FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention
A PROCESS TO PREPARE NOVEL PLATINUM NANOPARTICLES AND NANOPARTICLES THEREOF
2. Applicant(s)
Name Nationality Address
TATA CHEMICALS LIMITED INDIA BOMBAY HOUSE , 24 HOMI MODI STREET,
MUMBAI-400001
3. Preamble to the description
COMPLETE SPECIFICA TION
The following specification particularly describes the invention and the manner in which it is to be performed.

The disclosure generally relates to a modified nanoparticle and a method to prepare the same. More particularly the disclosure relates to a modified platinum nanoparticle and the method to prepare the same.
BACKGROUND
Pt nanoparticles (Pt- np) are used as catalyst in wide variety of applications, including as a catalyst for various oxidation reactions, including water gas shift reactions of carbon monoxide, three-way catalytic reactions, and selective oxidation reactions of carbon monoxide, and reduction reactions, such as reactions of removing nitrogen oxide. The synthesis of such nanoparticles is well known in the art (V. Mazumder, M. Chi, K. L. More, S. Sun (2010), "Synthesis and Characterization of Multimetallic Pd/Au and Pd/Au/FePt Core/Shell Nanoparticles", J. Am. Chem. Soc, 132, 7848-49). To serve various applications, it is often necessary to tune or fabricate functional properties of nanoparticles. A number of techniques have been developed to modify the functional properties of the metal nanoparticles. The synthesis of Au, Pt and Pd nanoparticles using thiol-functionalized ionic liquid (TFIL) to modify the properties of nanoparticles has also been reported in the literature (Dablemont et al.," FTIR and XPS Study of Pt Nanoparticle Functionalization and Interaction with Alumina'1'' Langmuir 2008, 24, 5832-5841).
However, such materials reported in the literature cannot be used as both: 1) proton conductor, and 2) catalytic sites in reactions especially at low temperature. These limitations restrict effective performance of the platinum nanoparticles as catalyst.
Thus there is a need for improved platinum nanoparticles which can effectively exhibit proton conducting properties, as well as catalytic activity at low temperature. Also, since the platinum is extremely expensive, it is desirable to utilize it's maximum surface area in

formulating a catalyst. Hence, it is considered of much practical utility to improve the properties of platinum nanoparticles to suit various chemical reactions.
SUMMARY
A modified platinum nanoparticle is disclosed. The modified platinum nanoparticle comprises of a platinum nanoparticle having at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, attached thereon.
A method of preparing a modified platinum nanoparticle is also disclosed. The method comprises of reacting a first solution comprising of a platinum precursor and at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, with a reducing agent to obtain a second solution. Followed by heating the second solution to a temperature that facilitates formation of a platinum nanoparticle having the mercapto alkyl acid attached thereon.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates particle size distributions of Pt np mercatopropyl sulfonic acid (MPSA) synthesized using formaldehyde and NaOH as reducing agent.
Figure 2 illustrates Fourier Transform-Infrared spectrum (FT-IR) of Pt MPSA np.
Figure 3 illustrates X-Ray Diffraction (XRD) profiles of Pt-MPSA synthesized using NaBH4 as reducing agent.
Figure 4 illustrates particle size distribution of Pt MPSA - Octane thiol np.
Figure 5: XRD profiles of nano silica supported Pt MPSA np [60 wt% Pt and Pt : MPSA = 1 : 0.241 (molar ratio)].
Figure 6: XRD profiles of nano silica supported Pt MPSA -Hexane thiol np [40 wt% Pt and Pt: MPSA : Hexane thiol = 1 : 0.241 : 0.241 (molar ratio)]

Figure 7: XRD profiles of fumed silica supported Pt MPSA- Hexane thiol np [40 wt% Pt and Pt: MPSA : Hexane thiol = 1 : 0.241 : 0.241 (molar ratio)]
Figure 8: XRD profiles of carbon supported Pt MPSA np [40 wt% Pt and Pt: MPSA = 1 : 0.241 (molar ratio)]
DETAILED DESCRIPTION
To promote an understanding of the principles of the invention, reference will be made to the embodiment and specific language will be used to describe the same. It will nevertheless be understood that no limitation of scope of the invention is thereby intended, such alterations and further modifications in the described product and such further applications of the principles of the inventions as disclosed therein being contemplated as would normally occur to one skilled in art to which the invention relates.
The following description discusses certain specific compounds such as reducing agent, solvent to explain the principles of the method. The method however is not restricted to such compounds as equivalent chemical compounds may be utilized to achieve the desired end result as taught by the disclosure. Reference throughout the specification to an embodiment, an aspect or similar language means that a particular feature, characteristic or step in connection with the embodiment is included in at least one embodiment of the described method. References to an aspect or an embodiment may, but do not necessarily all refer to the same embodiment.
The present disclosure generally relates to a modified platinum nanoparticle comprising a platinum nanoparticle functionalized with specific thiol group bearing ligand(s). More particularly, the present disclosure describes a modified platinum nanoparticle comprising of a platinum nanoparticle having at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid (MPSA), mercapto propionic acid (MPA) and mercapto succinic acid(MSA), attached thereon. By way of a specific example, the

