Self-doped Carbon Research Articles

Biomass Derived Self-Doped Carbon Nanosheets Enable Robust Hole Transport Layers with Ion Buffer for Perovskite Solar Cells.

The diffusion of iodine species and lead leakage during device degradation represent the main obstacles restricting the commercial application of perovskite solar cells (PSCs). Cobalt loaded ultrathin carbon nanosheets (Co(III)-CNS) derived from biomass are prepared as ion buffer material to construct robust hole transport layers (HTLs). The carbon nanosheets containing trivalent cobalt ions can facilitate the oxidation of the hole transport material while preserving the structural integrity and electrical properties of HTLs under thermal stress, thereby ensuring efficient carrier transport. The two-dimensional ultrathin graphitized lamellar structure of Co(III)-CNS is conducive to alleviate the corrosive effects of the outward diffusion of iodine species on HTLs and silver electrodes, while avoiding irreversible degradation of PSCs. With the improvement of HTL composition and the related interfaces, Co(III)-CNS doped devices can maintain intact device structure under thermal stress and remain above 80 % of the original power conversion efficiency (PCE) after thermal aging at 85 °C for 720 h. Notably, the chemical interactions between heteroatoms of self-doped carbon nanosheets and the mobile lead ions can effectively alleviate lead leakage and avoid the potential impacts of device degradation on ecosystem. Ultimately, the Co(III)-CNS doped PSCs with enhanced thermal stability exhibit a champion PCE of 22.32 %.

Enhancement effect of biomass-derived Carbon Quantum Dots (CQDs) on the performance of Dye-Sensitized Solar Cells (DSSCs)

Corn stover, an agricultural waste, was used to prepare nitrogen self-doped carbon quantum dots (CQDs) through a simple hydrothermal method with only water at near room temperature for the first time. The surface, electrochemical, and photovoltaic characteristics of CQDs doped TiO2 in dye-sensitized solar cells (DSSCs) were thoroughly and systematically examined. The average diameter of blue-fluorescence CQDs measured by a high-resolution transmission electron microscope (HR-TEM) was 4.63 ± 0.87 nm, which consisted of polar functional groups. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy of the biomass-derived CQDs, determined by the cyclic voltammetry (CV) test, were, −5.48 eV and −3.89 eV, respectively. The negative shift of flat band potential (Vfb) in CQDs incorporated photoanode implies the fermi level shifted upward. Experimental results revealed that the improved performance of DSSCs was due to charge transport enhancement and separation, which resulted in the improved energy level configuration between TiO2, CQDs, and electrolytes. In this regard, the CQDs serve as a mediator that enables charge carrier transport without hindrance. In this study, CQDs added to TiO2 + N719, increased short circuit current density (JSC) and power conversion efficiency (PCE) value by ∼26.00 % (10.13 to 12.69 mA/cm2) and 27.20 % (4.78 % to 6.08 %), respectively.

Molten salt-assisted synthesis of carbon nitride with defective sites as visible-light photocatalyst for highly efficient hydrogen evolution

The low light absorption capacity, fast recombination of photogenerated carriers and slow H+ reduction kinetics of carbon nitride severely limit its application in photocatalytic research. What's more, the challenge remains to efficiently utilise photogenerated electrons. In this work, sulfur (S) self-doped carbon nitride (SCN) was formed by thermal polymerisation, and the introduction of S stimulated the electron delocalisation of the active site and optimised the absorption of visible light by the carbon nitride. The introduction of defects and cyano (-C≡N) groups optimises the surface atomic and electronic structure of SCN, enhances photogenerated electron trapping and greatly suppresses charge recombination. The n-π* electron jump of the lone pair of electrons at the defect site gives rise to a new absorption band that broadens the response to visible light. The H2 evolution rate of SCNV under visible light reached 3437 μmol g−1 h−1, which was about 3.0 times higher than that of SCN (1148 μmol g−1 h−1). Density Functional Theory (DFT) calculations further show that the introduction of defects and -C≡N lowers the energy barrier of *H, enhances carrier separation, and forms an electron-rich structure, which effectively promotes the utilisation of photogenerated electrons and photocatalytic H2 evolution efficiency.

Smartphone-Assisted and Optical Quantification of Copper and Glucose Using Palm Wine-Tailored Carbon Dots and Their Multiple Logic Gate Application.

