|Title of Invention||
A PROCESS FOR THE PREPARATION OF POROUS GAS DIFFUSION ELECTRODES AND ELECTRODES THEREOF FOR FUEL CELLS AND RELATED ELECTROCHEMICAL APPLICATIONS
|Abstract||A handheld measuring device, for determining the concentration of an analyte in a sample where the device is adapted to receive a sensor strip and the device comprises; contacts; at least one display; and electronic circuitry establishing electrical communication between the contact and the display, comprising: an electric charger and a processor in electrical communication, the processor in electrical communication with a computer readable storage medium comprising computer readable software code, which when executed by the processor, causes the processor to implement a data treatment selected from the group consisting of semi-integral, derivative, semi-derivative, and combinations thereof.|
|Full Text||FORM - 2
THE PATENTS ACT, 1970 (39 OF 1970)
COMPLETE SPECIFICATION (See section 10; rule 13)
TITLE OF THE INVENTION
"Porous Gas Diffusion Electrodes For Fuel Cell And Related Electrochemical Applications "
(a) INDIAN INSTITUTE OF TECHNOLOGY Bombay (b) having administrative office at Powai, Mumbai 400076, State of Maharashtra, India and (c) an autonomous educational Institute, and established in India under the Institutes of Technology Act 1961
The following specification particularly describes the nature of the invention and the manner in which it is to be performed
Field of invention
The present invention relates to novel materials that are carbon coated metal dispersions on porous substrates and the process of their manufacture. The invention further relates to porous high surface area carbon based electrodes that exhibit high current density >200mA/cm2 and power density >250mW/cm2
Metal dispersion on porous substrates providing high surface areas are widely used in heterogeneous catalysts, gas diffusion systems, chromatographic applications, fuel cell electrodes etc.
Fuel cells are efficient energy conversion devices that produce electricity by electrochemically combining fuel (hydrogen) and oxidant (oxygen from air) gases. The performance and cost of the fuel cell depends on the electrodes.
There are problems associated with existing electrodes. For example in alkaline fuel cell, Raney-Ni bonded with poly tetra fluoro ethylene bonded gas diffusion electrodes have been used. These existing electrodes are expensive. They are also hydrophobic, highly resistive and have high gas diffusion resistance. Another problem is the degradation in the electrode activity with usage. The problem defined was a search for alternative materials for electrodes that would have low cost and equivalent performance. The current densities in fuel cells significantly affect the costs. In alkaline fuel cells with conventional electrodes the current density varies from 100mA/cm2 to 200mA/cm2. Maximizing the current density has been the focus of global R&D efforts.
Highly conducting carbon materials with evenly dispersed electrocatalysts can eliminate these difficulties, provided a method is developed to increase the porosity of the carbon. Among the different carbon materials, due to their high specific surface area, carbon nanotubes (CNT) have been considered as options for electrodes materials. Also electrodes made of CNT can have a pore structure determined by the open space between entangled fibers and therefore a high accessible surface area, unobtainable with other carbon materials as suggested by Chunming Niu et.al "High power electrochemical capacitors based on carbon nanotube electrodes" Appl. Phys. Lett. 70 (11), 17 March 1997. However, in their paper they do not mention any definite techniques for preparation of CNT.
Zhibin et.al in their article "Deposition and electrocatalytic properties of platinum nanoparticals on carbon nanotubes for methanol electrooxidation" (Materials Chemistry and Physics 85 (2004) 396-401) reported enhanced electrocatalytic properties of platinum (Pt) nanoparticles on carbon nanotube using graphite disk as a substrate for methanol oxidation. They investigated the electrocatalytic properties of Pt/CNTs/graphite electrodes for methanol oxidation by cyclic voltammetry (CV) in 1.0MCH3OH+0.5MH2SO4 aqueous solutions and the electrocatalytic activity (AQ,
defined by peak current density per unit of Pt deposition charge) can be observed even at low platinum deposition charge (Q = 1.24X10"4 Ccm.2). At Q = 3.72*10"3 Ccm2, the highest electrocatalytical activity of Pt/CNTs/graphite electrode reaches 4.62AC"1 and is about 2.3 times as high as that of Pt/graphite electrode. These electrodes were only used for methanol oxidation.
