Hollow nanoparticles with hybrid double layers

Abstract

The present invention discloses the morphology of hollow, double-shelled submicrometer particles generated through a rapid aerosol-based process. The inner shell is an essentially hydrophobic carbon layer of nanoscale dimension (5-20 nm), and the outer shell is a hydrophilic silica layer of approximately 5-40 nm, with the shell thickness being a function of the particle size. The particles are synthesized by exploiting concepts of salt bridging to lock in a surfactant (CTAB) and carbon precursors together with iron species in the interior of a droplet. This deliberate negation of surfactant templating allows a silica shell to form extremely rapidly, sealing in the organic species in the particle interior. Subsequent pyrolysis results in a buildup of internal pressure, forcing carbonaceous species against the silica wall to form an inner shell of carbon. The incorporation of magnetic iron oxide into the shells opens up applications in external stimuli-responsive nanomaterials.

1 . A method of producing hollow double shelled particles with an outer layer of ceramic, and an inner layer of carbon by an aerosol-based method, comprising the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source, (2) a carbon source, (3) an iron source, and (4) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the iron source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for pyrolysis under the flow of an inert gas, wherein the carbon source located in the interior of the particle generates an inner layer from the inside of the particle.   
     
     
         2 . The method of  claim 1 , wherein the ceramic is from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and the ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof. 
     
     
         3 . The method of  claim 1 , wherein the iron source is from the group consisting of ferric halides, and mixtures thereof. 
     
     
         4 . The method of  claim 1 , wherein the inert gas is from the group consisting of nitrogen, argon, and mixtures thereof. 
     
     
         5 . The method of  claim 1 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         6 . The method of  claim 1 , wherein the carbon source is a monosaccharide or polysaccharide. 
     
     
         7 . The method of  claim 1 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         8 . The method of  claim 7 , wherein the carbon source is sucrose. 
     
     
         9 . The method of  claim 1 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         10 . The method of  claim 1 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         11 . The method of  claim 1 , wherein 0.8 g-1.9 g of the iron source is added, 0.1 g-2.2 g of the surfactant is added, 1.0 mL-9 mL of the ceramic source is added, and 0.01 g-3 g of the carbon source is added. 
     
     
         12 . The method of  claim 1 , wherein 0.95 g of the iron source is added, 1.1 g of the surfactant is added, 4.5 mL of the ceramic source is added, and 1.0 g of the carbon source is added. 
     
     
         13 . The method of  claim 1 , wherein silica condensation and sucrose dehydration occur in step “c”. 
     
     
         14 . The method of  claim 1 , wherein the particles are 50 nm to 5000 nm in diameter. 
     
     
         15 . The method of  claim 1 , wherein the particles are 100 nm to 1000 nm in diameter. 
     
     
         16 . The method of  claim 1 , wherein the outer layer is 5 nm to 100 nm thick. 
     
     
         17 . The method of  claim 1 , wherein the inner layer is 5 nm to 100 nm thick. 
     
     
         18 . The method of  claim 1 , wherein the inner layer is 50 nm to 5000 nm in diameter. 
     
     
         19 . The method of  claim 1 , wherein the inner layer is 100 nm to 1000 nm in diameter. 
     
     
         20 . The method of  claim 1 , wherein the outer layer is hydrophilic. 
     
     
         21 . The method of  claim 1 , wherein the inner layer is hydrophobic. 
     
     
         22 . The method of  claim 1 , wherein the outer layer is nonporous after step “e”. 
     
     
         23 . The method of  claim 1 , wherein during step “e” the carbon source forms said inner layer adjoining the outer layer and leaving a fully hollow interior. 
     
     
         24 . The method of  claim 1 , further comprising the step of etching out the outer silica layer. 
     
     
         25 . The method of  claim 24 , wherein the etching is done by a highly acidic solution. 
     
     
         26 . The method of  claim 25 , wherein the highly acidic solution is from the group consisting of HF, HCl, and sulfuric acid. 
     
     
         27 . The method of  claim 24 , wherein the etching is done by a highly basic solution. 
     
     
         28 . The method of  claim 27 , wherein the highly basic solution is from the group consisting of NaOH and ammonium hydroxide. 
     
