Dual-doped Carbon Research Articles

DFT-guided synthesis of N, B dual-doped porous carbon from saccharina japonica for enhanced oxygen reduction catalysis

IntroductionThe oxygen reduction reaction (ORR) is a crucial determinant of the energy transformation capacity of fuel cells. This study investigates the performance of N and B dual-doped carbon in ORR.MethodsSix models using density functional theory (DFT) are developed to compare the performance of different doping strategies. A highly efficient dual-doped carbon ORR catalyst (S-850-1) is synthesized from Saccharina japonica, containing 4.54 at% N and 1.05 at% B atom.ResultsElectrochemical analysis reveals that S-850-1 significantly outperforms the nitrogen mono-doped carbon S-850, exhibiting a higher half-wave potential of 0.861 V and a greater limited current density of −5.60 mA cm⁻2, compared to S-850’s 0.838 V and −5.24 mA cm⁻2. Furthermore, S-850-1 surpasses the performance of 20% Pt/C, demonstrating enhanced durability and exceptional resistance to CO and methanol. The 1.40 V open circuit voltage produced by S-850-1 when integrated into a Zn-air battery can power an LED light.DiscussionBoth theoretical and practical evaluations validate the excellent ORR performance of nitrogen and boron dual-doped carbon, as evidenced by the agreement between the electrochemical results and DFT calculations. This work not only extends the range of ORR catalysts derived from biomass but also provides guidance on creating and producing affordable, effective catalysts that utilize natural resources.

Honeycomb-like N, S dual-doped porous carbons derived from pomelo peel by effective exogenous doping strategy for supercapacitor electrodes

Biomass has emerged as a pivotal precursor to synthesize supercapacitor electrode materials owing to its low-cost and plentiful resources. The optimization of heteroatoms and porous structures is believed to be a viable method to enhance the electrochemical properties of biomass-generated carbons. Herein, pomelo peel as a precursor using KOH as an activator and heteroatom dopants (urea and sodium sulfide) was successfully converted into N, S dual-doped porous carbons under the high temperature. The effective exogenous doping strategy realizes a high abundance of N/S heteroatoms, and KOH chemical activation promotes the development of nanopores and interconnected porosities. The resultant carbon CNS-800 with a high specific surface area of 1823.8 m2 g−1 and rich heteroatoms of N (2.51 wt%) and S (1.36 wt%) anticipately exhibits the outstanding electrochemical properties, including the excellent specific capacitance of 329.2 F g−1 at 1 A g−1 in a three-electrode (3E) system and the superb capacitance retention rate of 74.12 %. The fabricated CNS-800-based symmetric two-electrode (2E) supercapacitor demonstrates a good capacitance of 243.7 F g−1 and excellent cycling stability, as well as a superb energy density of 14.3 Wh kg−1. This work provides a compelling and cost-effective approach to transform biomass waste like pomelo peels into high-performance electrodes for supercapacitors.

Metal organic framework derived heteroatom doped porous carbon nanocubes enable efficient charge storage in a lithium-ion capacitor

Lithium-ion capacitors (LICs) are regarded as one of the promising technologies towards realizing energy & power dense energy storage systems. However, their energy densities at higher power densities are still limited due to the discrepancy between electrode kinetics of capacitor-like cathode and battery-like anode. Developing carbon materials with well-defined structures, porosity to match the chemical kinetics between electrodes are the major challenges to overcome. In the present work, we have devised a strategy to fabricate S, N dual-doped porous carbon nanocubes (S, N-PCNs) using zeolitic imidazole framework (ZIF)-8 precursors, and employed the PCNs as anode material in LICs. With its well-defined structure, hierarchical porous nature, and abundant heteroatom presence (1.9 % S, 16.2 % N), the pre-lithiated S, N-PCNs based anode has offered a greatly improved reversible storage capacity of ∼930 mAh g−1 at 0.1 A g−1 along with an impressive rate capability and cycling life. When S, N-PCNs anode is paired with activated carbon cathode, the 4 V dual-carbon LIC yields an energy density as high as 120.24 Wh kg−1 and 10.2 kW kg−1 of power density with a good cycle stability of 90.6 % after 5000 charge-discharge cycles. This work would open new scopes of exploring metal-organic framework derived heteroatom-doped porous carbons to make metal-ion capacitors more efficient.