Tang et.al, dispersed Platinum (Pt) electrocatalyst electrochemically on well-aligned carbon nanotube (CNT) arrays by a potential-step method and suggested potential applications in proton exchange membrane fuel cells in their article titled "High dispersion and electrocatalytic properties of platinum on well-aligned carbon nanotube arrays" (Carbon 42 (2004} 191-197). They found that when the Pt loading mass is low (Qdep % 9:744 ICcm-), the specific .c current of Pt/CNT electrode is 0.41 mAIC-1, which is 1.4 times as large as that of Pt/ graphite electrode. At high Qdep (572.5 ICcm-2), the specific current of Pt/CNT electrode is almost twice as large as that of Pt/graphite electrode. Such electrodes do not find efficient application in AFC.
Jae-Hee, al in their article titled "Growth characteristics of carbon nanotubes using platinum catalyst by plasma enhanced chemical vapor deposition", (Diamond and Related Materials 12 (2003) 878.883) used plasma enhanced chemical vapor deposition for growing CNT. They found the growth of carbon nanotubes (CNTs) using Pt catalyst by plasma enhanced chemical vapor deposition, effects of experimental parameters, such as NH plasma pre-treatment, NH IC2 H2 ratio and growth temperature, on the growth characteristics of CNTs were studied in details. This publication also does not mention any specific methods for preparations.
Rajesha et. al synthesized CNT by the template carbonization of polypyrrole on alumina membrane has been used as the support for Pt-W03, Pt-Ru, and Pt in their article Pt-W03 supported on carbon nanotubes as possible anodes for direct methanol fuel cells (Fuel 81 (2002) 2177-2190 ). These materials have been used as the electrodes for methanol oxidation in acid medium in comparison with E-TEK 20 wt% Pt and Pt-Ru on Vulcan XC72R carbon. They also noted that the catalytic activity for methanol oxidation increases from 80.5 to 98.5 mA/cm2for CNT electrode compare to graphite electrodes. Such electrodes cannot be put efficiently in AFC. All these CNT electrodes described use costly Pt as a catalyst, but in AFC non noble metal can be used.
In the article "Alkaline fuel cell: carbon nanobeads coated with metal catalyst over porous ceramic for hydrogen electrode" (Journal of Power Sources 117 (2003) 39-44), carbon beads electrodes are described. Reported current density in AFCs is also 170 mA/cm2, which is quite low and needs to be enhanced.
The prior art described above provides examples of a few attempts to make carbon-based electrodes with Pt based electrocatalyst. In all the above-mentioned attempts costly Pt electrodes have been used.
There has therefore been a need to develop cost effective and simple processes for preparation of electrodes without compromising the desired electrochemical properties.
The present invention addresses the problems of the prior art and provides novel gas diffusion electrodes with high porosity, low resistivity, high mechanical stability and high electrochemical activity. This type of electrode has wide range of application from fuel cells to sensors. To illustrate these properties, the electrodes were used effectively in AFC. Such electrodes may be efficiently used in PEM and PAFC cells also. Due to the high porosity and surface area these electrode have wide ranging electrochemical applications such as supercapacitors and batteries etc.
Summary of the Invention
The main object of the invention is to provide novel carbon coated metal dispersion on porous supports that have wide ranging applications as gas diffusion electrodes for fuel cell, gas sensors, catalyst supports etc.
It is another object of the invention to develop porous high surface area carbon based electrodes that exhibit high current density >200mA/cm2 and power density in the range of >250mA/cm2
It is yet another objective of the invention to provide a cost effective process for preparation of porous gas diffusion CNT electrodes.
It is yet another objective to provide two-stage CVD based methods for preparation of porous gas diffusion electrodes.
It is yet another objective of the invention to treat porous supports with carbon to prepare support for catalyst dispersion.
