Controlled-growth of platinum nanoparticles on carbon nanotubes or nanospheres by MOCVD in fluidized bed reactor

Multi-walled carbon nanotubes (MWNT) and carbon nanospheres; (NanoC) have been used as substrates for the deposition of platinum nanoparticles by Metal-Organic Chemical Vapor Deposition in a fluidized bed reactor starting from [PtMe2(COD)]. On untreated graphitic substrates no platinum deposition was observed at 110degreesC, a temperature at which Pt can be deposited from the same precursor on SiO2. An explanation based on the lack of oxygen-containing anchoring groups for the grafting of the platinum precursor on such carbon supports is proposed. Similar results were obtained on highly orientated pyrolytic graphite. It is shown that an oxidative treatment of MWNT and NanoC with nitric acid allows to functionalize the carbon surface through the formation of -COOH groups, and that the carboxylic acid groups can act as anchoring sites for platinum nanoparticles deposition. The platinum mean particle size was found to be smaller in the case of Pt/MWNT than for Pt/NanoC.