Surface Of Hollow Carbon Spheres Research Articles

Poly (3, 4-propylenedioxythiophene)/Hollow carbon sphere composites supported Pt NPs to facilitate methanol oxidation reactions

Direct methanol fuel cells (DMFCs) are thought of as portable, sustainable, and non-polluting energy devices. The exploration of efficient and affordable catalysts for the methanol oxidation reaction (MOR) is significant for the industrial application of DMFCs. In this study, nitrogen-doped hollow carbon spheres (HCS) derived from polydopamine were proposed for the catalyst support for platinum nanoparticles (Pt NPs) for serving as the anode catalyst for DMFCs, and a composite support material was fabricated by in-situ oxidation of 3,4-ethylenedioxythiophene (ProDOT) with HCS to get core-shell structured poly(3,4-propylenedioxythiophene) (PProDOT)-embellished hollow carbon spheres (HCS) (PProDOT/HCS) for further improving the catalytic activity for supported catalyst. The results indicated that the platinum (Pt) on the surface of HCS was well dispersed, and the Pt became smaller and more evenly distributed with the introduction of PProDOT. Simultaneously, the Schottky junction formed between PProDOT and Pt NPs contributes to enhanced charge transfer and catalytic activity of the catalyst. Notably, the core-shell structure of the ternary catalyst, its excellent charge transfer capability, and the interaction between platinum and the support contribute to its high electrocatalytic activity. Electrochemical tests demonstrated that the PProDOT/HCS/Pt catalyst exhibited a mass activity of 1169.6 mA mg−1Pt for methanol oxidation in acidic electrolytes, surpassing the activity of the HCS/Pt catalyst (472.4 mA mg−1Pt) and commercial Pt/C (281.0 mA mg−1Pt).

Coating zero valent iron onto hollow carbon spheres as efficient electrocatalyst for N2 fixation and neutral Zn-N2 battery

Electrocatalytic nitrogen reduction is an economical, efficient and eco-friendly method for ammonia synthesis. However, the faraday efficiency is very low (less than 10%) in most reported researches. In this work, zero valent iron particles are dispersed on the surface of hollow carbon spheres (Fe-HCS) as electrocatalyst. As reductant and electron donor, zero valent iron can promote the transfer of electrons to the antibonding orbitals of N2, thereby enhancing nitrogen adsorption. Meanwhile, Fe-HCS exerts extraordinary electron transfer and faraday efficiency owing to superior electrical conductivity. Especially, Fe-2HCS-8 displays fantastic NH3 yield of 64.76 μg h−1mgcat-1 and faraday efficiency of 40.81%, which overwhelmingly exceeds most reported iron-based catalysts. And the excellent energy output of power density (155.52 μW cm−2) is achieved by Zn-N2 battery. This work offers guidance for the reasonably design of zero valent metal catalysts and technology assistance toward electrochemical nitrogen fixation and energy production.

Hierarchical Co-Ni layered double hydroxide decorated on hollow carbon spheres from wood for high-performance supercapacitors

In this work, hollow carbon spheres from wood (WHCS) were prepared by liquefaction, emulsification, half-curing, carbonization and activation steps. Then, Co-Ni layered double hydroxide nanosheets (CoNiLDHs) were grown on the surface of hollow carbon spheres, forming a CoNiLDHs/WHCS composite with a core–shell structure. Benefitting from the excellent electrochemical activity of CoNiLDHs and the high surface area of WHCS, CoNiLDHs/WHCS electrode exhibited a high specific capacitance and excellent stability. Compared with WHCS and CoNiLDHs, the specific capacitance of CoNiLDHs/WHCS (∼1205.24 Fg−1) composite exhibited a superior retention rate (∼71.09% at 10 Ag−1) and excellent cycling stability (87.5% after 5000 cycles at 10 Ag−1). The synthesized CoNiLDHs/WHCS composite is a promising electrode material for developing high-performance supercapacitors.