modified platinum nanoparticle comprises of a platinum nanoparticle having mercaptopropyl sulfonic acid, attached thereon. The selected group of mercapto alkyl acid has smaller alkyl chain as compared to that disclosed in the prior art and is believed to increase the availability of platinum to the reacting molecules for catalysis, while modifying the surface property of the modified platinum particle. The mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, are thus found to be most active for the purposes of preparing the present modified platinum nanoparticle(s). Herein, the anionic component of the mercapto alkyl acid i.e. Sulfonic acid, propionic acid and succinic acid provides hydrophilic centres on the surface of the modified platinum nanoparticle and thus imparts proton conducting properties to the nanoparticle.
In accordance with an embodiment, the mercapto alkyl acid may be provided on the surface of the modified platinum nanoparticle in a random or an arranged manner and is preferably arranged.
In accordance with an aspect, the modified platinum nanoparticle(s) comprising at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid thereon, is supported on a substrate. The substrate may be any metal oxide including but not limited to rice husk ash, mesoporous silica, microporous silica, nanosilica and alumina.
In accordance with an embodiment, the modified platinum nanoparticle comprises of at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid and at least one alkyl thiol selected from the group consisting of hexane thioI(HT), octane thiol (OT), decane thiol(DT) and dodecane thiol(DDT), attached thereon. By way of a specific example, the modified platinum nanoparticle comprises of a platinum nanoparticle having mercatopropyl sulfonic acid and hexane thiol, attached thereon.

In the modified platinum nanoparticle, the platinum nanoparticle is attached to the mercapto alkyl acid and alkyl thiol through the mercaptan/thiol (-SH) group of the mercapto alkyl acid and alkyl thiol.
The anionic component of mercapto alkyl acid provides hydrophilic centres on the modified platinum nanoparticle whereas the alkyl group in alkyl thiol provides hydrophobic centres on the modified platinum nanoparticle. This combination of hydrophilic and hydrophobic centres on the modified platinum nanoparticle provides unique surface properties to the platinum nanoparticle. Further, the ratio of hydrophilic and hydrophobic centres on the modified platinum nanoparticle can be tailored to modulate the properties of the modified platinum nanoparticle. In accordance with an embodiment, the molar ratio of mercapto alkyl acid to alkyl thiol in the modified platinum nanoparticle can be either greater than 1, equal to 1 or less than 1, resulting in the modified platinum nanoparticle having higher hydrophilic property, equal hydrophilic and hydrophobic properties, and higher hydrophobic property respectively. By way of a specific example, a modified platinum nanoparticle comprising 0.05 mmol of mercapto propyl sulphonic acid and 0.05 mmol of hexane thiol exhibits equal hydrophilic and hydrophobic properties.
Furthermore, the mercapto alkyl acid and the alkyl thiol acts as a stabilizing agent and prevents agglomeration of the modified platinum nanoparticle(s) in a solution.
In accordance with an aspect, the modified platinum nanoparticle comprising at least one mercapto alkyl acid selected from the group comprising of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid and at least one alkyl thiol selected from the group comprising of hexane thiol, octane thiol, decane thiol and dodecane thiol attached thereon, is supported on a substrate. In accordance with an embodiment, the substrate may be any metal oxide including but not limited to rice husk ash, mesoporous silica, microporous silica, nanosilica, carbon and alumina.

In accordance with an aspect, functionalization of the platinum nanoparticle with mercapto alkyl acid and alkyl thiol also facilitates the immobilization of the modified platinum nanoparticle on the substrate.
In accordance with an aspect, the shape of the platinum nanoparticle may be spherical, tetrahedral, cubic, irregular-prismatic, icosahedral, cubo-hedral and is preferably spherical.
In accordance with an aspect, the particle size of the said modified platinum nanoparticle may range from 1-1000 nm and is preferably in the range of 2-20 nanometres.
In accordance with an embodiment, the molar ratio of the mercapto alkyl acid and the alkyl thiol on the modified platinum nanoparticle may be in the range of 0.01 to infinite and is preferably in the range of 0.25 to 100.
In accordance with an embodiment, the mercapto alkyl acid and the alkyl thiol may be provided on the surface of the platinum nanoparticle in a random or an arranged manner and is preferably arranged. Herein, hydrophilic and hydrophobic interaction of mercapto alkyl acid and alkyl thiol respectively, causes them to orient in an arranged manner.
In accordance with an aspect, the modified platinum nanoparticles are capable of exhibiting effective catalysis even at low temperatures with effective proton conduction. Hence, the catalyst has high industrial application. In accordance with another aspect, the modified platinum nanoparticle also finds potential uses in solid state electronic devices.
The present disclosure also provides a method for preparation of a modified platinum nanoparticle comprising a platinum nanoparticle having a mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid attached thereon. The said method comprises of reacting a first solution comprising of a platinum precursor and at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, with a reducing agent to obtain a second solution, followed by heating of the second solution to a