     
         29 . The method of  claim 1 , further comprising the step of removing the inner carbon layer by calcination. 
     
     
         30 . The method of  claim 1 , wherein the precursor solution further comprises a second metal. 
     
     
         31 . The method of  claim 30 , wherein the second metal is from the group consisting of tin, copper, palladium, chromium, zinc, rhodium, ruthenium, molybdenum, manganese, nickel, and aluminum. 
     
     
         32 . Hollow double shelled particles, comprising:
 a) a silica layer having an interior;   b) a carbon layer attached to the interior of the silica layer; and   c) iron particles incorporated in the silica layer.   
     
     
         33 . The particles of  claim 32 , wherein the particles are 50 nm to 5000 nm in diameter. 
     
     
         34 . The particles of  claim 32 , wherein the particles are 100 nm to 1000 nm in diameter. 
     
     
         35 . The particles of  claim 32 , wherein the silica layer is 5 nm to 100 nm thick. 
     
     
         36 . The particles of  claim 32 , wherein the carbon layer is 5 nm to 100 nm thick. 
     
     
         37 . The particles of  claim 32 , wherein the carbon layer is 50 nm to 5000 nm in diameter. 
     
     
         38 . The particles of  claim 32 , wherein the carbon layer is 100 nm to 1000 nm in diameter. 
     
     
         39 . The particles of  claim 32 , wherein the silica layer is hydrophilic. 
     
     
         40 . The particles of  claim 32 , wherein the carbon layer is hydrophobic. 
     
     
         41 . The particles of  claim 32 , wherein the silica layer is nonporous. 
     
     
         42 . The particles of  claim 32 , wherein the particles have a fully hollow interior. 
     
     
         43 . Particles produced by etching the silica layer out of the particles of  claim 32 . 
     
     
         44 . The particles of  claim 43 , wherein the etching is done by a highly acidic solution. 
     
     
         45 . The particles of  claim 44 , wherein the highly acidic solution is from the group consisting of HF, HCl, and sulfuric acid. 
     
     
         46 . The particles of  claim 43 , wherein the etching is done by a highly basic solution. 
     
     
         47 . The particles of  claim 46 , wherein the highly basic solution is from the group consisting of NaOH and ammonium hydroxide. 
     
     
         48 . Particles produced by removing by calcination the carbon layer of the particles of  claim 32 . 
     
     
         49 . The particles of  claim 32 , wherein the particles further comprise a second metal. 
     
     
         50 . The particles of  claim 49 , wherein the second metal is from the group consisting of tin, copper, palladium, chromium, zinc, rhodium, ruthenium, molybdenum, manganese, nickel, and aluminum, and mixtures thereof. 
     
     
         51 . The particles of  claim 32 , wherein the particles are prepared by an aerosol-based method. 
     
     
         52 . The particles of  claim 51 , wherein the aerosol-based method comprises the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source, (2) a carbon source, (3) an iron source, and (4) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the iron source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for pyrolysis under the flow of an inert gas, wherein the carbon source located in the interior of the particle generates an inner layer from the inside of the particle.   
     
     
         53 . The particles of  claim 52 , wherein the ceramic is from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and the ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof. 
     
     
         54 . The particles of  claim 52 , wherein the iron source is from the group consisting of ferric halides, and mixtures thereof. 
     
     
         55 . The particles of  claim 52 , wherein the inert gas is from the group consisting of nitrogen, argon, and mixtures thereof. 
     
     
         56 . The particles of  claim 52 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         57 . The particles of  claim 52 , wherein the carbon source is a monosaccharide or polysaccharide. 
     
     
         58 . The particles of  claim 52 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         59 . The particles of  claim 52 , wherein the carbon source is sucrose. 
     
     
         60 . The particles of  claim 52 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         61 . The particles of  claim 52 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         62 . The particles of  claim 52 , wherein 0.8 g-1.9 g of the iron source is added, 0.1 g-2.2 g of the surfactant is added, 1.0 mL-9 mL of the ceramic source is added, and 0.01 g-3 g of the carbon source is added. 
     
