Dual-doped Carbon Research Articles

Fast and stable potassium-ion storage achieved by in situ molecular self-assembling N/O dual-doped carbon network

Nitrogen and oxygen dual-doped amorphous carbon network (NOCN) facilely prepared via self-assembly method in this study as potassium ion battery’ anode for ultra-long and superior-rate capability. The as-synthesized NOCN exhibits an excellent reversible capacity of 464.9 mAh g-1 at 0.05 A g-1, outstanding performance of 175 mAh g-1 at a high current density of 5.0 A g-1, and ultra-long cycling performance with capacity decay less than 0.008% per cycle. The superior performance can be attributed to the unique ultra-stable network structure together with N and O co-doped. Supported by detailed fundamental analysis, the higher K-ion storage process in NOCN is contributed by the pseudocapacitive mechanism. The simple synthesis route as well as the hopeful electrochemical property shed a new insight into the quest for carbon-based K-storage anode materials with high energy and long-cycling life.

Design of a Functionalized Carbon Cloth Substrate for a Ni and Co-Based High-Performance Supercapacitor

Depressed reaction kinetics due to the electrochemical properties of transition metal materials themselves and a discordant coexistence relationship between substrates and these kinds materials remain major problems in developing high-performance supercapacitors (SCs). Here, a functionalized N, P dual-doped porous carbon cloth (NPPCC) substrate is designed using cotton spinning cloth as the original material, and the following NPPCC-supported Ni and Co bimetallic sulfide (NPPCC-BS) is applied to construct an SC. The porous carbon networks with structural defects and heteroatom doping exhibited in such a novel substrate are beneficial to not only robust and well-conditioned growth of active materials but also improved interface interrelation, thereby resulting in enhanced reaction kinetics of the hybrid electrode via strong coupling effect and stable combination between substrate and active materials. Accordingly, the NPPCC-BS electrode as positive electrode is fabricated into an all-solid-state asymmetric SC device; this device delivers high energy storage and supply capacity (45.8 Wh kg–1 at 15.7 kW kg–1) and an excellent long-term cycling life (88.6% capacity retention after 15000 cycles).

Nitrogen/sulfur dual-doped sponge-like porous carbon materials derived from pomelo peel synthesized at comparatively low temperatures for superior-performance supercapacitors

Pomelo peel is a popular biomass material that is eco-friendly and widely distributed worldwide. However, a large amount of pomelo peel is directly discarded instead of being utilized. This study synthesizes nitrogen/sulfur dual-doped porous carbon materials using pomelo peel and ammonium persulfate, followed by potassium hydroxide (KOH) activation at 600°C, which is lower than most average activation temperature. The as-obtained products are electrode materials applied in supercapacitors. Results indicate that the as-prepared nitrogen/sulfur dual-doped porous carbon material (NSC-600) has high nitrogen (5.89%) and sulfur (0.46%) contents, and a large surface area (1193m2g−1). As the current density is 0.5 A g−1, the specific capacitance of the NSC-600 material up to 310Fg−1. After 10,000cycles, the capacity retention is approximately 98.8% at a current density of 2 A g−1 in 6M KOH, which indicates outstanding cycling performance. Moreover, the assembled symmetric electrochemical capacitor exhibits a high energy density of 21.4Whkg−1 at a power density of 259.9Wkg−1. Therefore, the nitrogen/sulfur dual-doped porous carbon materials synthesized at comparatively low temperatures exhibit promising applications in superior-performance supercapacitors.

Onium salts-derived B and P dual-doped carbon microspheres as anode material for high-performance sodium-ion batteries

Boron (B) and phosphorus (P) dual-doped carbon microspheres (BPC) were successfully synthesized from onium salts by a facile one-step pyrolysis method. When employed as the anode material for sodium (Na)-ion batteries (NIBs), the resulting BPC delivers a reversible capacity of 221.9 mAh g−1 at 50 mA g−1. Impressively, the BPC can still deliver a capacity of 102 mAh g−1 after 1500 cycles at 1 A g−1 with the capacity retention up to 78%. The high performance of the BPC can be attributed to the significantly increased defects and dilated interlayer distance induced by synergistically B and P co-doping.

