FIELD OF THE INVENTION

The present invention discloses a hydrothermal process for preparation of doped carbon nano-foams. More particularly, the present invention discloses a process for preparation of doped carbon nano-foams using hydrothermal method in presence of surfactant(s). Use of the surfactant(s) improves the different key properties of the carbon nanofoam such as homogeneity of dopants in the carbon foam, increase in BET surface area, and homogeneity of pore-distribution on carbon nano-foams.

ABBREVIATIONS

Pt – Platinum
P – Phosphorous
B – Boron
As – Arsenic
Sb – Antimony
RuO2 – Ruthenium(IV) oxide
IrO2 – Iridium(IV) oxide
MnO2 – Manganese(IV) oxide
Triton x-100 – 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol
Span-20 – [2-(3,4-dihydroxyoxolan-2-yl)-2-hydroxyethyl] dodecanoate
M – Molar
m – meter
g – Gram
Å - Angstrom
KOH – Potassium hydroxide
GO – Graphene Oxide
rGO – Reduced Graphene Oxide
% - Percentage
°C – Degree Celsius

BACKGROUND OF THE INVENTION

Traditionally, noble metals (such as Pt) and metal oxides (such as RuO2, IrO2 and MnO2) are used as catalysts and electrode materials for new generation batteries, fuel cells and other energy related applications. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. One solution to these problems is development of doped carbon materials with high surface area and good electro-catalytic properties. Some of the prior-art documents disclosing doping of carbon using various amended processes are given below.

US 4668595 described the doping in variety of carbons, formed from carbon powders, carbon blacks and carbonized polymeric fibers. They used n-doped carbonaceous material as an active material for either of positive and negative electrodes in secondary battery.

US 5093216 described the doping of phosphorus in carbonized materials like resins, polymers and hydrocarbons for use as electrode in electrolyte cell. Such doped carbonized materials provided high energy density. Hence, doped carbon foams if used as anode can provide increased electronic conductivity resulting into higher energy and power density.

US 5358802A explained that doping of carbon foams with selected materials (P, B, As, Sb) can be done by incorporating the dopants during the polymerization or pyrolysis of the material. Dopants in this case will modify the localized graphitic structure to improve the intercalation properties.

US7838146 B2 explained the preparation of low conductivity carbon foams with improved cell size uniformity and high pore volume via carbonization of polyurethane foams or phenolic foams for lead-acid battery application.

WO 2015/193336 A1 described the preparation of nano-porous carbon foams from nano-porous nitrogen containing resin foam via two step heating process (200 to 650ºC and 650 to 1400ºC; Heating rate of 1 to 10ºC).

US20170304795A1 described the synthesis of nitrogen doped carbon aerogel with controlled nitrogen content for super-capacitor applications.

In recent past, hydrothermal method has also been reported for preparation of doped carbon nano-foams as it is a less energy intensive process than the annealing methods of synthesis. N-doped carbon foams has been prepared by hydrothermal reaction of carboxymethyl cellulose at 200-250 °C followed by thermal annealing at 900°C (CN104445138B). N-doped carbon foams have also been prepared by hydrothermal reaction of Broussonetia Papyrifera Bark in presence of dilute sulfuric acid followed by chemical activation using KOH at 700-900°C (Sci Rep., 6, 2016, 22646).

CN108288547A related to a preparation method of a nitrogen, phosphorus, and sulfur ternary co-doped ordered mesoporous carbon material and aims to solve the problem of limitation of existing single heteroatom doping on improvement of capacity of the mesoporous carbon material. The preparation method comprised the steps of preparing an ordered mesoporous silicon dioxide template (KIT-6) by hydrothermal synthesis; stirring and aging a sucrose, phosphoric acid and thiosemicarbazide mixed solution and a KIT-6 dispersion liquid; placing the obtained paste compound in a drying oven for drying; placing the product in a tubular furnace for pyrolysis for 1-3 hours under high-pure nitrogen; and immersing the carbonized composite material in an HF solution, performing stirring to remove the silicon dioxide template, performing filtering, washing with ultra-pure water and ethyl alcohol, and obtaining the nitrogen, phosphorus, and sulfur ternary co-doped ordered mesoporous carbon material (NPS-OMC) after drying.

