THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

This invention relates to 'Synthesis of Carbon Nanostructures dispersed with nanoparticles of transition metal based alloys/elements catalysts or Carbon Nanostructures modified with foreign dopant elements and dispersed with nanoparticles of transition metal based alloys/elements catalysts' materials therefrom for hydrogen storage.

Hydrogen is the ideal fuel for new types of fuel cell vehicles, but the 'bottleneck' is how to store hydrogen in the fuel cell vehicles. Hence, the development of hydrogen storage materials in an important aspect for possible application in Fuel cell run automobiles. DOE (department of energy, USA) has set the target of developing materias with 6.5 hydrogen wt% for 2015.

Practical issues with the storage of hydrogen in gaseous form are the high pressure in cylinders (~150 bar) and safety issues. Practical issues with the storage of hydrogen in liquid form are the cost of liquefaction/cryogenics and transportation. Therefore only the reversible solid-state hydrogen storage is the most promising potential solution. To date, no solid-state material has been identified that meets this criteria. Therefore, the main challenges to improve the hydrogen storage technologies are to increase the storage weight %, and reduce the cost of the material.

In this invention, we have demonstrated a hydrogen storage capacity of -10-14 wt % in Carbon Nanostructures. The Carbon Nanostructures are in the undoped form dispersed with nanoparticles of transition metal based alloys/elements catalysts or Carbon Nanostructures modified with foreign dopant elements and dispersed with nanoparticles of transition metal based alloys/elements catalysts.
A hydrogen storage capacity of -10-14 wt % is achieved in Carbon Nanostructures in the undoped form dispersed with nanoparticles catalysts or in Carbon Nanostructures modified with foreign dopant elements and dispersed with nanoparticles catalysts.

I. The Carbon Nanostructures are hybrid type including carbon nanotubes (CNT =SWNT, MWNT), Graphene and a mixture of carbon nanotubes and Graphene in the ratio x: (1-x) where x is the weight percentage of CNT (x=5-50%).

II. II. The foreign dopant elements are Boron, Nitrogen.

III. III. The catalysts are nanoparticles of transition metal based alloys combining the elements A and B (A= Pd, Pt, Zr B= Ni, Co, Fe, Au, Ag, Cr, V) or nanoparticles of elements (Pd, Pt, Ni, Co, Fe, Au, Ag, Zr, V, Cr, Cu).

The process of synthesis of Carbon Nanostructured materials, the process for doping of element process and process for dispersion of the transition metal based alloys/elements nanoparticles catalysts were performed by different methods. The hydrogen storage capacity of -10-14 wt % in Carbon Nanostructures in the hydrogen equilibrium pressures of 45, 55 bar and at 0 and 25 C is achieved which is about twice the target set for 2015 by DOE, USA.

Catalytically and Chemically modified carbon nanostructures were prepared in three methods.

I. Carbon nanotubes (CNT=SWNT, MWNT) were prepared by Catalytic Chemical Vapor Deposition (CCVD) method. Graphene sheets were prepared by a) hydrogen-induced exfoliation of graphitic oxide or b) solar exfoliation of graphitic oxide or c) thermal exfoliation of graphitic oxide. Carbon nanotubes (CNT=SWNT, MWNT) -graphene composite with x wt % of Carbon nanotubes (CNT=SWNT, MWNT; x=5-50%) and (1-x) wt % of graphene was prepared by the following:- Adding x wt % of CNT to 2(1-x) wt % of graphitic oxide and performing any one of the exfoliation methods. Nitrogen doping or Boron doping of these carbon nanostructures was obtained by adding necessary amount of melamine or boric acid to these carbon nanostructures and do calcination at 800 C. The dispersion of transition alloy/metal nanoparticles on the pure carbon nanostructures or N/B doped carbon nanostructures was done by adding salts of alloy/metal precursors to the undoped or doped carbon nanostructures and reduce them by chemical reduction method. The dispersed alloys are combining the elements A and B (A= Pd, Ft, Zr B= Ni, Co, Fe, Au, Ag, Cr, V) and the dispersed elements are (Pd, Ft, Ni, Co, Fe, Au, Ag, Zr, V, Cr, Cu). The dispersion of the nanoparticles catalysts is about 10-40 wt% on the Carbon Nanostructures support materials.

II. Carbon nanotubes (CNT=SWNT, MWNT) were prepared by Catalytic Chemical Vapor Deposition (CCVD) method and 'x' wt % is subsequently added with graphitic oxide of 2(1 -x) wt %. Necessary
amount of melamine or boric acid was added to this carbon nanostructures. Then the hydrogen exfoliation or solar exfoliation has been used to exfoliate the carbon composite. The dispersion of
transition alloy/metal nanoparticles on the pure carbon nanostructures or N/B doped carbon nanostructures was done by adding salts of alloy/metal precursors to the undoped or doped
carbon nanostructures and reduce them by chemical reduction method.

III. Carbon nanotubes (CNT=SWNT, MWNT) were prepared by Catalytic Chemical Vapor Deposition (CCVD) method and 'x' wt % is subsequently added with graphitic oxide of 2(1-x) wt %. Necessary
amount of melamine or boric acid was added to this carbon nanostructures. The precursors of the alloy or metal have been added to this carbon composite. Then the hydrogen exfoliation or solar exfoliation has been used to exfoliate the carbon composite to get these Carbon Nanostructures doped with N/B and dispersed with alloy/metal nanoparticles.

The morphology of the prepared Carbon Nanostructures was examined by using Scanning electron microscope (SEM) and transmission electron microscope (TEM). The amount of nitrogen/bopron doped was studied by XPS. The amount and the average particle size of the dispersed nanoparticles of alloy/element was investigated by TGA and EDAX. The doping of nitrogen and boron was found to be 3-10 % and the particle size of the alloy/metal nanoparticles was found in the range of 5-10 nm.