Greatly improved HER electrocatalytic activity by the composite of CoSe2 and N, S-dual doped graphitic carbon

Abstract Several composite catalysts were facilely fabricated by hydrothermal supporting CoSe2 on N, S dual-doped graphitic mesoporous carbon (SDGC) synthesized by pyrolyzing thiocarbamide and in-situ formed phenolic resin. The synthesized CoSe2/SDGC composites were characterized to have mesoporous structure distributed on the carbon matrix covered with the sphere like aggregates of CoSe2. Their electrocatalytic performances were evaluated by hydrogen evolution reaction (HER) in 0.5 M H2SO4. The results have shown that the as-prepared catalysts exhibited highly improved electrocatalytic activities for HER compared with the pristine CoSe2 and SDGC. Especially, the composite CoSe2/SDGC-60 with the optimized ratio of CoSe2 to SDGC has exhibited the highest electrocatalytic activity. The catalyst has obtained the lowest overpotential and Tafel slope of 203 mV (at 10 mA/cm2) and 58 mV/dec, respectively. It also showed impressive durability against 0.5 M H2SO4 and the electrocatalytic activity hardly decreased even after 5000 cycles.

Bi-structural fibers of carbon nanotube coated with nitrogen/oxygen dual-doped porous carbon layer as superior sulfur host for lithium-sulfur batteries

Lithium-sulfur batteries are one of the most promising secondary energy storage systems. However, their fast capacity fading and low reaction kinetics still remain a challenge. In the present study, a unique bi-structural porous carbon hybrid of fibers with carbon nanotube as core and nitrogen/oxygen dual-doped porous carbon as coating layer is synthesized by a self-assembly approach. The one-dimensional (1D) hybrid has large surface area, high porosity, rich nitrogen/oxygen dual-doping and high conductivity, which is admirable as sulfur host for lithium-sulfur battery cathodes. This novel structural carbon host enables the sulfur cathode a significant cyclic stability and superior rate capability. With a sulfur loading as high as 75 wt%, the sulfur cathode achieves an initial capacity of 1110 mAh g−1 and a capacity of 684 mAh g−1 retains after 200 cycles at 0.2 C. This work offers a new structural 1D porous carbon host and its fabrication method for high efficiency sulfur cathodes.

Co based N, S co-doped carbon hybrids for catalytic hydrogenation: Role of cobalt salt and doped S

A series of Co-based N, S dual-doped carbon catalysts were prepared successfully via the pyrolysis of porous organic polymers (POPs) impregnated with cobalt salt and characterized by TEM, XRD, XPS, etc. The successful construction of cobalt-nitrogen (Co-Nx) sites is confirmed by XPS spectra. It was found that the content of Co-Nx sites is markedly affected by the type of cobalt salt, and the catalyst derived by the pyrolysis of the complex of POPs with Co(NO3)2·6H2O displays the best activity and outstanding selectivity for catalytic hydrogenation of various aromatic nitro compounds, it also demonstrates good recyclability. According to the results of control experiments, the activity for catalytic hydrogenation is mainly attributed to the Co-Nx sites. In addition, the doped S species in carbon shells can promote the formation of the active sites, which can effectively improve the performance of catalysts. Thus, this work can provide an effective and green approach for design highly effective transition metal-based multi-doped carbon catalysts with abundant metal-Nx sites.