     
         63 . The particles of  claim 52 , wherein 0.95 g of the iron source is added, 1.1 g of the surfactant is added, 4.5 mL of the ceramic source is added, and 1.0 g of the carbon source is added. 
     
     
         64 . The particles of  claim 52 , wherein silica condensation and sucrose dehydration occur in step “c”. 
     
     
         65 . A method of producing hollow carbon particles by an aerosol-based method, comprising the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source, (2) a carbon source, (3) an iron source, and (4) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the iron source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for pyrolysis under the flow of an inert gas, wherein the carbon source located in the interior of the particle generates an inner layer from the inside of the particle; and   f) etching out the outer layer.   
     
     
         66 . The method of  claim 65 , wherein the ceramic is from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and the ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof. 
     
     
         67 . The method of  claim 65 , wherein the iron source is from the group consisting of ferric halides, and mixtures thereof. 
     
     
         68 . The method of  claim 65 , wherein the inert gas is from the group consisting of nitrogen, argon, and mixtures thereof. 
     
     
         69 . The method of  claim 65 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         70 . The method of  claim 65 , wherein the carbon source is a monosaccharide or polysaccharide. 
     
     
         71 . The method of  claim 65 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         72 . The method of  claim 65 , wherein the carbon source is sucrose. 
     
     
         73 . The method of  claim 65 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         74 . The method of  claim 65 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         75 . The method of  claim 65 , wherein 0.8 g-1.9 g of the iron source is added, 0.1 g-2.2 g of the surfactant is added, 1.0 mL-9 mL of the ceramic source is added, and 0.01 g-3 g of the carbon source is added. 
     
     
         76 . The method of  claim 65 , wherein 0.95 g of the iron source is added, 1.1 g of the surfactant is added, 4.5 mL of the ceramic source is added, and 1.0 g of the carbon source is added. 
     
     
         77 . The method of  claim 65 , wherein silica condensation and sucrose dehydration occur in step “c”. 
     
     
         78 . The method of  claim 65 , wherein the inner layer is 5 nm to 100 nm thick. 
     
     
         79 . The method of  claim 65 , wherein the inner layer is 50 nm to 5000 nm in diameter. 
     
     
         80 . The method of  claim 65 , wherein the inner layer is 100 nm to 1000 nm in diameter. 
     
     
         81 . The method of  claim 65 , wherein the etching is done by a highly acidic solution. 
     
     
         82 . The method of  claim 81 , wherein the highly acidic solution is from the group consisting of HF, HCl, and sulfuric acid. 
     
     
         83 . The method of  claim 65 , wherein the etching is done by a highly basic solution. 
     
     
         84 . The method of  claim 83 , wherein the highly basic solution is from the group consisting of NaOH and ammonium hydroxide. 
     
     
         85 . Thin hollow silica shelled particles, comprising:
 a) a silica outer layer having a thickness of 5 to 20 nm; and   b) iron particles incorporated in the silica layer.   
     
     
         86 . The particles of  claim 85 , wherein the diameter of the particles is 100 nm to 3000 nm. 
     
     
         87 . The particles of  claim 86 , wherein the diameter of the particles is 200 nm to 1000 nm. 
     
     
         88 . The particles of  claim 85 , wherein the silica later has a thickness of 7 nm to 20 nm. 
     
     
         89 . The particles of  claim 85 , wherein the silica later has a thickness of 7 nm to 15 nm. 
     
     
         90 . The particles of  claim 85 , wherein the silica later has a thickness of 10 nm to 15 nm. 
     
     
         91 . The particles of  claim 85 , wherein the particles have a fully hollow interior. 
     
     
         92 . The particles of  claim 85 , wherein the particles further comprise a second metal. 
     
     
         93 . The particles of  claim 92 , wherein the second metal is from the group consisting of tin, copper, palladium, chromium, zinc, rhodium, ruthenium, molybdenum, manganese, nickel, and aluminum. 
     
     
         94 . The particles of  claim 85 , wherein the particles are fractured by ultrasonication. 
     
     
         95 . The particles of  claim 85 , wherein the porosity of the particles is increased by adding sodium chloride. 
     
