Formation mechanism for oxidation synthesis of carbon nanomaterials and detonation process for core-shell structure

Abstract

A novel formation mechanism according to the oxidative dehydrogenation of organics has been proposed for the low-temperature preparation of carbon-based nanomaterials. Several typical organics including ethanol, 1-butanol, p-cymene and liquid paraffin are used as precursors to react with ammonium persulfate (APS) in an autoclave, and carbon particles are obtained as a validation. The reaction characteristics are comprehensively investigated by the differential scanning calorimetric and thermogravimetric analysis. The strongly exothermic oxidation reaction below 200 °C is a common feature during the process. The organic molecules are cleaved into small carbon species and further transform to amorphous carbon. When the organometallic compound is used as a reactant instead, such as magnesocene and allyltriphenyltin, carbon encapsulated MgO and SnS nanocrystals with core-shell structure are synthesized, respectively. A detonation introduced by the violent reaction occurs in the process with a very rapid liberation of heat and large quantities of thermally expanding gases. The large amounts of free atomic/radical species and reactive intermediates are generated as sources for the core-shell structure. It is a common strategy for the large scale production of carbon encapsulated oxide/sulfide nanocrystals by means of the moderate detonation process of the organometallic compound and APS in an autoclave.