Thus in accordance with this invention the process for the preparation of carbon coated metal dispersion of porous support to obtain active fuel cell electrode comprises:
Selecting the porous supports
Coating with Carbon by 1st stage CVD, to make it conducting Depositing metals-combinations on the porous supports Coating with carbon in a controlled manner by a 2nd stage CVD Obtaining the end product.
Alternatively for metals that are low melting, the process comprises:
Selecting the porous supports
Coating with Carbon by 1st stage CVD, to make it conducting
Depositing active metal catalyst for growing nano carbon on the support
Controlled coating by carbon by 2nd stage CVD Depositing low melting metals-combination Obtaining the end product
Detailed Description of the invention
Description of Figures:
Fig1: Process Flow chart
Fig 2: Schematic diagram of the CVD setup:
A - vaporizing furnace, B - pyrolysing furnace, C - quartz tube, D - quartz boat with ceramic substrate, E - quartz boat with precursor, F - flow regulator, G - gas cylinder, H - gas bubbler
Fig 3a: SEM image of Ni-Pt Hydrogen electrode
Fig 3b: SEM image of Ni-Sn Hydrogen electrode
Fig 4: SEM image of CNT grown with Ag catalyst
Fig 5a: TEM image of Ni-Pt Hydrogen electrode
Fig 5b: TEM image of Ni-Sn hydrogen electrode
Fig 6: TEM image of CNT grown with Ag catalyst
Fig 7: XRD patterns of Ni-Sn electrodes
Fig 8: Half cell l-E curves of CNT electrodes at scan rate 50mV/s of (a) Ni-Pt & (b) Ni-Sn
Fig 9: Half cell Chrono-amperiometric curves of CNT electrodes at 0.2V of (a) Ni-Pt & (b) Ni-Sn
Fig 10: Half cell Chrono-amperiometric curves of CNT electrodes at -1.058V of (a) Ag, Ag-Pt, Ag-Pd, (b) Ag-Mn, Ag-Co, Ag-Cu, Ag-Ni & (c) Ag-Mg, Ag-AI
Fig 11: Full cell l-E curves of CNT electrode at scan rate 50mV/s of
(a) Ni-Pt & (b) Ni-Sn
Fig 12: Full cell l-E curves of CNT electrodes at -1.058V of Ag, Ag-Pt, Ag-Pd,
(b) Ag-Mn, Ag-Co, Ag-Cu, Ag-Ni & (c) Ag-Mg, Ag-AI
Fig 13: Full cell Chrono-amperiometric curves of CNT electrodes at 0.9V of (a) Ni-Pt & (b) Ni-Sn
Fig 14: Full cell Chrono-amperiometric curves of CNT electrodes at 0.2V of
(a) Ag, Ag-Pt, Ag-Pd, (b) Ag-Mn, Ag-Co, Ag-Cu, Ag-Ni & (c) Ag-Mg, Ag-AI
Fig 15: Full Cell (H2 electrode II 30% KOH II 02 electrode) l-E characteristics curves at scan rate 50mV/s
Fig 16: Full Cell (H2 electrode II 30% KOH II 02 electrode) chrono-amperiometric curves at 0.9V
Porous gas diffusion electrodes with different carbon nanomaterials have been prepared using a two-stage Chemical Vapour Deposition process. The process flow chart is given in Figure 1.
The chemical vapour deposition unit consists of two furnaces. One long quartz tube is inserted in both furnaces, which are placed side-by-side.
