Carbon Nitride Nanotubes for Superior Polymer Fuel Cell Electrode Catalyst Fabricated by a Simple, Rapid, Effective and Green Process Say Nanjing University Chemists

Nanjing University (Nanjing, Jiangsu, CN) researchers, led by Chemistry Professor Zheng Hu, with Yanwen Ma, Bing Yue and  Leshu Yu, have fabricated electrode catalyst of carbon nitride nanotubes supported by platinum and ruthenium nanoparticles. The nanomaterials have been produced by a simple, rapid, effective and green process. The materials are suitable for proton exchange membrane fuel cells or direct methanol fuel cells, as well as other chemical reactions catalyzed by Pt and Ru. 

The process makes use of the affinity of carbon nitride nanotubes to platinum and ruthenium atoms, Pt and Ru nanoparticles could be directly deposited on carbon nitride nanotubes by the reduction reaction, hereby avoiding the pre-activation or modification process needed by carbon nanotubes. The electrode catalysts produced in this way are suitable for proton exchange membrane fuel cells or direct methanol fuel cells, as well as other chemical reactions catalyzed by Pt and Ru.  The manufacturing method is detailed in U.S. Patent Applicadtion 20100041544.

Carbon nitride nanotubes, also called nitrogen-doped carbon nanotubes, are prepared by doping nitrogen atoms in the graphitic carbon lattices by the formation of C--N bonds. Carbon nitride nanotubes have higher conductivity than carbon nanotubes since the nitrogen atoms in carbon nitride nanotubes provide additional electrons. Recent research reveals that carbon nitride nanotubes act as Lewis base, and may be used to catalyze the oxygen reduction reaction in fuel cells

The unique properties of carbon nitride nanotubes have received much research attention. Using the intrinsic chemical reactivity of carbon nitride nanotubes, A. Zamudio et al have directly deposited Ag nanoparticles onto carbon nitride nanotubes without pre-modification.  The results of recent research demonstrates that carbon nitride nanotubes are better electrode catalyst support thancarbon nanotubes because they possess large surface area, high electrical conductivity, good stability, intrinsic capacity for catalysis and metal nanoparticle immobilization. Therefore, it is important to develop the preparation method of carbon nitride nanotube supported Pt and Ru nanoparticles for both theoretical and practical purposes. 

provide a new method of depositing Pt, Ru and their alloyed nanoparticles on carbon nitride nanotubes to produce electrode catalyst with high specific area, high conductivity, good stability and excellent catalytic properties.

The inventors provide a metod for making an electrode catalyst of carbon nitride nanotube supported Pt and Ru nanoparticles. The carbon nitride nanotubes are multi-walled, single-walled or a mixture of both types, having the nitrogen content of 0.01-1.34 in N/C ratios, denoted as CN_x, wherein x is equal to 0.01-1.34. The Pt and Ru nanoparticles have diameters of 0.1-15 nm, and their content in the composite catalyst are 1%-100% (wt %) with respect to the weight of the supporting carbon nitride nanotubes.

The method for preparing carbon nitride nanotube supported Pt and Ru nanoparticles containing the following steps: carbon nitride nanotubes are evenly dispersed into the solution of platinum and ruthenium salts; the salts are reduced by reducing agents, forming carbon nitride nanotube supported Pt and Ru nanoparticles; the electrode catalyst of carbon nitride nanotube supported Pt and Ru nanoparticles is obtained after purification.