temperature that facilitates formation of the platinum nanoparticle having the mercapto alkyl acid attached thereon.
Herein, the said first solution is prepared by the addition of the mercapto alkyl acid to a platinum precursor solution under constant stirring. The reducing agent is then added to the first solution preferably at the rate of 1 millilitre/min, followed by stirring, to obtain the second solution. The second solution is then heated to a temperature in the range of 30- 100 degree Celsius under stirring for a predetermined time period. Ethanol is added to the solution thus obtained and kept in freeze for overnight. The modified platinum nanoparticle(s) is then obtained by centrifugation of the solution. In accordance with an embodiment, the second solution is preferably heated at varied temperatures over a pre determined time period. By way of a specific example, the second solution is first heated at 50 degree Celsius for 30 minutes followed by heating at 80 degree Celsius for 42 hours to facilitate the formation of a platinum nanoparticle(s) having the mercapto alkyl acid attached thereon.
The present disclosure further provides a method for obtaining the above disclosed modified platinum nanoparticle(s), supported on a substrate. To obtain the modified platinum nanoparticle(s) supported on a substrate, the said first solution is prepared by the addition of the platinum precursor, mercapto alkyl acid and the alkyl thiol to a substrate solution, under constant stirring. The reducing agent is then added to this first solution, preferably at the rate of 1 millilitre/min, followed by stirring for a predetermined time period, to obtain the second solution. The second solution is then heated under stirring to a predetermined temperature over a predetermined time period to facilitate the formation of supported modified platinum nanoparticle(s). The supported modified platinum nanoparticle(s) thus obtained is then filtered and washed with distilled water several times followed by drying at approximately 30 degree Celsius for a time period in the range of 1- 24 hours.

The present disclosure also provides a method for the preparation of the modified platinum nanoparticle comprising a platinum nanoparticle having a mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid and an alkyl thiol selected from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol, attached thereon. The said method comprises of reacting a first solution comprising of a platinum precursor, at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid and at least one alkyl thiol selected from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol, with a reducing agent to obtain a second solution, followed by heating the second solution to a temperature that facilitates formation of the platinum nanoparticle having the mercapto alkyl acid and the alkyl thiol attached thereon.
Herein, the said first solution is prepared by the addition of the mercapto alkyl acid and the alkyl thiol to a platinum precursor solution under constant stirring. To this first solution, the reducing agent is preferably added at the rate of 1 millilitre/min, followed by stirring for a predetermined time period, to obtain the second solution. The second solution is then heated to a temperature in the range of 30- 100 degree Celsius under stirring for a predetermined time period. Ethanol is added to the solution thus obtained and kept in freeze for overnight. The modified platinum nanoparticle(s) is then obtained by centrifugation of the solution. In accordance with an embodiment, the second solution is preferably heated at varied temperatures over a predetermined time period. By way of a specific example, the second solution is first heated at 50 degree Celsius for 30 minutes followed by heating at 80 degree Celsius for 42 hours to facilitate the formation of a platinum nanoparticle having the mercapto alkyl acid and the alkyl thiol attached thereon.

The present disclosure further provides a method for the preparation the above disclosed modified platinum nanoparticle, supported on a substrate. Herein, the said first solution is prepared by the addition of the platinum precursor, mercapto alkyl acid and the alkyl thiol to a substrate solution, under constant stirring. To this first solution, the reducing agent is preferably added at the rate of 1 millilitre/min, followed by stirring for predetermined time period, to obtain the second solution. The second solution is then heated under stirring at a predetermined temperature and over a predetermined time period to facilitate the formation of supported modified platinum nanoparticle(s). The supported modified platinum nanoparticle(s) thus obtained is then filtered and washed with distilled water several times, followed by drying at approximately 30 degree Celsius for a time period in the range of 1- 24 hours.
In accordance with an aspect, the first solution is preferably prepared at 0 degree Celsius.
In accordance with an aspect, the second solution is heated to a temperature in the range of 30-100 degree Celsius and is preferably heated at 60 degree Celsius. In accordance with a related aspect, the second solution is heated for a period in the range of 30 minutes - 60 hours.
In accordance with an embodiment, the platinum precursors may be any salt of platinum including but not limited to PtCl2, PtCI4, K2PtCl6 and K2PtCl6
In accordance with an embodiment, any known reducing agent may be used in the method described above, and is preferably selected from the group comprising of NaBRj, HCHO/NaOH and HCHO.
In accordance with an aspect, the molar concentration of the platinum precursor is in the range of .001 mM and 2M.
In accordance with an embodiment, the molar concentration of mercapto alkyl acid is at least 0.00 1mM.
In accordance with another embodiment, the molar concentration of alkyl thiol is at least .001mM.

In accordance with an aspect, temperature conditions during the method may vary between 0-120 degrees.
The following examples are provided to explain and illustrate certain preferred embodiments of the method of the present disclosure and should not be understood to be in any way limiting.
Example 1:
330 milligrams of PtCI4 (98%, 0.96 mmol) is dissolved in 200 mililitres double distilled water (11.11 mol) and is placed under ice to obtain a solution of PtCLt. 173 milligrams of mercapto propylsulfonic acid (MPSA) (99%. 0.96 mmol) is added to the solution of PtCI4 followed by stirring for 10 minutes to obtain a first solution. 367.7 milligrams of NaBH4 (98%, 9.925 mmol) is dissolved in 100 millilitres distilled water (kept below 0 degree Celsius) and added to the first solution over a time period of 1 hour under continuous stirring, and further stirred for an additional hour, to obtain a second solution. Thereafter, the temperature of the second solution is raised and maintained to 28 degree Celsius under constant stirring for 16 hours. Temperature of the second solution is further raised to 80 degree Celsius accompanied by stirring for 90 minutes, followed by the addition of ethanol. This solution is then kept in freeze for overnight. The modified platinum nanoparticle(s) thus obtained is then centrifuged. Particles size distribution is found to be in the range of 80 to 110 nanometres with maxima at 100 nanometres. Example 2:
33.7 milligrams of PtCLt (0.098 mmol) is dissolved in 40 millilitres double distilled water and is placed under ice to obtain a solution of PtCI4. 17.8 miligrams of MPSA (0.099 mmol) is added to PtCI4 solution and stirred for 10 minutes to obtain a first solution. 300 microlitres formaldehyde (39%, 0.0017 mmol) is then added to the first solution under stirring for 2 hours. This solution is then heated at 28 degree Celsius for 15 minutes followed by

