Carbon-coated Structure Research Articles

Novel V2O3@N-C cathode for superior aqueous zinc-ion batteries via melamine foam templating

Aqueous zinc-ion batteries (AZIBs) are increasingly garnering attention due to their inherent safety features and the economic benefits of using metallic zinc. Among the promising cathode materials for AZIBs, V2O3-based compounds are extensively studied because of their unique tunnel structure and high energy density. However, the broader application of V2O3-based materials is hindered by several challenges, including sluggish reaction kinetics, poor cycling stability, and the lack of effective methods for large-scale synthesis. In response to these limitations, this study utilizes melamine foam as a self-sacrificing template to develop a V2O3@N-C cathode that aims to enhance the performance of aqueous zinc-ion batteries. The resulting cathode benefits from the uniform dispersion of V2O3 nanoparticles and a trace carbon-coated structure enriched with oxygen vacancies, yielding significant reversible capacity (569.62 mA h g−1 at 0.5 A g−1 and 411.63 mA h g−1 at 20 A g−1) and superior cycling stability (369.66 mA h g−1 after 3200 cycles at 10 A g−1). Additionally, ex-situ characterization techniques have been employed to thoroughly investigate the zinc storage mechanism, offering novel insights for the development of high-performance cathode materials for AZIBs.

Controllable preparation of Co-based catalysts doped with Cu and Mo for boosting hydrogen evolution

Hydrogen evolution from ammonia borane hydrolysis is a promising way for utilization of clean energy. Development of efficient and stable non-noble catalysts for improvement of hydrogen generation rate is essential but still a challenge. Herein, the heterostructured Co-based catalysts were controllably designed by combining the synergistic effect with oxygen vacancy engineering to improve the hydrogen generation rate. CoCu1Mo3-NC-O-15 exhibits the TOF value of 24.44 min−1 at 298 K with addition of 0.44 M NaOH, which is nearly 68 times that of Co-NC. The activation energy over CoCu1Mo3-NC-O-15 is 28.44 kJ mol−1. The CoCu1Mo3-NC-O-15 catalyst presents the good stability in ammonia borane hydrolysis reaction due to the carbon-coated structure. The strong synergistic effect and oxygen vacancy are favorable to the adsorption and dissociation of NH3BH3 and H2O molecules, leading to an astonishing improvement of catalytic activity. This study provides a novel way to design the heterostructured catalysts and a rational way to boost the dehydrogenation rate from AB.

Green synthesis of carbon coated macrostructured catalysts: Optimized methodology and enhanced catalytic performance

A novel green and efficient synthesis methodology for carbon-coated macrostructured catalysts was assessed. Sodium alginate was used as a dispersant to promote a suitable dispersion of the modified carbon nanotubes (CNT) to be incorporated on a structured support. The coating conditions were optimized to synthesize active and stable carbon-coated macrostructured catalysts. Achieving a total dispersant decomposition was one of the key steps to guarantee the coating stability, 550 °C being the optimal temperature. To assess the catalytic activity for these catalysts, the carbon-coated structures were tested as main catalysts for oxalic acid degradation through ozonation, and as support for bimetallic Pd-Cu catalysts, applied in NO3− conversion. The results achieved during ozonation allowed to outperform the ones obtained with macrostructured catalysts synthesized by more established techniques (such as chemical vapor deposition) with oxalic acid degradation, in a continuous system, of around 75%. As for the bimetallic samples, the species proved to be quite dispersed on the catalyst support, allowing a NO3− conversion of around 20% with a corresponding N2 selectivity of 55%, outperforming, again, the same type of catalyst synthesized with “less green” surfactants. This newly developed methodology is an important step for the sustainability of the structured catalyst design area.