In one of the embodiments in the first stage CVD the first furnace is used to vaporize carbon precursors such as natural precursors like camphor, turpentine oil, cashewnut shell etc, or petroleum based precursors like, C2H2, C6H6, CH4 etc., and the other furnace is used to pyrolyze the vapour. Temperature of first furnace is maintained above the vaporizing temperature of the precursors, while that of the second furnace, which contains the ceramic substrate, is maintained at pyrolysing temperature in the range 700°C to 1000°C. The carrier gas is selected from Ar, Ne, N2, He and their like including hydrogen & ammonia gas carries the carbon vapour of the precursors from the first to the second furnace for pyrolysis. Pyrolyzed carbon is deposited over the selected ceramic substrate. The ceramic porous substrate is selected from pumice stone, Al203 pellets or porous Silicon substrate etc. After 1st stage CVD, different metals-combinations to function as catalyst (for Hydrogen electrodes the combination is selected from Ni, Pt, Pd, Fe, Co, Sn etc. and for oxygen electrode the metal combination is selected from Ag, Pt, Pd, Co, Al, Mg, Mn etc) in desired compositions are electroplated over the carbon coated porous substrate at current density of - 100mA/cm2 to 700 mA/cm2 followed by growing of carbon particles such as nanoparticles by a second stage CVD to obtain the desired end product.
In another embodiment as indicated in the process flow chart, for low melting point metal first carbon nano-materials is grown and then low melting catalyst was electroplated.
The invention is now illustrated with a few non-limiting examples.
Example 1: Ni-Pt hydrogen electrode
The Ni-Pt electrode was prepared by two-stage CVD process. Pumice as porous support coated with conducting carbon by CVD of turpentine oil at 1000°C in Ar atmosphere. Then metal solutions (H2PtCI6 and nickel nitrate) with different bimetallic composition of Ni - Pt in molar ratios 0:100, 10:90, 50:50 90:10 and 100:0 were prepared a cell of configuration "carbon coated ceramic II metal salt solution II Pt" was used for electrodeposition of metal over carbon-coated ceramic by applying constant current followed by reduction in H2 atmosphere at 450°C for three hours. Then a layer of CNT was deposited by CVD process.
Example 1a: Ni-Sn hydrogen electrode
The Ni-Sn hydrogen electrode was prepared by two-stage CVD process. Pumice as porous support coated with conducting carbon by CVD of turpentine oil at 1000°C in Ar atmosphere. Cobalt metal was then electroplated busing a cell of configuration "carbon coated ceramic II cobalt salt solution II Pt" over carbon-coated ceramic. Then a layer of CNT was deposited by CVD process. Over these CNT electrodes bimetallic Ni-Sn with molar ratio 15:85, 50:50 and 90:10 were electroplated.
Example 2: Oxygen electrode preparation
In the above process, Ag, Pt, Pd, Mn, Cu, Co, Ni, Mg and Al are used instead of Ni-Pt and Ni-Sn. The carbon nanotubes were grown over ceramic by two stage CVD process as described in example 1. In first stage CVD, porous ceramic was coated with conducting carbon. Then metals such as Ag, Pt, Pd, Mn, Cu, Co, Ni, Mg, Al was electroplated from binary mixture of metal solution at constant current density. The metal deposited ceramics were then reduced and finally CNT were grown over this ceramic electrode by CVD
The samples prepared were characterised using XRD, TEM and SEM. The SEM images of the CNT electrodes with Ni-Pt and Ni-Sn (example 1,1a) in Fig-3a and b respectively show the presence of highly dense and interconnected CNT on the surface. SEM images of CNT grown with Ag, catalyst (example 2) in Fig. 4 also shows that the metallic particles are dispersed on the nanotubes.
The TEM image of electrodes shows the presence of carbon nanotubes as shown in Fig. 5a and 5b indicate the average diameters of the CNT to be 10-30nm. TEM images of CNT electrodes of example-2 (Fig 6) show the presence of CNT deposited on the electrodes. Some CNT are also filled with the catalyst.
