This invention relates to Pt/multi walled nanotubular coils (MWNC) electrocatalysts.
One of the uses to which the above mentioned nanotubular coils can be put are for oxygen reduction in Proton Exchange Membrane Fuel Cell.
Purified multi walled nanotubular coils (MWNC) have been functionalized with carboxyl, hydroxyl and carbonyl groups by treating with concentrated acids. Well dispersed Pt catalysts on MWNC support for Polymer Electrolyte Membrane Fuel Cell (PEMFC) have been prepared by chemical reduction method using pre functionalized MWNC. Membrane electrode assembly (MEA) for PEMFC has been fabricated using different compositions of Pt/MWNC and Pt/C as electrodes.
This invention relates to the functionalization of MWNC with carboxyl, hydroxyl and carbonyl groups for better dispersion of Pt over MWNC by chemical reduction method and more particularly, to use above prepared Pt/MWNC as electrode materials for PEMFC applications.

The polymer electrolyte membrane fuel cell (PEMFC) has attracted much attention due to its advantageous features such as a low operating temperature, sustained operation at high current density, low weight, compactness, potential for low cost and volume, long stack life, fast start-up and suitability for discontinuous operation. But its wide application is hindered by its high cost. It is generally believed that the large amount of platinum required as a catalyst in PEMFCs is one of the main reasons why fuel cells are excluded from commercialization. In the past two decades, many efforts have been devoted to increase the utilization of Pt and reduce the amount of Pt used in PEMFCs. The search for active electrocatalyst has involved the variation of catalyst preparation and composition, the use of supported or unsupported catalysts, and more recently, recognition of the importance of the atomic structure of the carbon support on the catalyst. Electrocatalysts with small size and high dispersion result in high electrocatalytic activity. Supporting materials with high surface area are essential to disperse catalyst particles, so as to reduce the catalyst loading and thereby improving the fuel cell performance. A key consideration in improving fuel cell performance is the nature of the carbon support, which can assist both in dispersion of the metal catalyst and in possibly facilitating electron and mass transfer kinetics at the electrode interface. A variety of carbon supports have been

investigated in this direction including graphite nanofibers, SWNT, MWNT, and high surface area carbon blacks. A new type material from carbon family in the form of nanotubular coils (MWNC), attracted researchers due to the combination of coil morphology and properties of nanotubes. MWNC can be potential candidates for fuel cell applications as catalyst support materials due to their superior mechanical, electrical properties apart from their morphology and interesting properties such as nanometer size, high accessible surface area, good electronic conductivity and high stability. There are different methods for dispersing platinum on carbon supports to improve metal dispersions on, mainly through optimization of the metal supporting procedures or functionalisation of the carbon surface. Hence, achieving a higher degree of dispersion of Pt on
MWNC support is an important goal for maximum utilization of high surface area, conductivity and porosity of MWNC. The key proposal of this invention is to combine Pt nanoparticJes and MWNC to modify the electrodes of fuel cells in order to improve their electroactivity for better performance.

It is thus an object of the present invention to disperse the Pt nanoparticles on MWNC by a simple chemical reduction by functionalizing MWNCs and to study their suitability in the field of fuel cells as supporting materials for electrocatalyst. The process, according to this invention, for the preparation of Pt/multi walled nanotubular coils (MWNC) electrocatalysts comprises the steps of ultrasonicating purified MWNC in concentrated acids, the ultrasound producing microscopic bubbles in the liquid, said bubbles while collapsing resulting in shock waves, which are highly effective in increasing the nanotube wetting; refluxing the liquid, after sonication, in nitric acid under constant agitation, followed by repeated washing with de-ionized water and drying the sample in vacuum; ultrasonicating the dried sample in a solvent; adding Pt containing solution slowly during stirring.; reducing the mixture by adding reducing solution; and finally washing the solution with de-ionized water; filtering and drying by vacuum filtration; drying the recovered Pt loaded MWNCs.
While carrying out the process as described above it is exemplified hereunder that:

Ultrasonicating purified MWNC in concentrated acids is carried out for 3 h.
i.e reducing solution useis 0.1M NaBH4+1M Na0N
Refluxing the liquid, after sonication, in nitric acid under constant
agitation is carried out for 12 h.
Ultrasonicating the dried sample in a solvent is carried out for 1 h.
Reducing the mixture is carried out after 12 hours.
The recovered Pt loaded MWNCs are dried for 3h
The invention is useful for maicihg high pertorltiance electrodes using MWNC as cata/st spportina material, which in turn helps in commercialization of fuel cells.

We Claim:
1. A process for the preparation of Pt/multi walled nanotubular coils (MWNC) electrocatalysts comprising the steps of ultrasonicating purified MWNC in concentrated acids, the ultrasound producing microscopic bubbles in the liquid, said bubbles while collapsing resulting in shock waves, which are highly effective in increasing the nanotube wetting; refluxing the liquid, after sonication, in nitric acid under constant agitation, followed by repeated washing with de-ionized water and drying the sample in vaccum; ultrasonicating the dried sample in a solvent; adding Pt containing solution slowly during stirring.; reducing the mixture by adding reducing solution; and finally washing the solution with de-ionized water, filtering and drying by vacuum filtration; drying the recovered Pt loaded MWNCs.
2. A process as claimed in Claim 1 wherein ultrasonicating purified MWNC in concentrated acids is carried out for 3 h.
3. A process as claimed in Claim 1 or Claim 2 wherein refluxing the liquid, after sonication, in nitric acid under constant agitation is carried out for 12 h.
4. A process as claimed in any one of the preceding Claims wherein ultrasonicating the dried sample in a solvent is carried out for l.h.
5. A process as claimed in any one of the preceding Claims wherein reducing the mixture is carried out after 12 hours.
6. A process as claimed in any one of the preceding Claims wherein the recovered Pt loaded MWNCs are dried for 3h.
i

7. A process for the preparation of Pt/multi walled nanotubular
coils (MWNC) electrocatalysts substantially as herein
described.
8. Pt/multi walled nanotubular coils (MWNC) electrocatalysts
whenever manufactured by a process as claimed in any one of the
preceding Claims.