Nitrogen-doped carbon layer encapsulating NiFeP nanosheet arrays as high-performance electrocatalyst for oxygen evolution reaction

With water electrolysis restricted to the slow kinetics of oxygen evolution reaction (OER), developing catalysts with both high activity and durability has become an urgent requirement for the development of current water electrolysis technology. Herein, we successfully prepared nitrogen-doped carbon layer encapsulating NiFe phosphide nanosheet arrays (denoted as N-C@NiFeP) catalysts by using a simple hydrothermal method combined with low temperature plasma technique. Phosphating conversion, carbonization, and nitrogen doping were realized by the same high-efficiency plasma treatment process. The nitrogen-doped carbon-coated structure modifies the NiFeP electronic structure, resulting in remarkable OER performances of N-C@NiFeP nanosheet arrays. The N-C@NiFeP nanosheet arrays possessed a tiny Tafel slope value of 27 mV dec−1 and a low overpotential of 229 mV at 10 mA cm−2. Meanwhile, the N-C@NiFeP nanosheet arrays also exhibited impressive long-term durability of 100 h under sequential OER testing at 100 mA cm−2. Our work was instrumental in paving new pathways for the construction of efficient and stable OER electrocatalysts.

Modulating nanostructure and electronic structure of P and W co-doped carbon encapsulated heterovalent NiCo composite for accelerating urea oxidation reaction

The primary intermediate substances of urea oxidation reaction (UOR) catalyzed by NiOOH are *CON, *CONH and *COO. However, the strong binding between Ni3+ and *COO makes *COO difficult to desorption, it is difficult for most nickel-based catalysts to meet the activity requirements. Herein, P and W co-doped carbon‐encapsulated NiCo (P-W-NiCo@C) nanoparticles/nanosheets structure catalysts was synthesized via hydrothermal method and calcination to enhance the activity and durability of Ni based catalysts toward UOR. As expected, the carbon-coated structure was found to facilitate the transfer of electrons from NiCo alloy to the carbon layer, while the introduction of P and W optimized the electronic structure of the central metal site. Benefiting from the co-doped, carbon‐encapsulated, alloying, electron interaction and nanoparticles/nanosheets structure, P-W-NiCo@C can deliver current density of 300 mA cm−2 at 1.34 V (vs. RHE) during the UOR. Most importantly, P-W-NiCo@C as cathode and anode catalyst still has good electrochemical properties in artificial urine (E10/300 = 1.13/2.17 V), indicating that P-W-NiCo@C has potential practical application value in electrolyzing urea rich wastewater.

Iron nanoparticle embedded carbon nanofibers as flexible electrodes for selective chloride ions capture in capacitive deionization

Developing steady material for selective chloride ion capture is a challenging task to match the high capacity of counterparts during the practice of capacitive deionization (CDI). Iron-based materials have presented great potential for its environmentally friendly and low-cost features as chloride ion trapping electrodes. However, the severe capacity fading occurs due to the uncontrollable aggregation during cycling. Herein, iron nanoparticles embedded carbon fibers are creatively fabricated via an electrospinning technology followed by an anneal treatment. The presence of iron greatly increases the capacity of the electrode, while the coating structure of carbon nanofibers improves stability. Due to the synergistic effect of the electric double layer and the pseudocapacitance behavior, when employed as an anode for capacitive deionization device, this material shows an excellent adsorption capacity (82.5 mg g−1) and fast adsorption rate (20.4 mg g−1 min−1) during the desalting process. Meanwhile, the carbon-coated structure greatly prevents the dissolution or aggregation of iron nanoparticles in the reaction process, so that the electrode displays a splendid cycle stability and there is still a 93 % capacity retention rate after 30 cycles. In short, this work provides a new strategy for capacitive desalination of chloride ion trapping electrode with excellent performance by means of encapsulating iron nanoparticles into carbon nanofibers.

Nano GeSe2/C anchored in carbon sponge skeleton for free-standing flexible lithium-ion battery electrodes

As a typical conversion alloyed anode material, Germanium selenide (GeSe2) exhibits isotropic lithiation behavior and high theoretical charge-discharge specific capacity. However, pure GeSe2 anode faces significant volume expansion (∼250 %−360 %) and further exploration is needed in the preparation of flexible electrode materials and structural design. Herein, a simple strategy is designed to load GeSe2/C-2 nanoparticles with porous carbon-coated structure on a flexible cross-networking substrate. The 3D network substrate is composed of highly conductive carbon nanotubes and adhesive cotton cellulose fibers. A two-step method involving coating and cross-linking is designed to achieve the fabrication of self-supporting flexible electrodes. As an anode for LIBs, the one layer GeSe2 discs with ∼0.65 mm thickness manifest capacities of 827.1, 744.4, 676.3, and 472.9 mAh g−1 at 0.1, 0.2, 0.5, and 1 A g−1, respectively. This superior Li+ storage performance can be attributed to the positive collective impact from the integration of nano-scale material, low crystalline properties, and carbon sponge skeleton. Furthermore, the GITT tests indicate that the diffusion coefficient of Li+ in the GeSe2-based electrodes ranged from 10−15 to 10−12 cm2/s, and the thickness of the flexible electrode (including two layers) has a negligible impact on its electrochemical performance.