The XRD pattern of CNT electrodes showed the characteristic graphitic peaks (29 value) at 26.58 (002) along with its other planes at 42.34 (100), 44 (101), 54.43 and (004). The XRD pattern of film grown with Ni-Sn is shown in Fig 7 (example 1a) where composition of Ni-Sn has been changed from 10% to 90% of Sn in Ni. In Fig 7(c), the peaks at 30.81 (101) and 43.99 (511) correspond to the alloy composition Ni3Sn2 and Ni3Sn4 peaks. In addition to the carbon peaks, Sn (220) and Ni (220) are
also seen. In Fig 7 (b), Ni-Sn alloy peaks at 29.95 (311) and for alloy Ni3Sn peak are obtained at 43.205 (002). Peaks for Ni (111), and (220), Sn (110) and (220) lattice planes are also seen. In Fig. 7 (a), Ni-Sn (311) and Ni3Sn (002) compositions are also seen at 29.95 and 43.99. XRD pattern clearly show bimetallic alloy formation.
To measure the conductivity of electrodes, variation of resistance with respect to temperature was recorded in an Argon atmosphere by utilizing Vander-Pauw Resistivity method.
The variations of resistivity with temperature of electrodes reveal that, all the electrodes were highly conducting.
The electrochemical performance of the electrodes was investigated by incorporating the hydrogen electrode as working electrode in an AFC. The hydrogen/ oxygen dissociation voltage (ODV), half and full cell l-E characteristics and chrono-potentiometry of the half and full cell were measured in a Pine potentiostat AFRDE4. Hydrogen dissociation voltage (HDV) was measured using Calomel electrode as reference electrode, platinum as counter electrode and hydrogen electrode as working electrode in a three-electrode configuration "Hydrogen electrode H2 II 30%KOH II SCE/Pt". Using the same configuration, half-cell l-E characteristics and chrono-potentiometry were measured. For full cell characteristics, silver deposited carbon CNT electrode was used as cathode and hydrogen electrodes as working electrode of configuration: "Hydrogen electrode, H2 II 30%KOH II Oxygen electrode, 02".
For example-1, Ni gave the highest HDV of around -1011 mV. Among all the electrodes Ni-Pt (50:50) gave highest HDV of-1021 mV.
Similarly in example 2, Ag-Pt (50:50) and Ag-Pd (50:50) gave almost the same but highest ODV of 168 mV and 167 mV respectively. Amongst the transition metals, Ag-Co (70:30) and Ag-Mn (90:10) exhibited enhanced performance. Amongst the non-noble, non-transition metals the maximum ODV (165 mV) was recorded for Ag-Mg (70:30).
The half cell l-E characteristics of Ni-Pt and Ni-Sn (example-1,1a) electrodes are given in Fig 8 a and , b, respectively. Among the different CNT electrode with Ni catalyst showed maximum current density of 356 mA/cm2, whereas maximum current densities of 382 mA/cm2, and 376 mA/cm2 were recorded for Ni-Pt (50:50) and Ni-Sn (85:15) respectively.
For chrono-amperiometric characteristics also, CNT electrode with Ni catalyst gave stable current density of 201 mA/cm2. Similarly for Ni-Pt (50:50) (Fig 9a) and Ni-Sn (85:15) (Fig 9b) electrodes stable current densities of 217.3 mA/cm2 and 214.1 mA/cm2 respectively were recorded.
Similarly for example-2, half-cell coulometric curves of respective representative electrodes in 30% KOH solution with respect to SCE at -1.058 V are given in Fig 10. Ag, Ag-Pt and Ag-Pd electrodes produced stable current densities of 351 mA/cm2, 396 mA/cm2, 389 mA/cm2 respectively (Fig 10a). For transition metals, current densities 351 mA/cm2, 358 mA/cm2, 366 mA/cm2 and 351 mA/cm2 (Fig 10b) were measured for the electrodes Ag-Mn (90:10), Ag-Cu (90:10), Ag-Co (70:30) and Ag-Ni (90:10) respectively. For Ag-Mg (70:30) electrode, current density of 387 mA/cm2 (Fig 10c) was recorded, whereas for Ag-AI (90:10) its value was 358 mA/cm2.
The full cell l-E characteristics at 0.9 V of Ni-Pt and Ni-Sn bimetallic electrodes at scan rate of 50 mV/s are shown in Fig. 11a, and b respectively. The maximum current 349 mA/cm2 and 339 mA/cm2 were obtained for Ni-Pt (50:50) and Ni-Sn (85:15) electrodes respectively.