heating at 70 degree Celsius for 30 minutes. Further, 7.71 grams NaOH solution (5%, 1.66 mmol) is added to the above solution to obtain a second solution. The second solution is then heated at 50 degree Celsius for 30 minutes and at 80 degree Celsius for 42 hours. 300 microlitres formaldehyde (39%, 0.0017 mmol) is further added to the second solution at 80 degree Celsius under stirring for 1 hour, followed by the addition of 60 millilitres of ethanol. This solution is kept in freeze for overnight. The modified platinum nanoparticles are then centrifuged. Particles size distribution is measured and is found to be in the range of 1.50 to 2.33 nanometres with maxima at 1.74 nanometres as shown in Figure 1. Example 3:
33.7 milligrams of PtCI4 (0.098 mmol) is dissolved in 40 millilitres double distilled water and is placed under ice to obtain a solution of PtCI4. 35.30 milligrams of MPSA (0.196 mmol) is added to the solution of PtCI4 followed by stirring for 10 minutes. 200 microlitres formaldehyde (39%, 0.0012 mmo) is then added to the solution of PtCI4 and MPSA under stirring for 2 hoursto obtain a first solution. 100 microlitres formaldehyde is further added to first solution under stirring for 30 minutes to obtain a second solution. Thereafter, temperature of the second solution is raised to 28 degree Celsius for 1 hour, followed by heating again at 80 degree Celsius for 17 hours. The modified platinum nanoparticles thus obtained are then centrifuged. Particles size distribution is measured and is found to be in the range of 5 to 8 nanometres. This method can be used for the synthesis Pt np MPA, except 0.196 mmol of MPA instead of MPSA. Similarly, Pt np MSA is synthesized by using 0.196 mmol of MSA instead of MPSA. Example 4:
810 milligrams of K2PtCI6 (99%, 1.65 mmol) is dissolved in 70 millilitres double distilled water and is placed under ice to obtain a solution of K2PtCI6 60 milligrams of mercapto propylsulfonic acid (MPSA) (0.33 mmol) is added to the solution of K2PtCI6

followed by stirring for 10 minutes to obtain a first solution. 630 milligrams of NaBH4 (98%, 3.50 mmol) is dissolved in 20 millilitre distilled water (kept under ice) and is added to the first solution over a time period of 55 minutes under stirring, followed by further stirring for 30 minutes to obtain a second solution. Thereafter, temperature of the second solution is brought to 28 degree Celsius, followed by addition of 100 millilitres of ethanoJ. This solution is then kept in freeze for overnight. The modified platinum nanoparticles thus obtained are then centrifuged. Particles size distribution is found to be in the range of 4-6 nanometres. XRD profile of modified platinum nano particles is shown in Figure 3. This method can be used for the synthesis Pt np MPA, except 0.33 mmol of MP A is used instead of MPSA. Similarly, Pt np MSA is synthesized by using 0.33 mmol of MSA instead of MPSA.
Example 5:
33.7 milligrams of PtCl4 (0.098 mmol) is dissolved in 40 millilitres double distilled water and is placed under ice to obtain a solution of PtCI4. 9 miligrams of MPSA (0.05 mmol) is added to the solution of PtCI4. 7.2 microlitre of n-Hexane thiol (98%, 0.05 mmol) in 10 mililitre of ethanol is then added to solution of PtCI4 and MPSA followed by stirring for 10 minutes at -3 degree Celsius to obtain a first solution. 200 microlitre formaldehyde (39%, 0.0012 mmol) is then added to the first solution under stirring for 2 hours. To this solution, 100 microlitres formaldehyde is further added under stirring for 15 minutes. Temperature of this solution is raised to 28°C for 2 hours, followed by heating at 80 degree Celsius for 17 hours. 1 gram NaOH (5% aqueous) is added to above solution at 80 degree Celsius followed by stirring for 5 hours to obtain a second solution. 100 millilitres of ethanol is then added to the second solution after cooling it. This solution is kept in freeze for overnight followed by aging at 28°C for 7 days. The modified platinum nanoparticles thus" obtained are then centrifuged. Particle size distribution is measured and is found to be in the range of 6.5-10.1