Phosphorus and Nitrogen Dual-Doped Hollow Porous Carbon Spheres toward Enhanced Cycling Stability of Room-Temperature Na-S Batteries.

Development of room-temperature sodium-sulfur (RT Na-S) batteries with satisfactory cycling life and rate capability remains challenging due to the unfavorable electric conductivity from S species, sluggish redox kinetics of S conversion, and serious shuttle effects of sodium polysulfides (NaPSs). To address these issues, a phosphorus and nitrogen dual-doped hollow porous carbon sphere (PN-HPCs) is synthesized as the S hosts, which enhances the electric conductivity, ion diffusion, and conversion of polysulfides. Such a hollow hierarchically porous structure is beneficial to accommodate the volume variations of S species and shorten the ion/electron transfer distances during electrochemical reaction process. As a result, the S@PN-HPCs600 cathode delivers noticeable cycling performance (313 mAh g-1 after 4500 cycles at 5.0 C, and capacity degeneration of only 0.01% per cycle) and rate capability (646.4 mAh g-1@1.0 and 527.5 mAh g-1@3.0 C). This work presents an efficient strategy based on structural confinement and dual-heteroatom doping engineering for long-life RT Na-S batteries.

Enhanced Zinc-air battery performance and local electrochemical evaluation of atomically dispersed Co and Ni in S, N-codoped carbon nanofibers via scanning electrochemical microscopy

This study reports the successful synthesis of a novel electrocatalyst for oxygen reduction reactions (ORR), comprising S,N dual-doped carbon nanofibers with atomically dispersed Co/Ni species (denoted as Co,Ni-SAs/S,N-CNFs), leveraging electrostatic spinning to achieve a unique spatial architecture that maximizes both active site density and mass transport efficiency. Density functional theory (DFT) analysis identified the initial proton-electron transfer to adsorbed O2 as the rate-limiting step, with CoN3S1-NiN3S1 emerging as the pivotal active site structure catalyzing this critical reaction. The fabricated Co,Ni-SAs/S,N-CNFs electrocatalyst exhibited remarkable ORR performance, characterized by a high half-wave potential of 0.84 V and a low Tafel slope of 57.9 mV dec-1. To gain a comprehensive understanding of its catalytic behavior, a tailored temperature-controlled scanning electrochemical microscopy (SECM) was employed, enabling the mapping of reactivity distribution under simulated operating conditions while preserving structural integrity. Liquid zinc-air batteries (ZABs) with this electrocatalyst excelled, reaching 175 mW/cm2 power density and enduring 1240 cycles. The electrospun membrane catalyst enabled both button and flexible ZABs, adaptable to diverse environments. This study advances non-precious metal electrocatalyst design and offers insights for ZAB applications, fostering green energy prospects.

Development of an efficient bifunctional electrocatalyst based on Co/CoSe2 nanoparticles embedded in N, Se co-doped carbon for AEMFC and rechargeable Zn-air battery

We suggest a hollow-structured N, Se dual-doped carbon framework embedded with Co/CoSe2 nanoparticles (Co/CoSe2@NSeC) as highly efficient bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The prepared electrocatalyst exhibits high electrochemical active surface area attributed to its unique hollow/porous structure and defective heteroatom doping sites. Furthermore, the strongly coupled heterojunction between Co and CoSe2 species not only provides abundant and highly active sites but also generates built-in electric field, thereby promoting electron transfer during the electrocatalytic reaction. Based on the above considerations, the prepared catalyst shows excellent bifunctional electrocatalytic performance. Leveraging the excellent ORR activity of Co/CoSe2@NSeC, alkaline exchange membrane fuel cells (AEMFC) with the Co/CoSe2@NSeC as air cathode exhibits high power density of 171.23 mW cm2. Furthermore, the rechargeable Zn-air battery employing the Co/CoSe2@NSeC shows high specific capacity (729.4 mAh gZn−1), peak power density (192.88 mW cm2), and sustained stability over 300 cycles.

