Heteroatom doping can increase the surface wettability, electronic conductivity and electroactive surface area of carbonmaterials, and heteroatoms (such as N, O, S and B) have been introduced into carbonmaterials to enhance the electrochemical performance [21-31]. However, the traditional heteroatom functionalization needs to add a certain amount of heteroatom sources and normally coupled with increasing cost and instable cycle performance. Therefore, it is of great significance to explore a facile and low-cost method to prepare heteroatom-dopedcarbonmaterials with high capacitance and long cycling stability. Biomass materials generally possess unique elaborate structures and various functional groups, which are beneficial for the synthesis of heteroatom self- dopedcarbonmaterials with a unique structure . Thus, biomass-derived carbon electrode materials for high-performance supercapacitors have garnered more and more research interest in recent years [33-37]. For example, Cao et al.  synthesized nitrogen-doped hierarchical porous carbon nanosheets from natural silk. The obtained carbon showed a specific capacitance of 242 F g −1 at 0.1 A g −1 and high cycling stability (91% retained after 10,000 cycles). Xie et al.  reported a grass- derived heteroatom-doped hierarchical porous carbon, which exhibited a high specific capacitance of 336 at 1 A g −1 , and the capacitance remained approximately 88% after 2000 cycles. In the work of Liu et al. , Platanus seed fibres were selected to synthesize sulfur-nitrogen dual doped hierarchical porous carbonmaterials, which possessed a high specific capacitance of 287 F g −1 at 0.25 A g −1 and an excellent capacity retention of 97% after 10,000 cycles. Notably, the biomass-derived carbonmaterials exhibit superior electrochemical properties.
. Recently, nitrogen (N)-dopedcarbonmaterials seemed promising catalyst supports through the effects of N-doping on surface physicochemical properties, electron transfer and nanostructures of the supports and catalysts, which exhibited higher catalytic activity and durability [11-15]. Two methods have been usually employed for the synthesis of N-dopedcarbon nanoma- terials: by direct N-doping during preparation of the carbon nanomaterials and treatment of the carbon com- posites with N-containing precursors [11-19]. PANI could be a good candidate for such precursors owing to the facile post-treatment for its carbonization [14,15,18-20]. Also, it exhibits a strong interaction with aromatic graphenes in carbon nanomaterials, which facilitates easy fabrication of uniform nanostructured
In situ nitrogen doped porous carbonmaterials (NC) has been architectured vis hydrothermal - carbonization coupling method by the nitrogen-rich biomass, black garlic (BG). The resulting NC performs a high specific surface area, above 2000 m 2 g −1 with abundant mesoporous and microporous hierarchical structure, as well as a high graphitization degree demonstrated by XRD and Raman. Further electrochemical measurements revealed that the corresponding electrode prepared by these NC can lead to a significantly high specific capacitance of 331 F g −1 in a 6 M KOH aqueous electrolyte, which is higher than other porous carbonmaterials obtained by most biomass. Furthermore, the corresponding electrode shows a high degree of cycling stability. This contribution shows that the NC derived from nitrogen-rich biomass are more environmental-friendly and less energy consuming than that of nitrogen dopedcarbonmaterials obtained from other conventional methods. Also, the effect of hydrothermal treatment has been discussed relative to the conventional one-step carbonization.
cost, together with weak stability and low tolerance to methanol, have severely hindered its commercial applications [7-9]. In recent years, vast endeavors have focused on developing low-cost precious metals or metal-free catalysts as alternatives to expensive and scarce Pt, among which carbon integrated with nitrogen represents a group of promising substitutes for Pt-based catalysts because of the low-cost and high ORR activity [10-15]. It has been demonstrated that N-dopedcarbonmaterials are very active towards the ORR and may act as substitutes for noble metal catalysts. Thus, it is an urgent challenge to develop a low-cost, highly-efficient, and highly-reproducible method for fabricating N-dopedcarbonmaterials for ORR catalysts. [16-21].