Hydrogen adsorption studies were carried out in the pressure range 1-50 bar and in the temperature range 0-100 °C using a high-pressure Sieverts' apparatus. The unit has been calibrated with high-purity hydrogen (99.99%) at various initial pressures. At various pressures and temperatures, the volume of gas contained in the empty sample cell was precisely measured after confirming leak-free system. At high pressures, the ideal gas law was corrected using van der Waals equation for the volume of gas molecules and molecular interactions. Each time, over 250 mg of sample was loaded in the sample cell and activated by vacuum heat treatment before exposing to hydrogen to remove the oxide layers. In each activation process, the sample was evacuated to a vacuum of 10 Torr and heated at 250 °C for 2 h. It was then cooled to 100 °C, and hydrogen was allowed to interact with the sample. The sample was subsequently cooled to 75 °C, 50 °C, 25 °C and 0°C. The pressure-composition relationships were obtained by calculating the hydrogen storage capacity in wt % from the pressure drop during the hydrogen adsorption at constant temperature. After each cycle, the sample was degassed for 3 h at 250 °C under a vacuum of 10 Torr. During the experiment the room temperature was maintained at 24 ± 1 °C.

The hydrogen storage capacity of -10-14 wt % in Carbon Nanostructures in the hydrogen equilibrium pressures of 45, 55 bar and at 0 and 25 C is achieved which is about twice the target set for 2015 by DOE, USA.

It is noteworthy:

• Hydrogen storage is the major application areas of this invention.

• This invention involves a significant reduction in the cost of raw materials involved in its preparation because of use of graphite.

• This invention is a simple and scalable process adaptable to mass manufacturing and immediate adoption as retrofit to existing systems.

• The hydrogen storage capacity of "10-14 wt % in Carbon Nanostructures in the hydrogen equilibrium pressures of 45, 55 bar and at 0 and 25 C is achieved which is about twice the target set for 2015 by DOE, USA.

We Claim:

1. A method of manufacture of the Carbon Nanostructures which are hybrid type including carbon nanotubes (SWNT, MWNT), Graphene and a mixture of carbon nanotubes and Graphene in the ratio x: (1-x) where x is the weight percentage of Carbon Nanotubes (x=5-50%); including N/B doped carbon nanostructures of about 3-10 wt %; including nanoparticles catalysts of alloys/elements which is about 10-40 wt% on the Carbon Nanostructures support materials.

2. The carbon nanotubes (CNT = SWNT, MWNT) are prepared by chemical vapor deposition method; a few layered

Graphene sheets are prepared by hydrogen exfoliation method or solar exfoliation method or thermal exfoliation method.

3. A method for doping Nitrogen and or Boron in carbon nanotubes, Graphene and Graphene-CNT hybrid Carbon Nanostructures by chemical method; wherein melamine or boric acid is used during hydrogen exfoliation method or solar exfoliation method or thermal exfoliation method to dope N/B; Nitrogen and or Boron of about 3-10 wt % doped Carbon nanotubes, Graphene and hybrid Graphene-CNT Carbon Nanostructures is used as support materials for the dispersion of catalysts.

4. A method for the dispersion of the catalysts; the catalyst is one of the nanoparticles of transition metal based alloys combining the elements A and B (A= Pd, Pt, Zr B= Ni, Co, Fe, Au, Ag, Cr, V) or nanoparticles of elements (Pd, Pt, Ni, Co, Fe, Au, Ag, Zr, V, Cr, Cu); the nanoparticles catalysts dispersion is performed by using the appropriate salt precursors and reduction by the chemical method, hydrogen exfoliation, solar exfoliation methods. The dispersion of the nanoparticles catalysts is about 5-40 wt% on the Carbon Nanostructures support materials.

4. Characterization of the these Carbon Nanostructures, modified with foreign elements (B, N) and dispersed with nanoparticles of transition metal based alloys combining the elements A and B (A= Pd, Pt, Zr B= Ni, Co, Fe, Au, Ag, Cr, V) or nanoparticles of elements (Pd, Pt, Ni, Co, Fe, Au, Ag, Zr, V, Cr, Cu). Figure 1 shows the Raman Spectra of Pd-TM alloy on nitrogen doped Graphene-CNT. Figure 2 shows the SEM image of Pd-TM alloy on nitrogen doped Graphene.

5. Measurement of hydrogen storage capacity and the desorption capacity in these Carbon Nanostructures, modified with foreign elements (B, N) and dispersed with one of the nanoparticles of transition metal based alloys combining the elements A and B (A= Pd, Pt, Zr B= Ni, Co, Fe, Au, Ag, Cr, V)
or nanoparticles of elements (Pd, Pt, Ni, Co, Fe, Au, Ag, Zr, V, Cr, Cu) in the temperature range 0 C - 100 C by pressure reduction technique using Sievert's facility in the hydrogen equilibrium pressure 1-50 bar; ). Figure 3 shows the hydrogen storage capacity in Pd-TM alloy on nitrogen doped Graphene- CNT

6. Invention of materials having hydrogen storage capacity of around 10-14 wt % in undoped Carbon Nanostructures and Carbon Nanostructures which are modified with above mentioned foreign dopant elements and dispersed with above mentioned nanoparticles catalysts at 45, 55 bar and at 0 C and 25 C hydrogen equilibrium pressures.

7. Manufacture of Carbon Nanostructures which are modified with above mentioned foreign dopant elements and dispersed with above mentioned nanoparticles catalysts therefrom for hydrogen storage applications when manufactured by a method as claimed in any one of the preceding Claims.