Dual-doped Carbon Research Articles

Nitrogen/sulfur dual-doped micro-mesoporous hierarchical porous carbon as host for Li-S batteries.

A simple hydrothermal process employing sucrose and glutathione as the source of carbon and nitrogen-sulfur, respectively, a porous carbon/sulfur composite material doped with nitrogen and sulfur (NSPCS) was synthesized. The detailed structure information of the material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The morphology information was investigated through Scanning Electron Microscope (SEM) methods. Structure of the pores and pore size distribution were investigated employing N2 adsorption-desorption isotherm. The material was treated Thermogravimetric analysis (TGA) in order to know the weight ratio of sulfur. The synthesized NSPCS composite produced high specific capacity, excellent rate performance and exceptionally good cycle stability when used as the positive electrode in Li-S batteries.

Incorporation of ZIF-67 derived Co-N/C core-shell nanoparticles on functionalized MWCNT as a highly efficient electrocatalyst for nonenzymatic H2O2 sensor

This work focuses on the fabrication of zero-dimensional (0D) and one-dimensional (1D) based nanocomposite materials for hydrogen peroxide (H2O2) sensing applications. We demonstrate an environmentally friendly synthesis approach for ZIF-67 growth on CTAB functionalized MWCNT using deionized water as a solvent medium (ZIF-67@CT-MWCNT). The pyrolysis treatment effectively formed a 0D/1D composite structure consisting of core-shell Co/N dual-doped carbon nanospheres and a CT-MWCNT network (referred to as Co-N/C@CT-MWCNT). The characteristic properties of composite materials were clearly investigated by SEM, TEM, XRD, micro-Raman, and XPS analysis. The electrocatalytic properties of Co-N/C@CT-MWCNT toward H2O2 reduction are also examined by cyclic voltammetry and amperometry techniques. The results indicated that the Co-N/C@CT-MWCNT modified electrode shows fast electron transfer kinetics for reduction of H2O2 in pH 7 electrolyte compared to other control electrodes. It mainly depends on the high catalytic activity of Co-Nx active species and the high electron conductive carbon network in the composite structure. Amperometry determination of H2O2 reduction on Co-N/C@CT-MWCNT electrode was performed at − 0.4 V (vs. Ag/AgCl), which shows rapid H2O2 sensing response time within 2 s, resulting in a wide linear range (0.5 μM - 25.74 mM) with the detection limit of 0.18 μM. The Co-N/C@CT-MWCNT sensor also showed excellent sensitivity (868.88 μA mM−1 cm−2), operational stability, and selectivity to H2O2 sensing. Thus, our proposed hybrid electrocatalyst material could be able to fabricate with commercial screen-printed carbon electrodes for the real-time H2O2 sensing application.

Pseudocapacitance-rich carbon nanospheres with graphene protective shield achieving favorable capacity-cyclability combinations of K-ion storage

Pseudocapacitance points out a new direction for the recent research and development of potassium ion anode materials because of its fast energy storage kinetics, which has yielded lots of successful pseudocapacitance-rich examples by introducing more active sites such as doped heteroatoms. However, the negative reactions with the electrolyte in electrochemical process often cause the serious inactivation of active sites, giving a hit for seeking higher pseudocapacitance. In this work we proposed a new strategy to wrap the protective shield for the pseudocapacitance-rich materials to alleviate this matter. By the ultrasonic-induced rGO self-encapsulation of S, N dual-doped carbon spheres, the directional contact between active sites and the electrolyte is blocked, while the rGO films with enlarged interlayer spacing and lots of defects also like filter membrane, accelerate the K+ desolvation and fast diffusion into carbon matrix. Benefiting from the synergistic effect of rGO shielding and filtrating, the pseudocapacitance of S, N dual-doping carbon spheres is fully activated. As the potassium-ion battery anode, the obtained S, N dual-doping carbon sphere@rGO delivers a state-of-the-art capacity of 596 mAh g−1, which achieves a 52.5 % capacity enhancement in contrast to that without rGO shield. As a proof of application, the resultant high-pseudocapacitance carbon anode is incorporated into a potassium ion hybrid capacitor, showing the most favorable capacity-cyclability combinations with the high energy–density of 83 Wh kg−1 after 6500 cycles at 5A g−1.