In this work, potassium, sulfur, nitrogen, and chlorine self-doped carbon dots (CDs) were hydrothermally synthesized using palm wine as a carbon source. The palm wine-derived CDs (PW-CDs) are amorphous in nature and displayed an average particle size of 4.19 ± 0.89 nm. The as-synthesized CDs are used to fabricate a photoluminescent sensing probe to simultaneously detect Cu2+ and glucose via the "Turn ON-OFF-ON" mechanism. The PL quenching mechanism of PW-CDs enables the selective and sensitive detection of Cu2+ ions with a detection limit (LOD) of 0.8 ppb (4.7 nM). The sensing probe quantified Cu2+ in tap water, drinking water, and e-waste samples to prove its viability. Using CDs to quantify copper in e-waste leachate samples is a novel approach as no prior instances of such application have been reported. The system's performance is considered to be highly reproducible due to the relative standard deviation being <6.64%, along with excellent recoveries within the range of 93.24-109.86%. The quenched PL can be recovered by introducing glucose into the PW-CD + Cu2+ system; this strategy is employed to quantify glucose with a LOD of 0.11 ppm (0.61 μM). The feasibility of this sensor was confirmed by the determination of glucose in actual human plasma specimens of diabetic patients. It is to be noted that these samples were neither diluted nor spiked with glucose. The developed PW-CD + Cu2+ sensing system yields satisfactory recoveries of 93.45-107.37%. This probe was also incorporated into a smartphone-based sensing platform to detect Cu2+ and glucose with desirable recoveries. The proposed smartphone-based sensing platform is flexible, reliable, and accurate, making it suitable for resource-constrained areas. Furthermore, based on the effect of Cu2+ ions and glucose on the PL response and absorbance spectra of PW-CDs, four logic gates (YES, IMPLICATION, NOT, and OR) were designed, and PW-CDs were also used for cell imaging applications.

Resource utilization of sewage sludge as a nitrogen self-doped carbon quantum dot for specific detection of Fe3+ and Hg2+

With the widespread application of sewage biological treatment technology, a large amount of sewage sludge is generated during the sewage treatment process, which not only poses a threat to the environment but also results in wastage of C and N resources. In this study, the nitrogen self-doped fluorescent carbon dots (N-CDs) with an average particle size of 3.43 nm were synthesized green through a two-stage hydrothermal method. It was found that N-CDs can detect Fe3+ through internal filtration effect (IFE), with a linear detection range of 0–250 μM and a detection limit of 2.207 μM. Furthermore, N-CDs can also serve as a “turn off–on” probe for monitoring Hg2+, with a linear detection range of 2–10 μM and a detection limit of 0.989 μM. Interestingly, oxygen-containing groups were shown to be sensitive to Hg2+, which has been demonstrated for the first time. Moreover, the practical application of N-CDs as a double ion sensor in the detection of Fe3+ and Hg2+ has achieved good results for real power plant wastewater.

Tailoring the Optoelectronic Properties of Soybean-Derived Nitrogen Self-Doped Carbon Dots through Composite Formation with KCl and Zeolite, Synthesized Using Autogenic Atmosphere Pyrolysis

This article investigates the environmentally friendly synthesis and characterization of carbon dots (CDs) derived from soybean biomass, in conjunction with their composites containing potassium chloride (KCl) or zeolite. By using an environmentally sustainable synthetic approach, this study sought to unlock the potential of these materials for various applications. The physicochemical properties of the CDs and composites were comprehensively analyzed using various techniques including scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis. In addition, various optical properties such as UV–Vis absorption, band gap, and excitation–emission behavior were investigated. A key finding to arise from this study was that the inclusion of a doping agent such as KCl or zeolite significantly reduced the size of the resulting CDs. In this light, whereas the undoped species are associated with average sizes of 8.86 ± 0.10 nm, those doped with either zeolite or KCl were associated with average sizes of 3.09 ± 0.05 and 2.07 ± 0.05 nm, respectively. In addition, it was shown that doping with either zeolite or KCl resulted in an alteration of the elemental composition of the CDs and influenced their optical properties, especially their excitation-dependent emission. These promising results point to potential applications in environmental sensing and energy-related fields.

Synthesis of O–N–S self-doped carbon quantum dots from a discarded football for Fe3+ detection

Abstract A discarded-waste football was served as a carbon precursor to build O–N–S self-doped carbon quantum dots (CQDs) by a hydrothermal route. The CQDs have strong cyan luminescence, excellent stability, and their excitation is wavelength-dependent. The CQDs were acted as a fluorescent probe for the detection of Fe3+, exhibiting sensitivity and selectivity, which is of great significance for the effective monitoring of human health.

