N-doped Amorphous Carbon Research Articles

Highly efficient charge transfer from small-sized cadmium sulfide nanosheets to large-scale nitrogen-doped carbon for visible-light dominated hydrogen evolution

Slow charge transfer and carrier recombination are key issues in photocatalytic reactions. The current solution is to load small-sized cocatalysts onto large-sized photocatalysts. Here a new strategy is proposed. Small-sized photocatalysts of cadmium sulfide (CdS) nanosheets are grown onto large-sized cocatalysts of N-doped amorphous carbon (a-CN) to construct CdS @ a-CN photocatalysts. Photoluminescence spectra and transient photocurrent demonstrate that optimized CdS @ a-CN shows effective charge separation compared with CdS. The corresponding photocatalytic H2 yield of optimized CdS @ a-CN is ∼244 μmol, which is 3.6 times higher than that of CdS. Besides, the hydrogen yield for CdS under visible-light irradiation is significantly improved from ∼44 μmol to ∼217 μmol for the optimized CdS @ a-CN. Our design strategy provides an effective way to construct photocatalytic systems with outstanding photocatalytic performance.

Engineering structure constructed CoP anode with enhanced bulk phase diffusion ability for superior potassium-ion storage

Due to its considerable theoretical capacity and high availability through conversion reaction, CoP is regarded as a promising candidate for potassium-ion batteries (PIBs). However, huge volume change and low intrinsic conductivity seriously impede the further development of CoP anode in PIBs. Generally, structural design and composition regulation can well improve potassium storage performance of CoP via increasing capacitive contribution rate, but are unfavorable for realizing a high energy density in a K-full cell. Therefore, how to optimize the bulk phase diffusion ability of CoP to enhance the diffusion-dominated potassium storage is of great importance. Herein, CoP nanoparticles (about 20–40 nm) with enormous voids embedded in carbon-cage structure encapsulated in N-doped amorphous carbon are reported (CoP/C@NC-PDA), in which CoP particles with appropriate nano-size benefit the bulk phase diffusion process. Besides, the existence of amorphous carbon coating layer and voids can provide sufficient space to buffer volume expansion, while carbon-cage architecture and its high graphitization degree accelerate fast ions/electrons transfer, respectively. As a result, CoP/C@NC-PDA achieves an excellent diffusion-controlled capacity ratio (77.5% at 0.05 A g−1, 75.0% at 1.0 A g−1), and a good cycle lifespan over 1000 cycles with nearly 100% Coulombic efficiency.

Phase-Controlled Synthesis of Nickel-Iron Nitride Nanocrystals Armored with Amorphous N-Doped Carbon Nanoparticles Nanocubes for Enhanced Overall Water Splitting.

Transition metal nitrides (TMNs) nanostructures possess distinctive electronic, optical, and catalytic properties, showing great promise to apply in clean energy, optoelectronics, and catalysis fields. Nonetheless, phase-regulation of NiFe-bimetallic nitrides nanocrystals or nanohybrid architectures confronts challenges and their electrocatalytic overall water splitting (OWS) performances are underexplored. Herein, novel pure-phase Ni2+ x Fe2- x N nanocrystals armored with amorphous N-doped carbon (NC) nanoparticles nanocubes (NPNCs) are obtained by controllable nitridation of NiFe-Prussian-blue analogues derived oxides/NC NPNCs under Ar/NH3 atmosphere. Such Ni2+ x Fe2- x N/NC NPNCs possess mesoporous structures and show enhanced electrocatalytic activity in 1m KOH electrolyte with the overpotential of 101 and 270mV to attain 10 and 50mAcm-2 current toward hydrogen and oxygen evolution reactions, outperforming their counterparts (mixed-phase NiFe2 O4 /Ni3 FeN/NC and NiFe oxides/NC NPNCs). Remarkably, utilizing them as bifunctional catalysts, the assembled Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC electrolyzer only needs 1.51V cell voltage for driving OWS to approach 10mAcm-2 water-splitting current, exceeding their counterparts and the-state-of-art reported bifunctional catalysts-based devices, and Pt/C||IrO2 couples. Additionally, the Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC manifests excellent durability for OWS. The findings presented here may spur the development of advanced TMNs nanostructures by combining phase, structure engineering, and hybridization strategies and stimulate their applications toward OWS or other clean energy fields.

