METHOD FOR THE SYNTHESIS OF NANOPARTICLES OF HETEROMETALLIC NANOCOMPOSITE MATERIALS

Abstract

A simple one pot sol-gel method for the synthesis of bi-metal nanostructures is based on non-noble metals (Fe, Co and Sn) and titanium. The method involves the synthesis of mixed metal nanoscale composites using low cost precursors which allow for the synthesis of desired nanocomposite materials with self-scarifying titanium or silica supports. The procedure does not require any surfactant or any need for pH controlled step. Applicants' method involves the in-situ generation of precursors and their simultaneous entrapment in a gel. This simple one pot synthesis allows for the synthesis of homogenous size, shape and distribution of targeted nanostructures. Further, this method can be applied for the preparation of various nanocomposite materials using different choices of metals and self-scarifying supports. Applicants also show that Pd, the noble metal based nanocomposite is feasible.

Claims

1. A sol-gel method for the synthesis of nanoparticles of heterometallic nanocomposite materials, said method comprising: a first mass of tetrahydrofuron (THF) and a second smaller quantity of trifilic acid (TFC) added to said tetrahydrofuron for polymerization of said tetrahydrofuron; and once a gel is formed the reaction mixture including said gel was transferred to one or more crucibles and transferred into a muffled furnace at a temperature raised to 500 C. at a rate of 4 C. per minute and held at 500 C. for 2 hours as shown by the following formula: ##STR00003## wherein M=Fe, Sn, Co, Pb, Pt and Pd and X=a halide, or an organic ligand including acetylacetonate and pentadienyl and similarly metal-silicon nanocomposites are prepared.

2. The method for the synthesis of iron titanite (Fe.sub.9TiO.sub.15.TiO.sub.2) according to claim 1, and including the steps of ferrocene (1 g, 5.37 mM) dissolved in 5 mL of tetrahydrofuron in a 20 mL glass bottle and 5 mL of tetrahydrofuron added to said ferrocene and (0.2 mL, 22.6 mM) is added dropwise and slowly followed by titanium isopropoxide (1.80 L, 0.59 mM); the reaction mixture is stirred for 2 hours to form a gel that is transferred to a crucible containing a reaction mixture inclusive of said sol-gel and placed in a muffle furnace and heated to 500 C. at a rate of 4 C. per minute and held at 500 C. for 2 hours to form a yellow product (Fe.sub.9TiO.sub.15.TiO.sub.2).

3. The method for the synthesis of iron titanite at silica (Fe.sub.9TiO.sub.15.SiO.sub.2) according to claim 2, in which ferrocene (1 g, 5.37 mM) is dissolved in 5 mL of tetrahydrofuron for the method for the synthesis of (titanium palladium oxide at titania) comprising the steps according to claim 1, and providing a mass of tetrahydrofuron and a second mass of Pd(NO.sub.3.(H.sub.2O)0.2 g, 0.8 mM) is dropwise added followed by a dropwise addition of trifilic acid (0.2 mL, 22.6 mM) and slow addition of tiisoproxide (1.314 mL, 4.335 mM); the temperature in the furnace is raised to 450 C. at a rate of 4 C. per minute and held at 450 C. for 2 hours to produce a solid brown product Ti.sub.4Pd.sub.2O.TiO.sub.2.

4. The method for the synthesis of Titanium palladium oxide at titania (Ti.sub.4Pd.sub.2O.TiO.sub.2) according to claim 1, in which Pd(NO3).xH2O (0.2 g, 0.8 mM) was dissolved in 5 mL tetrahydrofuron followed by dropwise addition of trifilic acid (0.2 mL, 22.6 mM) and slow addition of Tiisoproxide (1.314 mL, 4.335 mM) at the end, the reaction mixture was stirred for 2 hours, transferred to a crucible and placed in a muffle furnace, the temperature in the furnace was raised to 450 C., at a rate of 4 C. per minute, and held for 2 hours until a solid brown product Ti.sub.4Pd.sub.2O.TiO.sub.2 is formed.