Facile synthesis of N/O dual-doped carbon spheres with excellent electrochemical performance

Sodium ion battery is a new energy star to meet carbon neutrality idea due to abundant resources and low price. The exploration of proper anode materials to accommodate Na+ is a significant research subject. Here, N/O dual-doped carbon spheres (NOCS) derived from polyaniline have been easily prepared via pyrolysis treatment of polyaniline spheres (PS). When applied as an anode material for SIBs, NOCS shows the superior capacity (314 mAh g−1 at 50 mA g−1), good rate performance (139 mAh g−1 at 2 A g−1) and excellent structural stability. The great electrochemical capacity of NOCS can be attributed to the unique spherical structure, large carbon interlayer distance (0.375 nm), proper specific surface area (211 m2 g−1) and abundant heteroatom content (6.27 at% of nitrogen and 14.88 at% of oxygen). NOCS also displays excellent capacitance (104.4 F g−1 at 20 A g−1) and long cycling life (145.4 F g−1 at 1 A g−1 after 5000 cycles) as an electrode material for supercapacitors. These results illustrate that designing structure and composition will effectively promote the electrochemical properties of carbon materials.

Non-Precious Metal-Doped Carbon Materials Derived From Porphyrin-Based Porous Organic Polymers for Oxygen Reduction Electrocatalysis.

The cathodic oxygen reduction reaction (ORR) is important in the development of renewable energy devices, to produce novel and non-precious metal catalysts with high electrocatalytic activity to reduce the consumption of non-renewable platinum (Pt) catalyst. In this work, we developed N-doped and Fe/N dual-doped porous carbons as catalysts for ORR simply by high-temperature pyrolysis of porphyrin-based conjugated microporous polymers (CMPs). By combination of heteroatom doping, highly porous structure and tubular morphology, the as-prepared carbon samples exhibited high electrocatalytic activity with 4-electron transfer mechanism, nearly close to the commercial Pt/C catalyst. In particular, among these samples, the Fe/N-CMP-1000 displayed a higher onset potential (0.95 eV), positive half-wave potential (0.85 eV) and limiting current density value (5.1 mA cm-2 ) as well as good durability and better methanol tolerance contrasting with Pt/C catalyst, suggesting that the as-prepared metal-free catalysts from porphyrin-based CMPs show great potential for ORR.

From Volatile Ethanolamine to Highly N, B Dual Doped Carbon Superstructures for Advanced Zn-Ion Hybrid Capacitors: Unveiling the Respective Effects Heteroatom Functionalities

Understanding the active sites of heteroatoms in carbon matrix is highly desired to design advanced Zn-ion hybrid capacitors (ZICs) with high charge storage capability. Herein, N, B dual doped carbon nanosheet covering network (BN-SCN) superstructures were successfully prepared by simply pyrolysis of volatile ethanolamine in the presence of boric acid. The intermediated product formed between ethanolamine and boric acid can prevent the ethanolamine from evaporating during the pyrolysis process. Benefiting from the N and B enriched reactants, the resulting samples have a high level of heteroatoms (6.04 at % B and 9.73 at % N), which afford sufficient pseudo-capacitance to boost the specific capacity. Consequently, the as-assembled aqueous ZIC device yielded a high capacity of 133.8 mAh g−1 at 0.1 A g−1, high specific energy of 107 W h kg−1, and an outstanding power output of 16 kW kg−1. The ex situ XPS analysis results confirm a reversible transformation of the configuration of oxygen functional groups, which can offer additional pseudo-capacitance. Except for nitrogen functional groups, the presence of abundant B containing functional groups can further enhance the chemical absorption/desorption of Zn2+ ions.