Facile synthesis of NiMoO4@MnO2 nanoflower and waste biomass-derived N, P, and S self-doped carbon for advanced asymmetric supercapacitor electrode materials

Green energy storage technologies have been demonstrated by the use of sustainable biomass-derived carbon as an electrode. Herein, for a high performance all-solid-state asymmetric supercapacitor, we used biowaste material to derive multi-heteroatom doped carbon as a non-faradaic electrode along with NiMoO4@MnO2 Nano-flower-like hybrid structure on nickel foam as a Faradaic electrode. Due to the combined effect of the large specific surface area, hierarchical porous structure of biomass-derived activated carbon (FDAC3) and the highly specific capacitance of the NiMoO4@MnO2 hybrid, designed all-solid-state asymmetric supercapacitor achieved a remarkable specific capacitance of 109.1 F g−1 at 1.4 A g−1 and maximum specific energy of 54.7 Wh/kg within a voltage window of 1.8 V. Moreover, for the practical application of designed cell devices, two different devices were connected in a series to light up different colors light emitting diodes (LEDs). These findings provide new insights to realize the full utilization of biomass waste and a novel low-cost pathway for producing high-performance materials for energy storage applications.

High-rate electrochimcal supercapacitor with attractive energy density assembling from infused-undaria-pinnatifida-based activated carbon

In order to achieve attractive energy density and specific capacitance of electrochemical supercapacitor, multi-heteroatom self-doped carbon is prepared by pyrolyzing the aquatic biomass undaria pinnatifida (UP) filled with magnesium acetate (Mg(CH3COO)2). The pyrolysis product of magnesium oxide (MgO), acting as rigid filling, can shape the pore and help to keep the original pore system. The resultant immersed-undaria-pinnatifida-based activated carbon (IUPAC-700) co-doped with multi-heteroatom shows specific surface area of 1116 m2 g−1, pore volume of 1.63 cm3 g−1 and desired pore size distribution. The electrode basing on it delivers specific capacitance of 579.7 F g−1 at the current density of 0.50 A g−1 and 306.0 F g−1 at 100.0 A g−1 in the electrolyte of 1.0 M H2SO4. It exhibits a high specific capacitance of 488.6 F g−1 in the two-electrode system and provides a significant energy density of 28.7 W kg−1 at the power density of 164.0 W kg−1. It also displays perfect cyclic life after 8000 times charge-discharge at the current density of 5.0 A g−1. The assembled supercapacitor can power the LED lights. The sample IUPAC-700 featured with self-doped multi-heteroatoms is a very competitive electrode material for energy storage device with desired comprehensive performance.

High-Efficiency Corrosion Inhibitor of Biomass-Derived High-Yield Carbon Quantum Dots for Q235 Carbon Steel in 1 M HCl Solution.

Eco-friendly self-doped carbon quantum dots (ZCQDs) with excellent corrosion inhibition ability were prepared via solid-phase pyrolysis only using Zanthoxylum bungeanum leaves as the raw material. Compared with the relevant research, a simpler and higher yield (25%) preparation process for carbon quantum dots was proposed. ZCQDs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy, and the average size of ZCQDs with multitudes of O- and N-containing functional groups was about 2.53 nm. The prepared ZCQDs were used to inhibit the corrosion of Q235 steel in HCl solution, and the inhibition behavior was investigated through weight loss, electrochemical test, surface analysis, and adsorption thermodynamic analyses. The results showed that the ZCQDs, acted as a mixed corrosion inhibitor, have an effective corrosion inhibition for Q235, the corrosion inhibition efficiency reached 95.98% at 200 mg/L, and at this concentration, effective protection of at least 132h (IE > 90%) is provided. Moreover, the adsorption mechanism of ZCQDs was consistent with that of Redlich-Peterson adsorption, including chemisorption and physisorption. A new corrosion inhibition mechanism of ZCQDs has been thoroughly studied and proposed; ZCQDs have functional groups containing O and N, which can form a protective barrier through physical adsorption and chemisorption, but the coverage of the protective film is low at low concentrations. With the increase of concentration, the protective film formed by ZCQDs on the metal surface will first increase the coverage and then adsorb more ZCQDs on the protective film to form a thicker and denser protective film to protect the metal. The carbon quantum dots prepared in this paper have advantages including a green, renewable precursor, a fast method, high yield, and excellent corrosion inhibition. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in HCl solutions.