5. The method for the synthesis of titanium tin oxide at titania (Sn.sub.0.39Ti.sub.0.631O.sub.2), said method comprising: providing a mass of tetrahydrofuron, tin chloride (SnCl.sub.2) (0.5 g, 2.2 mM) and Tiisoproxide (6.6 mM, 2 mL which are dissolved in 5 mL tetrahydrofuron and its polymerization initiated by adding 0.2 mL (22.6 mM.sub.3); and a mixture is stirred for 2 hours, transferred into a crucible and placed in a furnace and heated to 400 C. at 3 C. per minute, and held at 400 C. for 2 hours to produce a clay white product (Sn.sub.0.39Ti.sub.0.61O.sub.2.TiO.sub.2) is formed.

6. The method for the synthesis of cobalt titanium perovskite at titania (CoTiO.sub.3.TiO.sub.2) according to claim 1, in which cobalt acetyalacetonate (0.5 g, 1.944 mM) is dissolved in 5 mL tetrahydrofuron and 0.2 mL (22.6 mM) of trifilic acid is slowly added by dropwise addition and followed by Tiisoproxide (9.72 mM, 2.94 mL); and after 2 hours of stirring the reaction is placed in a crucible and transferred to an oven heated to 500 C. and held at this temperature for 2 hours.

7. The method for the synthesis of Hausmannite (Mn.sub.2.88Fe.sub.0.12)O.sub.4 according to claim 1, in which manganese acetate (0.5 g, 2.04 mM) is added to 5 mL tetrahydrofuron, adding 0.2 mL (22.6 mM) of trifilic acid and ferrocene (0.085 mM, 0.015 g) in a reaction mixture was sonicated for 10 times followed by stirring for 2 hours and then heated to 500 C. at a rate of 4 C. per minute and calcined for 2 hours before slowly cooling it down.

8. The method for the synthesis of Bixbyite (MnFeO.sub.3) according to claim 1, in which manganese acetate (0.5 g, 2.04 mM), trifilic acid (0.2 mL, 22.6 mM) and ferrocene (0.38 g, 2.04 mM) are dissolved in 5 mL tetrahydrofuron and the reaction mixture placed in a crucible and heated to 500 C. at a rate of 4 C. per minute and calcined for 2 hours.

9. The method for the synthesis of Iron Titanium Oxide at titania (Fe.sub.1.696Ti.sub.0.228O.sub.3.TiO.sub.2) according to claim 1, in which ferrocene (1 g, 5.37 mM) is dissolved in 5 mL of tetrahydrofuron in a 20 mL glass bottle and trifilic acid (0.2 mL, 22.6 mM) was added dropwise and slowly followed by dropwise addition of Titanium isopropoxide (1.80 L, 0.59 mM) and the reaction mixture stirred for 2 hours forming a gel that is transferred to a crucible and placed in a muffle furnace and heated to 500 C. at a rate of 4 C. per minute and maintained at 500 C. for 4 hours.

10. The method for the synthesis of Trevorite (Ni.sub.1.43Fe.sub.1.7O.sub.4) and Trevorite at titania (Ni.sub.1.43Fe.sub.1.7O.sub.4.TiO.sub.2) nanocomposites according to claim 1, in which nickel acetylacetonate (1.946 mM, 0.5 g) and ferrocene (1.946 mM, 0.36 g) and dissolved in 5 mL of tetrahydrofuron followed by addition of trifilic acid (0.2 mL, 22.6 mM), stirring for 2 hours and transferring the resulting gel to one or more crucibles and placing said one or more crucibles in a muffle furnace to heat the reaction mixture including the gel to 500 C. at a rate of 3 C. per minute and maintained at 500 C. for 3 hours.

11. A sol-gel method for the synthesis of nanoparticles of heterometallic nanocomposite materials, said method consisting of: a first mass of tetrahydrofuron (THF) and a second smaller quantity of trifilic acid (TFC) added to said tetrahydrofuron for polymerization of said tetrahydrofuron; and once a gel is formed the reaction mixture including said gel was transferred to one or more crucibles and transferred into a muffled furnace at a temperature raised to 500 C. at a rate of 4 C. per minute and held at 500 C. for 2 hours as shown by the following formula: ##STR00004## wherein M=Fe, Sn, Co, Pb, Pt and Pd and X=a halide, or an organic ligand including acetylacetonate and pentadienyl and similarly metal-silicon nanocomposites are prepared.