Tailored MoS2 bilayer grafted onto N/S-doped carbon for ultra-stable potassium-ion capacitor

Few-layers MoS2-based materials have a comprehensive advantage in accommodating potassium-ions due to the rich active S-Mo-S sites and rapid ionic dynamics. Unfortunately, the serious self-stacking of MoS2 molecular layer resulted in insufficient space to buffer the stress/strain caused by K-ions intercalation, which makes MoS2-based electrode exhibits low capacitance and poor cyclic stability in practical studies. To solve this, an in situ induced deposition strategy is proposed to construct a MoS2/C hybrid (labelled as NS-C@b-MoS2). In this NS-C@b-MoS2 hybrid, the MoS2 molecular with bilayer structure is grafted onto a 3D N/S dual-doping carbon skeleton in one spatial-chemical doubly confined mode. This unique hybrid mode not only expose more S-Mo-S bonds to adsorb K-ions, but also avoid the structural collapse of electrode by spatial-chemical doubly confinement effect of carbon skeleton. Consequently, the resultant NS-C@b-MoS2 anode delivers a high specific capacity of 451.2 mAh g−1 at 0.1 A g−1 and an ultra-long cycle stability up to 20,000 cycles with only 0.0013 % fading per cycle. Moreover, the assembled NS-C@b-MoS2//NSAC potassium-ion capacitor delivers a high energy density of 126.5 Wh kg−1 and retains 55.2 Wh kg−1 after 65,000 cycles at 3800 W kg−1, which over the state-of-the-art reported performance.

Experimental and DFT studies of oxygen reduction reaction promoted by binary site Fe/Co–N–C catalyst in acid

• The Fe–Co bimetallic sites were confirmed in FeCo–N–C by one-step pyrolysis. • The as-prepared catalyst achieves high ORR performance in acidic electrolytes. • The bimetallic site can result in facile cleavage of the O–O bond and thus a direct 4e − ORR process. • The FeCoNC-10 exhibits remarkable performance in DMFCs with superior methanol tolerance. The cost and efficiency issues of cathodic electrocatalyst for oxygen reduction reaction (ORR) hinder a broad application of fuel cells. Therefore, it is necessary to develop highly efficient and sustainable ORR electrocatalysts of platinum group metal-free (PGM-free). The atomically dispersed FeCoNC-10 electrocatalysts were constructed by incorporating Fe phthalocyanine (FePc) molecules into bimetallic metal–organic frameworks (BMOF) followed by one-step pyrolysis. It showed remarkable ORR activity in acidic medium compared with FeNC and CoNC catalysts. The Fe–Co bimetallic sites were confirmed in FeCo–N–C, together with abundant isolated FeN 4 and CoN 4 sites. Theoretical study revealed that the bimetallic site can enhance O 2 adsorption and elongate O–O bond length rather than FeN 4 and CoN 4 . This can result in facile cleavage of the O–O bond and thus a direct 4e − ORR process. FeCoNC-10 catalyst showed enhanced ORR stability, due to very weak Fenton-type reaction related to Co species. Membrane electrode assemblies (MEAs) consisted of the FeCoNC-10 was applied in the cathode. It showed a peak power density of 100 mW cm −2 in a direct methanol fuel cells (DMFCs) with superior methanol tolerance. This work sheds light on the mechanism of atomically dispersed Fe/Co dual-doped carbon in enhancing ORR activity and stability, which enables the cost-effective ORR electrocatalyst design to achieve robust fuel cell performance.

Gradient Supramolecular Preorganization Endows the Derived N/P Dual-Doped Carbon Nanosheets with Tunable Storage Performance toward Sodium-Ion Batteries

Gradient Supramolecular Preorganization Endows the Derived N/P Dual-Doped Carbon Nanosheets with Tunable Storage Performance toward Sodium-Ion Batteries

Large-scale doping-engineering enables boron/nitrogen dual-doped porous carbon for high-performance zinc ion capacitors

Large-scale doping-engineering enables boron/nitrogen dual-doped porous carbon for high-performance zinc ion capacitors

Metal-Free Boron/Phosphorus Co-Doped Nanoporous Carbon for Highly Efficient Benzyl Alcohol Oxidation.