S, N co-doped rod-like porous carbon derived from S, N organic ligand assembled Ni-MOF as an efficient electrocatalyst for oxygen reduction reaction

Efficient catalyst for the oxygen reduction reaction (ORR) is of significance in the development of fuel cell and metal-air battery technologies. Heteroatom doped carbon materials have been considered as one of most promising alternatives to Pt-based catalysts. In this work, we exploit a nitrogen and sulfur dual-doped one-dimensional carbon rod catalyst with porous graphene-like layers on the surface derived from a Ni based metal-organic framework (MOF). The Ni-NSPC-6 catalyst with uniform distribution of N and S atoms in the carbon skeleton possesses a porous structure and a considerable specific surface area. Benefited from the special one-dimensional morphology, the convenient channel provided by the porous structure, the synergistic effect from the homogeneous co-doping of N and S, and the existence of proper amount of Ni3S2, the Ni-NSPC-6 affords a remarkable electrocatalytic performance toward ORR, including positive onset and half-wave potentials, a high catalytic current density, a low Tafel slope for oxygen reduction reaction and a remarkable ORR durability. The controllable synthesis of MOF derived S, N co-doped carbon materials with porous nanostructure will offer prospects in developing high performance electrocatalysts.

Nitrogen and Fluorine Dual-Doped Carbon Nanosheets for High-Performance Supercapacitors

Doping carbon materials with heteroatoms such as N, F is an effective approach to elevating the capacitive performance of supercapacitors. In this paper, nitrogen and fluorine dual-doped two-dimensional (2D) porous carbon nanosheets (PCNSs) have been fabricated by a straightforward template carbonization method, using trisodium citrate as carbon source and self-template, and ammonium fluoride as N/F dopants. The N/F-doped carbon samples are well characterized by a series of techniques and measured in a three-electrode system and two-electrode system, respectively. As a result, N/F-doped carbon has delivered large capacitance of 110[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text] and high-energy density of 3.82[Formula: see text]W h kg[Formula: see text] at the power density of 0.5[Formula: see text]kW[Formula: see text]kg[Formula: see text]. It is also revealed that semi-ionic C–F bonds in PCNSs have enhanced electrical conductivity, hence, facilitating electron transport in the electrode. For comparison, ammonium chloride is used as sole dopant for producing N-doped carbon materials, whose capacitive performances are much lower than the N/F-codoped one, indicating the synergistic effect of N/F for capacitive improvement.

A nitrogen, sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline coating for high-performance sodium-selenium batteries

Sodium-selenium (Na-Se) battery has been emerging as a new rechargeable energy storage system with high capacity, low cost and high rate capability. However, the shuttling of polyselenides from the cathode to the anode causes dramatic capacity decay, severely impeding their practical applications. Herein, we report a combinational strategy of nitrogen and sulphur dual-doped hierarchical porous carbon with interconnected conductive polyaniline (PANI) coating to incorporate Se as stable cathodes (i-PANI@NSHPC/Se) for Na-Se batteries. Ex situ characterizations and density functional theory (DFT) calculations demonstrate that the i-PANI@NSHPC/Se cathode can provide both physical diffusion barrier and strong chemical affinity for polyselenides. In addition, the interconnected conductive polyaniline network enhances the conductivity for electrons and ions. With this strategy, the i-PANI@NSHPC/Se cathode delivered a high reversible capacity of 617 mAh g−1 after 200 cycles at 0.2C with a low capacity decay rate of 0.013% per cycle and an excellent rate capability at 20 C. Importantly, stable cycling performances were achieved with high capacities at different Se areal mass loadings (1.2, 2.3, 3.5 mg cm−2). This work could provide an efficient approach for developing Na-Se batteries with high active material mass loading, high rate capacity and long cycle life.

Sulfur and nitrogen dual-doped porous carbon nanosheet anode for sodium ion storage with a self-template and self-porogen method

The porous carbon nanosheets (as thin as 8 nm) doped with sulfur and nitrogen have been synthesized by directly carbonizing laminaria japonica with a self-template and self-porogen method. Laminaria japonica contains plenty of sodium chloride and potassium compounds, which can be a natural template and the natural porogen, respectively. The obtained carbons possess a three-dimensional connected nanosheet structure with a large specific surface area of 1900 m2 g−1, a total pore volume of 1.04 cm3 g−1, a pore size distribution centering mainly at around 1.4 nm and 2.7 nm, a S-content of 9.12% and a N-content of 4.52%. Used as sodium-ion battery anode, the optimized sample exhibits an excellent rate performance (210 mA h g−1 at 1 A g−1 and 120 mA h g−1 at 5 A g−1) with a good initial coulombic efficiency of 51.5% and specific capacity of 214 mA h g−1 after 300 cycles at 100 mA g−1.