Biomass based composite used as anode materials: Porous ZnO anchored on the rice husk-derived carbon substrate for Li-ion batteries

As an anode material, ZnO has attracted the interest of researchers because of its high theoretical specific capacity. Unfortunately, low conductivity and pulverization caused by the volume change of ZnO have been two stumbling blocks on its application. Herein, we designed a novel structure that porous ZnO crystals are firmly anchored on the surface of hollow carbon spheres derived from rice husk (RH). When used as an anode material for lithium-ion batteries, the composite material delivered a high discharge specific capacity of 1111 mAh g−1 at 0.2C after 150 cycles. The excellent electrochemistry performance is attributed to good strain accommodation of carbon skeleton and its nanoporous structure. The unique skeleton of the three-dimensional hollow carbon nanospheres enhanced conductivity and alleviated the volume expansion of ZnO nanoparticles during charge and discharge. Additionally, the pore-rich structure promoted the intercalation/deintercalation of lithium ions and the charge transfer on the electrode.

A Study of 3D flake MnO2 nanoflower decorated hollow carbon spheres as cathode material for pseudo-capacitive deionization

Capacitive deionization (CDI) is an emerging brackish water desalination technology, Manganese dioxide (MnO2) is a promising material for CDI because of its good pseudo-capacitance performances. However, the agglomeration phenomenon of MnO2 nanosheets is serious in the application process. It is critical to improve the performance of MnO2 by increasing its dispersibility. In this work, the x-MnO2/HCS was prepared by in-situ growth of MnO2 on the surface of hollow carbon spheres (HCS), which were prepared with P123 and sodium oleate (SO) as templates and glucose as carbon precursor. The load of MnO2 in x-MnO2/HCS was controlled by adjusting the addition amount of KMnO4 (x is the mass ratio of KMnO4: HCS, x = 2, 4 and 8). Then put HCS and x-MnO2/HCS as anode and cathode respectively assembled into HCS||x-MnO2/HCS (H||x-M/H) asymmetric cells for CDI tests. The influence of different KMnO4 addition amount on the performances of x-MnO2/HCS electrodes were studied. Results show that HCS with good sphericity and uniform size, excellent electrical conductivity and hydrophilicity, which effectively reduces the agglomeration of MnO2 and makes more active sites to participate in ions intercalation, enhance the capacitive performance of the composites. Electrochemical tests show that the 4-MnO2/HCS exhibits the highest specific capacitance (264.75 F/g). And the CDI tests show that H||4-M/H cell has the largest adsorption capacity (30.86 mg/g), the highest charge efficiency (76%), the lowest energy consumption (0.018 kwh/mol) and excellent cycling stability (92.4%).

Fabrication of hollow carbon spheres modified by molybdenum compounds towards toxicity reduction and flame retardancy of thermoplastic polyurethane

AbstractThis article mainly studied novel hollow carbon microspheres modified with molybdenum compounds for flame retardancy and toxicity reduction in thermoplastic polyurethane (TPU) elastomer. The structure of hollow carbon spheres (HCS) was investigated by X‐ray photoelectron spectroscopy and scanning electron microscopy‐energy‐dispersive spectrometer, respectively. The specific molybdenum compounds on the surface of HCS were further investigated by X‐ray diffraction. The flame retardancy and toxicity reduction of hollow carbon microsphere in TPU composites were studied by cone calorimeter, thermogravimetric analysis, and Fourier transform infrared spectroscopy, and so forth. The result shows that HCS modified by molybdenum compounds (MOH) can reduce fire hazards and toxic release of TPU during combustion. For example, under the same load, the peak heat release rate of TPU/MOH composite decreased by 63.39%, that of TPU composite prepared by modified HCS with ammonium molybdate (TPU/AMH) decreased by 52.89%, and that of TPU composite prepared by introducing acidulated carbonized HCS (TPU/CAH) decreased by 40.73%, compared with that of pure TPU. The peak smoke production rate (pSPR), peak carbon monoxide production (pCOP), and peak carbon dioxide production (pCO2P) of TPU/MOH composite decreased by 52.34%, 72.4%, and 68.3%, respectively. Therefore, there is a novel strategy to incorporate modified HCS to TPU, facilitating its widely promising applications in TPU.