Highly Porous Nitrogen and Phosphorus Dual-Doped Carbon with Increased Phosphorus Content As an Efficient Oxygen Reduction Electrocatalyst

Highly porous nitrogen and phosphorus dual-doped carbon (NPC) was synthesized using acetylene black as a carbon source in two steps: (1) solid–gas mechanochemical treatment to prepare nitrogen-doped carbon (NC), (2) heat treatment to dope the NC with phosphorus. X-ray photoelectron spectroscopy and N2 gas adsorption analysis revealed that the solid–gas mechanochemical treatment using a ball mill incorporated nitrogen atoms into the carbon network and increased the pore volume and surface area. Furthermore, the resulting NC exhibited enhanced reactivity with ammonium dihydrogen phosphate, which was used as a phosphorus source, upon heat treatment. The phosphorus content in NPC synthesized by two-step mechanochemical and heat treatments reached 1.91 at%, a 14-fold increase compared to that of phosphorus-doped carbon synthesized by heat treatment. The NPC exhibited higher electrocatalytic activity for the oxygen reduction reaction than NC, suggesting that the additional phosphorus doping into NC can improve its electrocatalytic performance.

N, P Dual-Doped Carbons as Metal-Free Catalysts for Hydrogenation.

The activation of molecule hydrogen (H2) by metal-free catalysts is always a challenge in the field of catalysis. Herein, a series of N, P dual-doped carbon catalysts were constructed by the pyrolysis of chitosan and phytic acid and utilized as metal-free catalysts for the hydrogenation of nitrobenzene. The characterization indicated that the doping of phosphorus atoms not only formed the species with catalytic activity for hydrogenation reaction but also promoted the doping of N. The experimental results indicated that their catalytic performance could be improved by the regulation of pyrolysis temperature and heating rate. CP-900-1 (pyrolysis at 900 °C with a heating rate of 1 °C/min) exhibited a promising catalytic activity with >99% nitrobenzene conversion. N, P codoping was the key factor to its catalytic performance. All results indicated that the excellent catalytic activity of CP-900-1 was attributed to the synergistic interaction among pyridinic N, P-C species, and graphitic N. This work provides an effective route for the rational design and construction of highly efficient metal-free catalysts for hydrogenation.

Phosphorous and Nitrogen Dual-Doped Carbon as a Highly Efficient Electrocatalyst for Sodium-Oxygen Batteries.

Sodium-oxygen batteries have been regarded as promising energy storage devices due to their low overpotential and high energy density. Its applications, however, still face formidable challenges due to the lack of understanding about the influence of electrocatalysts on the discharge products. Here, a phosphorous and nitrogen dual-doped carbon (PNDC) based cathode is synthesized to increase the electrocatalytic activity and to stabilize the NaO2 superoxide nanoparticle discharge products, leading to enhanced cycling stability when compared to the nitrogen-doped carbon (NDC). The PNDC air cathode exhibits a low overpotential (0.36 V) and long cycling stability (120 cycles). The reversible formation/decomposition and stabilization of the NaO2 discharge products are clearly proven by in-situ synchrotron X-ray diffraction and ex-situ X-ray diffraction. Based on the density functional theory calculation, the PNDC has much stronger adsorption (-2.85 eV) for NaO2 than that of NDC (-1.80 eV), which could efficiently stabilize the NaO2 discharge products.

Preparation and Subsequent Characterization of Sulfur and Nitrogen Dual-doped Carbon Nanotubes

Preparation and Subsequent Characterization of Sulfur and Nitrogen Dual-doped Carbon Nanotubes

A Nitrogen/Oxygen Dual-Doped Porous Carbon with High Catalytic Conversion Ability toward Polysulfides for Advanced Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) have attracted widespread attention due to their high theoretical energy density and low cost. However, their development has been constrained by the shuttle effect of lithium polysulfides and their slow reaction kinetics. In this work, a nitrogen/oxygen dual-doped porous carbon (N/O-PC) was synthesized by annealing the precursor of zeolitic imidazolate framework-8 grown in situ on MWCNTs (ZIF-8/MWCNTs). Then, the N/O-PC composite served as an efficient host for LSBs through chemical adsorption and providing catalytic conversion sites of polysulfides. Moreover, the interconnected porous carbon-based structure facilitates electron and ion transfer. Thus, the S/N/O-PC cathode exhibits high cycling stability (a stable capacity of 685.9 mA h g−1 at 0.2 C after 100 cycles). It also demonstrates excellent rate performance with discharge capacities of 1018.2, 890.2, 775.1, 722.7, 640.4, and 579.6 mAh g−1 at 0.2, 0.5, 1.0, 2.0, 3.0, and 5.0 C, respectively. This work provides an effective strategy for designing and developing high energy density, long cycle life LSBs.