An in‐depth understanding of the electronic structures of catalytically active centers and their surrounding vicinity is key to clarifying the structure–activity relationship, and thus enabling the design and development of novel metal‐free carbon‐based materials with desired catalytic performance. In this study, boron atoms are introduced into phosphorus‐doped nanoporous carbon via an efficient strategy, so that the resulting material delivers better catalytic performance. The doped B atoms alter the electronic structures of active sites and cause the adjacent C atoms to act as additional active sites that catalyze the reaction. The B/P co‐doped nanoporous carbon shows remarkable catalytic performance for benzyl alcohol oxidation, achieving high yield (over 91% within 2 h) and selectivity (95%), as well as low activation energy (32.2 kJ mol−1). Moreover, both the conversion and selectivity remain above 90% after five reaction cycles. Density functional theory calculations indicate that the introduction of B to P‐doped nanoporous carbon significantly increases the electron density at the Fermi level and that the oxidation of benzyl alcohol occurs via a different reaction pathway with a very low energy barrier. These findings provide important insights into the relationship between catalytic performance and electronic structure for the design of dual‐doped metal‐free carbon catalysts.

Boosting electrocatalysis of oxygen reduction and evolution reactions with cost-effective cobalt and nitrogen-doped carbons prepared by simple carbonization of ionic liquids

Development of cost-effective, bi-functional carbon electrocatalysts via direct carbonization of ionic liquids (bis(cholinium) tetrachlorocobaltate(II) ([Ch] 2 [CoCl 4 ]) and bis(1-butyl-3-methylimidazolium) tetrachlorocobaltate(II) ([Bmim] 2 [CoCl 4 ])) is reported herein for the first time. Carbon electrocatalysts, dual-doped with cobalt and nitrogen, were tested for oxygen reduction (ORR) and oxygen evolution (OER) reactions. Both materials show high bi-functional catalytic activity and excellent stability due to synergistic effects arising from the presence of nitrogen and cobalt. Electrocatalyst prepared by carbonization of [Ch] 2 [CoCl 4 ] show exceptional activity and selectivity toward ORR. Conversely, electrocatalyst prepared from [Bmim] 2 [CoCl 4 ] showed a slightly better OER performance indicating that different catalytic sites are responsible for O 2 reduction and H 2 O oxidation. Parent CoO particles with graphitic nitrogen boost activity for ORR, while elemental Co supported by nitrogen atoms is responsible for OER activity. Finally, energy consumption during electrolytic oxygen production was calculated revealing energy saving when using two materials as anode electrocatalysts. • Co,N dual-doped carbons are prepared by direct carbonization of ionic liquids. • A next-level of bi-functional electrocatalysts are developed for ORR and OER. • C Ch shows superior electrocatalytic performance for ORR with transfer of 4 e−. • Materials display high OER efficiencies with Tafel slope as low as 115 mV dec −1 . • Different highly active catalytic sites are responsible for efficient ORR and OER.

A Highly Efficient Sulfur Host Enabled by Nitrogen/Oxygen Dual‐Doped Honeycomb‐Like Carbon for Advanced Lithium–Sulfur Batteries

High energy density and long cycle life of lithium-sulfur (Li-S) batteries suffer from the shuttle/expansion effect. Sufficient sulfur storage space, local fixation of polysulfides, and outstanding electrical conductivity are crucial for a robust cathode host. Herein, a modified template method is proposed to synthesize a highly regular and uniform nitrogen/oxygen dual-doped honeycomb-like carbon as sulfur host (N/O-HC-S). The unique structure not only offers physical entrapment for polysulfides (LiPSs) but also provides chemical adsorption and catalytic conversion sites of polysulfides. In addition, this structure offers enough space for loading sulfur, and a regular space of nanometer size can effectively prevent sulfur particles from accumulating. As expected, the as-prepared N/O-HC900-S with high areal sulfur loading (7.4mg cm-2 ) shows a high areal specific capacity of 7.35 mAh cm-2 at 0.2 C. Theoretical calculations also reveal that the strong chemical immobilization and catalytic conversion of LiPSs attributed to the spin density and charge distribution of carbon atoms will be influenced by the neighbor nitrogen/oxygen dopants. This structure that provides cooperative chemical adsorption, high lithium ions flux, and catalytic conversion for LiPSs can offer a new strategy for constructing a polysulfide confinement structure to achieve robust Li-S batteries.