Based on the investigation, carbonmaterialsdoped with dual or multi heteroatoms have also been developed. Because of two different heteroatoms co-doped carbons can conjugate into carbon system to change the electronic structure or create new-electron-neutral sites, changing the distribution of electron density and improving the electron spin density, it has been confirmed to be effective for activity enhancement in ORR [18-23]. For instance, B/N co-doped graphene has been demonstrated to show excellent ORR performance in alkaline solution . Likewise, P/N [24, 25], S/N [26, 27], and S/P/N [21, 28] co-dopedcarbonmaterials have also been synthesized and studied. On the other hand, the synthesis methods of heteroatom doped graphene involve chemical vapor deposition (CVD) [13, 29, 30]; thermal annealing with heteroatom-containing precursors or gas (NH 3 ,H 2 S,CS 2 ) [20, 26, 31,
Moreover, the structural design, introducing heteroatoms such as nitrogen (N), sulfur (S), oxygen (O), phosphorus (P) and boron (B) in the electrode carbon framework is an another important way improve the supercapacitor performance [29-31]. These heteroatoms can not only generate reversible pseudocapacitance effectively but also enhance electronic conductivity and wettability of the obtained materials. N-dopedcarbonmaterials have great promise in achieving high energy density supercapacitors in recent years [32, 33]. Wang et al. fabricated nitrogen-doped porous carbon (NPCs) by activation process, and as the supercapacitors electrode, the NPCs exhibited excellent electrochemical performance with a high specific capacitance of 343 F g -1 at current density 0.5 A g -1 in 1 M H 2 SO 4
there is a scarcity of multiferroic material in nature because the conditions for being simultaneously ferroelectric and ferromagnetic are difﬁcult to achieve due to the usual atomic- level mechanism. 3,4) Therefore, it remains a major challenge to obtain new multiferroic materials at room temperature. There are four ways to obtain and to develop the multiferroic materials: i) enhancing the performances of natural multi- ferroic materials such as BiFeO 3 , 5) ii) synthesis of new
To understand the nature and characterise the transformation of both the SWNTs and the hosting PVA polymer matrix, several identical SWNT-PVA samples underwent high-power ultrashort pulse laser action at different powers (from 15 to 50 mW, which correspond to pulse energies in the range 0.9–2.63 nJ) and exposure times (10 minutes to 40 hours). The laser has been set at a pump power of 600 mW, achieving the output pulse energy of 2.63 nJ, with a corresponding optical fluence of 2.3 mJ·cm −2 . Since the output coupler in the laser ring cavity had 50/50 splitting ratio, we can assume that the laser irradiation launched on SWNT sample was of the same energy value. In a series of control measurements, samples of pure PVA and PVA with SDBS – the surfactant used for stabilisation of the SWNT suspension during materials processing – were ablated for 2 hours with the same optical fluence.
Manganese/zinc ferrite (Mn/Zn ferrite), a soft ferrite, is one of the most important ferrites due to its high magnetic properties. It has been used extensively as ferrite cores in electronics, magnetic transformer and other electrical applications (Maspol, 2001). In this study, nanostructured magnetic materials of manganese and zinc doped ferrite were prepared via chemical co-precipitation method. These materials were characterized in order to understand the effect of Zn/Mn ratio and calcinations temperature towards properties of the resulted materials. Besides, novel Mn/Zn ferrite materials coated with biocompatible polymer including polyethylene glycol (PEG) and polyvinyl alcohol (PVA) were synthesized in order to further improve their thermal stability and magnetic behavior.
water under visible-light irradiation. Interestingly, Antonietti and coworkers have demonstrated that highly condensed and crystalline carbon nitrides tend to be less active photocatalysts than ‘defect-containing’ (more hydrogen, less crystallinity) carbon nitrides.  Therefore, it is instructive to synthesize different forms of ‘defect-containing’ carbon nitrides and investigate their photoactivity to see how the activity relates to these structures. Although most research focuses on melon-type materials (one-dimensional, heptazine-based carbon nitrides) due to its rather low band gap (2.7 eV),  fewer researchers investigate the photoactivity of the less condensed carbon nitride materials which undergo less condensation than melon but are, on average, more condensed than melem. Herein we have chosen to synthesize these melem oligomers in an open system at relatively low temperatures in order to prevent good crystallization and check whether we can obtain forms of less condensed melon-type materials. Melem and melon are well studied carbon nitride materials. Melem (2,5,8-triamino-tri-s-triazine) C 6 N 7 (NH 2 ) 3 can be obtained by thermal treatment of simpler, less condensed C-N-H compounds
Abstract— Increasing demand for energy requirement has attracted considerable attention among researchers to develop efficient energy storage. One of the energy storage devices is supercapacitor, has great potential for it’s capability to deliver more power than batteries and store more energy than conventional capacitor. For making such Supercapacitors various types of carbonmaterials like activated carbon, carbon nanotubes, carbon aerogel, carbon derived carbon, graphite, etc are use as a electrode material. To produce this type of carbon special furnaces are required. This furnace has it’s own parameters in terms of pressure, temperature, weight, power, dimensions. So it was decided to develop new kind of furnace which can make high quality carbon for energy storage devices such as mainly used for supercapacitor.
immobilise the graphene nanomaterials on the electrodes (66–71). Furthermore, the aggregation of the graphene nanosheets during electrode preparation led to loss of electrocatalytic activity towards the oxidation of biomolecules (8, 10). Thus a protocol for the fabrication of surfactant- free graphene-based biosensors is needed and this was illustrated in our previous studies (65). In the study, chemical vapour deposition (CVD) grown graphene films were used as a modifying material for the indium tin oxide (ITO) electrode for the detection of DA and UA (Figure 1). The choice of the working electrode was based on the fact that the ITO electrodes are less commonly used as electrochemical electrode materials (72, 73), although they have profound application in energy storage and energy devices (38, 40, 74, 75). We found that under optimised differential pulse voltammetry (DPV) conditions, Gr/ITO electrode exhibited wide linear ranges, fairly reasonable stability and reproducibility, as well as good selectivity for both DA and UA. However, the Gr/ITO suffered poor sensitivity and high detection limits (S:N = 3) for DA and UA, with the limits of detection determined to be 4.23 µM and 5.94 µM, respectively. The promising electrocatalytic performance was ascribed to the ‘flat’ 2D structure of the graphene films due to the abundance of surface carbon atoms available for electron transfer with both DA and UA. Thus, the results showed that with further improvements such as control of the defect density and the thickness of the graphene films, Gr/ITO electrodes are promising candidates for simultaneous determination of DA and UA.