Synthesizing copper-doped silicon/carbon composite anode as cost-effective active materials for Li-ion batteries

Potentially useful anodic material with prospects for use within rechargeable lithium-ion batteries are fabricated from silicon (Si)-based compounds. The active Si/electrolyte contact and weak conductivity, however, constantly produce side reactions, which dramatically reduce cycling stability. The only metallic current collector that demonstrates to facilitate lithium-ion transfer and electron conduction without alloying reactions is copper (Cu). In this study, we created Si-based multicomponent anode materials made of Si/Cu/Cu3Si alloy nanoparticles (Si/Cu/Cu3Si@C) coated in amorphous carbon. This is accomplished utilizing a straightforward, low-cost approach that combines hydrothermal technology and high-intensity ball milling. To further increase conductivity, Si/Cu/Cu3Si alloy is used as the active component. Through the use of a micro-sized amorphous carbon-coated structure, the volume problem of the active material can be successfully resolved. Additionally, the micro-sized amorphous carbon may inhibit nanoparticle agglomeration and alloy interfacial side reactions. As a result, it is anticipated that the Si/Cu/Cu3Si@C composite will display favorable electrochemical performances and possess a remarkable reversible specific capacity of 984 mAh g−1 at 0.5 C. The GITT test is used to determine the DLi+ of the Si/Cu/Cu3Si@C electrode, which ranges from 10−11 to 10−8 cm−2 s−1. Additionally, the full-cell is constructed by coupling a Li(Ni1/3Co1/3 Mn1/3)O2(NCM111) cathode with a solution-based chemically Si/Cu/Cu3Si@C anode that exhibits an enhanced initial coulombic efficiency (84.9%) and outstanding cycle performance.

Recent Advances in the Structural Design of Silicon/Carbon Anodes for Lithium Ion Batteries: A Review

As the capacity of lithium-ion batteries (LIBs) with commercial graphite anodes is gradually approaching the theoretical capacity of carbon, the development of silicon-based anodes, with higher energy density, has attracted great attention. However, the large volume variation during its lithiation/de-lithiation tends to lead to capacity decay and poor cycling performance. While rationally designed silicon/carbon (Si/C) anodes can exhibit higher specific capacity by virtue of silicon and high electrical conductivity and volume expansion suppression by virtue of carbon, they still show poor cycling performance with low initial coulombic efficiency. This review focuses on three strategies for structural design and optimization of Si/C anodes, i.e., carbon-coated structure, embedded structure and hollow structure, based on the recent researches into Si/Canodes and provides deeper insights into the problems that remain to be addressed.

Application of N-Doped Carbon–Silicon Oxycarbide Based on POSS Synthesis in Lithium-Ion Batteries

Si/C materials have attracted much attention as anode materials for lithium-ion batteries. Here, nitrogen-doped silica carbon composites with a carbon-coated structure were synthesized using poly(1-vinylimidazole) in the presence of octavinyl-silsesquioxane followed by annealing and magnesium thermal reduction processes of the polymer precursor (PPVIm). Benefiting from the moderate Si–O–C bonds, the prepared NSiOC possesses a high first discharge capacity of 1862.3 mAh·g–1 at 0.2 A·g–1 and an initial Coulombic efficiency of 70.0% at 30 °C. When the temperature rises to 60 °C, the first discharge and charge specific capacities of the synthesized anode material at 0.2 A·g–1 increase to 2103.0 and 1528.7 mAh·g–1 with an ultralong lifespan of more than 1000 cycles. Moreover, the results show that the degradation of performance during the initial phase of cycles can be ascribed to the formation of an SEI layer and insufficient electrolyte penetration. The battery maintains a steady state (nearly 600 consecutive cycles) for a long time afterward as the activation of the anode material increases, attributed to the low expansion coefficient originating from the porous structure of the carbon capping layer and silicon oxide. In addition, the electrochemical attenuation process of the electrode material with a unique inorganic silica skeleton and exceptional electrochemical performance was also investigated for the assistance of future design in high-performance electrode materials.