Atomically dispersed Co/Mn immobilized on O, N dual doped hollow carbon spheres as sulfur host for lithium sulfur batteries

The regulation of the chemical coordination environment in the electrocatalyst can effectively suppress the shuttle effect of sulfur species in lithium-sulfur batteries. However, the mechanism of the atomically dispersed dual metal atom with the coordination of various heteroatoms used as the sulfur cathode catalyst and trapper remains unknown. This study introduces, for the first time, atomically dispersed Co and Mn in-situ immobilized on O, N dual-doped hollow carbon spheres (SACoMn/C-(N, O)) as sulfur host. Experiments combined with density functional theory calculations reveal that the synergy between Co-(N, O) and Mn-(N, O) sites enhances the nucleation/deposition and decomposition capabilities of Li2S. This enhancement is attributed to the anchoring-coupling-conversion behavior of sulfur species on the SACoMn/C-(N, O) surface, which effectively restrains the shuttle effect and facilitates the conversion kinetics. Moreover, the cooperation of dual metal atoms with O, N non-metal atoms embedded in the carbon network structure accelerates electric transport and ion diffusion kinetics. The cathode demonstrates a high initial specific capacity of 890 mAh·g−1 at 1 C and show exceptional long-term cycling durability, with a low capacity degradation of 0.037 % per cycle after 1700 cycles. This research may offer novel insights into the design of dual metal atom-decorated, functionalized carbon materials to improve the conversion reaction in sulfur cathodes.

Honeycomb-structured S and N-codoped highly graphitized carbon as a catalyst support for Rh nanoparticles: A new benchmark electrocatalyst for hydrogen evolution reaction

State-of-the-art electrocatalysts are based on catalytically active metal deposited on conductive porous carbon. Herein, we report a new strategy of engineering of a honeycomb-structured S and N dual-doped graphene-like carbon (SNG) as a supporting material for Rh catalysts by a simple low-temperature (850 °C) pyrolysis of S-doped carbon nitride (S-CN) in the presence of Mg. Interestingly, here Mg plays a marvelous dual role not only as a reducing agent for graphitizing the S-CN but also as a precursor for new Mg3N2 and MgS products, which play as pore-generating templates for honeycomb-like structures. This features highly robust graphitized carbon with excellent electrical conductivity, proper S and N content, and porosity, making it highly desirable as catalyst support. Supporting Rh (5.2 wt.%) on SNG outperforms state-of-the-art commercial Pt/C electrodes for hydrogen evolution reaction (HER) under alkaline settings (1.0 M KOH) with an extremely lower overpotential of 13 mV at 10 mA cm−2, a lower Tafel value, and a higher turnover frequency. In addition, Rh/SNG as the cathode for industrial water electrolysis in 6.0 M KOH electrolyte at 70 °C shows excellent performance with only 1.76 Vcell to achieve 500 mA cm−2 and maintains long-term durability with negligible decay. The distinctive properties of SNG, including S and N dual doping, high graphiticity, superior electrical conductivity, and honeycomb-like hierarchical meso‑ and macropore structure, are credited with this remarkable HER performance. The S and N dopants in the SNG framework optimize the electronic structure of the Rh by synergistic interaction between them as illustrated by first-principal density functional theory calculations and electronic structure analysis.

Waste tobacco-derived N, P dual-doped porous carbon loaded with heterostructured CoFe/CoFe2O4 nanoparticles for efficient oxygen electrocatalysis and Zn-air batteries