A label-free nano-probe for sequential and quantitative determination of Cr(VI) and ascorbic acid in real samples based on S and N dual-doped carbon dots.

A fluorescent sulfur and nitrogen dual-doped carbon dots (S,N-CDs) was prepared by a simple and one-step acid-base neutralization and exothermic carbonization method. Hexavalent chromium (Cr(VI)) could effectively quench the fluorescence of S,N-CDs based on inner filter effect (IFE) and dynamic quenching, whereas ascorbic acid (AA) could recover the fluorescence of S,N-CDs/Cr(VI) because of IFE weakening. So an "on-off-on" and label-free nano-probe consecutive determination of Cr(VI) and AA was constructed. This nano-probe system demonstrated excellent selectivity and sensitivity to Cr(VI) and AA with linear range of 0.065-198 μmol/L (3.38-10,296 μg/L) and 6.6-892 μmol/L (1.16-157 mg/L), respectively. Meanwhile, the as-prepared S,N-CDs possess low toxicity and could be used for multi-color cell imaging in SMMC 7721 cells. More importantly, this nano-probe was successfully employed for detection of Cr(VI) in tap water and AA in food samples. In view of its simple detection condition, rapid response, wide linear range, low detection limit and inexpensive instrument, the as-constructed nano-probe system could have a wide range of potential application, including water quality monitoring and evaluation, food inspection and testing and biomedical analysis.

One pot hydrothermal synthesis of fluorescent NP-carbon dots derived from Dunaliella salina biomass and its application in on-off sensing of Hg (II), Cr (VI) and live cell imaging

The impact of hazardous chemicals and toxic metal ions in the environment played havoc to the ecosystem. In the present work green chemistry approach was applied for one-step hydrothermal synthesis of nitrogen, phosphorus dual doped carbon dots, utilizing green precursor i.e, biomass of halophilic microalgae Dunaliella salina (algal derived nitrogen phosphorous carbon dots i.e A-NPCDs). Synthesized A-NPCDs were characterized through TEM, FT-IR, P-XRD, DLS and XPS. It showed appreciable optical properties with significant fluorescence quantum yield (8%)and exhibited blue color under UV – light (λex = 365 nm). A-NPCDs acted as fluorescent turn off sensor for toxic metal ion such as Hg (II) and Cr (VI) with good selectivity and sensitivity. Interestingly, ANPCDs detected Cr (VI) up to 0.018μM which was below the permissible level of Cr (VI) in drinking water. Such sensing resulted because of combination of inner filter effect and dynamic quenching mechanism. Moreover, it also showed good selectivity (0.018μM) for Hg (II) via dynamic quenching mechanism. MTT assay of A-NPCDs on HEK-293 cell line showed biocompatibility with negligible cytotoxicity. Therefore, these were successfully employed for live cell imaging and intracellular detection of Hg (II) and Cr (VI) in HEK-293 cell line. Thus, green synthesized A-NPCDs may be a good alternative for chemically derived CDs in intracellular detection of Hg (II) and Cr (VI) of a complex biological environment.

Sustainable biowaste strategy to fabricate dual-doped carbon frameworks with remarkable performance for flexible solid-state supercapacitors

Flexible solid-state supercapacitors show great promise in portable electronics, in which developing advanced electrode materials is a key yet a challenge. This report details an efficient strategy that uses soybean dreg as precursor to purposely prepare nitrogen/oxygen dual-doped porous carbon frameworks by hydrothermal and pyrolysis/activation methods for the first application in flexible solid-state devices. The employed procedure efficiently alleviates the restacking of carbon sheets and well regulates their textural properties and electroactivity to realize outstanding performance. The optimal carbon shows excellent capacitance and rate performance in both three-electrode cell (435 and 336 F g−1 at 0.5 and 50 A g−1) and two-electrode cell (308 and 233 F g−1 at 0.5 and 50 A g−1), which are among the best levels recorded. Significantly, our solid-state supercapacitor achieves integrated high energy and power densities of 9.3 Wh kg−1 and 9883 W kg−1, with a remarkable durability up to 10000 cycles. This device can also work well under various mechanical deformations. For an actual demonstration, two devices are integrated serially, powering a timer for 240 min. This research not only widens the path for designing carbon-based materials, but also brings new idea for device design.