A comparison of fluorescent N-doped carbon dots supported on the surface of hollow and solid carbon spheres, and solid silica spheres

Fluorescent carbon dots (Cdots) have attracted many researchers due to their strong optical photoluminescence (PL) properties; however, due to their small size they agglomerate in the solid state which makes it difficult to remove them from solution. To overcome these problems, Cdots can be deposited on a support, but to date, few systematic studies of Cdots-support systems have been reported, especially those on carbon supports. Herein, we report a systematic study of the effect of the use of N-Cdots (5, 10, 15 and 20%) supported on the surface of hollow carbon spheres (HCSs), solid carbon spheres (SCSs) and silica spheres (SSs). The morphology of the Cdots and their composites (Cdots/SSs, Cdots/HCSs and Cdots/SCSs) was studied by TEM, TGA, XRD, FTIR, UV–vis and PL techniques. The FTIR, XRD and TGA data suggest different interactions of the Cdots with the supports. The PL quantum yield for bare Cdots was 34% and this value was dependent on the supports, in the order Cdots/SSs > Cdots/HCSs > Cdots/SCSs due to different interactions between the Cdots and the support.

Ultrathin MnO2 nanosheets grown on hollow carbon spheres with enhanced capacitive performance

Ultrathin MnO2 nanosheets grown on the surface of hollow carbon spheres (MnO2/HCSs) were fabricated by the redox reaction between carbon spheres with KMnO4 in aqueous solution. Due to the porous structure and large amounts of active sites, MnO2/HCSs exhibit excellent capacitive performance with 227.5 Fg−1 at 1 Ag−1. After 5000 cycles, the capacity retention of MnO2/HCSs remains 96%, indicating its good cycling stability. These results demonstrate that MnO2/HCSs are promising supercapacitor electrode material and this work provide a facile method for growth of ultrathin MnO2 nanosheets on carbon substrate.

MoS2 nanosheets grown on hollow carbon spheres as a strong polysulfide anchor for high performance lithium sulfur batteries.

Lithium sulfur batteries are expected to be one of the most promising energy storage systems due to their high energy density, low cost and environmental friendliness. However, the shuttle effect of lithium polysulfides severely hampers their practical application. The design of the sulfur cathode is one of the most important approaches to overcome the problem. In this work, MoS2 nanosheets have been successfully grown on the surface of hollow carbon spheres (HCS) to obtain MoS2@HCS nanocomposites with uniform morphology. The growth behavior of MoS2 nanosheets was also proved by adjusting the pore structure of HCS. With a sulfur loading of 74%, the MoS2@HCS/S cathode exhibits a high initial reversible capacity of 1419 mA h g-1 at a current density of 0.1 C and remains at 1010 mA h g-1 after 100 cycles. Even at 0.5 C, a capacity of 795 mA h g-1 can be retained after 600 cycles, corresponding to a capacity retention rate of 63.1%. By adjusting the concentration of the sulfur source, the relationship between different growth quantities of MoS2 and the cycling performance of the battery was also investigated. The excellent electrochemical performance of the MoS2@HCS/S cathode can be fully attributed to its physical and chemical double adsorption effect on lithium polysulfides, which has been confirmed through the visible adsorption and X-ray Photoelectron Spectroscopy (XPS) experiments. This work provides a simple design concept and method to synthesize a nanocomposite-based sulfur host for high performance lithium sulfur batteries.

Fabrication of Co3O4 nanowires assembled on the surface of hollow carbon spheres for acetone gas sensing

Sensitive analysis of specific volatile organic compounds from exhaled breath from human body can provide useful information for early diagnosis of diseases, and therefore, design and fabrication of sensitive gas sensing materials with low working temperature have attracted extensive attention. In this study, Co3O4 nanowires assembled on the surface of hollow carbon spheres (Co3O4 NWs-HCSs) is successfully realized. Cobalt carbonate hydroxide nanowires assembled on hollow carbon spheres (CoCH NWs-HCSs) were first synthesized by hydrothermal method and the Co3O4 NWs-HCSs were then obtained through the post-annealing treatment (350 °C). It was found that without annealing treatment, the prepared CoCH NWs-HCSs are unstable for the acetone sensing at low temperature, with the optimum operation temperature of 200 °C and the highest response intensity of 3.71 toward 200 ppm acetone. Differently, the Co3O4 NWs-HCSs are stable for the acetone sensing at low temperature with the optimum operation temperature decreasing to 150 °C and the response intensity increases to 23 which is 6 times as high as that of CoCH NWs-HCSs. In addition, the annealed hybrid structure showed high sensitivity to acetone at much lower working temperature of 75 °C, indicating the promising application of such Co3O4 NWs-HCSs for low-temperature acetone gas sensors and a step forward to develop new devices.