nanometres as shown in Figure 5. This method can be used for the synthesis Pt np MPSA-OT, Pt np MPSA-DT and Pt np MPSA-DDT by using Octane thiol (8.8 microlitre, 98%, 0.05 mmol), Decane thiol (10.8 microlitre, 96%, 0.05 mmol) and Dodecane thiol (12.2 microlitre, 98%, 0.05 mmol), respectively, instead of n-Hexane thiol (7.2 microlitre). Similarly, Pt np MPA-L and Pt np MSA-L derivatives are prepared by taking MPA and MSA instead of MPSA. (Herein, L refers to alkyl thiol selected from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol.) Example 6:
49 milligrams of K2PtCI6 (0.1 mmol) is dissolved in 10 millilitres double distilled water at 28 degree Celsius. 9 milligrams of mercaptosulfonic acid (0.05 mmol) is added to K2PtCI6 solution followed by stirring for 30 minutes. 10 microlitres of Octane thiol (98%, 0.056 mmol) in 3 millilitres of ethanol is then added to solution of K2PtCI6 and MPSA followed by stirring for 10 minutes to obtain a first solution. 38 milligrams of NaBH4 (10 mmol) is dissolved in 27 millilitres ethanol and added to the first solution drop wise under stirring for 30 minutes to obtain a second solution. Thereafter, the temperature of the second solution is raised to 60 degree Celsius with stirring for 2 hours. The modified platinum nanoparticles thus obtained are then centrifuged. Particles size distribution is measured and average particle size is found to be in the range of 200 to 400 nanometres. This method is used for the synthesis Pt np MPSA-HT, Pt np MPSA-DT and Pt np MPSA-DDT by taking n-hexane thiol. Decane thiol and Dodecane thiol, respectively, instead of Octane thiol. Similarly, Pt np MPA-L and Pt np MSA-L derivatives are prepared by taking MPA and MSA instead of MPS A.
The following examples of making the modified platinum nanoparticles supported on a substrate are exemplary and should not be understood to be in any way limiting. Example 7: 60 wt% nano silica : 40 wt% Pt and Pt: MPSA = 1 : 0.241 (molar ratio)

150 milligrams of nano silica was added in 50 millilitres distilled water at once and stirred for 20 minutes to get it well dispersed at 0 degree Celsius. 22.28 milligrams of mercapto propylsulfonic acid (MPSA) (99%, 0.124 mmol) was then added to the above and stirred for 30 minutes at 0 degree Celsius followed by adding 253 milligrams of K2PtCI6 (99%, 0.514 mmol) and stirring for 30 minutes to obtain a first solution. 17.04 milligrams of NaBH4 (98%, 0.442 mmol) was dissolved in 6 millilitres distilled water and added to the first solution at the rate of 1 millilitre/minute, followed by stirring for 20 minutes to obtain a second solution. Finally, the second solution was heated at 80 degree Celsius under stirring for 1 hour. The nano silica supported modified platinum nanoparticles (Pt-MPSA np) thus obtained, were then filtered and washed with distilled water several times, followed by drying at 30 degree Celsius for 16 hours.XRD profiles of nano silica supported Pt-MPSA np is shown in Figure 5.
Further, 2, 5, 10, 15,20, 25, 30, 35,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 98 percent by weight of platinum supported on nano silica can be obtained by taking 4900, 1900, 900, 566.67, 400, 300, 233.33, 185.72, 122.22, 100, 81.82, 66.67, 53.85, 42.86, 33.33, 25, 17.65, 11.11. 5.26, 2.08 milligrams of nano silica, respectively, in place of 150 milligrams nano silica (40 wt% loading) under similar reaction conditions. However, 500, 350, 200 and 100 millilitre of water should be added for 2, 5, 10 and 15 percent by weight of platinum, respectively, to nano silica by maintaining pH around 10-11 by addition of NaBH4.
This method was used for the synthesis of nano silica supported Pt-MPA np and Pt-MSA np by using MPA and MSA, respectively, instead of MPSA.
Example 8: 60 wt% fumed silica : 40 wt% Pt and Pt: MPSA = 1:1 (molar ratio)
150 milligrams of fumed silica was added in 50 millilitres distilled water at once and stirred for 20 minutes to get it well dispersed at 0 degree Celsius. 92.53 milligrams of mercapto propylsulfonic acid (MPSA) (99%, 0.514 mmol) was then added to the above and

stirred for 30 minutes at 0 degree Celsius followed by adding 253 milligrams of K2PtCI6 (99%, 0.514 mmol) and stirring for 30 minutes to obtain a first solution. 71 milligrams of NaBH4 (98%, 1.84 mmol) was dissolved in 25 millilitres distilled water and added to the first solution at the rate of 1 millilitre/minute, followed by stirring for 20 minutes t obtain a second solution. Finally, the second solution was heated at 80 degree Celsius under stirring for 1 hour. The fumed silica supported modified platinum nanoparticles (Pt-MPSA np) thus obtained, were then filtered and washed with distilled water several times, followed by drying at 30 degree Celsius for 16 hours.
Pt : MPSA molar ratio of 1:0.60, 1:0.70, 1:0.80, 1:90 and 1 : 1 can be prepared by taking 55.52, 64.77, 74.02, 83.27 and 92.53 milligrams of MPSA (99%), respectively, under similar reaction conditions. NaBH4 requirement for different Pt: MPSA molar ratio is given in Table 1.
Further, 2, 5, 10, 15, 20, 25, 30, 35, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 98 percent by weight of platinum supported on fumed silica can be prepared by taking 4900, 1900, 900, 566.67, 400, 300, 233.33, 185.72, 122.22, 100, 81.82, 66.67, 53.85, 42.86, 33.33, 25, 17.65, 11.11, 5.26, 2.08 milligrams of fumed silica, respectively, in place of 150 milligrams of fumed silica (40 wt% loading) under similar reaction conditions. However, 500, 350, 200 and 100 millilitres of water should be added for 2, 5, 10 and 15 percent by weight of platinum, respectively, to fumed silica by maintaining pH around 10-11 by addition of NaBH4. Other sources of Platinum such as PtCl2, PtCI4, K2PtCI6 and Pt(acac)2 can also be used in place of K2PtCI6 on similar molar basis.
This method was used for the synthesis of fumed silica supported Pt-MPA np and Pt-MSA np by using MPA and MSA, respectively, instead of MPSA.