Nitrogen and oxygen co-doping carbon microspheres by a sustainable route for fast sodium-ion batteries

Heteroatom-doping has been regarded as an effective strategy to regulate the Na storage performance of carbon materials. In this paper, N and O dual-doped carbon microspheres (NO-CS) from the rinds of corn stalks have been fabricated via a tailored carbonization and solution doping route. NO-CS reveals both high O (15.6 at.%), N (6.4 at.%) contents and high specific surface area (746.48 m2 g−1). The NO-CS derived carbon anode shows tremendous reversible capacity, rate capability and cycling stability, e.g. 270 mAh g−1 over 200 cycles at 50 mA g−1, 130 mAh g−1 over 3500 cycles at 5 A g−1. The superior Na storage property may due to the abundant porosity and dual-doping that boost fast ion adsorption at the graphene layer defects and nitrogen oxygen moiety of carbon. Scalable and cost-effective synthesis route with outstanding Na storage performance makes NO-CS a competitive anode material for Na-ion batteries.

Synergistical Coupling Interconnected ZnS/SnS2 Nanoboxes with Polypyrrole-Derived N/S Dual-Doped Carbon for Boosting High-Performance Sodium Storage.

Metal sulfides possess tremendous potentials owing to their high specific capacity for sodium storage. However, the huge volume expansion, accompanied with structural collapse and unsatisfied electric conductivity upon continuous cycling, always lead to inferior rate capability and severe cycling fading. In this work, binary metal sulfide (ZnS/SnS2 ) nanoboxes confined in N/S dual-doped carbon shell (ZSS@NSC) are fabricated through a facile co-precipitation method involving the wrapping of polypyrrole, and subsequent in situ sulfidation process. Such a well-designed heterogeneity between ZnS and SnS2 provides rapid Na+ insertion and enhanced charge transport by creating an electric field at the heterointerface. More significantly, the formation of polypyrrole-derived N/S dual-doped carbon is synergistically coupled with the ZnS/SnS2 to create a unique and robust architecture, further strengthening the interconnect function at the heterointerface, which improves electric/ion transfer and mitigates the volume variation during the long-term cycling process. Herein, this as-prepared ZSS@NSC exhibits satisfied specific capacity, excellent rate property, and superior cyclic stability (a reversible capacity of 456.2 mAh g-1 with excellent capacity retention of 97.2% after 700 stable cycles at ultrahigh rate of 5 A g-1 ). The boosted Na-storage properties demonstrate that the optimized strategy of structure-engineering has a broad prospect to promote energy storage applications.

Nitrogen and oxygen dual-doped porous carbon derived from natural ficus microcarpas as host for high performance lithium-sulfur batteries

A novel nitrogen and oxygen dual-doped porous carbon (NOPC) has been prepared from the aerial roots of ficus microcarpas through a facile carbonization and activation approach using KOH as the chemical activating agent. The obtained NOPC has very large specific surface area of 2294 m2 g−1 and high pore volume of 1.15 cm3 g−1. Thanks to the high specific surface area and the doping of nitrogen and oxygen, the prepared NOPC/S cathode with a sulfur content of 55.9% shows a high initial discharge capacity of 1338 mA h g−1 at 0.1 C and retains 1047 mA h g-1 after 200 cycles. What is more, the NOPC/S-62.9% cathode also remains high capacity of 1036 mA h g-1 and the coulomb efficiency remains 98.3% after 200 cycles. Taking into account of the low cost, green and sustainable development, NOPC/S composites show good prospects in the application of lithium-sulfur batteries.