Hollow nanospheres constructed by ultrafine few-layered MoS2 partially with amorphous fragments homogeneously incorporated in N-doped amorphous carbon for enhanced lithium storage performance

The rational design of ultrathin and few-layered structures for three-dimensional MoS2 nanospheres is crucial for achieving attractive lithium-ion batteries (LIBs). Herein, hollow nanospheres constructed by ultrafine and few-layered MoS2 homogeneously incorporated in N-doped amorphous carbon (HUF-MoS2/NC) have been successfully synthesized as high-performance anode for LIBs. Using Mo-glycerol spheres as templates and dopamine hydrochloride as coordination ligands, hollow Mo-glycerol-polydopamine precursors are formed with Mo-containing groups which are surrounded by organic carbon species. Consequently, the MoS2 is confined to the nanoscale and grows partially amorphous fragments while being uniformly embedded in NC. This unique architecture can not only hinder the substantial restacking between MoS2 interlayers, offering more active sites, but also vastly enhance the electrical conductivity and relieve the mechanical stress ascribed to volume changes. As a result, the HUF-MoS2/NC composite anode exhibits excellent cyclic stability (980mAhg−1 after 300 cycles at 0.2Ag−1) and superior rate performance (498mAhg−1 at 5.0Ag−1) for LIBs.

Interconnected 3D carbon network with enhanced reaction kinetics and architecture stability for advanced potassium-ion hybrid capacitors.

Due to their high energy/power densities and ultralong cycle lifespan, potassium-ion hybrid capacitors (PIHCs) have attracted increasing research interest for large-scale energy storage systems. However, the kinetics mismatch between the battery-type anodes and capacitor-type cathodes severely hampers the further development of PIHCs. Herein, the kinetics-enhanced N-doped amorphous porous carbon with an interconnected three-dimensional (3D) network (marked as NPC) is reported. The existence of an amorphous configuration can provide numerous storage potassium sites, while the interconnected 3D network contributes to electron transfer, thus improving the reversible capacity and reaction kinetics of NPC. The expanded carbon interlayer spacing, well-established porous structure and plentiful active sites induced by N-doping greatly boost the structural stability and further increase kinetics. Benefiting from these structure merits, the NPC electrode delivers a high capacity (257.7 mA h g-1 at 0.5 A g-1), an excellent rate capability (199.5 mA h g-1 at 2 A g-1), and an extraordinary cycling stability over 3000 cycles at 2 A g-1. Moreover, coupling with activated carbon (AC) cathode and NPC anode, the assembled PIHCs exhibit ultra-large energy/ultra-high power density (177.3 W h kg-1 and 19348.3 W kg-1) with a long cycling life (81.6% capacity retention after 3000 cycles).

Popcorn-like Co3O4 nanoparticles confined in a three-dimensional hierarchical N-doped carbon nanotube network as a highly-efficient trifunctional electrocatalyst for zinc–air batteries and water splitting devices

A novel unique 3D hierarchical structural electrocatalyst is synthesized, where popcorn-like Co3O4 nanoparticles coated with N-doped amorphous carbon anchor onto the tips of N-doped carbon nanotubes (NCNTs), and the NCNTs grow on carbon nanofiber.