Engineering Electronic Transfer Dynamics and Ion Adsorption Capability in Dual-Doped Carbon for High-Energy Potassium Ion Hybrid Capacitors

Sodium and potassium ions energy storage systems with low cost and high energy/power densities have recently drawn increasing interest as promising candidates for grid-level applications, while the lack of suitable anode materials with fast ion diffusion kinetics highly hinders their development. Herein, we develop a nanoscale confined in situ oxidation polymerization process followed by a conventional carbonization treatment to generate phosphorus and nitrogen dual-doped hollow carbon spheres (PNHCS), which can realize superior sodium and potassium ion storage performance. Importantly, the density functional theory calculation and combined characterizations, e.g., in situ Raman spectroscopy and ex situ X-ray photoelectron spectroscopy, decipher that the P/N doping can enhance the electronic transfer dynamics and ion adsorption capability, which are responsible for enhanced electrochemical performance. Inspiringly, the practicability of the PNHCS anode is demonstrated by assembling the potassium ion hybrid capacitors (KIHCs), where the prominent energy density is 178.80 Wh kg-1 at a power density of 197.65 W kg-1, with excellent cycling stability, can be achieved. This work not only promotes the development of efficient anode material for sodium/potassium ion storage devices but also deciphers the embedded ion storage mechanism.

Upcycling of electroplating sludge into Fe3C-decorated N,P dual-doped porous carbon via microalgae as efficient sulfur host for lithium–sulfur batteries

Some crystal planes of metal compound nanocrystals play an important role in the anchoring and transformation of lithium polysulfide (LiPSs), which effectively improves the shuttle effect and electrochemical reaction kinetics of LiPSs. While, as a new generation of secondary batteries with great potential, the commercial applications of Li-S batteries are limited by rapid capacity decay due to the shuttle effect of LiPSs and large volume change of sulfur. Herein, nano-Fe3C@N,P dual-doped porous carbon microspheres (Fe3C@NPC) were designed as cathode hosts of Li-S batteries. Fe3C@NPC composite materials were prepared by upcycling mental from electroplating sludge via microalgae. The adsorption transformation of microalgae enables Fe3C nanocrystals of 10–30 nm to be evenly embedded in the N and P dual-doped carbon materials, which makes the crystal planes (220) of Fe3C nanocrystals more involved in the reaction, thus improving the coulomb efficiency and long cycle stability of Li-S battery. Besides, the hierarchically porous spherical structure with high specific surface area not only effectively adapts to the change of sulfur volume during the charging/discharging process, but also significantly increases the electrolyte contact area and shortens the Li ion transport distance. Therefore, Fe3C@NPC, as the multifunctional hosts of sulfur for Li-S batteries, realizes high catalytic activity and strong chemical binding with LiPSs, providing a high reversible coulomb efficiency (> 99%) and a high reversible capacity of 575 mAh g−1 at 1 C after 500 cycles, with low-capacity decay rates of 0.056% per cycle.

Favorable pore size distribution of biomass-derived N, S dual-doped carbon materials for advanced oxygen reduction reaction

Metal-free carbon materials offer prominent performance towards the oxygen reduction reaction (ORR). The pore size distribution of carbons plays the vital role in promoting the electrocatalytic property. Herein, a succession of N, S dual-doped carbons decorated with 3D interpenetrated hierarchically porous structure are successfully obtained through utilizing ZnCl 2 and Zn(OH) 2 as porogens during carbonizing biomass-wastes. The nanopore amounts with specific sizes can be manipulated through changing diverse biomass-wastes as precursors, while different pore sizes can be optimized by tuning the dosage ratios of ZnCl 2 to Zn(OH) 2 . Accompany with the increased amounts of nanopores with sizes of 4.6, 12, 17 and 27 nm, the ORR activity of carbon materials has been significantly promoted. These suitable pore sizes ensure the highly effecient mass transfer through providing abundantly accessible delivery channels and reactive zones for ORR-related intermediates. The optimized catalyst delivers the excellent ORR activity with a half-wave potential of 0.83 V vs. RHE as well as the remarkable long-term stability and methanol resistance ability in alkaline medium. Moreover, two series-connected Zn-air batteries with the catalysts can continuously lighten 216 LEDs over 24 h. The application of biomass-wastes to synthesize N, S dual-doped hierarchical porous carbons is beneficial for achieving the goals of turning waste into treasure. The amounts of pores with sizes of 4, 12, 17 and 27 nm show an apparent control on ORR activity according to biomass-wastes derived carbon materials, achieving the goals of turning waste into treasure and providing a rational guidance in preparing the high-performance electrocatalysts. • Continuously regulating the nanopore amount of carbon materials has been achieved. • The application of biomass-wastes realizes the goal of turning waste into treasure. • The optimized catalyst delivers the impressive ORR catalytic activity. • The assembled Zn-air battery continuously drives 216 LEDs for 24 h. • This work identifies the favorable pore size of carbon materials towards ORR.