12. The method for the synthesis of iron titanite (Fe.sub.9TiO.sub.15.TiO.sub.2) according to claim 11, and further consisting of the steps of ferrocene (1 g, 5.37 mM) dissolved in 5 mL of tetrahydrofuron in a 20 mL glass bottle and 5 mL of tetrahydrofuron added to said ferrocene and (0.2 mL, 22.6 mM) is added dropwise and slowly followed by titanium isopropoxide (1.80 L, 0.59 mM); the reaction mixture is stirred for 2 hours to form a gel that is transferred to a crucible containing a reaction mixture inclusive of said sol-gel and placed in a muffle furnace and heated to 500 C. at a rate of 4 C. per minute and held at 500 C. for 2 hours to form a yellow product (Fe.sub.9TiO.sub.15.TiO.sub.2).

13. The method for the synthesis of iron titanite at silica (Fe.sub.9TiO.sub.15.SiO.sub.2) according to claim 12, and further consisting of the steps in which ferrocene (1 g, 5.37 mM) is dissolved in 5 mL of tetrahydrofuron for the method for the synthesis of (titanium palladium oxide at titania) comprising the steps according to claim 1, and providing a mass of tetrahydrofuron and a second mass of Pd(NO.sub.3.(H.sub.2O)0.2 g, 0.8 mM) is dropwise added followed by a dropwise addition of trifilic acid (0.2 mL, 22.6 mM) and slow addition of tiisoproxide (1.314 mL, 4.335 mM); the temperature in the furnace is raised to 450 C. at a rate of 4 C. per minute and held at 450 C. for 2 hours to produce a solid brown product Ti.sub.4Pd.sub.2O.TiO.sub.2.

14. The method for the synthesis of Titanium palladium oxide at titania (Ti.sub.4Pd.sub.2O.TiO.sub.2) according to claim 11, and further consisting of the steps in which Pd(NO3).xH2O (0.2 g, 0.8 mM) was dissolved in 5 mL tetrahydrofuron followed by dropwise addition of trifilic acid (0.2 mL, 22.6 mM) and slow addition of Tiisoproxide (1.314 mL, 4.335 mM) at the end, the reaction mixture was stirred for 2 hours, transferred to a crucible and placed in a muffle furnace. The temperature in the furnace was raised to 450 C., at a rate of 4 C. per minute, and held for 2 hours. A solid brown product Ti.sub.4Pd.sub.2O.TiO.sub.2.

15. The method for the synthesis of titanium tin oxide at titania (Sn.sub.0.39Ti.sub.0.631O.sub.2) said method consisting of: providing a mass of tetrahydrofuron, tin chloride (SnCl.sub.2) (0.5 g, 2.2 mM) and Tiisoproxide (6.6 mM, 2 mL which are dissolved in 5 mL tetrahydrofuron and its polymerization initiated by adding 0.2 mL (22.6 mM.sub.3); a mixture stirred for 2 hours, transferred into a crucible and placed in a furnace and heated to 400 C. at 3 C. per minute, and held at 400 C. for 2 hours to produce a clay white product (Sn.sub.0.39Ti.sub.0.61O.sub.2.TiO.sub.2).

16. The method for the synthesis of cobalt titanium perovskite at titania (CoTiO.sub.3.TiO.sub.2) according to claim 11, and further consisting of the steps in which cobalt acetyalacetonate (0.5 g, 1.944 mM) is dissolved in 5 mL tetrahydrofuron and 0.2 mL (22.6 mM) of trifilic acid is slowly added by dropwise addition of followed by Tiisoproxide (9.72 mM, 2.94 mL); and after 2 hours of stirring the reaction is placed in a crucible and transferred to an oven heated to 500 C. and held at this temperature for 2 hours.

17. The method for the synthesis of Hausmannite (Mn.sub.2.88Fe.sub.0.12)O.sub.4 according to claim 11, and further consisting of the steps in which manganese acetate (0.5 g, 2.04 mM) is added to 5 mL tetrahydrofuron, adding 0.2 mL (22.6 mM) of trifilic acid and ferrocene (0.085 mM, 0.015 g) in a reaction mixture was sonicated for 10 times followed by stirring for 2 hours and then heated to 500 C. at a rate of 4 C. per minute and calcined for 2 hours before slowly cooling it down.