Rational Construction of Atomically Dispersed Mn-Nx Embedded in Mesoporous N-Doped Amorphous Carbon for Efficient Oxygen Reduction Reaction in Zn-Air Batteries

Rational Construction of Atomically Dispersed Mn-N_<i>x</i> Embedded in Mesoporous N-Doped Amorphous Carbon for Efficient Oxygen Reduction Reaction in Zn-Air Batteries

An individual sandwich hybrid nanostructure of cobalt disulfide in-situ grown on N doped carbon layer wrapped on multi-walled carbon nanotubes for high-efficiency lithium sulfur batteries

Binding and trapping of lithium polysulfide (LPS) are being conceived as the most effective strategies to improve lithium-sulfur (Li-S) battery performance. Therefore, exploiting a simple but cost-effective approach for the absorption and conversion of LPS and the transfer of electrons and Li+ ions is of paramount importance. Herein, sandwich structure MWCNTs@N-doped-C@CoS2 integrated with multiple nanostructures of zero-dimensional (0D) CoS2 nanoparticles, 1D carbon nanotubes (CNTs), and 2D N-doped amorphous carbon layer was obtained, where MWCNTs was firstly uniformly attached with a polydopamine (PDA) of excellent adhesion, followed by hydrothermal method, the Co2+ nanoparticles were in-situ grown on the PDA by the formation of complex compound of Co2+ and N atoms in PDA, and then the CoS2 nanoparticles were in-situ grown on CNTs in a point-surface contact way by a bridging of N-doped amorphous carbon layer derived from the carbonization of attached PDA after the vulcanization at 500 °C under Ar atmosphere. The multifunction synergism of absorption, conductivity, and the kinetics of LPS redox is significantly improved, consequently effectively suppressing the shuttle effect and tremendously increasing the utilization rate of active substance. For the Li-S battery assembled with MWCNTs@N-doped-C@CoS2-modified separator, its rate capacity and cycling performance can be greatly enhanced. It can exhibit a high initial discharge capacity of 1590 mAh g−1 at 0.1 C, a stable long-term cycling performance with a relatively low capacity decay of 0.07% per cycle during 500 cycles at 1 C, and a reversible capacity of 772 mAh g−1 and a capacity decay of 0.04% per cycle during 250 cycles at 2 C. Even at a large current density of 4 C, an initial specific discharge capacity of 634 mAh g−1 can still be delivered. With a high sulfur loading of 5.0 mg cm−2, additionally, an outstanding cycling stability can also be well maintained at 685 mAh g−1 at 0.1 C after 50 cycles. This work provides a novel and simple but effective strategy to develop such sandwich hybrid materials comprised of polar metal sulfides and conductive networks via an effective bridging to help realize durable and stable Li-S battery.

Electromagnetic response characteristics of lightweight hierarchical 2D nitrogen-doped graphene@amorphous carbon

Two dimensional (2D) nitrogen-doped graphene@amorphous carbon was constructed by in-situ polymerization of sandwich-like structured polyaniline/graphene oxide composites then carbonization at 650 °C in vacuum. The results revealed that the as-prepared 2D N-doped graphene@amorphous carbon and N-doped amorphous carbon nanorods have almost the same decomposition degree and crystal structure. However larger defective degree and more polar bonds are conducive to enhance the polarization loss capacity, and larger dielectric constant can contribute to prominent conductive loss potential. The standing-wave ratio at 13.325 GHz of 2D N-doped graphene@amorphous carbon is 1.08426 approaching to 1, almost perfect impedance-matching level achieving. HFSS simulations certify phase mutation, group delay and the resonance response between N-doped graphene@amorphous carbon and testing microwave, as well as the stronger microwave loss capacity and better impedance matching. Both of the above make 2D N-doped graphene@amorphous carbon a promising microwave absorbing material. The minimum reflection loss (RL) of nitrogen-doped graphene@amorphous carbon can reach −29.5 dB and the effective absorbing bandwidth (EAB, RL < −10 dB) can reach 5.355 GHz ranging from 12.56 to 17.915 GHz only at a thickness of 2.25 mm.