ZnS modified N, S dual-doped interconnected porous carbon derived from dye sludge waste as high-efficient ORR/OER catalyst for rechargeable zinc-air battery

Facile and rational design of high-efficient oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts is significant for rechargeable Zinc-air batteries. In this study, ZnS modified N, S dual-doped interconnected porous carbon (ZnS/NSC) derived from the dye sludge waste is successfully fabricated via a facile ZnCl2-assisted pyrolysis process. The effect of ZnCl2 and carbonization temperature on the microstructure and electrocatalytic performance is systematically investigated. By virtue of the synergistic effect between ZnS nanoparticles and N, S dual-doped porous carbon network, the obtained catalyst ZnS/NSC calcined at 1000 °C exhibits a decent bifunctional electrocatalytic performance with potential gap (ΔE=EOER,10-EORR,1/2) of 0.76 V comparable with commercial electrocatalysts (Pt/C and RuO2). In addition, a rechargeable zinc-air battery employed ZnS/NSC-1000 as the air cathode also displays the favorable electrochemical performance, in which the power density is 125 mW cm−2, the specific capacity is 763.27 mAh g−1 and the cycling stability at 10 mA cm−2 is more than 85 h, indicating a promising application prospect in rechargeable Zinc-air batteries.

Interfacial Electron Transfer Strategy to Improve the Hydrogen Evolution Catalysis of CrP Heterostructure.

Though several Pt-free hydrogen evolution reaction (HER) catalysts have been reported, their employment for industry is challenging. Here, a facile pyrolysis method to obtain phase-pure CrP nanoparticles supported on N, P dual-doped carbon (CrP/NPC) is reported to be tuned toward industrial HER. Interestingly, CrP/NPC exhibits excellent HER activity that requires an overpotential of 34 mV to attain a current density of 10 mA cm-2 , which is only 1 mV positive to commercial Pt/C and a potential of 55 mV to achieve a current density of 200 mA cm-2 which is better than Pt/C. In addition, the long-term durability of CrP/NPC is far superior to Pt/C due to the strong interaction between CrP and C support, restricting any agglomeration or leaching. Density functional theory (DFT) calculations suggest that electronic modulation at the interface (CrP/NPC) optimizes the hydrogen adsorption energy. The Cr-Cr bridge site with required density of states near the Fermi level is found to be the active site. Overall, this report provides a practical scheme to synthesize rarely investigated CrP based materials along with a computational mechanistic guideline for electrocatalysis that can be utilized to explore other phosphides for various applications.

N/O dual-doped hierarchical porous carbon boosting cathode performance of lithium—sulfur batteries

A combination of NaOH activation and continuous pyrolysis of biomass is used to prepare N and O dual-doped hierarchical porous carbon as the carrier of Li—S batteries from egg, yolk and albumen respectively. Among the three sources, the biomass porous carbon derived from albumen has the most abundant hierarchical pore morphology. Its specific surface area, average pore diameter, and sulfur loading are 693.0 m2 · g−1, 3.1 nm and 62.0 wt.%, respectively. The albumen-derived porous carbon/sulfur (AC/S) electrode exhibits excellent reversibility and electrochemical performance (1115 mAh · g−1 at 0.05 C) due to the synergistic effect of hierarchical pore structure and element doping. The rate capacity of AC/S is 15% and 25% higher than that of egg-derived porous carbon/sulfur (EC/S) and yolk-derived carbon/sulfur (YC/S) at 2 C. And the capacity retention rate of AC/S after 50 cycles is 77%, which is 15% and 11% higher than those of EC/S and YC/S, respectively.

N, P Dual-Doped Porous Carbon Nanosheets for High-Efficiency CO2 Electroreduction

N, P Dual-Doped Porous Carbon Nanosheets for High-Efficiency CO₂ Electroreduction