18. The method for the synthesis of Bixbyite (MnFeO.sub.3) according to claim 11, and further consisting of the steps in which manganese acetate (0.5 g, 2.04 mM), trifilic acid (0.2 mL, 22.6 mM) and ferrocene (0.38 g, 2.04 mM) are dissolved in 5 mL tetrahydrofuron and the reaction mixture placed in a crucible and heated to 500 C. at a rate of 4 C. per minute and calcined for 2 hours.

19. The method for the synthesis of Iron Titanium Oxide at titania (Fe.sub.1.696Ti.sub.0.228O.sub.3.TiO.sub.2) according to claim 11, and further consisting of the steps in which ferrocene (1 g, 5.37 mM) is dissolved in 5 mL of tetrahydrofuron in a 20 mL glass bottle and trifilic acid (0.2 mL, 22.6 mM) was added dropwise and slowly followed by dropwise addition of Titanium isopropoxide (1.80 L, 0.59 mM) and the reaction mixture stirred for 2 hours forming a gel that is transferred to a crucible and placed in a muffle furnace and heated to 500 C. at a rate of 4 C. per minute and maintained at 500 C. for 4 hours.

20. The method for the synthesis of Trevorite (Ni.sub.1.43 Fe.sub.1.7O.sub.4) and Trevorite at titania (Ni.sub.1.43Fe.sub.1.7O.sub.4.TiO.sub.2) nanocomposites according to claim 11, and further consisting of the steps in which nickel acetylacetonate (1.946 mM, 0.5 g) and ferrocene (1.946 mM, 0.36 g) and dissolved in 5 mL of tetrahydrofuron followed by addition of trifilic acid (0.2 mL, 22.6 mM), stirring for 2 hours and transferring the resulting gel to one or more crucibles and placing said one or more crucibles in a muffle furnace to heat the reaction mixture including the gel to 500 C. at a rate of 3 C. per minute and maintained at 500 C. for 3 hours.

Description

DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1, metal compounds, as precursors of metal composite materials were added in tetrahydrofuron (THF) and polymerization of THF was initiated by the addition of a small quantity of trifilic acid (TFC) as shown in FIG. 1. No other oxidizing, reducing agent or any surfactant was required. Slow polymerization of THF was allowed out at room temperature. Once gel was formed by reaction, the mixture was transferred into crucibles and crucibles transferred into a furnace. The temperature was then raised to 500 C. at a rate of 4 C. per minute and held at that temperature for 2 hours.

##STR00002##

Wherein M=Fe, Sn, Co, Pb or any other metal, X=halide, or any organic ligand such as acetylacetonate and pentadienyl. Similarly, Metal-Silicon nanocomposites were prepared;

[0058] FIG. 2A illustrates the XRD patterns of the various nanocomposites calcined at 500 C. for 2 hours;

[0059] FIG. 2B illustrates SEM micrographs of Fe.sub.9TiO.sub.15.TiO.sub.2 nanocomposite showing highly porous architecture;

[0060] FIG. 3A illustrates an elemental mapping;

[0061] FIG. 3B illustrates an EDS spectrum of Fe.sub.9TiO.sub.15.TiO.sub.2;

[0062] FIG. 4A illustrates the elemental mapping;

[0063] FIG. 4B illustrates an EDS spectrum of Ti.sub.4Pd.sub.2O.TiO.sub.2 nanocomposite;

[0064] FIG. 5 illustrates HRTEM images of Fe.sub.9TiO.sub.15.TiO.sub.2 nanocomposite;

[0065] FIG. 6 illustrates HRTEM images of Ti.sub.4Pd.sub.2O.TiO.sub.2 nanocomposite;

[0066] FIG. 7 illustrates Fe-catalysed reduction of nitroarenes to anilines: Reaction conditions: 0.5 mmol nitroarene, 5-7 mg catalysts, 2.5 mmol hydrazine hydrate, 2 mL THF, 15-20 h, 100 C. Yields we determined using n-hexadecane standard; and