Optimized Synthesis of Nitrogen and Phosphorus Dual-Doped Coal-Based Carbon Fiber Supported Pd Catalyst with Enhanced Activities for Formic Acid Electrooxidation.

Development of a Pd-based catalyst with highly active and durable properties for formic acid oxidation reaction at the anode remains an important matter of interest in the research community. Herein, we have designed novel coal-based carbon fibers (Coal-CFs) with dicyandiamide (DCD) as nitrogen (N) source, triphenylphosphine (TPP) as phosphorus (P) source dual-doped to support Pd catalysts (Pd/NP-Coal-CFs(DCD/TPP)), which exhibit superior catalytic performance toward formic acid oxidation reaction. Mass activity of formic acid oxidation of Pd/NP-Coal-CFs(DCD/TPP) catalyst is 536.6 mA·mg-1Pd, which is 2.5 times higher than that of Pd/Coal-CFs catalyst. The higher specific surface areas, exclusive electron transport path, and the high synergistic interaction of N and P are the favorable phenomena for catalytic performance. The addition of coal not only increases the abundant defects sites but also makes the utilization of coal with high added value. This N and P dual-doped catalyst inspires an idea for promoting applications in practical fuel cells.

Stacking of Tailored Chalcogenide Nanosheets around MoO2-C Conductive Stakes Modulated by a Hybrid POM⊂MOF Precursor Template: Composite Conversion-Insertion Cathodes for Rechargeable Mg-Li Dual-Salt Batteries.

Mg anode has pronounced advantages in terms of high volumetric capacity, resource abundance, and dendrite-free electrochemical plating, which make rechargeable Mg-based batteries stand out as a representative next-generation energy storage system utilized in the field of large-scale stationary electric grid. However, sluggish Mg2+ diffusion in cathode lattices and facile passivation on the Mg anode hinder the commercialization of Mg batteries. Exploring a highly electroactive cathode prototype with hierarchical nanostructure and compatible electrolyte system with the capability of activating both an anode and a cathode is still a challenge. Here, we propose a POM⊂MOF (NENU-5) core-shell architecture as a hybrid precursor template to achieve the stacking of tailored chalcogenide nanosheets around MoO2-C conductive stakes, which can be employed as conversion-insertion cathodes (Cu1.96S-MoS2-MoO2 and Cu2Se-MoO2) for Mg-Li dual-salt batteries. Li-salt modulation further activates the capacity and rate performance at the cathode side by preferential Li-driven displacement reaction in Cu+ extrusible lattices. The heterogeneous conductive network and conformal dual-doped carbon coating enable a reversible capacity as high as 200 mAh/g with a coulombic efficiency close to 100%. The composite cathode can endure a long-term cycling up to 400 cycles and a high current density up to 2 A/g. The diversity of MOF-based materials infused by functional molecules or clusters would enrich the nanoengineering of electrodes to meet the performance demand for future multivalent batteries.

Visible light photocatalytic mineralization of bisphenol A by carbon and oxygen dual-doped graphitic carbon nitride

A facile thermal polymerization was applied to synthesize carbon and oxygen dual-doped graphitic carbon nitride (MACN) with controllable electronic band structure using malonic acid and urea as precursors. The C and O atoms substituted the sp2 N atom in graphitic carbon nitride (CN). The 1MACN (1 represented that the weight ratio of malonic acid to urea is 1% during the synthesis) with optimal band structure could decompose 15 ppm bisphenol A (BPA) within 150 min, and the mineralization rate reached to 52%. The superior photocatalytic performance of 1MACN was mainly ascribed to electronic band structure together with optical properties. On the one hand, the formation of delocalized big π bonds favored the electrons transfer after the introducing of carbon atoms. On the other hand, a positive charge density existed on the C atoms because of high electronegativity of contiguous O (3.44) that substituted N compared with C (2.55), which could attribute to high activity of MACN catalyst. The study will contribute to the further improvement of visible-light photocatalytic BPA degradation and mineralization.