Soft Chemical Synhesis, Cutting And Catalyst Behavior Of Carbon Nanotubes Based On The "C-H-O" System

This thesis focuses on the discussion for synthesis, cutting, and modification for thecarbon nanotubes, which are based on the soft chemistry in the "C-H-O"system.The synthesis and fabrication carbon nanotubes are carried out by soft chemistrymethods in "C-H-O"system. As results, graphite can be transformed into pristine carbonnanotubes with one-step treatment, under the assistance of water, only at atmospheric pressureand without any catalyst. A novel and 'green' oxygen assisted pyrogenation approach wasdeveloped for the fabrication of carbon nanotubes: from grass to CNTs, using renewablenatural products as the carbon sources and the oxygen, as a benign oxidation reagent. Alow-temperature hydrothermal route has been successfully developed to synthesize CNTs at160℃without catalysts by using PEG as the carbon source. In a polyoxometalates-assistedmild hydrothermal system, active carbon powder can be transformed into carbonnanoparticals, carbon nanotubes, and carbon nanobelts by using different kindpolyoxometalates as catalyst. This is a convenient, controllable, and renewable approach forthe synthesis of carbon nanomaterials with the participation of polyoxometalates. In addition,single-walled carbon nanotubes, cubic carbon nanocrystals, and other carbon nanostructuresalso can be synthesized through a polyoxometalates-assisted soft electrochemical reductionprocess at room temperature.A simple polyoxometalates assisted mild hydrothermal method was developed forcontrolled cutting carbon nanotubes without increasing sidewall damage. After the reaction,the polyoxometalates used were changed into heteropoly blues, which can be converted backto the polyoxometalates with the addition of a small amount of H2O2 solution. Moreover, aseries of novel polyoxometalates nanocrystals have been prepared by a surfactant-assistedsolution-and solid-phase route. We have further directly observed the attachment ofpolyoxometalates nanoparticles to oxidized carbon nanoparticals due to the chemicaladsorption between carboxylic acid groups of carbon nanoparticals and polyoxometalatesnanoparticles.Multi-walled carbon nanotubes are directly used as catalyst for the hydroxylation ofaromatic hydrocarbons. Curved sp2-hybridized carbon surface of carbon nanoparticals playsan important role in the selective catalytic reactions. The active oxygenated species, withstrong oxene characters, may be generated through the interaction between the hydrogenperoxide and the carbon nanoparticals. Without the assistance of any solvent or additive, highselectivity up to 98% was obtained. Carbon nanoparticals were proved to be a high-active,high-selective, and good-reproductive heterogeneous catalyst.