Magubane, Alice2018-01-052018-01-052017Magubane, Alice (2017) Synthesis of copper nanoparticles contained in mesoporous hollow carbon spheres as potential catalysts for growing helical carbon nanofibers, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/23629>http://hdl.handle.net/10539/23629A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment for the degree of Master of Science in Chemistry, 2017The aim of this study was to synthesize helical carbon nanofibers with controlled diameter by using copper nanoparticles contained inside hollow carbon sphere. In this work, different methods have been explored to synthesize copper nanoparticles contained inside mesoporous hollow carbon spheres in order to minimize the sintering effect of the copper nanoparticles. Mesoporous hollow carbon spheres were used not only as a support for the copper nanoparticles but to stabilize and disperse these nanoparticles to prevent the formation of aggregates. Mesoporous hollow carbon spheres were synthesized using a hard templating method, in which mesoporous silica spheres or polystyrene spheres were used as a sacrificial template. Carbon nanofibers with different morphologies, including straight and helical fibers were obtained by a chemical vapor deposition method where acetylene was decomposed over copper nanoparticles contained inside mesoporous hollow carbon spheres catalyst at 350 °C. The synthesized carbon nanofibers were grown on the surface of the mesoporous hollow carbon spheres as the methods used to synthesize the catalyst failed to incorporate copper nanoparticles inside the spheres. Differences in the diameter of the straight and helical carbon nanofibers were observed from both catalysts. This supports the important effect of particle size on influencing the shape of the synthesized carbon nanofibers.Online resource (xix, 80 leaves)enCarbon nanofibersNanoparticlesNanostructured materialsCatalysisThesis