Bimetallic MOF-derived CoSe2 embedded within N-doped carbon with enhanced lithium storage properties

Transition metal selenides are considered to be a potential anode material for lithium-ion batteries (LIBs) owing to their excellent electronic conductivity and high theoretical capacity. However, the application of transition metal selenides electrodes is still limited by their large volume expansion and sluggish kinetics during cycling. Herein, CoSe2 nanoparticles embedded in N-doped carbon nanotubes (CNTs) and carbon layer (CoSe2@NC) were constructed by pyrolysis of CoZn-based zeolitic imidazolate framework (CoZn-ZIFs) and melamine mixtures followed by selenization. During the pyrolytic process, the volatilization of zinc derived from CoZn-ZIFs, the retardation of the complete decomposition of g-C3N4 derived from melamine by Zn species played important roles in the formation of enriched N-doped carbon nanotubes (CNTs) and amorphous carbon layer. As a result, CoSe2@NC could show a large reversible lithium-ion storage capacity of 395 mAh g−1 at 0.5 A g−1 over 200 cycles, good rate capabilities of 367 mAh g−1 even at 2 A g−1, which outperformed CoSe2@NC-1 and CoSe2@NC-2 derived from carbonization of Co-Zn-ZIFs and Co-ZIF/melamine precursors followed by selenization, respectively. The enhanced lithium storage performance of CoSe2@NC could owe to the unique structure, where the N-doped CNTs and amorphous carbon layer can provide a rapid electron transfer channel and enable surface-dominated pseudocapacitive lithium storage, and the robust interface between CoSe2 and carbon can also effectively alleviate the volume expansion and enhance the integrity during the charge-discharge process.

Nickel-Iron nitrides and alloy heterojunction with amorphous N-doped carbon Shell: High-efficiency synergistic electrocatalysts for oxygen evolution reaction

Transition metal nitrides have received a great deal of attention as highly efficient OER catalysts due to their excellent electrical conductivity, which grants them lower overpotential values than precious metal oxide catalysts (RuO2, IrO2, etc.). Herein, we report the characteristics of Nickel-Iron nitrides, alloy heterogeneous nanostructures (Ni2Fe2N, Ni2Fe2N/Ni3Fe, Ni3Fe/Ni2Fe2N), and amorphous N-doped carbon shells differing only in nitridation temperature. Heterogeneous Nickel-Iron nitrides and alloy with amorphous N-doped carbon shells showed superior OER performance such as a low overpotential value of 251 mV at current density of 10 mA/cm2, Tafel slope of 35.0 mV/dec, and great stability even after 24 h. Additionally, this study accurately identified that the heterogeneous nanostructure and amorphous N-doped carbon shell improve the catalytic properties and durability of the Nickel-Iron nitrides and alloy nanoparticles. The morphological control strategy used to produce the heterogeneous nanostructure and amorphous N-doped carbon shell can be applied to improve electrochemical properties or encapsulation in strong alkaline solution.

Layered VO2@N-doped carbon composites for high-performance rechargeable aqueous zinc-ion batteries

The electrochemical performance of rechargeable aqueous zinc-ion batteries (AZIBs) to a great extent depends on the conductivity and structural stability of the cathode material. Herein, we report a facile calcination process to prepare the composite of VO2 and amorphous N-doped carbon using ultrathin V6O13 nanobelts coated with polydopamine as precursors. The amorphous structure of N-doped carbon enables the layered VO2@N-doped carbon composites to have more active sites and higher conductivity, and the amorphous structure has less structural change during ion diffusion. Therefore, the VO2@N-doped carbon composites exhibit excellent electrochemical performance. This work should open a new and efficient avenue for designing the cathodes of AZIBs with excellent performance.