Working electrode preparation process: Foamed nickel was used as the current collector. Before use, it was ultrasonically cleaned for 3 times with ethanol and ultrapure water and dried for weighing. According to the mass ratio of 85:10:5, acertain amount of sample. Conductive Carbon blacks and bonding agent were weighed. After thoroughly mixed, it was applied evenly onto the foamed nickel and the application area was controlled to be 1 cm 2 . After vacuum drying at 60 ºC, it was compacted (10
In this work a theoretical expression for gain was achieved in a fluoride-based thulium-doped fiber. Although the pumping scheme and the set of parameters for the fiber were not optimized, the measured gain of (>9.5 dB) allowed us to validate the numerical model developed for TDFA. Then, we can estimate the opto-geometric parameters to reach a probable gain.
ABSTRACT: Nanosized ﬂuorescent carbon particles, carbon dots (CDs), are a kind of ﬂuorescent material that has many applications in recent years. They have biological application like delivery of therapeutic payloads for cancer therapy mainly due to their biocompatibility and unique optical properties. Fluorescent carbon dots overcome the short comings of high toxicity of traditional nano materials. Moreover, the preparation procedure of fluorescent carbon dots is simple and easy. Therefore, fluorescent carbon dots have great potential applied in photocatalysis, biochemical sensing, bioimaging, drug delivery and other related areas. Many functional groups or passivation agents are used to cover the surface of the CDs outside the carbon core, to make CDs with high quantum yield (QY), chemical stability and good water solubility. CDs can be easily conjugated with target molecules to expand their functionality. These traits make them an ideal alternative to semiconductor quantum dots such as CdTe and CdSe. Amoung multi- coloured fluorescent carbon dots, green CDs(GCDs) shows high potential in biological labelling and bioimaging .
Meanwhile, different morphology and pore structure of carbon carrier lead to different performance of the sulfur electrode. For example, mesoporous carbon has large specific surface area and pore volume, controllable pore diameter distribution and ordered pore structure, particularly, carbon nanotubes and CMK-3[14,24]. As sulfur carrier, the interconnected mesoporous pipeline not only facilitates the transmission of solvated Li + during charging and discharging, but also help to trap the dissolved polysulfide anions within the porous. CMK-3/S composites with 70% sulfur load showed a reversible capacity of over1000 mA h g -1 after 20 cycles. However, the cycle performance remains an issue for this kind of sulfur cathodes. It is possible that mesoporous dsorption capacity is limited for polysulphide.
The sensitizing treatment was carried out in 200mL of solution containing 10g of tin (II) chloride (SnCl2) and 2mL of hydrochloric acid for 15-30 mins. Then the sensitized carbon fibers were rinsed in distilled water. Then it was transferred to activating 200ml solution containing 0.5g of Silver Nitrate and 2ml of hydrochloric acid and stirred for 15-30 mins. The activated carbon fibers are rinsed in distilled water. And was transferred to the bath containing 5g of Cupric Sulphate and 5g of Ferrous Sulphate dissolved in sulphuric acid along with distilled water. 5g of Sodium Citrate, 5g of NaOH pellets and 5ml of hydaxine was added and mixed using mechanical stirrer and allowed for a day. The coated carbon fibers were drained, rinsed and was subjected for characterization. (Refer Fig. 1)
The method proposed was compared with a different CNTs-based electrochemical sensor reported for determination of caffeine (see Table 1). The proposed method gives a reasonably lower detection limit and wider linear range. The reason mainly depends on the performances of uniform and dense LB films of Nafion-NCNTs. The result suggests also that the LB films of Nafion-NCNTs as voltammetric sensing materials might be a very promising platform.
Figure 2 shows the FE-SEM and TEM images of the purified samples. The selectivity to carbon species was determined statistically according to the number of counts of CNM at different regions of the TEM and FE-SEM images. The images of C5N1 are not given here for they are similar to those of C450 and C450N. As shown in Figure 2a,d, the major constitu- tion of C450 is long and composed of linear carbon nanofibers (LCNF). The rest is irregular carbon com- plexes, and there is no detection of helical carbon nanofibers (HCNF). According to the TEM images, the average diameter of LCNF is ca. 20 nm. In other words, LCNF can be synthesized in large scale with high selectiv- ity using this method. As shown in Figure 2b,e, the major product of C450N is still LCNF, but there is sighting of helical structures. As shown in the inset of Figure 2b, there are sightings of long HCNF. The TEM images indicate that the obtained LCNF and HCNF have average diameter of ca. 30 nm. The results show that with the doping of nitrogen into graphitic lattices, there is change in CNM morphology: the generation of helical structures. When the reaction temperature is 500°C, the major product of C500N is the long spiny carbon nanofibers (SCNF) (Figure 2c,f), having average diameter of ca.