Surfactant-enhanced reduction of soil-adsorbed nitrobenzene by carbon-coated nZVI: Enhanced desorption and mechanism

The reduction process of pollutants by nano zero-valent iron (nZVI) is limited by mass transfer and its effective utilization, and previous studies have ignored the electron loss caused by its oxidative passivation. The carbon-coated structure can effectively inhibit the oxidation of nZVI, but the effectiveness of carbon-coated nZVI (Fe0@C) as a reducing agent in soil remediation is unclear. Therefore, in this study, the Fe0@C/surfactant system was used to remove soil-adsorbed nitrobenzene (NB) to simultaneously enhance the mass transfer process and effective utilization of nZVI. The results showed that the use of surfactants effectively promoted the desorption of NB adsorbed by the soil, and the desorption process was affected by factors such as the type and concentration of surfactants, water-soil ratio, and soil organic matter (SOM) content. The enhanced desorption of NB by the surfactant in the soil system promoted the effective contact between the composite and NB, thereby enhancing the reduction of NB by the composite. In addition, Fe0@C exhibited excellent performance for the reduction of soil-adsorbed NB compared with the conventional nZVI, and this advantage was more obvious in the potting soil system. However, the composite will be gradually passivated due to the alkaline environment during the reduction process, and this phenomenon was especially obvious in the campus soil system. When the pH value decreased from 9 to 3, the proportion of aniline (AN) generated in the campus soil system increased from 19.37 % to 69.29 %. In addition, in potting soil systems with high SOM content, the adsorption of soil particles to the composite and the high dissolved organic matter (DOM) content resulting from the high SOM content also negatively affected the reduction process. The conclusions of this study demonstrate the great potential of the Fe0@C/surfactant system for in-situ contaminated site remediation applications.

MOF-Derived Long Spindle-like Carbon-Coated Ternary Transition-Metal-Oxide Composite for Lithium Storage.

Fe3O4 is a promising alternative for next-generation lithium-ion batteries (LIBs). However, its poor cycle stability due to the large volume effect during cycling and poor conductivity hinders its application. Herein, we have successfully designed and prepared a carbon-coated ternary transition-metal-oxide composite (noted as (FeCoNi)3O4@C), which is derived from FeCoNi-MOF-74 (denoted as FeCoNi-211-24). (FeCoNi)3O4@C perfectly inherited the long spindle-shaped precursor structure, and (FeCoNi)3O4 particles grew in situ on the precursor surface. The ordered particles and the carbon-coated structure inhibited the agglomeration of particles, improving the material’s cycle stability and conductivity. Therefore, the electrode exhibited excellent electrochemical performance. Specifically, (FeCoNi)3O4@C-700 presented excellent initial discharge capacity (763.1 mAh g–1 at 0.2 A g–1), high initial coulombic efficiency (73.8%), excellent rate capability, and cycle stability (634.6 mAh g–1 at 0.5 A g–1 after 505 cycles). This study provides a novel idea for developing anode materials for LIBs.

Engineering of CuSx@C derived from Cu-MOF as long-life anodes for sodium-ion batteries

Copper sulfides are proved to be good candidates as anode materials for sodium ion batteries due to their abundant resources, moderate cost, and relatively high electrical conductivity. However, poor rate performance and cycling life still hinder their development as anode materials for sodium-ion batteries. Herein, we synthesized carbon-coated copper sulfide nanorod assembled into octahedron composites (CuSx@C) by sulfuration of a Cu-based metal-organic framework (Cu-MOF) under different temperatures. These composites with hierarchical structure exhibited superstable cycling performance as anodes of sodium-ion batteries. The CuSx@C sample obtained under 500 ​°C showed discharge capacity of 208 ​mA ​h ​g-1 ​at 2 ​A ​g-1 over 6300 cycles. Porosity and hierarchical stucture facilitate the storage of sodium ion, and carbon-coated structure buffers volume change of anode materials during the electrochemical reaction.