Bifunctional oxygen reduction/oxidation reaction (ORR/OER) electrocatalysts can be derived from waste biomass for implementing rechargeable Zn–air batteries, which not only turns waste into wealth, but also provides a novel approach for solving the energy crisis and promoting environmental restoration. Herein, heterostructured CoFe/CoFe2O4 nanoparticles grown on waste tobacco-derived N,P-co-doped carbon (CoFe/CoFe2O4@PNC) are constructed. Benefiting from the accelerated electron transfer due to the synergistic effect of CoFe and CoFe2O4 along with the enlarged active area owing to N,P-codoping, the CoFe/CoFe2O4@PNC electrocatalysts exhibit remarkable OER/ORR activity, reaching a half-wave potential of 0.86 V for ORR solution and driving 10 mA cm−2 by OER overpotential of 360 mV in 1.0 M KOH. Moreover, the zinc-air battery assembled with CoFe/CoFe2O4@PNC can reach a power density of 141.5 mW cm−2 and exhibit impressive durability for exceeding 300 h, which are superior to the power density and stability of zinc-air batteries assembled with precious metal-based materials. This work opens up new possibilities for preparing advanced ORR/OER catalysts for efficient Zn-based batteries.

Air-engaged synthesis of yeast biomass-derived porous O, P-codoped biochar as metal free catalyst towards water decontamination

Facile and sustainable preparation of effective metal-free catalysts using natural biomass as a feedstock is essential but challenging for peroxymonosulfate activation in degrading organic pollutants in wastewater. In this study, we develop an air-engaged pyrolysis method to successfully prepare O, P dual-doped porous carbon material (Yeast-T) using biomass yeast as a feedstock. Among the samples, Yeast-650 exhibits the highest performance in activating peroxymonosulfate towards the destruction of methyl orange, achieving a removal efficiency of 98 % in 30 min and a rate constant of 0.226 min-1. The non-radical pathway, with singlet oxygen as the active substance, dominates the destruction of methyl orange over the Yeast-650/peroxymonosulfate system. Based on the detected intermediates, four possible pathways for methyl orange degradation by the Yeast-650/peroxymonosulfate system are unveiled. The toxicity analysis of the degradation products was evaluated by calculating and comparing the radicle length of mung bean in different solutions and the germination of wheat seeds in different solutions. This study presents a simple and feasible air-mediated synthetic method for high-performance metal-free peroxymonosulfate activators in the removal of organic pollutants.

Methotrexate-loaded manganese nitrogen dual-doped carbon quantum dots as targeted nano drug-delivery system for potential use in cancer theranostics

The present work highlights manganese nitrogen dual-doped carbon quantum dots as a novel pH-sensitive drug delivery system, for the delivery of methotrexate, targeted to cancer cells, along with the simultaneous real-time monitoring of cellular uptake and drug delivery using fluorescence imaging. Briefly, methotrexate was conjugated with the as-prepared quantum dots to form a nano drug-delivery system through non-covalent interactions. The developed material demonstrated drug loading efficiency of ∼91 % and a very efficient (∼80 %) pH-responsive drug release at pH 5.5. The cytotoxic properties of the developed nano-platform viz. manganese, nitrogen dual-doped carbon quantum dots, and methotrexate conjugated manganese nitrogen dual-doped carbon quantum dot complex were evaluated in cancer cells (HeLa) and healthy human cells (L929). The conjugated complex demonstrated excellent biocompatibility, high cellular uptake, and a substantial drug release. Healthy human cells were largely unaffected when incubated with both the MTX-conjugated Mn-, N-CQD and the free drug. Additionally, in vitro, the fluorescence bio-imaging potential of the developed nano-platform was also assessed, where the unconjugated (free) quantum dots exhibited better blue fluorescence imaging potential compared to that of the conjugated complex, which can be attributed to fluorescence quenching due to the presence of methotrexate. This study highlights the manganese nitrogen dual-doped carbon quantum dots capable of pH-responsive methotrexate drug delivery selective to cancer cells. The combination of drug delivery and fluorescence imaging creates an efficient platform for targeted therapy, allowing very precise drug release while accessing non-invasive monitoring of therapeutic response. This method holds a great promise for advancing cancer treatment strategies, with the potential for increased efficacy and decreased side effects.

Nitrogen-phosphorus dual-doped auricularia auricula porous carbon as host for Li-S battery.

A nitrogen-phosphorus dual-doped porous spore carbon (NP-PSC) positive electrode matrix was prepared using native auricularia auricula as solid medium based on the principle of biomass rot. Yeast was introduce and cultured by the auricularia auricula solid medium. The freeze-drying and carbonization activation processes made the materials present a three-dimensional porous spore carbon aerogel properties. Yeast fermentation transformed auricularia auricula from blocky structure to porous structure and introduced nitrogen-phosphorus dual-doping. The physical and chemical properties of the prepared materials were characterized in detail. Electrochemical performance of NP-PSC in Li-S batteries was systematically investigated. Porous structure and heteroatom-doping improved the electrochemical performance, which is much superior to conventional activated carbon materials.

