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The ongoing research toward meeting global energy demands requires novel materials from abundant renewable resources. This work involves an investigation on nitrogen-doped carbon nanotubes (N-CNTs) synthesized from relatively low-cost and readily available biomass as carbon precursors and their use as electrodes for supercapacitors. The influence of the ionic liquid 1-butyl-3-methylimidazolium chloride, or its combination with either sugarcane bagasse or cellulose (IL-CNTs, ILBag-CNTs, and ILCel-CNTs, respectively), in the synthesis of N-CNTs and the resultant effect on their physical and electrochemical properties was studied. Systematic characterizations of the N-CNTs employing transmission electron microscopy (TEM), thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), elemental analysis, nitrogen sorption analysis, cyclic voltammetry, and electrochemical impedance spectroscopy were performed. TEM data analysis showed that the mean outer diameters decreased, in the order of IL-CNTs > ILBag-CNTs > ILCel-CNTs. The N-CNTs possess only pyridinic and pyrrolic nitrogen-doping moieties. The pyridinic nitrogen-doping content is lowest in IL-CNTs and highest in ILCel-CNTs. The N-CNTs are mesoporous with surface areas in the range of 21–52 m2 g−1. The ILCel-CNTs had the highest specific capacitance of 30 F g−1, while IL-CNTs has the least, 10 F g−1. The source of biomass is beneficial for tuning physicochemical properties such as the size and surface areas of N-CNTs, the pyridinic nitrogen-doping content, and ultimately capacitance, leading to materials with excellent properties for electrochemical applications.
Kudzai Mugadza; Annegret Stark; Patrick Ndungu; Vincent Nyamori. Effects of Ionic Liquid and Biomass Sources on Carbon Nanotube Physical and Electrochemical Properties. Sustainability 2021, 13, 2977 .
AMA StyleKudzai Mugadza, Annegret Stark, Patrick Ndungu, Vincent Nyamori. Effects of Ionic Liquid and Biomass Sources on Carbon Nanotube Physical and Electrochemical Properties. Sustainability. 2021; 13 (5):2977.
Chicago/Turabian StyleKudzai Mugadza; Annegret Stark; Patrick Ndungu; Vincent Nyamori. 2021. "Effects of Ionic Liquid and Biomass Sources on Carbon Nanotube Physical and Electrochemical Properties." Sustainability 13, no. 5: 2977.
Considering its availability, renewable character and abundance in nature, this review assesses the opportunity of the application of biomass as a precursor for the production of carbon-based nanostructured materials (CNMs). CNMs are exceptionally shaped nanomaterials that possess distinctive properties, with far-reaching applicability in a number of areas, including the fabrication of sustainable and efficient energy harnessing, conversion and storage devices. This review describes CNM synthesis, properties and modification, focusing on reports using biomass as starting material. Since biomass comprises 60–90% cellulose, the current review takes into account the properties of cellulose. Noting that highly crystalline cellulose poses a difficulty in dissolution, ionic liquids (ILs) are proposed as the solvent system to dissolve the cellulose-containing biomass in generating precursors for the synthesis of CNMs. Preliminary results with cellulose and sugarcane bagasse indicate that ILs can not only be used to make the biomass available in a liquefied form as required for the floating catalyst CVD technique but also to control the heteroatom content and composition in situ for the heteroatom doping of the materials.
Kudzai Mugadza; Annegret Stark; Patrick G. Ndungu; Vincent O. Nyamori. Synthesis of Carbon Nanomaterials from Biomass Utilizing Ionic Liquids for Potential Application in Solar Energy Conversion and Storage. Materials 2020, 13, 3945 .
AMA StyleKudzai Mugadza, Annegret Stark, Patrick G. Ndungu, Vincent O. Nyamori. Synthesis of Carbon Nanomaterials from Biomass Utilizing Ionic Liquids for Potential Application in Solar Energy Conversion and Storage. Materials. 2020; 13 (18):3945.
Chicago/Turabian StyleKudzai Mugadza; Annegret Stark; Patrick G. Ndungu; Vincent O. Nyamori. 2020. "Synthesis of Carbon Nanomaterials from Biomass Utilizing Ionic Liquids for Potential Application in Solar Energy Conversion and Storage." Materials 13, no. 18: 3945.
Presented herein is the nitrogen-doped multiwalled carbon nanotubes (N-MWCNTs) production from a residue, sugarcane bagasse, using 1-butyl-3-methylimidazolium chloride [C4MIM]Cl as the solvent and nitrogen source, and ferrocene as the catalyst source. N-MWCNTs were synthesised using the floating catalyst chemical vapour deposition method at 850 °C. The synthesised N-MWCNTs were characterised using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), X-ray diffraction (XRD) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. Hollow tubular structures of N-MWCNTs were observed using TEM. These observations correlated morphology from SEM which showed spaghetti-like structures, and also EDS detected the presence of nitrogen. Raman spectroscopy indicated MWCNT bands, around 1350 and 1580 cm−1 assigned to D-band and G-band due to defective and graphitic carbon vibrations, respectively. Also, XRD patterns showed typical N-MWCNT structures with a strong intensity peak at 2θ = 26.4° which was indexed as the C(002) reflection of graphite. TGA showed an N-CNTs thermogram curve, with the main decomposition temperature around 590 °C. The study showed that N-MWCNTs were successfully synthesised from sugarcane bagasse. The study significantly establishes a strategy for utilisation and value addition of a residue which is abundant from sugar production mills.