Carbon coating enhances single-electron oxygen reduction reaction on nZVI surface for oxidative degradation of nitrobenzene

Research on the in-situ generation of hydrogen peroxide (H2O2) using nano zero-valent iron (nZVI) has received more and more attention in recent years. However, the low utilization rate of nZVI, strict production conditions, and high energy consumption limit the application of this technology in actual environmental pollution remediation. In this study, carbon-coated nZVI (Fe0@C) was used to synthesize H2O2 in situ and realize the mineralization of nitrobenzene (NB). The results showed that the composite removed 91% of NB through adsorption, reduction, and oxidation within 120 min, of which oxidation accounts for 42.92%. Not only that, the composite material could achieve effective mineralization of NB under the wide pH range of 3–7. Quantitative experiments of hydroxyl radicals (HO) showed that the composite could generate 185.64 μM HO in 120 min without any extra energy consumption. The carbon-coated structure effectively inhibits the formation of the passivation layer on the surface of the nZVI, thereby ensuring the high activity of the Fe0. In addition, the carbon coating strengthens the sequential single-electron transfer process by changing the oxygen reduction pathway on the surface of the nZVI, so that the Fe0 can efficiently generate HO through the superoxide radical (O2−) pathway under neutral conditions. This study provides a fundamental understanding of the in-situ synthesis of H2O2 to mineralize NB by carbon-coated nZVI.

Low cost Na2FeSiO4/H–N-doped hard carbon nanosphere hybrid cathodes for high energy and power sodium-ion supercapacitors

Na 2 FeSiO 4 (NFS)/H–N-doped hard carbon nanospheres (HN-HCNSs) hybrid cathodes have been synthesized by using ferrous gluconate as template and carbon source via sol-gel method for the first time. In the structure of this hybrid cathode, the ultrathin NFS nanosheets are uniformly anchored in the mesoporous network structure of HN-HCNSs coating, forming the fast conductive transport pathways for electrons and Na + -ions. The NFS/HN-HCNSs hybrid cathode shows a hybrid energy storage mechanism with high initial discharge capacity of 218.4 mAh g −1 at 0.1 C and in the voltage range of 1.2–4.6 V versus Na/Na + . It also shows excellent long-term cycling stability (the capacity retention rates of 73.8% at 1 C after the 3300 cycles and 56.8% at 5 C after the 750 cycles in the voltage range of 1.5–4.6 V). Moreover, the unique mesoporous carbon-coated structural features endow the hybrid cathode with a maximum energy density of 331.99 W h kg −1 and a maximum power density of 2431.87 W kg −1 within working voltage range of 1.5–4.6 V. • Na 2 FeSiO 4 /H–N-doped mesoporous hard carbon nanosphere hybrid cathodes was synthesized. • Ferrous gluconate template controlled the formation of mesoporous carbon-coated structure. • This structure gives a remarkable synergic effect of Na-ion battery-supercapacitor. • This hybrid electrode delivers high energy and power densities.

Highly graphitic carbon shell on molybdenum carbide nanosheets by iron doping for stable hydrogen evolution

The graphitic degree of carbon layer on molybdenum carbide (MC) surface might affect its catalytic performance toward the hydrogen evolution reaction (HER). In this study, an iron (Fe)-doping method was investigated to adjust the graphitic degree of the carbon layer, and subsequently explore the catalytic activity of the generated MCs. A series of Fe-doped MCs was synthesized, and the optimization of their doping level led to distinctly higher HER activity compared to the undoped MC, in both acidic and alkaline solutions, due to the electronic effect. Transmission electron microscopy was applied to determine carbon-coated structure of the obtained Fe-doped MCs while Raman spectra demonstrated the successful adjustment of the carbon layer's graphitic degree with the change of the doping level. As a result, the well-preserved catalytic activity after a 10,000-circles stability test indicated the stable performance of HER on the Fe-doped MC, whereas the enhanced durability was supported by the high graphitic degree of carbon coating layer.