CN103560016A related to a method for preparing a multi-stage channel graphene/carbon composite material by using a graphene aerogel as a three-dimensional skeleton and in situ organic-organic self-assembly by a hydrothermal route, and belongs to the technical field of nano-functional carbon material preparation technology. The main process of the method of the invention is: using a surfactant as a structure directing agent, the polymer prepolymer is a carbon precursor, synthesizing a single micelle solution in an aqueous solution system, and immersing the freeze-dried graphene aerogel therein. Dry after hydrothermal reaction. The material is then subjected to reflux extraction or placed in a tube furnace under inert gas for roasting to remove the surfactant. After cooling to room temperature, a multistage channel graphene-based carbon material having micropores, ordered mesopores, and macropores is finally obtained. An advantage of the present invention is that an ordered mesoporous structure is formed on the surface of the graphene aerogel while maintaining the macroporous structure of the graphene aerogel. The present invention can be applied to an electric double layer capacitor and a lithium battery negative electrode material.

Shelby Taylor Mitchell et al. in Carbon, Volume 95, December 2015, Pages 434-441disclosed a production of carbon nanofoam using a hydrothermal autoclave reactor with a sucrose solution and a small-added amount of naphthalene. The foam has an average density of 85 mg/cc and is uniform in its appearance.

Qingqing Ke et al. in RSC Advances, Issue 50, 2014 disclosed an easy method to synthesize surfactant-modified graphene for a supercapacitor is demonstrated through the intercalation of graphene oxide (GO) with a triblock copolymer Pluronic F127 (F127). A rationalized, reduced GO-F127 is obtained by hydrothermal and thermal annealing-driven structural reconstruction. The F127 successfully intercalates into the GO layers and facilitates the stabilization of the single-layer or few-layer structure of graphene sheets during the reduction process. An increased surface area of 696 m2/g is achieved in the surfactant-modified graphene, which is about three times higher than that of pristine graphene (200 m2/g). The electrocapacitive behaviors of the resultant composites are systematically investigated by cyclic voltammetry and galvanostatic charge–discharge techniques. The rGO-F127 sample thermal-treated at 400°C delivers a maximum specific capacitance of 210 Fg-1 at a scanning rate of 1 mVs-1 in 6 M KOH electrolyte and has an excellent cycling stability, retaining over 95.6% of the initial capacity after 1000 cycles.

Yet there is need to develop a process for the preparation of doped nanofoam overcoming disadvantages of prior-arts like less surface area, average electro-catalytic properties, high cost, low selectivity, poor stability and detrimental environmental effects.

The process of the present invention discloses a process for the preparation of doped carbon nanofoam by overcoming said limitation(s) of the prior-art documents.

OBJECTIVES OF THE INVENTION

It is the primary objective of the present invention is to provide a preparation of doped carbon nanofoams using hydrothermal method.

It is the further objective of the present invention is to provide process for the preparation of boron, nitrogen and phosphorous doped as well as iron-nitrogen doped carbon nanofoams using hydrothermal method.

It is the further objective of the present invention is to provide a process which is less energy intensive than the annealing methods of synthesis.

It is the further objective of the present invention is to provide a process involving use of surfactant to increase the homogeneity of dopants/ components in the carbon foam, to increase the BET surface area of the carbon foam, and to obtain the homogeneous pore-distribution on carbon nanofoams.

SUMMARY OF THE INVENTION

In an aspect of the present invention, the present invention discloses a hydrothermal process for the synthesis of doped solid carbon nanofoams, comprising: taking first carbon source in a high pressure reactor; adding dopant to prepare a reaction mixture; adding surfactant to above reaction mixture; adding second carbon source to the reaction mixture; treating the reaction mixture obtained in for 2-5 hours at 100-200°C to obtain doped solid carbon nanofoam in the reaction mixture; separating said doped solid carbon nanofoam from unreacted reaction mixture by filtration; washing the doped solid carbon nanofoam with warm water to remove unreacted material and impurities attached with the doped solid carbon nanofoam; drying said doped solid carbon nanofoam in oven for 5 hours at 100°C; performing thermal annealing of said dried doped solid carbon nanofoam at 600-1000°C for 1-5 hours at a heating rate of 5°C/minute under nitrogen or argon gas to obtain doped solid carbon nanofoam.

