractive N-doped porous carbon materials for supercapacitors but also offers a novel insight into the rational design of biochar carbon derived from waste peelings.