Regulating the reactive site density of two-dimensional N self-doped carbon for boosted Fenton-like catalytic ability

The mediocre catalytic ability of metal-free carbon-based catalysts limits its practical application in wastewater treatment. Herein, a facile “steam-etching” method is utilized to boost the catalytic ability of N self-doped carbon (NSDC) catalysts. Compared to the original NSDC catalyst (NSDC-N2), the NSDC-H2O-50 catalyst modified with the water vapor content of 50 % exhibits much better catalytic performance. The pseudo-first-order kinetic rate constant k of NSDC-H2O-50 is 4.88 times that of NSDC-N2. The presence of water vapor can cause a massive vacancy-like defects in the carbon structure, which is conducive to form more edge reactive groups. Pyrrolic N and CN groups are proved to be the reactive sites for the catalytic reaction. Reactive site density can be easily adjusted by changing the water vapor content. The prepared NSDC-H2O catalysts can effectively activate peroxydisulfate (PDS) to degrade various organic pollutants with high efficiency in the pH range of 2.02–10.28. In addition, the NSDC-H2O/PDS system exhibits strong anti-interference ability to common anions and humic acid. The catalytic ability has not been affected in actual water sources. By a simple calcination treatment, most of the catalytic ability can be restored. Therefore, the prepared NSDC-H2O catalysts show strong application potential in organic wastewater treatment. Furthermore, singlet oxygen is proved to be the main active species in the NSDC-H2O/PDS system, and sulfate radical and superoxide radical play an auxiliary role.

Effect of energy band alignments in carbon doped ZnO/TiO2 hybrid heterojunction photocatalyst on the photodegradation of ofloxacin

The present study highlights the influence and efficacy of a self-doped carbon (C)–ZnO/TiO2 hybrid heterojunction for the photocatalytic degradation of ofloxacin (OFX) in aqueous media. The flower-like hybrid heterojunction was prepared via hydrothermal treatment at varying concentrations of ZnO and TiO2. C doping was internally introduced to the ZnO lattice by the decomposition of polyvinylpyrrolidone as a source to achieve better band alignment. A systematic investigation was performed to elucidate the mechanism of photodegradation by the heterojunction via analyzing the parameters such as composition, dosage, and pH of the system. The optimized sample 1:2 (Zn: Ti) ratio exhibited a photodegradation efficiency of 99.9% for OFX within 60 min, demonstrating a reaction rate 1.6 times higher than that of C–ZnO. Moreover, the involvement of charge carriers was analyzed through scavenging experiments. The results showed that trapping superoxide anions resulted in a 57.8% reduction in photoactivity, confirming their significant involvement in the process. The n-doping of C and subsequent defects level formation in the heterojunction hybrid was supported by X-ray photoelectron spectroscopy. The mechanism for the effective and extended photodegradation of hybrid heterojunctions was proposed by investigating band-gap using Tauc plot and valence band spectra using ultraviolet photoelectron spectroscopy. The valence band spectra verified the uplift of energy bands via doping, confirming the strong reducing power of the heterojunction hybrids. Additionally, liquid chromatography-mass spectroscopy was employed to perform the identification of the degradation pathway and intermediates.

Multifunctional carbon dots originated from waste garlic peel for rapid sensing of heavy metals and fluorescent imaging of 2D and 3D spheroids cultured fibroblast cells

Here, we prepared sulfur and nitrogen self-doped carbon dots derived from garlic peel extract (GPSNCDs) using a hydrothermal method. The as-synthesized GPSNCDs were confirmed using Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The analytical techniques indicate that the resulting GPSNCDs exhibit distinct emissive carbon-core with functionalities (owing to various ligands in the GPSNCDs). These functionalities are responsible for excellent hydrophilic and optical properties, including excitation-dependent emission and anti-photobleaching. Fluorescence intensities of GPSNCDs were quenched in the existence of Mn2+ and Fe3+ ions. This indicates that the GPSNCDs were sensitive to Fe3+ and Mn2+ ions with a limited range from 5 to 50 µM and showed lower recognition at ∼0.75 and 0.95 µM, respectively. In addition, the sensing results were generated in a short time (20 s). The cytotoxicity of GPSNCDs was tested to demonstrate that they are sufficiently safe to use for cellular imaging. The novel fluorescent GPSNCDs-based sensor can be used as a high-performance sensor for environmental monitoring. Further, GPSNCDs showed greater biocompatibility with normal fibroblast cells, and In Vitro fluorescent imaging of GPSNCDs revealed strong fluorescence signals in the two-dimensional (2D) and three-dimensional (3D) spheroids cultured fibroblast cells. The properties mentioned above demonstrate that the GPSNCDs can be applied to imaging normal cells without further modifications.