In an embodiment of the present invention, the first carbon source is sucrose.

In an embodiment of the present invention, the dopant is selected from a group consisting of boron, nitrogen, phosphorus and iron-nitrogen.

In an embodiment of the present invention, the boron containing dopant is boric acid; nitrogen containing dopant is selected from a group consisting of N-acetylglucosamine, diethanolamine, urea, ammonia solution, diethanolamine and propylenediamine; phosphorous containing dopant is selected from a group consisting of phytic acid and triphenyl phosphine; iron containing dopant is selected from a group consisting of iron nitrate, ferric chloride and iron sulphate.

In an embodiment of the present invention, the surfactant is selected from a group consisting of non-ionic surfactant and ionic surfactant.

In an embodiment of the present invention, the non-ionic surfactant is selected from the group consisting of 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol and [2-(3,4-dihydroxyoxolan-2-yl)-2-hydroxyethyl] dodecanoate .

In an embodiment of the present invention, the ionic surfactant is selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulphate, dioctyl sodium sulfosuccinate, sodium sterate, sodium dodecyl sulfate and cetrimonium bromide.

In an embodiment of the present invention, the nano-foam is having pore size 1-5Å.

In an embodiment of the present invention, the second carbon source is polycyclic aromatic hydrocarbon.

In an embodiment of the present invention, the polycyclic aromatic hydrocarbon is naphthalene.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates process flow-chart of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention accounts a preparation of doped carbon nanofoams using hydrothermal method from sucrose solution (0.1 – 1M) as easily available carbon source as detailed in Figure 1. In the current invention doping by boron, nitrogen, phosphorus, and iron-nitrogen is done using suitable dopants. Suitable surfactant is added to reaction mixture to prepare the improved carbon nano-foam with higher BET surface area, better homogeneity of dopants and homogeneous pore distribution in the prepared doped carbon nanofoam. The hydrothermal reaction of above components is carried out in a stainless steel high pressure reactor. The reactor is properly closed and reaction is carried out for 2-5 hours at 100-200ºC in the presence of aromatic hydrocarbons, more specifically polycyclic aromatic hydrocarbons, i.e. naphthalene. After reactor is cooled, reaction mixture was taken out and solid doped carbon foam was separated from remaining unreacted sucrose solution by filtration. The solid carbon foam was washed with warm water to remove any unreacted materials and impurities attached with the product. The doped carbon foam was dried in oven at 100°C for 5 hours. Further thermal annealing was performed at 600-1000°C for 1-5 hours at a heating rate of 5°C/ min under nitrogen gas (flow rate = 25-100 ml/minute) in presence of nitrogen to increase the surface area of the carbon foams.
The doped carbon nanofoams obtained using surfactant displayed many advantages over the carbon nanofoams prepared without using surfactant. The homogeneity of dopants/components in the carbon foam as well as pore-distribution on the carbon nanofoams increased when surfactant was used as compared to the carbon nanofoams where surfactant was not used during the synthesis. Moreover, BET surface area of the carbon nanofoams also increased when surfactant was used. For example, BET surface area of the Fe/N-coped carbon nanofoam increased to 815 m2/g, when surfactant is used in their preparation, from 699 m2/g, when surfactant was not used. The content of different dopants is varied between 1-26 % in the carbon nanofoams. The pore size of the doped carbon nanofoams is 1-5 Å.
The present invention discloses a hydrothermal process for the synthesis of doped carbon nanofoams, comprising: taking sucrose solution as carbon source in a stainless steel high pressure reactor; adding dopant selected from a group consisting of boron, nitrogen, phosphorus or iron-nitrogen to prepare a reaction mixture; adding surfactant, preferably non-ionic surfactant to above reaction mixture; treating said reaction mixture for 2-5 hours at 100-200°C in the presence of aromatic hydrocarbons, more specifically polycyclic aromatic hydrocarbons, i.e. naphthalene; separating solid doped carbon nanofoam from unreacted reaction mixture by filtration; washing the solid doped carbon nanofoam with warm water to remove unreacted material and impurities attached with the solid doped carbon nanofoam; drying said solid doped carbon nanofoam in oven for 5 hours at 100°C; performing thermal annealing of said dried solid doped carbon nanofoam at 600-1000°C for 1-5 hours at a heating rate of 5°C/minute under nitrogen gas to obtain solid doped carbon nanofoam with increased surface area having pore size 1-5Å.
The present invention discloses a hydrothermal process for the synthesis of doped carbon nanofoams, comprising: taking sucrose solution as carbon source in a stainless steel high pressure reactor; adding dopant selected from a group consisting of boron, nitrogen, phosphorus or iron-nitrogen to prepare a reaction mixture; optionally, adding co-dopant to the above reaction mixture; adding surfactant, preferably non-ionic surfactant to above reaction mixture; treating said reaction mixture for 2-5 hours at 100-200°C in the presence of aromatic hydrocarbons, more specifically polycyclic aromatic hydrocarbons, i.e., naphthalene; separating solid doped carbon nanofoam from unreacted reaction mixture by filtration; washing the solid doped carbon nanofoam with warm water to remove unreacted material and impurities attached with the solid doped carbon nanofoam; drying said solid doped carbon nanofoam in oven for 5 hours at 100°C; performing thermal annealing of said dried solid doped carbon nanofoam at 600-1000°C for 1-5 hours at a heating rate of 5°C/minute under nitrogen gas to obtain solid doped carbon nanofoam with increased surface area having pore size 1-5Å.