Kudzai Mugadza; Patrick G. Ndungu; Annegret Stark; Vincent O. Nyamori. Conversion of residue biomass into value added carbon materials: utilisation of sugarcane bagasse and ionic liquids. Journal of Materials Science 2019, 54, 12476 -12487.
AMA StyleKudzai Mugadza, Patrick G. Ndungu, Annegret Stark, Vincent O. Nyamori. Conversion of residue biomass into value added carbon materials: utilisation of sugarcane bagasse and ionic liquids. Journal of Materials Science. 2019; 54 (19):12476-12487.
Chicago/Turabian StyleKudzai Mugadza; Patrick G. Ndungu; Annegret Stark; Vincent O. Nyamori. 2019. "Conversion of residue biomass into value added carbon materials: utilisation of sugarcane bagasse and ionic liquids." Journal of Materials Science 54, no. 19: 12476-12487.
Carbon nanostructured materials (CNMs) have vast capability in the field of energy, for storage and conversion purposes. Consequently, extensive greener and environmentally benign synthesis techniques that employ natural and readily renewable, low-cost waste materials need to be established. Herein, cellulose is considered as an alternative precursor source for the synthesis of CNMs. In the past decade, ionic liquids (ILs) have exhibited a great potential in a diverse number of applications. However, insignificant attention has been paid to the structure of ILs in relation to their extended application as a media for the dissolution of cellulose to avail carbon for CNMs synthesis. As baseline, a number of ionic liquids were used as carbon sources for CNM production, and distinct differences were found, depending on the type of ionic liquid used and the temperature of synthesis. Furthermore. CNMs were fabricated using a combination of the ionic liquid, 1-butyl-3-methylimidazolium chloride, [C4MIM]Cl, and cellulose, in the presence of ferrocene as catalyst precursor, using the floating catalyst chemical vapour deposition technique. Typical spaghetti like, hollow tubular structures with bamboo compartments, resembling N-doped multiwalled tubular carbon nanomaterials were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Thermal stability studies showed thermogram profiles with a stability of around 550 °C. The sample synthesised with cellulose was more stable than the sample synthesised from IL and ferrocene only. Characteristic D- and G-bands were observed around 1380 and 1560 cm−1, respectively, for Raman spectroscopy. X-ray diffraction (XRD) showed characteristic tubular carbon nanomaterials and or graphitic/N-graphitic diffraction patterns.
Kudzai Mugadza; Patrick G. Ndungu; Annegret Stark; Vincent O. Nyamori. Ionic liquids and cellulose: Innovative feedstock for synthesis of carbon nanostructured material. Materials Chemistry and Physics 2019, 234, 201 -209.
AMA StyleKudzai Mugadza, Patrick G. Ndungu, Annegret Stark, Vincent O. Nyamori. Ionic liquids and cellulose: Innovative feedstock for synthesis of carbon nanostructured material. Materials Chemistry and Physics. 2019; 234 ():201-209.
Chicago/Turabian StyleKudzai Mugadza; Patrick G. Ndungu; Annegret Stark; Vincent O. Nyamori. 2019. "Ionic liquids and cellulose: Innovative feedstock for synthesis of carbon nanostructured material." Materials Chemistry and Physics 234, no. : 201-209.
Metal nanoparticle (MNP) catalysts used for the synthesis of multiwalled carbon nanotubes (MWCNTs) consisted of single metals (Fe, Ni or Co) and bimetallic mixture (CoFe, NiFe or NiCo). MWCNTs were successfully synthesised at 200 °C in 10 min using liquefied petroleum gas as carbon source with non-equilibrium plasma enhanced chemical vapour deposition (PECVD) method. The nanostructures and the morphology of the MNPs and the MWCNTs film were characterised using relevant microscopic and spectroscopic methods. The synthesised MWCNTs were used as part of the electrode material in organic solar cell (OSC) set-up. Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) was used as an electron transporter and poly-3-hexyl thiophene (P3HT) as an electron donor. The performance of OSC devices was tested using standard electrical measurements and solar simulator operating at 100 mW/cm2. The measured power conversion efficiencies was found to be dependent on the metal catalyst used during synthesis. Among all the catalysts employed in this investigation, the best device performance was found from the synthesis of MWCNTs using Fe as a catalyst followed by Co and then Ni, respectively.
Kudzai Mugadza; Vincent O. Nyamori; Genene Tessema Mola; Reuben H. Simoyi; Patrick G. Ndungu. Low temperature synthesis of multiwalled carbon nanotubes and incorporation into an organic solar cell. Journal of Experimental Nanoscience 2017, 12, 363 -383.
AMA StyleKudzai Mugadza, Vincent O. Nyamori, Genene Tessema Mola, Reuben H. Simoyi, Patrick G. Ndungu. Low temperature synthesis of multiwalled carbon nanotubes and incorporation into an organic solar cell. Journal of Experimental Nanoscience. 2017; 12 (1):363-383.
Chicago/Turabian StyleKudzai Mugadza; Vincent O. Nyamori; Genene Tessema Mola; Reuben H. Simoyi; Patrick G. Ndungu. 2017. "Low temperature synthesis of multiwalled carbon nanotubes and incorporation into an organic solar cell." Journal of Experimental Nanoscience 12, no. 1: 363-383.