Hollow Hierarchical Carbon Spheres Decorated with Ultrathin Molybdenum Disulfide Nanosheets as High‐Capacity Electrode Materials for Asymmetric Supercapacitors

AbstractA hierarchically structured nanocomposite consisting of ultrathin MoS2 nanosheets densely dispersed on the surface of hollow carbon spheres (MoS2@HCS) is prepared through a glucose‐assisted, one‐pot synthesis. When evaluated as the cathode material for supercapacitors, MoS2@HCS exhibits pseudocapacitive behavior in a KOH electrolyte. More importantly, the capacitive performance of MoS2@HCS can be further boosted by activating the composite electrode in a KOH solution. The activation process partially removes the carbonaceous materials covering the MoS2 surface, which leads to more exposure of active electrode materials to the electrolyte. Activated MoS2@HCS exhibits a high specific capacitance value of 458 F g−1 at 1 A g−1, which is approximately 2.5 times higher than that of the MoS2 electrode. Furthermore, MoS2@HCS exhibits remarkable cycling stability, with a capacitance retention of about 86% over 1000 cycles at 8 A g−1. To further demonstrate the practical applications of composite electrode, an asymmetric supercapacitor device (ASC) is fabricated by using activated MoS2@HCS and reduced graphene oxide as the positive and the negative electrodes, respectively. The fabricated device delivers a maximum energy density of 13.7 Wh kg−1 at a power density of 616 W kg−1. Even at a high power density of 4.9 kW kg−1, the ASC device can still retain 80% of the maximum energy density.

Supercapacitor electrodes based on nano-polyaniline deposited on hollow carbon spheres derived from cross-linked co-polymers

Nano-polyaniline (nano-PANI) was deposited on hollow carbon spheres (HCS) to prepare nano-PANI/HCS composites via in-situ chemical polymerization. The composites combined the high pseudocapacitance of nano-PANI and the excellent porous structure of HCS which were prepared by the carbonization of a cross-linked co-polymer, poly(styrene-co-divinylbenzene-co-methylacrylic acid). The structure and properties of the resulting composites were characterized by Fourier-transform infrared spectroscopy (FTIR) and nitrogen (N2) adsorption measurements, and the electrochemical behaviors were examined in 1M H2SO4 aqueous solution. Morphology was studied by scanning electron microscopy (SEM) and transition electron microscopy (TEM). SEM and FTIR characterizations reveal that nano-PANI was successfully deposited on the surface of HCS; and electrochemical tests indicated that the nano-PANI/HCS composites exhibited a high specific capacitance of 435.0Fg−1, along with good long-term cyclic stability (≈60% retention after 2000 cycles).

Hollow carbon spheres with wide size distribution as anode catalyst support for direct methanol fuel cells

Hollow carbonaceous composites (HCCs) possessing sphere and hemisphere shape, which had wide size distribution between several tens of nanometers and several micrometers, were prepared through a facile hydrothermal method using glucose as carbon source with the assistance of sodium dodecyl sulfate (SDS). Pyrolysis of these hollow carbonaceous composites at 900 °C under nitrogen flow produced carbonized hollow carbon spheres (HCSs) without changing their structures. Platinum (Pt) was directly deposited on the surface of the HCSs by incipient wet method, using the NaBH 4 as the reductant. TEM, SEM, powder XRD and FT-IR were utilized to characterize all these samples. It was found that Pt nanoparticles were uniformly anchored on the outer and the inner surface of HCSs. The electrocatalytic properties of the Pt/HCS electrode for methanol oxidation have been investigated through cyclic voltammetry and chronoamperometry. The Pt/HCS electrode showed significantly higher electrocatalytic activity and more stability for methanol oxidation compared with Pt supported carbon microspheres (Pt/CMs) and commercial carbon (Pt/XC-72) electrode. The excellent performance for the Pt/HCS might be attributed to the high dispersion of platinum catalysts and the particular hollow structure of HCSs.

Sea urchin shaped carbon nanostructured materials: carbon nanotubes immobilized on hollow carbon spheres

Novel sea urchin shaped nanostructured carbon spheres (carbon nano-urchins) were fabricated by the growth of carbon nanotubes on the surface of hollow carbon spheres. The carbon nano-urchins were successfully used as a catalyst support for methanol electrochemical oxidation.