In a feature of the present invention, the first carbon source is sucrose.

In a feature of the present invention, the second carbon source is polycyclic aromatic hydrocarbon.

In a feature of the present invention, the dopant is selected from a group consisting of boron, nitrogen, phosphorus and iron-nitrogen.

In a feature of the present invention, the iron in a mixture of iron-nitrogen dopant can be replaced with chromium, manganese, cobalt, nickel or copper.

In a feature of the present invention, the surfactant is selected form the group comprising of non-ionic surfactant and ionic surfactant.

In a feature of the present invention, the non-ionic surfactant is selected from the group consisting of 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol and [2-(3,4-dihydroxyoxolan-2-yl)-2-hydroxyethyl] dodecanoate.

In a feature of the present invention, the ionic surfactant is selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulphate, dioctyl sodium sulfosuccinate, sodium sterate, sodium dodecyl sulfate and cetrimonium bromide.

In a feature of the present invention, the nano-foam is having pore size 1-5Å.

In a feature of the present invention, the polycyclic aromatic hydrocarbon is naphthalene. Further, naphthalene assists the formation of carbon foams in hydrothermal reaction.

In a feature of the present invention, the boron containing dopant such as boric acid is used.

In a feature of the present invention, nitrogen containing dopants such as N-acetylglucosamine, diethanolamine, urea, ammonia solution, diethanolamine, or propylenediamine are used.
In a feature of the present invention, phosphorous containing dopants such as phytic acid or triphenyl phosphine are used.

In a feature of the present invention, iron containing dopants such as Iron nitrate, Ferric chloride, or Iron sulphate are used.

