Synthesis of CNS, ZnO/CNS and ZnCnO4/CNS composites from patchouli biomass by using microwave for remediation of pesticide contaminated surface water in paddy field

Patchouli biomass is a potential precursor for CNS synthesis. In this research, the patchouli was pyrolyzed using the microwave. The purpose of this research is to study the effect of microwave energy and activator toward physicochemistry of CNS and composite (ZnO/CNS) and application of ZnCr2O4/CNS for the pesticide polluted surface water remediation in paddy field. In the process, the biomass was pyrolyzed at four and 8W with and without the ZnCl2 activator. The products were blended and evaporated to obtain CNS and ZnO/CNS. The products were characterized using FTIR spectrometry, XRD, and dispersion test. The composites were used to synthesize ZnCr2O4/CNS at 600W in the microwave. The composites were used for buthylphenylmethyl carbamate pesticide degradation test (BPMC) for 48 h with H2O2 oxidation. The FTIR spectra indicated better carbonization for products taken using an activator at both microwave energies. The X-ray diffractograms showed the turbostratic structure of carbon obtained at 4W pyrolysis (with activator), meanwhile 8W pyrolysis (without activator). ZnO and turbostratic carbon structures were shown by the product of 8W pyrolisis with activator. The calcined composite indicated ZnCr2O4/CNS. The degradation test showed that ZnCr2O4/CNS(8W) catalyst decreased the BMPC concentration almost three times that of the composite (4W).

The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments

An innovative approach for the design of air electrodes for metal–air batteries are free-standing scaffolds made of electrospun polyacrylonitrile fibres. In this study, cobalt-decorated fibres are prepared, and the influence of carbonisation temperature on the resulting particle decoration, as well as on fibre structure and morphology is discussed. Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, and inductively coupled plasma optical emission spectrometry are used for characterisation. The modified fibre system is compared to a benchmark system without cobalt additives. Cobalt is known to catalyse the formation of graphite in carbonaceous materials at elevated temperatures. As a result of cobalt migration in the material the resulting overall morphology is that of turbostratic carbon. Nitrogen removal and nitrogen-type distribution are enhanced by the cobalt additives. At lower carbonisation temperatures cobalt is distributed over the surface of the fibres, whereas at high carbonisation temperatures it forms particles with diameters up to 300 nm. Free-standing, current-collector-free electrodes assembled from carbonised cobalt-decorated fibre mats display promising performance for the oxygen reduction reaction in aqueous alkaline media. High current densities at an overpotential of 100 mV and low overpotentials at current densities of 333 μA·cm−2 were found for all electrodes made from cobalt-decorated fibre mats carbonised at temperatures between 800 and 1000 °C.

Studies on Carbon Materials Produced from Salts with Anions Containing Carbon Atoms for Carbon Paste Electrode

In the presented work, the properties of carbon materials obtained in the reaction of sodium bicarbonate (C–SB) and ammonium oxalate (C–AO) with magnesium by combustion synthesis were investigated. For the materials obtained in this way, the influence of the type of precursor on their properties was analyzed, including: Degree of crystallinity, porous structure, surface topography, and electrochemical properties. It has been shown that the products obtained in magnesiothermic process were found to contain largely the turbostratic carbon forming a petal-like graphene material. Both materials were used as modifiers of carbon paste electrodes, which were then used to determine the concentration of chlorophenol solutions by voltammetric method. It was shown that the peak current determined from the registered differential pulse voltammograms was mainly influenced by the volume of mesopores and the adsorption capacity of 4-chlorophenol for both obtained carbons.

Two-dimensional N/O co-doped porous turbostratic carbon nanomeshes with expanded interlayer spacing as host material for potassium/lithium half/full batteries

The development of carbon nanomaterials with the resource-rich and environment-friendly merits as stabilized rechargeable ion batteries anode is facing enormous challenge due to the limited interlayer spacing and tardy kinetics....

Role of in-situ formed free carbon on electromagnetic absorption properties of polymer-derived SiC ceramics

In order to enhance dielectric properties of polymer-derived SiC ceramics, a novel single-source-precursor was synthesized by the reaction of an allylhydrido polycarbosilane (AHPCS) and divinyl benzene (DVB) to form carbon-rich SiC. As expected, the free carbon contents of resultant SiC ceramics annealed at 1600 °C are significantly enhanced from 6.62 wt% to 44.67 wt%. After annealing at 900–1600 °C, the obtained carbon-rich SiC ceramics undergo phase separation from amorphous to crystalline feature where superfine SiC nanocrystals and turbostratic carbon networks are dispersed in an amorphous SiC(O) matrix. The dielectric properties and electromagnetic (EM) absorption performance of as-synthesized carbon-rich SiC ceramics are significantly improved by increasing the structural order and content of free carbon. For the 1600 °C ceramics mixed with paraffin wax, the minimum reflection coefficient (RCmin) reaches –56.8 dB at 15.2 GHz with the thickness of 1.51 mm and a relatively broad effective bandwidth (the bandwidth of RC values lower than –10 dB) of 4.43 GHz, indicating the excellent EM absorption performance. The carbon-rich SiC ceramics have to be considered as harsh environmental EM absorbers with excellent chemical stability, high temperature, and oxidation and corrosion resistance.