N, S, O Self-Doped Carbon Derived from Grapefruit Peel for High-Performance Supercapacitors.

The development of high-capacity carbon for supercapacitors is highly desirable but challenging. In this work, we design a N, S, O self-doped carbon electrode (NSOC-800) with high capacitance and good stability via the carbonization of grapefruit peel via a one-step KOH activation method without extra dopants. The existence of heteroatoms enables the NSOC-800 to have a high specific capacitance of 280 F/g and a great cycling performance, with 90.1% capacitance retention after 5000 cycles. Moreover, the symmetric supercapacitor with NSOC-800 electrodes delivers a maximum energy density of 5 Wh/kg with a power density of 473 W/kg. Such a promising method to achieve carbon materials with self-doping heteroatwoms is of great significance for developing highly efficient electrodes for energy storage devices.

Study of the pH effect on the optical and morphological properties of S, N self-doped carbon dots applied as fluorescent anti-counterfeiting ink and pH sensor

The pH value is an important parameter as it is part of several processes, whether environmental or biological. In this report, S, N self-doped carbon dots (CDs) were synthesized by a simple hydrothermal method using cysteine (cys) and citric acid as precursors for a detailed investigation of size, morphological, photoluminescent, and structural changes at different pH values and its use as pH sensor and fluorescent ink. The fluorescence intensity of cys-CDs was dependent on the pH, presenting a linear relationship with pH values in the range of 2.0–9.0. Using spectroscopic techniques, a mechanism for the pH-dependent fluorescence is proposed, based on the aggregation of cys-CDs and also protonation/deprotonation of surface functional groups that change the excited state. The cys-CDs were found to be efficient as fluorescent pH sensors using real samples (distilled water and tap water). Furthermore, the pH changes in cys-CDs can be used for the visual enhancement of anti-counterfeiting technologies. Thus, the results of this study show that cys-CDs can act as an efficient and pH sensitive fluorescent sensor, which can be used to measure the pH value of water samples, due to its high fluorescence intensity, and can be applied successfully as a fluorescent ink.

Green synthesis of nitrogen self-doped porous carbons from waste garlic peels for high-performance supercapacitor applications

Based on the biological structure of biomass materials, the preparation of carbon materials with special pore structures and rich surface groups is an important route in the development of new carbon materials for electrodes. In this work, a nitrogen self-doped carbon with unique tubular channel structures was synthesized from garlic peels for the high-performance supercapacitor electrode application. The mild KHCO3 was selected as the activator and therefore the biological structure of garlic peels is well preserved, showing a large number of long tubular channels with a diameter of around 50 nm. It was found that a nitrogen self-doped porous carbon material (SPC-4KC) with a nitrogen relative content of 1.77% and a large specific surface area of 1993.73 m2 g−1 was formed at 800 ℃ at a KHCO3/SPC mass ratio of 4:1. Using as the electrode material, the mass-specific capacitance of the SPC-4KC-based electrode reached 303.38 F g−1 at a current density of 1 A g−1 in the three-electrode system. In the two-electrode system, when the energy density is 7.42 W h kg−1, the power density is 314.33 W kg−1. Also, the material exhibits excellent cycle stability, with a capacitance retention of 94.87% after 5000 cycles at a current density of 10 A g−1.

Self-interlocked down Biomass-based carbon fiber aerogel for highly efficient and stable solar steam generation

Carbon aerogels have demonstrated superior properties for generating clean water through sustainable solar steam generation. However, the complex, time-consuming preparation process and the various harmful chemicals involved seriously inhibit the development and applications of carbon aerogels. Herein, down biomass-based carbon fiber aerogel (DCFA) consisting of physically self-interlocked carbon fibers was developed through the simple low-temperature carbonization of natural down cluster (DC) for highly effective solar evaporation. The resulting DCFA has a large amount of carbon (>80 %) and small amounts of sulfur and nitrogen due to its natural disulfide bonds and amino groups, suggesting a unique self-doped carbon property. The low density and high porosity of the DCFA increased the total solar absorbance and suppressed the energy loss during evaporation. As a result, the DCFA possessed solar absorbance of 97.03 %, as well as high evaporation rates of 2.05 and 2.11 kg·m−2·h−1 for the treatment of saline water and dye water, respectively, which are higher than most reported results. Moreover, the resulting DCFA could self-float without external assistance, demonstrating that it could be a facile evaporator in practical applications. Additionally, the DCFA retained its evaporation performance after 10 times tests for the evaporation of 3.5 wt% saline water and actual dye wastewater, indicating a long-term capacity for practical employment. These findings suggest that the DCFA could be a feasible alternative for solar-driven evaporation. Simultaneously, the simple, efficient, and chemical-free strategy will inspire subsequent research on the construction of fiber-based functional aerogels and their further development/application in water treatment, thermal insulation, energy generation, energy storage, and other related areas.