Table 1. Surface area of prepared doped carbon nanofoams
S. No. Sample details BET Surface Area (m2/g)
1. B-doped carbon nanofoams without using surfactant 242
2. B-doped carbon nanofoams using surfactant 671
3. N-doped carbon nanofoams without using surfactant 499
4. N-doped carbon nanofoams using surfactant 658
5. P-doped carbon nanofoams without using surfactant 457
6. P-doped carbon nanofoams using surfactant 483
7. Fe/N-doped carbon nanofoams without using surfactant 699
8. Fe/N-doped carbon nanofoams using surfactant 815

Example 1
Synthesis of B-doped carbon nanofoams without using surfactant
0.1 - 0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Boron containing dopant boric acid (1 – 20 %, wt/wt) and naphthalene (5 mg) are added to the sucrose. The reactor is properly closed and reaction is carried out for 2 – 5 hours at 100 - 200ºC. After completion of the reaction, reaction mixture is taken out and solid boron doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600 - 1000°C for 1 - 5 hours at a heating rate of 5°C/ min under nitrogen gas to obtain the final B-doped carbon nanofoam.

Example 2
Synthesis of B-doped carbon nanofoams using surfactant
0.1 - 0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Boron containing dopant boric acid (1 - 20 %, wt/wt), non-ionic surfactant Triton x-100 (0.1 – 1 %, wt/wt) and naphthalene (5 mg) are added to the sucrose solution. The reactor is properly closed and reaction is carried out for 2-5 hours at 100 - 200ºC. After completion of the reaction, reaction mixture is taken out and solid boron doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600 - 1000°C for 1 - 5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final B-doped carbon nanofoam. As detailed in Table 1, surface area of the B-doped carbon nanofoam increased from 242 m2/g to 671 m2/g, when surfactant is used.

Example 3
Synthesis of N-doped carbon nanofoams without using surfactant
0.1 - 0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Nitrogen containing dopants (1 – 30 %, wt/wt) and naphthalene (5 mg) are added to the sucrose solution. Nitrogen containing dopant urea is used as doping agent. The reactor is properly closed and reaction is carried out for 2 – 5 hours at 100 - 200ºC. After completion of the reaction, reaction mixture is taken out and solid nitrogen doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600 - 1000°C for 1 - 5 hours at a heating rate of 5°C/ min under nitrogen gas to obtain the final N-doped carbon nanofoam.

Example 4
Synthesis of N-doped carbon nanofoams using surfactant
0.1 - 0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Nitrogen containing dopants (1 – 30 %, wt/wt), non-ionic surfactant Triton x-100 (0.1 – 1 %, wt/wt) and naphthalene (5 mg) are added to the sucrose solution. Nitrogen containing dopant urea is used as doping agent. The reactor is properly closed and reaction is carried out for 2 – 5 hours at 100 - 200ºC. After completion of the reaction, reaction mixture is taken out and solid nitrogen doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600 - 1000°C for 1 - 5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final N-doped carbon nanofoam. Using BET surface area analysis, it is found that surface area of the N-doped carbon nanofoam increased from 499 m2/g to 658 m2/g, when surfactant is used (Table 1).

Example 5
Synthesis of P-doped carbon nanofoams without using surfactant
0.1 - 0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Phosphorous containing dopant such as triphenyl phosphine (1-20 %, wt/wt), and naphthalene (5 mg) are added to the sucrose solution. The reactor is properly closed and reaction is carried out for 2-5 hours at 100 - 200ºC. After completion of the reaction, reaction mixture is taken out and solid phosphorous doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600 - 1000°C for 1-5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final P-doped carbon nanofoam.

Example 6
Synthesis of P-doped carbon nanofoams using surfactant
0.1-0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Phosphorous containing dopant triphenyl phosphine (1-20 %, wt/wt), non-ionic surfactant such as Triton x-100 (0.1-1 %, wt/wt) and naphthalene (5 mg) are added to the sucrose solution. The reactor is properly closed and reaction is carried out for 2-5 hours at 100-200ºC. After completion of the reaction, reaction mixture is taken out and solid phosphorous doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600-1000°C for 1-5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final P-doped carbon nanofoam. As detailed in Table 1, surface area of the P-doped carbon nanofoam increased from 457 m2/g to 483 m2/g, when surfactant is used.