[0067] FIG. 8 illustrates current density (I)-vs Time (s) characteristics of the (a) Ti.sub.4Pd.sub.2O photocathode, (b) Sn.sub.0.6Ti.sub.0.61O.sub.2 (c) Fe.sub.9TiO.sub.15 (d) CoTiO.sub.3 photoanodes recorded at 0 V in an 1 M aqueous K.sub.2SO.sub.4 electrolyte solution.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Examples

[0068] Applicants' methods can be applied for the preparation of a variety of nanocomposite materials with different choices of metals combinations and self-scarifying supports. Nanostructures prepared by these methods were homogeneous with well control over size and shape. These methods are highly reproducible and allow the synthesis of nanocomposites of desired combination even for composites not synthesized before in their nano-form. This could be a breakthrough for different applications in nanotechnology including but not limited to catalysis, water splitting, fuel cells, super-capacitors charge storage and sensing applications.

[0069] Metal precursors which are soluble in tetrahydrofuron (THF) are best suited for this method. Once a homogenous solution is made polymerization is initiated with trifilic acid (TFC) and allowed till the formation of a gel which is then decomposed and calcined at optimized temperatures. Following are few examples for nanocomposites prepared by this method.

Example 1

[0070] Synthesis of Fe.sub.9TiO.sub.15.TiO.sub.2 (Iron titanate). Ferrocence (1 g, 5.37 mM) was dissolved in 5 mL of THF, in a 20 mL glass bottle. TFC (0.2 mL, 22.6 mM) was added dropwise and slowly followed by dropwise addition of Titanium isopropoxide (1.80 L, 0.59 mM). The reaction mixture was left on stirring for 2 hours. A gel was formed which was transferred to a crucible. The crucible containing all reaction mixture was placed in a muffle furnace. The furnace was heated to 500 C. at a rate of 4 C. per minute and kept at 500 C. for 2 hours. A solid yellow product Fe.sub.9TiO.sub.15.TiO.sub.2 was obtained which was characterized by XRD (FIG. 2A) and tested as catalyst for nitroarenes reduction to nitroamines.

Example 2

[0071] Synthesis of Fe.sub.9TiO.sub.15.SiO.sub.2 (Iron titanate at silica). Ferrocence (1 g, 5.37 mM) was dissolved in 5 mL of THF, in a 20 mL glass bottle. 0.5 g of mesoporous silica (SiO.sub.2) was added as an external support, TFC (0.2 mL, 22.6 mM) was added dropwise and slowly followed by dropwise addition of Titanium isopropoxide (1.628 mL, 5.37 mM). The reaction mixture was left on stirring for 2 hours. A gel was formed which was transferred to a crucible. The crucible containing all reaction mixture was placed in a muffle furnace. The furnace was heated to 500 C. at a rate of 4 C. per minute and kept at 500 C. for 2 hours. A solid yellow product Fe.sub.9TiO.sub.15.TiO.sub.2 was obtained which was characterized and tested as catalyst for nitroarenes reduction to nitroamines.

Example 3

[0072] Synthesis of Ti.sub.4Pd.sub.2O. TiO.sub.2 (Titanium palladium oxide at titania). Pd(NO3).xH2O (0.2 g, 0.8 mM) was dissolved in 5 mL THF followed by dropwise addition of TFC (0.2 mL, 22.6 mM) and slow addition of Tiisoproxide (1.314 mL, 4.335 mM) at the end. The reaction mixture was stirred for 2 hours, transferred to a crucible and placed in a muffle furnace. The temperature in the furnace was raised to 450 C., at a rate of 4 C. per minute, and held for 2 hours. A solid brown product Ti.sub.4Pd.sub.2O. TiO.sub.2 was obtained and characterized by XRD (FIG. 2A).

Example 4

[0073] Synthesis of Sn.sub.0.39Ti.sub.0.61O.sub.2. TiO.sub.2 (Titanium Tin Oxide at titania). SnCl.sub.2 (0.5 g, 2.2 mM) and Tiisoproxide (6.6 mM, 2.0 mL) were dissolved in 5 mL THF and its polymerization was initiated by adding 0.2 mL (22.6 mM) of TFC. Like in all other experiments, the reaction mixture was stirred for 2 hours, transferred in a crucible and placed in the furnace, heated to 400 C., at 3 C. per minute, and held for 2 hours. A clay white product was obtained. XRD of Sn.sub.0.39Ti.sub.0.61O.sub.2. TiO.sub.2 is shown in FIG. 2A.