The full cell l-E characteristics of the representative electrodes of example 2 are given in Fig 12. Maximum current densities of 346mA/cm2 and 333 mA/cm2 were recorded for Ag-Pt (50:50) and Ag-Pd (50:50) bimetallic electrodes (Fig 12a) respectively. For the transition metals, Ag-Co (70:30) (Fig 12b) gave the highest current density of 278 mA/cm2. Again high current densities of 341 mA/cm2 and 309 mA/cm2 were measured for electrodes Ag-Mg (70:30) and Ag-AI (90:10) (Fig 12c).
The chrono-potentiometry curves for the above mentioned electrodes of example 1 are shown in Fig. 13. The stable current densities of 266 mA/cm2 and 261 mA/cm2 were recorded for Ni-Pt (50:50) and Ni-Sn (90:10) bimetallic electrodes.
For full cell coulometry, the stable current densities of electrodes Ag, Ag-Pt (50:50) and Ag-Pd (50:50) (Fig 14a) were 230 mA/cm2, 277 mA/cm2 and 261 mA/cnr respectively. The transition metals electrodes Ag-Co (70:30) (Fig 14b) gave stable current density of 242 mA/cm2. On the other hand, for non-noble, non-transition metals i.e. Ag-Mg (70:30) and Ag-AI (90:10), stable current densities of 267 mA/cm2 and 229 mA/cm2 (Fig 13c) were recorded.
Example 3. Efficient fuel cell-
The power output obtained by different electrodes for hydrogen and oxygen electrodes are given in table 1 and 2
Table 1 Power output for full cell obtained with different hydrogen electrode
Catalyst Carbon nanotube
Ni 209 mW/cm2
Ni-Pt(50-50) 240 mW/cm2
Table 2 Power output for full cell obtained with different oxygen electrode
Catalyst Carbon nanotube
Ag 207 mW/cm2
Ag-Pt(50-50) 249 mW/cm2
Ag-Pd(50-50) 235 mW/cm2
Ag-Mg(70-30) 240 mW/cm2
The full cell l-E characteristics and chrono amperometry obtained with Ni-Pt, Ni-Sn and Ni as hydrogen electrode and Ag-Mg and Ag as oxygen electrode are given in fig. 15 and 16 respectively. The results obtained for AFC having Ni-Sn (85:15)||Ag-Mg (70:30) configuration are as follows:
Imax for l-E at scan rate 50 mV/s 374 mA/cm*
Istabie for coulometry at 0.9 V 287 mA/cm*
Power 259 mW/cm*
It is evident that two stage CVD based methods result in cost effective porous high surface area carbon based electrodes exhibiting high current density >200mA/cm2 and power density >250mW/cm2.
What is claimed is
1. A process for the preparation of carbon coated metal dispersion of porous
supports to obtain active fuel cell electrode comprise:
selecting the porous supports
coating with carbon by 1st stage CVD, to make it conducting depositing metals-combinations on the porous supports coating with carbon in a controlled manner by a 2 stage CVD obtaining the product.
2. A process for the preparation of carbon coated metal dispersion on porous
supports for catalysts that are low melting to obtain active fuel cell electrode, the
selecting the porous supports
coating with carbon by 1st stage CVD, to make it conducting
depositing active metal catalyst for growing nano carbon on the support
controlled coating by carbon by 2nd stage CVD
depositing low melting metals-combination
obtaining the product
3. A process for the preparation of porous gas diffusion electrodes as claimed in claims 1-2, wherein the porous support is selected from pumice stone, AI2O3 pellets, porous silicon substrate and their like.
4. A process for the preparation of active gas diffusion electrodes for fuel cells as claimed in claims 1-3, wherein the carbon precursors to be pyrolized in the CVD are selected from natural precursors like camphor, turpentine oil, cashew nut shell, and their like, or petroleum based precursors such as C2H2, C6H6, CH4 and their like.