Self-Doped Carbon Dots Decorated TiO2 Nanorods: A Novel Synthesis Route for Enhanced Photoelectrochemical Water Splitting

Herein, we have successfully prepared self-doped carbon dots with nitrogen elements (NCD) in a simple one-pot hydrothermal carbonization method, using L-histidine as a new precursor. The effect of as-prepared carbon dots was studied for photoelectrochemical (PEC) water splitting by decorating NCDs upon TiO2 nanorods systematically by changing the loading time from 2 h to 8 h (TiO2@NCD2h, TiO2@NCD4h, TiO2@NCD6h, and TiO2@NCD8h). The successful decorating of NCDs on TiO2 was confirmed by FE-TEM and Raman spectroscopy. The TiO2@NCD4h has shown a photocurrent density of 2.51 mA.cm−2, 3.4 times higher than the pristine TiO2. Moreover, TiO2@NCD4h exhibited 12% higher applied bias photon-to-current efficiency (ABPE) than the pristine TiO2. The detailed IPCE, Mott–Schottky, and impedance (EIS) analyses have revealed the enhanced light harvesting property, free carrier concentration, charge separation, and transportation upon introduction of the NCDs on TiO2. The obtained results clearly portray the key role of NCDs in improving the PEC performance, providing a new insight into the development of highly competent TiO2 and NCDs based photoanodes for PEC water splitting.

A hybrid of Co3O4 nanoparticles coupled with B, Co/N-codoped C@B4C as an efficient bifunctional catalyst for oxygen reduction and oxygen evolution reactions

The design of novel cost-effective, highly-efficient and highly-durable non-noble-metal bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been an important research subject in the sustainable energy fields such as regenerative fuel cells and rechargeable metal-air batteries. Here, a hybrid of Co3O4 nanoparticles coupled with core-shell structured B, Co/N-codoped carbon on nano-B4C (Co3O4/B4C@CoNBC) was demonstrated to be an effective bifunctional catalyst. For the first time, nano-B4C was used as a catalytic material not only a catalyst support. The B4C@BC prepared by annealing nano-B4C had ORR catalytic activity due to B self-doped carbon shell. Then, we combined B4C@BC and Co3O4 nanoparticles effectively and doped with N in the meanwhile by the hydrothermal method to obtain Co3O4/B4C@CoNBC. Remarkably, the Co3O4/B4C@CoNBC showed the overall oxygen redox activity (OER/ORR) was only 0.70 V in 0.1 M KOH, outperforming the recently reported highly active non-noble metal bifunctional catalysts. The excellent catalytic activities were attributable to the synergetic effects of Co3O4, B self-doped carbon and Co/N-doped carbon in Co3O4/B4C@CoNBC. In addition, the B4C with strong chemical stability could be used as a support through synergistic effect with Co3O4 and CoNBC to effectively improve the stability of the hybrid.

Metal-Organic Framework-Derived NiSe Embedded into a Porous Multi-Heteroatom Self-Doped Carbon Matrix as a Promising Anode for Sodium-Ion Battery.

A self-doping strategy is applied to prepare a multi-heteroatom-doped carbonaceous nickel selenide NiSe@C composite by introducing N and P-containing ligand hexa(4-carboxyl-phenoxy)-cyclotriphosphazene (HCTP-COOH) into a Ni-based MOF precursor. The MOF-derived NiSe@C composite is characterized as NiSe particles nested in a multi-heteroatom-doped carbon matrix. The multi-heteroatom-doped NiSe@C composite with a unique structure shows an excellent sodium-ion storage property. The Na-ion battery from the NiSe@C electrode exhibits a capacity of 447.8 mA h g−1 at 0.1 A g−1, a good rate capability (240.3 mA h g−1 at 5.0 A g−1), and excellent cycling life (227.8 mAh g−1 at 5.0 A g−1 for 1200). The prospects of the synthesis methodology and application of NiSe@C in sodium-ion batteries (SIBs) devices are presented.