Example 5

[0074] Synthesis of CoTiO.sub.3.TiO.sub.2 (Cobalt titanium perovskite at titania). Cobalt acetyalacetonate (0.5 g, 1.944 mM) was dissolved in 5 mL THF, 0.2 mL (22.6 mM) of TFC was slowly added followed by dropwise addition of Tiisoproxide (9.72 mM, 2.94 mL). After 2 h of stirring, reaction mixture was placed in a furnace, heated to 500 C. and held at this temperature for 2 hours. The product obtained was characterized by XRD (FIG. 2A).

Example 6

[0075] Synthesis of (Mn.sub.2.88Fe.sub.0.12)O.sub.4 (Hausmannite). Manganese acetate (0.5 g, 2.04 mM) was added in 5 mL THF. Manganese acetate was partially soluble in THF, however, after addition of 0.2 mL (22.6 mM) of TFC it became completely soluble. Ferrocene (0.085 mM, 0.015 g) was also added in the same solution and reaction mixture was sonicated for 10 mins followed by stirring for 2 hours. The reaction mixture was heated to 500 C., at a rate of 4 C., and calcined for 2 hours before slowly cooling it down. XRD of (Mn.sub.2.88Fe.sub.0.12)O.sub.4 is represented in FIG. 7.

Example 7

[0076] MnFeO.sub.3 (Bixbyite). MnFeO.sub.3 pervoskite was synthesized by dissolving manganese acetate (0.5 g, 2.04 mM), TFC (0.2 mL, 22.6 mM) and ferrocene (0.38 g, 2.04 mM,) in 5 mL THF as described in the previous experiment. The reaction mixture was heated to 500 C., at a rate of 4 C., and calcined for 2 hours. The product was characterized by XRD (FIG. 7).

Example 8

[0077] Synthesis of Fe.sub.1.696Ti.sub.0.228O.sub.3. TiO.sub.2 (Iron Titanium Oxide at titania). Ferrocence (1 g, 5.37 mM) was dissolved in 5 mL of THF, in a 20 mL glass bottle. TFC (0.2 mL, 22.6 mM) was added dropwise and slowly followed by dropwise addition of Titanium isopropoxide (1.80 L, 0.59 mM). The reaction mixture was left on stirring for 2 hours. A gel was formed which was transferred to a crucible. The crucible containing all reaction mixture was placed in a muffle furnace. The furnace was heated to 500 C. at a rate of 4 C. per minute and kept at 500 C. for 4 hours. XRD of Fe.sub.1.696Ti.sub.0.228O.sub.3. TiO.sub.2 is shown in FIG. 7.

Example 9

[0078] Synthesis of Ni.sub.1.43 Fe.sub.1.7O.sub.4 (Trevorite), and Ni.sub.1.43Fe.sub.1.7O.sub.4. TiO.sub.2 (Trevorite at titania) nanocomposites. For Ni.sub.1.43 Fe.sub.1.7O.sub.4 synthesis, Nickel acetylacetonate (1.946 mM, 0.5 g) and ferrocene (1.946 mM, 0.36 g) were dissolved in 5 mL of THF followed by addition of TFC (0.2 mL, 22.6 mM). The reaction mixture was stirred for 2 hours and resulting gel was transferred to a crucible and placed in a muffle furnace. The furnace was heated to 500 C. at a rate of 3 C. per minute and kept at 500 C. for 3 h. Ni.sub.1.43Fe.sub.1.7O.sub.4. TiO.sub.2 nanocomposite was synthesized by repeating the above procedure after adding 0.5 g of TiO.sub.2 in the reaction mixture. XRD (FIG. 7) and Rietveld (RIR) analysis (FIG. 8) showed the successful synthesis of nanocomposites in the desired ratios.

[0079] While the invention has been defined in accordance with its preferred embodiments, it should be recognized that changes and modifications may be made therein without departing from the scope of the appended claims.