5. A process for the preparation of active gas diffusion electrodes for fuel cells as claimed in claims 1-4, wherein the carrier gas for the CVD is selected from Ar, Ne, N2, He and their like including hydrogen & ammonia gas.
6. A process for the preparation of active gas diffusion electrodes for fuel cells as claimed in claims 1-5, wherein after the 1st stage CVD, for hydrogen electrodes
metal combination is selected from Ni, Pt, Pd, Fe, Co, Sn, Al and for oxygen electrode the metal combination is selected from Ag, Pt, Pd, Co, Al. Mg, Mn are electroplated over the carbon coated porous substrate at current density of -100mA/cm2 to 700 mA/cm2 followed by growing of carbon particles such as nanoparticles by a second stage CVD to obtain the desired end product.
7. An active gas diffusion hydrogen electrode for fuel cell as claimed in claims 1-6
wherein the bimetallic system is selected from Ni-Pt (10-90 to 50-50); Ni-Fe (85-
15 to 90-10); Ni-Sn (85-15 to 90-10); Ni-Co (85-15 to 90-10); Co-Pt (10-90 to 20-
8. An active gas diffusion oxygen electrode for fuel cell as claimed in claims 1-6, wherein the bimetallic system is selected from Ag-Pt (20-80 to 50-50), Pd-Ag (10-80 to 30-70), Ag-Mn (80-20 to 90-10), Ag-Cu (70-30 to 90-10), Ag-Co (80-20 to 90-10), Ag-Ni (80-20 to 90-10), Ag-Mg (70-30 to 90-10), Ag-AI (80-20 to 90-10).
9. An active gas diffusion hydrogen electrode for fuel cell prepared by the process as claimed in claims 1-7 wherein the power output for full cell is > 190 mW/cm2 w.r.t Ag-CNT electrode for oxygen and oxygen electrodes prepared by the process as claimed in claims 1-6 and 8 with power output >200 mW/cm2 w.r.t Ni-CNT electrode for hydrogen.
10. An active gas diffusion hydrogen electrode for fuel cell prepared by the process as claimed in claims 1-7 with Ni, Ni-Pt (50-50) and Ni-Sn (85:15) exhibiting HDV and half cell l-E characteristics and chronopotentiometric characteristics of at least 1000 mV and current density of > 350 mA/cm2 and stable current density of > 200 mA/cm2 respectively and oxygen electrodes prepared by the process as claimed in claims 1-6 and 8 with Ag-Pt (50:50) and Ag-Pd (50:50), Ag-Co (70:30), Ag-Mn (90:10) and Ag-Mg (70:30) exhibiting ODV > 160 mV , full cell coulometry stable current density >230 mA/cm2 and complete fuel cell power density obtained 259mW/cm2.
Dated: Dr Prabuddha Ganguli
Agent on behalf of Applicant
The present invention relates to novel carbon coated metal dispersions on porous substrates and process of their manufacture. This metal dispersion on porous substrate providing high surface areas can be widely used in heterogeneous catalyst, gas diffusion systems, chromatographic applications, fuel cell electrodes etc. This patent describes the process for preparation of carbon coated metal dispersion of porous supports to obtain fuel cell electrode that comprise of selecting porous supports, coating them with carbon by 1st stage of CVD to make it conducting, depositing metal combinations on porous support, coating with carbon in a controlled manner by 2nd stage CVD and finally obtaining the product. The porous high surface area carbon based electrodes for fuel cell exhibit high current density >200mA/cm2 and power density in the range of 250mA/cm2.
|Indian Patent Application Number||959/MUM/2006|
|PG Journal Number||11/2010|
|Date of Filing||19-Jun-2006|
|Name of Patentee||INDIAN INSTITUTE OF TECHNOLOGY, BOMBAY|
|Applicant Address||INDIAN INSTITUTE OF TECHNOLOGY BOMBAY, POWAI, MUMBAI-400076,|
|PCT International Classification Number||H01M4/86,H01M4/88|
|PCT International Application Number||N/A|
|PCT International Filing date|