Solubility-dependent gelatination toward N-doped SnOx/C deriving from commercial SnO2 for the ultrastable lithium storage

More than 200% volume change is the major restriction for the practical application of Sn-based anode materials in lithium-ion batteries. In order to prepare carbon-coated structure by a facile, low-cost, facile and common method, the solubility-dependent gelatination of carboxylated chitosan is developed for the precursors of N-doped SnOx/C composites with commercial SnO2 nanoparticles as Sn source. The phase, porosity and ratio of Sn/C of the composites can be easily controlled by changing the raw materials ratio and calcination temperature. According to the results, N-doped SnOx/C anode material shows excellent stability (93.9% retention of the second cycle) and superior specific capacity (679.8 and 542.3 mAh g−1 after 300 cycles at 200 mA g−1 and 1000 mA g−1, respectively). This strategy lights on the illuminating design of 3D carbon-coated Sn-based anode by liquid carbon source and commercial solid tin source, which can improve electrochemical performance for next-generation lithium-ion batteries.

N-S co-doped C@SnS nanoflakes/graphene composite as advanced anode for sodium-ion batteries

Tin sulfides have attracted great attentions as sodium-batteries anode materials due to the remarkable high theoretical capacity, but their application is vastly limited by the poor rate capability and cycle stability. In this report, we constructed a double carbon-coated structure of carbon-coated tin (II) sulfide nanoflakes anchored on reduced graphene sheets (C@SnS-rGO) by a one-pot solvothermal synthesis with a subsequent annealing process. The carbon layer deposited on the surface of nanoflakes and the rGO sheet substrate combined into a framework which can enhance the electric conductivity and structural stability. Moreover, the carbon skeleton is doped with nitrogen and sulfur atoms which can increase the active sites and surface-capacitive effect of the as-prepared composite. As anode materials for sodium-ion batteries, the C@SnS-rGO composite electrode exhibits high capacity, good rate capability and cycling stability. The superior electrochemical performances are attributed to the improved electronic conductivity and good structural stability of the composite electrode.

Lithium storage performance improvement of NaTi2(PO4)3 with nitrogen-doped carbon derived from polyaniline

NASICON-type NaTi2(PO4)3 has been acknowledged as a promising anode for energy storage due to high ion conductivity and low cost. Nevertheless, intrinsic low electrical conductivity of NaTi2(PO4)3 and low stability in aqueous electrolyte limit its further applications in aqueous lithium rechargeable battery. In this paper, polyaniline as carbon and nitrogen sources was employed to synthesize nitrogen-doped carbon coated NaTi2(PO4)3 (NTP-P) composite by sol-gel approach and following calcination treatment. The loose and carbon-coated structure endows NTP-P with good structure stability and improved electrochemical kinetics. Compared with glucose-derived carbon-coated NaTi2(PO4)3 composite, NTP-P exhibits superior rate and cycling performance. NTP-P with proper carbon content delivers the discharge capacity of 119.4 and 83.4 mAh g−1 at rate of 0.2 and 15 C, and its capacity retention can maintain 85.8% after 1000 cycles at 5 C. This research reveals that the integration of carbon coating and nitrogen doping by using polyaniline give an excellent method to enhance the electrochemical properties of electrode materials.

Silicon-Based Composite Negative Electrode Prepared from Recycled Silicon-Slicing Slurries and Lignin/Lignocellulose for Li-Ion Cells

A large amount of kerf loss silicon slurries has been produced in the photovoltaics industry by direct diamond-wire slicing. The high-purity silicon particles in the slurries are suitable for reutilization as anode materials for lithium-ion batteries. In this study silicon particles from the kerf loss of silicon ingot slicing, coupled with lignin or lignocellulose as carbon precursors, are employed to form carbon–silicon composite materials. A pyrolysis thermal treatment in the presence of argon was applied to carbonize the biomass on the silicon materials in order to increase the conductivity of silicon-based anodes. Due to the different carbonaceous precursors, the composites formed different structures. The lignin-silicon electrode with a carbon-coated structure delivered an initial charge capacity of up to 2286 mAh/g and retained 880 mAh/g after 51 cycles at 300 mA/g. On the other hand, the pyrolyzed lignocellulose formed an interconnected structure with silicon particles, providing extra space to acc...