Example 9: 60 wt% nano silica : 40 wt% Pt, Pt: MPSA = 1 : 0.241 (molar ratio), MPSA : Hexane thiol = 1:1 (molar ratio).
150 milligrams of nano silica was added in 50 millilitres distilled water at once and stirred for 20 minutes to get it well dispersed at 0 degree Celsius. 22.28 milligrams of mercapto propylsulfonic acid (MPSA) (99%, 0.124 mmol) was added to the above and stirred for 30 minutes at 0 degree Celsius followed by adding 253 milligrams of K2PtCI6 (99%, 0.514 mmol) and 17.85 µL of n-Hexane thiol (98%, 0.124 mmol) in 10 millilitres of ethanol and stirring for 30 minutes at 0 degree Celsius to obtain a first solution. 17.04 milligrams of NaBH4 (98%, 0.442 mmol) dissolved in 6 millilitres distilled water was added to the first solution at the rate of 1 millilitre/minute, followed by stirring for 20 minutes to obtain a second solution. Finally, the second solution was heated at 80 degree Celsius under stirring for 1 hour. The modified platinum nanoparticles supported on nano silica thus obtained, are then centrifuged and washed with distilled water several times followed by drying at 30 degree Celsius for 16 hours. XRD profiles of nano silica supported Pt-MPSA np is shown in Figure 6.
Similarly, 2, 5, 10, 15, 20, 25, 30, 35, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 98 percent by weight of platinum supported on nano silica can be obtained by taking 4900, 1900, 900, 566.67, 400, 300, 233.33, 185.72, 122.22, 100, 81.82, 66.67, 53.85, 42.86, 33.33, 25, 17.65, 11.11, 5.26, 2.08 milligrams of nano silica, respectively, in place of 150 milligrams nano silica (40 wt% loading) under similar reaction conditions. However, 500, 350, 200 and 100 millilitres of water was added for 2, 5, 10 and 15 percent by weight of Platinum, respectively, to nano silica by maintaining pH around 10-11 by addition of NaBH4.

Pt : MPSA molar ratio of 1:0.05, 1:0.10, 1:0.20, 1:0.30, 1 : 1.40 and 1:0.50, can also be prepared by taking 4.63, 9.25, 18.51, 27.76, 37.01 and 46.30 milligrams of MPSA (99%), respectively, under similar reaction conditions.
MPSA : n-hexane thiol molar ratio of 1 : 0.25, 1: 0.50, 1 : 0.75, 1 : 1.25, 1 : 1.50, 1: 75, 1 :2 were also prepared under similar reaction conditions.
Other sources of Pt such as PtCI2, PtCI4, K2PtCI6 and Pt(acac)2 were also used in place of K2PtCI6 on similar molar basis.
This method can also be used for the synthesis of nano silica supported Pt-MPA-L np and Pt-MSA-L np by using MPA and MSA. respectively, instead of MPSA.
Example 10: 60 wt% fumed silica : 40 wt% Pt, Pt : MPSA = 1 : 0.241 (molar ratio), MPSA : Hexane thiol = 1:1 (molar ratio).
150 milligrams of fumed silica was added in 50 millilitres distilled water at once and stirred for 20 minutes to get it well dispersed at 0 degree Celsius. 22.28 milligrams of mercapto propylsulfonic acid (MPSA) (99%, 0.124 mmol) was added to the above and stirred for 30 minutes at 0 degree Celsius followed by adding 253 milligrams of K2PtCI6 (99%, 0.514 mmol) and 17.85 µL of n-Hexane thiol (98%, 0.124 mmol) in 10 millilitres of ethanol and stirred for 30 minutes at 0 degree Celsius to obtain a first solution. 17.04 milligrams of NaBH4(98%, 0.442 mmol) dissolved in 6 millilitres distilled water was added to the first solution at the rate of 1 millitre/minute, followed by stirring for 20 minutes to obtain a second solution. Finally, the second solution was heated at 80 degree Celsius under stirring for 1 hour. The modified platinum nanoparticles supported on fumed silica thus obtained, were filtered and washed with distilled water several times, followed by drying at 30 degree Celsius for 16 hours. XRD profiles of fumed silica supported Pt-MPSA np is shown in Figure 7.