Disclosing the intrinsic nature of efficient removal of antibiotics in N/S dual-doped porous carbon-based materials: The manipulation of internal electric field

N/S co-doping has emerged as a prevailing strategy for carbon-based adsorbents to facilitate the antibiotic removal efficiency. Nevertheless, the underlying interplay among N, S, and their adjacent vacancy defects remains overlooked. Herein, we present a novel in situ strategy for fabricating pyridinic-N dominated and S dual-doped porous carbon adsorbent with rich vacancy defects (VNSC). The experimental results revealed that N (acting as the electron donor) and S (acting as the electron acceptor) form an internal electric field (IEF), with a stronger IEF generated between pyridinic-N and S, while their adjacent vacancy defects activate carbon π electrons, thus enhancing the charge transfer of the IEF. Density functional theory (DFT) calculations further demonstrated that the rich charge transfer in the IEF facilitated the π-π electron donor-acceptor (EDA) interaction between VNSC and tetracycline (TC) as well as norfloxacin (NOR), and thus is the key to adsorption performance of VNSC. Consequently, VNSC exhibited high adsorption capacities toward TC (573.1 mg g−1) and NOR (517.0 mg g−1), and its potential for environmental applications was demonstrated by interference, environmentally relevant concentrations, fixed-bed column, and regeneration tests. This work discloses the natures of adsorption capacity for N/S dual-doped carbon-based materials for antibiotics.

Pomegranate-like heterostructured SnS2/CoS2 particles encapsulated in S, N dual-doped carbon framework enabling high-rate and durable sodium ion storage

As a promising anode material for sodium-ion batteries, SnS2 has attracted increasing attention owing to its high theoretical capacity and abundant reserves. Unfortunately, the poor electrical conductivity and drastic volume changes lead to unsatisfactory cycling and rate performance, largely limiting its practical application. Herein, we report a pomegranate-like composite of heterostructured SnS2/CoS2 spheres encapsulated in S, N dual-doped carbon framework (SnS2/CoS2@SNC) obtained by a simple ion adsorption, in situ polymerization coating of polydopamine and subsequent calcination strategy. The integration of CoS2 with SnS2 particles with abundant interfaces can provide rich redox chemistry and accelerated ion diffusion kinetics, while the coated S, N dual-doped carbon shell enables good electrical conductivity and reinforced structural integrity as well by accommodating the volume changes and inhibiting the collapse/pulverization of active materials during the cycling process. As a consequence, the pomegranate-like heterostructured SnS2/CoS2@SNC anode exhibited a higher capacity (743 mAh g−1 at 1 A g−1), excellent rate capability (213 mAh g−1 at 50 A g−1) and outstanding cycling stability (560 mAh g−1 at 5 A g−1 after 1000 cycles), showing the application feasibility of this anode material for developing high-rate and durable SIBs.

Collapsed N&S dual-doped carbon nanocages as high-density anode for ultrahigh volumetric performance of Li-ion batteries

Compact lithium-ion batteries for miniaturized devices require high-volumetric-performance anodes. Either the graphite with high density or the porous nanocarbons with high gravimetric performance is limited in volumetric performance. Herein, we construct a series of anode materials, i.e. the collapsed carbon nanocages with different dopants, by capillarity compression, which achieves a high density of ∼0.97 g cm−3 but remains abundant micropores with increased active sites and enlarged interlayer distance. The N&S dual-doping redistributes the charges of sp2 carbon to an optimal status, leading to the high Li-ion capacity, meanwhile facilitates the wettability at the electrode/electrolyte interface, leading to the enhanced Li-ion diffusion coefficient. Accordingly, the collapsed N&S dual-doped carbon nanocages (cNSCNC) anode exhibits a record-high volumetric capacity of 1578 mAh cm−3 at 0.1 A g−1, excellent rate capability and cycling stability, thus achieving an ultrahigh volumetric energy density of 1087 Wh L−1 at 120 W L−1 for the cNSCNC//LiFePO4 full cell.