Amorphous CoS1.4 ultrathin nanosheets/amorphous N-doped carbon nanobox: A dual-amorphous confined structure for superior potassium storage

Potassium-ions batteries (KIBs) are regarded as an alternative to lithium-ion batteries (LIBs) owing to their affordable cost, abundance and high working voltage. Transition metal sulfides (TMSs) are considered to be attractive anode materials for KIBs, but the practical development is hampered by their inferior conductivity and large volume expansion upon potassiation/depotassiation process. Herein, we report a dual-amorphous confined structure composing of amorphous CoS1.4 ultrathin nanosheets confined in amorphous N-doped carbon nanobox (a-CoS NS/NCB) as an anode material for KIBs. The isotropic nature of amorphous CoS1.4 ultrathin nanosheets (about four atomic layers in thickness) can effectively accommodate volume strain as well as decrease the resistance of the carrier to phase transition due to their high level of disorder. Besides, the amorphous N-doped carbon nanobox has the advantages of enhancing electronic conductivity, avoiding the direct contact of active material and electrolyte and restraining the excessive growth of solid electrolyte interphase film. As a result, the a-CoS NS/NCB anode delivers a capacity of 235.3 mAh g−1 at 100 mA g−1 after 800 cycles. While the results prove the new anode is a promising candidate for KIBs, it also opens the door for broader application of amorphous composite in metal-ions batteries.

Co-Catalyzed Synthesis of Primary Amines via Reductive Amination employing Hydrogen under very mild Conditions.

Nanostructured and reusable 3d‐metal catalysts that operate with high activity and selectivity in important chemical reactions are highly desirable. Here, a cobalt catalyst was developed for the synthesis of primary amines via reductive amination employing hydrogen as the reducing agent and easy‐to‐handle ammonia, dissolved in water, as the nitrogen source. The catalyst operates under very mild conditions (1.5 mol% catalyst loading, 50 °C and 10 bar H2 pressure) and outperforms commercially available noble metal catalysts (Pd, Pt, Ru, Rh, Ir). A broad scope and a very good functional group tolerance were observed. The key for the high activity seemed to be the used support: an N‐doped amorphous carbon material with small and turbostratically disordered graphitic domains, which is microporous with a bimodal size distribution and with basic NH functionalities in the pores.

Interface Engineering Based on Multinanoscale Heterojunctions between NiO Quantum Dots, N-Doped Amorphous Carbon and Ni for Advanced Supercapacitor

Energy storage ability is determined by the ion arrangement and electron transfer at the electrode–electrolyte interface, which depends on combining materials that form complex heterogeneous interf...

Sodium-storage behavior of electron-rich element-doped amorphous carbon

In recent years, sodium ion batteries (SIBs) have been widely investigated due to limited lithium resources. Though sodium and lithium elements have similar physical and chemical properties, some decently performing anodes of lithium ion batteries are problematic in SIBs. Hence, it is of great importance to develop suitable anodes for SIBs. In recent works, doped amorphous carbon has been considered a prospective and serviceable anode for the storage of sodium. Nevertheless, there is no commonly accepted explanation for the sodium storage mechanism and doping effect of doped carbon to explain why doping can improve the sodium-storage performance in SIBs. In this study, sodium-storage behavior in electron-rich, element-modified, amorphous carbon is addressed, considering N and P. The affinity of N-doped amorphous carbon is identified by calculating the electron distributions of the N-doped structures. Furthermore, the adsorption energies of sodium in the P-doped amorphous carbon systems are analyzed to elucidate the storage behavior of doping. From the above analysis, the internal structure of co-doped carbon is characterized and pyrrolic N and P-O structures reveal excellent sodium-storage performance. Consequently, hydrothermal treatment is designed to build the precursor of the required P-O structure. Based on the sodium-storage theory, a carbon anode doped with dual electron-rich elements is synthesized successfully, which shows enhanced electrochemical performances in terms of cycle life and capacity in batteries. As a result, these research results fill the theoretical gap of the sodium-storage behavior of electron-rich, element-doped, amorphous carbon and provide the experimental basis for its application.