Example 7
Synthesis of Fe/N-doped carbon nanofoams without using surfactant
0.1-0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Iron containing dopants (1-20 %), nitrogen containing dopants (1-30 %), and naphthalene (5 mg) are added to the sucrose solution. Iron doping is done using dopant Iron nitrate. Similarly, nitrogen doping is done using urea. The reactor is properly closed and reaction is carried out for 2-5 hours at 100-200ºC. After completion of the reaction, reaction mixture is taken out and solid Fe/N-doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600-1000°C for 1-5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final Fe/N-doped carbon nanofoam.

Example 8
Synthesis of Fe/N-doped carbon nanofoams using surfactant
0.1-0.5 M sucrose solution is taken in a stainless steel high pressure reactor. Iron containing dopants (1-20 %), nitrogen containing dopants (1-30 %), non-ionic surfactant Triton x-100, (0.1-1 %, wt/wt) and naphthalene (5 mg) are added to the sucrose solution. Iron doping is done using dopant Iron nitrate. Similarly, nitrogen doping is done using dopant urea. The reactor is properly closed and reaction is carried out for 2-5 hours at 100-200ºC. After completion of the reaction, reaction mixture is taken out and solid Fe/N-doped carbon foam is separated from remaining unreacted sucrose solution by filtration. The solid carbon foam is washed with warm water to remove any impurities attached with the product. The doped carbon nanofoam is dried in oven at 100°C for 5 hours. Thermal annealing is performed at 600-1000°C for 1-5 hours at a heating rate of 5°C/min under nitrogen gas to obtain the final Fe/N-doped carbon nanofoam. Using BET surface area analysis, it is confirmed that surface area of the Fe/N-doped carbon nanofoam increased from 699 m2/g to 815 m2/g, when surfactant is used (Table 1).

WE CLAIM:
1. A hydrothermal process for the synthesis of doped solid carbon nanofoams, comprising:
i. taking first carbon source in a high pressure reactor;
ii. adding dopant to prepare a reaction mixture;
iii. adding surfactant to above reaction mixture;
iv. adding second carbon source to the reaction mixture;
v. treating the reaction mixture for 2-5 hours at 100-200°C to obtain doped solid carbon nanofoam in the reaction mixture;
vi. separating said doped solid carbon nanofoam from unreacted reaction mixture by filtration;
vii. washing the doped solid carbon nanofoam with warm water to remove unreacted material and impurities attached with the doped solid carbon nanofoam;
viii. drying said doped solid carbon nanofoam in oven for 5 hours at 100°C;
ix. performing thermal annealing of said dried doped solid carbon nanofoam at 600-1000°C for 1-5 hours at a heating rate of 5°C/minute under nitrogen or argon gas to obtain doped solid carbon nanofoam.

2. The process as claimed in claim 1, wherein the first carbon source is sucrose.

3. The process as claimed in claim 1, wherein the dopant is selected from a group consisting of boron, nitrogen, phosphorus and iron-nitrogen.

4. The process as claimed in claim 3, wherein the boron containing dopant is boric acid; nitrogen containing dopant is selected from a group consisting of N-acetylglucosamine, diethanolamine, urea, ammonia solution, diethanolamine and propylenediamine; phosphorous containing dopant is selected from a group consisting of phytic acid and triphenyl phosphine; iron containing dopant is selected from a group consisting of iron nitrate, ferric chloride and iron sulphate.

5. The process as claimed in claim 1, wherein the surfactant is selected from a group consisting of non-ionic surfactant and ionic surfactant.

6. The process as claimed in claim 5, wherein the non-ionic surfactant is selected from the group consisting of 2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol and [2-(3,4-dihydroxyoxolan-2-yl)-2-hydroxyethyl] dodecanoate .

7. The process as claimed in claim 5, wherein the ionic surfactant is selected from the group consisting of ammonium lauryl sulfate, sodium lauryl sulphate, dioctyl sodium sulfosuccinate, sodium sterate, sodium dodecyl sulfate and cetrimonium bromide.

8. The process as claimed in claim 1, wherein the second carbon source is polycyclic aromatic hydrocarbon.

9. The process as claimed in claim 8, wherein the polycyclic aromatic hydrocarbon is naphthalene.

10. The process as claimed in claim 1, wherein the nanofoam is having pore size 1-5Å.