Similarly, 2, 5, 10, 15, 20, 25, 30, 35, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 98 percent by weight of the platinum supported on the fumed silica was loaded by taking 4900, 1900, 900, 566.67, 400, 300, 233.33, 185.72, 122.22, 100, 81.82, 66.67, 53.85, 42.86, 33.33, 25, 17.65, 11.11, 5.26, 2.08 milligrams of fumed silica, respectively, in place of 150 milligrams of fumed silica (40 wt% loading) under similar reaction conditions. However, 500, 350, 200 and 100 millilitres of water was added for 2, 5, 10 and 15 wt% Pt loading, respectively, to fumed silica by maintaining pH around 10-11 by addition of NaBH4.
Pt : MPSA molar ratio of 1:0.05, 1:0.10, 1:0.20, 1:0.30, 1 : 1.40 and 1:0.50, can also be prepared by taking 4.63, 9.25, 18.51, 27.76, 37.01 and 46.30 milligrams of MPSA (99%), respectively, under similar reaction conditions.
MPSA : n-hexane thiol molar ratio of 1 : 0.25, 1: 0.50, 1 : 0.75, 1 : 1.25, 1 : 1.50, 1: 75, 1 :2 were also prepared under similar reaction conditions.
Other sources of Pt such as PtCb, PtCl4, K2PtCI6 and Pt(acac)2 were also used in place of K2PtCI6 on similar molar basis.
This method can also be used for the synthesis of fumed silica supported Pt-MPA-L np and Pt-MSA-L np by using MPA and MSA, respectively, instead of MPSA.
Example 11: 60 wt% Carbon : 40 wt% Pt and Pt: MPSA = 1 : 0.241 (molar ratio)
150 milligrams of Vulcan carbon was added in 50 millilitres distilled water at once and stirred for 20 minutes to get it well dispersed at 0 degree Celsius. 22.28 milligrams of mercapto propylsulfonic acid (MPSA) (99%, 0.124 mmol) was added to the above and stirred for 30 minutes at 0 degree Celsius followed by addition of 253 milligrams of K2PtCl6 (99%, 0.514 mmol) was then added and stirred for 30 minutes. 14.20 milligrams of NaBH4 (98%, 0.368 mmol) dissolved in 5 millilitres distilled water was added with rate of 1 millilitre/minute,

followed by stirring for 20 minutes. Finally, it was heated at 60 degree Celsius under stirring for 1 hour. Catalyst was filtered and washed with distilled water several times and dried at 30 degree Celsius for 16 hours. XRD profiles of carbon supported Pt-MPSA np is shown in Figure 8.
2, 5, 10, 15, 20, 25, 30, 35, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 98 percent by weight of the platinum supported on carbon was loaded by taking 4900, 1900, 900, 566.67, 400, 300, 233.33, 185.72, 122.22, 100, 81.82, 66.67, 53.85, 42.86, 33.33, 25, 17.65, 11.11, 5.26, 2.08 mg of carbon, respectively, in place of 150 milligrams carbon (40 wt% loading) under similar reaction conditions. However, 500, 350, 200 and 100 millilitres of water was added for 2, 5, 10 and 15 wt% Pt loading, respectively, on carbon by maintaining pH around 10-11 by addition of NaBH4
Other sources of Pt such as PtCI2, PtCI4, K2PtCI6 and Pt(acac)2 were also used in place of K2PtCI6 on similar molar basis.
This method can be used for the synthesis of carbon supported Pt-MPA np and Pt-MSA np by using similar mole of MPA and MSA, respectively, instead of MPSA.
The following examples illustrate the catalytic activity of the modified platinum nanoparticles of the present disclosure:
Example 12:
In 300 millilitre Parr Autoclave, 2 grams of xylose, 25 millilitre of water and 75 grams of toluene were added. 20 milligrams of Pt-MPSA np (1 percent by weight with respect to xylose) was then added and heated at 150 degree Celsius under autogenous pressure with 500 rotations per minute for 1 hour. The product was collected and filtered off to remove the modified platinum nanoparticles. Aqueous and organic phase were separated using separating

funnel and product were analyzed using HPLC. The conversion of xylose was 52%. The selectivity of furfural was 99%.
Similarly, other reactions were carried out in which temperature was varied between 60 and 180 degree Celsius; duration of reaction was varied from 15 minutes to 2 hours; and amount of modified platinum nanoparticles was varied from 0.10 to 5 percent by weight. Thus, 10 to 80% conversion of xylose was observed and selectivity of furfural varied from 70 to 99%.
Example 13:
In another reaction, Nano silica, amorphous silica, microporous silica and mesoporus silica supported Pt-MPSA-L np, Pt-MPA-L np and Pt-MSA-L np were used. The reaction procedure remains the same as described in Example 11.
Similarly, other reactions were carried out in which temperature were varied between 60 and 180 degree Celsius, and duration of reaction was varied from 15 minutes to 2 hours, and amount of modified platinum nanoparticles was varied from 0.10 to 5 percent by weight. Thus, 10 to 80% conversion of xylose was observed and selectivity of furfural varied from 70 to 99%.
Example 14:
Benzyl alcohol was reacted with acetic acid using Pt MPSA - OT np with varying molar ratio (OT: MPSA = 10, 5, 1, 0, 1, 5, 10) in a batch reactor. The reactions were carried out in 100 millilitres round bottomed flasks by mixing 5 g of benzyl alcohol (46.24 mmol), 3.05 g acetic acid (50.86 mmol) and 1-5 wt% of the modified platinum nanoparticles (Pt MPSA-OT np) at 60-90 degree Celsius for 1 to 7 hours. The reaction products were then characterized using capillary column Gas Chromatography. The conversion percentage of benzyl alcohol was found to be 70 to 96%.

SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A modified platinum nanoparticle comprising a platinum nanoparticle having at least one
mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid.
mercapto propionic acid and mercapto succinic acid, attached thereon.
Such modified platinum nanoparticle(s), further comprising at least one alkyl thiol selected
from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol
attached to the platinum nanoparticle.
Such modified platinum nanoparticle(s), wherein the modified platinum nanoparticle is
supported on a substrate.
Such modified platinum nanoparticle(s), wherein the substrate is selected from the group
comprising of rice husk ash, mesoporous silica, microporous silica, nanosilica and alumina.
Such modified platinum nanoparticle(s), wherein the molar ratio of the mercapto alkyl acid
and the alkyl thiol varies in the range of 0.25 to 100.
Such modified platinum nanoparticle(s), wherein the size of the platinum nanoparticle varies
in the range of 1 -1000nm.
Such modified platinum nanoparticle(s), wherein the modified platinum nanoparticle
comprises platinum in the range of 5 to 98 wt%.
FURTHER SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A method of preparing a modified platinum nanoparticle comprising reacting a first
solution comprising of a platinum precursor and at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, with a reducing agent to obtain a second solution and heating the second solution to a temperature that facilitates formation of a platinum nanoparticle having the mercapto alkyl acid attached thereon.

Such method(s), wherein the first solution further comprises at least one alkyl thiol selected
from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol to
obtain platinum nanoparticle having the mercaoto alkyl acid and the alkyl thiol attached thereon.
Such method(s), wherein the first solution further comprises of a substrate, to yield the
modified platinum nanoparticle supported on the substrate.
Such method(s), wherein the substrate is selected from the group comprising of rice husk ash,
mesoporous silica, microporous silica, nanosilica and alumina.
Such method(s), wherein the second solution is heated to a temperature in the range of 50-
100 degree Celsius.
Such method(s), wherein the first solution is prepared at 0 degree Celsius.
INDUSTRIAL APPLICABILITY
The modified platinum nanoparticle described above is cost effective and highly efficient. It finds its uses as catalyst in various types of industrial applications and in solid state electronic devices. The said modified platinum nanoparticle(s) exhibits proton conduction properties and catalytic activity even at low temperatures. The modified platinum nanoparticles disclosed above can be used for esterification of benzyl alcohol with acetic acid to benzyl acetate. The method to prepare the said modified platinum nanoparticle described above is easy to perform and inexpensive.

We claim:
1. A modified platinum nanoparticle comprising a platinum nanoparticle having at least one mercapto alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto propionic acid and mercapto succinic acid, attached thereon.
2. A modified platinum nanoparticle as claimed in claim 1, further comprising at least one alkyl thiol selected from the group consisting of hexane thiol, octane thiol, decane thiol and dodecane thiol attached to the platinum nanoparticle.
3. A modified platinum nanoparticle as claimed in claim 1 or 2, wherein the modified platinum nanoparticle is supported on a substrate.
4. A modified platinum nanoparticle as claimed in claim 3, wherein the substrate is selected from the group comprising of rice husk ash, mesoporous silica, microporous silica, nanosilica and alumina.
5. A modified platinum nanoparticle as claimed in claim 2. wherein the molar ratio of the mercapto alkyl acid and the alkyl thiol varies in the range of 0.25 to 100.
6. A modified platinum nanoparticle as claimed in claim 1 or 2, wherein the size of the platinum nanoparticle varies in the range of l-1000nm.
7. A modified platinum nanoparticle as claimed in claim 1 or 2, wherein the modified platinum nanoparticle comprises platinum in the range of 5 to 98 wt%.

8. A method of preparing a modified platinum nanoparticle comprising;
reacting a first solution comprising of a platinum precursor and at least one mercapto
alkyl acid selected from the group consisting of mercatopropyl sulfonic acid, mercapto
propionic acid and mercapto succinic acid, with a reducing agent to obtain a second
solution; and
heating the second solution to a temperature that facilitates formation of a platinum nanoparticle having the mercapto alkyl acid attached thereon.
9. A method of preparing a modified platinum nanoparticle as claimed in claim 8, wherein the first solution further comprises at least one alkyl thiol selected from the group consisting of hexane thiol, octane thiol,, decane thiol and dodecane thiol to obtain platinum nanoparticle having the mercaoto alkyl acid and the alkyl thiol attached thereon.
10. A method of preparing a modified platinum nanoparticle as claimed in claim 8 or 9, wherein the first solution further comprises of a substrate, to yield the modified platinum nanoparticle supported on the substrate.
11. A method of preparing a modified platinum nanoparticle, as claimed in claim 10 wherein the substrate is selected from the group comprising of rice husk ash, mesoporous silica, microporous silica, nanosilica and alumina,
12. A method of preparing a modified platinum nanoparticle as claimed in claim 8 or 9 wherein the second solution is heated to a temperature in the range of 50- 100 degree Celsius.

13. A method of preparing a modified platinum nanoparticle as claimed in claim 8 or 9 wherein the first solution is prepared at 0 degree Celsius.
14. A modified platinum nanoparticle substantially as herein descried with reference to and as illustrated by the accompanying figures.
15. A method of preparing a modified platinum nanoparticle substantially as herein descried with reference to and as illustrated by the accompanying figures.