Rationalized atomic/clusters dispersion of Fe/Se/Al on interconnected N-doped carbon nanofibers for fast sodiation

The greater availability of sodium with large storage capacity motivates the fabrication of advanced electrodes materials for sodium ion batteries (SIBs) to promote in potential market of smart appliances. Multiple metals atomic dispersion into carbon framework can enhance the adsorption property of sodium for high performance SIBs. In this work, rationalized atomic/clusters of Fe/Se/Al are dispersed on N-doped amorphous carbon fibers through electrospinning and direct selenization (DS) processes. The developed product of DS-Fe/Se/Al@NC-650 nanofibers are employed as anode materials of SIBs, exhibitinga high specific capacity of 432 mAh g−1 at 100 mA g−1 a desirable cycling stability with a capacity retention of 99 % after 700 cycles. Such an excellent storage capacity initiates through synergistic effects of the uniformly distributed Fe/Se/Al and the interconnected nitrogen-doped carbon network. For the apprehension of capacity and stability of DS-Fe/Se/Al@NC-650 nanofibers for SIBs, the theoretical calculations were carried out and provide strong evidences which proves the electron/ion transport in experimental results.

A durable MXene-based zinc ion hybrid supercapacitor with sulfated polysaccharide reinforced hydrogel/electrolyte

A N-doped MXene wrapped with N-doped amorphous carbon was synthesized. DFT results reveal an enlarged work function of N-Ti3C2(OH)2@N–C. A durable MXene-based ZHSC with reinforced PAM-co-PAA/κ-CG/ZnSO4 hydrogel demonstrates excellent electrochemical performance.

Synthesis of N-doped straw sheaf–like porous MnO@C composite as anode of advanced lithium-/sodium-ion batteries

N-doped straw sheaf–like porous MnO@C composite is synthesized through a L-histidine-assisted hydrothermal method with consequent annealing in Ar. The straw sheaf–like porous structure is assembled by MnO nanoparticles with a diameter of ~ 15 nm and be uniformly wrapped in amorphous N-doped carbon matrix. MnO@C-N displays attractive electrochemical properties when used as anode of lithium-/sodium-ion batteries. A high reversible capacity of 832.5 mA h g−1 could be obtained at 100 mA g−1 in LIBs and 250 mA h g−1 at 50 mA g−1 with outstanding cycling stability in SIBs. The study also compared MnO@C-N with commercial MnO particles in LIBs and shows that MnO@C-N anode has excellent cycling performance with 614.0 mA h g−1 retained after 200 cycles. However, commercial MnO displays only 413.5 mA h g−1 after 132 cycles. The present synthesis strategy opens the possibility of fabricating MnO@C-N nanocomposites for high-performance batteries.

Iron oxide modified N-doped porous carbon derived from porous organic polymers as a highly-efficient catalyst for reduction of nitroarenes

Fabrication of cost-effective non-noble metal-based catalysts is significant for heterogeneous catalysis. Here, we prepared a porous organic polymer (POP) through the facile condensation of p-phenylenediamine with ferrocene carboxaldehyde, and then the ferrocene-functionalized POP material was carbonized under inert atmosphere, obtaining the γ-Fe2O3 nanoparticles (NPs) modified N-doped porous carbon catalyst (γ-Fe2O3/NPC). Various characterizations (such as XRD, BET, TEM and XPS etc.) indicated that the obtained γ-Fe2O3/NPC catalyst exhibits unique structural properties with uniformly dispersed γ-Fe2O3 species, porous morphology, and N-doped defective amorphous carbon. The γ-Fe2O3/NPC catalyst shows excellent activity in the catalytic reduction of nitroarenes with hydrazine hydrate as reductant. The synergistic effect between γ-Fe2O3 NPs and N-doped porous carbon improve the hydrazine hydrate adsorption and activation for active hydrogen atoms production, which is beneficial for nitroarenes reduction. Moreover, the γ-Fe2O3/NPC catalyst could be easily recycled by using a magnet and reused without obviously loss of catalytic activity. Therefore, this work should provide a useful platform for designing and fabricating stable non-noble metal NPs based catalysts derived from POP materials that have potential for various catalytic applications.