     
         96 . The particles of  claim 95 , wherein 0.01-1.0 g of sodium chloride is added. 
     
     
         97 . The particles of  claim 95 , wherein 0.4 g of sodium chloride is added. 
     
     
         98 . The particles of  claim 96  or  97 , wherein the pore size is 0.5 nm to 100 nm in diameter. 
     
     
         99 . The particles of  claim 96  or  97 , wherein the pore size is 10 nm in diameter. 
     
     
         100 . The particles of  claim 85 , wherein the particles are prepared by increasing the amount of surfactant. 
     
     
         101 . The particles of  claim 85 , wherein the particles are prepared by an aerosol-based method. 
     
     
         102 . The particles of  claim 101 , wherein the aerosol-based method comprises the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source, (2) an iron source, and (3) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the iron source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for pyrolysis under the flow of an inert gas.   
     
     
         103 . The particles of  claim 102 , wherein the ceramic is from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and the ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof. 
     
     
         104 . The particles of  claim 102 , wherein the iron source is an iron source from the group consisting of ferric halides, and mixtures thereof. 
     
     
         105 . The particles of  claim 102 , wherein the inert gas is from the group consisting of nitrogen, argon, and mixtures thereof. 
     
     
         106 . The particles of  claim 102 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         107 . The particles of  claim 102 , further comprising a carbon source that is a monosaccharide or polysaccharide. 
     
     
         108 . The particles of  claim 107 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         109 . The particles of  claim 108 , wherein the carbon source is sucrose. 
     
     
         110 . The particles of  claim 102 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         111 . The particles of  claim 102 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         112 . The particles of  claim 102 , wherein 0.8 g-1.9 g of the iron source is added, 0.1 g-2.2 g of the surfactant is added, and 1.0 mL-9 mL of the ceramic source is added. 
     
     
         113 . The particles of  claim 102 , wherein 0.95 g of the iron source is added, 1.1 g of the surfactant is added, and 4.5 mL of the ceramic source is added. 
     
     
         114 . The particles of  claim 107 , wherein 0.01 g-3 g of the carbon source is added. 
     
     
         115 . The particles of  claim 107 , wherein 1.0 g of the carbon source is added. 
     
     
         116 . The particles of  claim 102 , wherein the size of the shell thickness decreases with decreasing amounts of the silica source. 
     
     
         117 . The particles of  claim 85 , wherein the particles are nonporous. 
     
     
         118 . The particles of  claim 102 , further comprising the step of adding sodium chloride. 
     
     
         119 . The particles of  claim 118 , wherein 0.01-1.0 g of sodium chloride is added. 
     
     
         120 . The particles of  claim 118 , wherein 0.4 g of sodium chloride is added. 
     
     
         121 . The particles of  claim 119  or  120 , wherein the pore size is 0.5 nm to 100 nm in diameter. 
     
     
         122 . The particles of  claim 119  or  120 , wherein the pore size is 10 nm in diameter. 
     
     
         123 . The particles of  claim 1 ,  32  or  85 , wherein the particles encapsulate a compound. 
     
     
         124 . The particles of  claim 123 , wherein the compound is a pharmaceutical agent. 
     
     
         125 . The particles of  claim 1  or  32 , wherein the particles are used to stabilize emulsions. 
     
     
         126 . The particles of  claim 1 ,  32  or  85 , wherein the particles are used as a catalytic support. 
     
     
         127 . The particles of  claim 1 ,  32  or  85 , wherein the particles are used for drug delivery. 
     
     
         128 . The particles of  claim 1  or  32 , wherein the particles are used for Li-ion batteries. 
     
     
         129 . The particles of  claim 1  or  32 , wherein the particles are used for fuel cell catalysts. 
     
     
         130 . The particles of  claim 1 ,  32  or  85 , wherein the particles are magnetically responsive. 
     
     
         131 . Hollow double shelled particles, comprising:
 a) a silica outer layer;   b) a titania inner layer attached to the silica outer layer; and   c) iron particles incorporated in the silica layer.   
     
     
         132 . The particles of  claim 131 , wherein the silica outer layer is etched out. 
     
     
         133 . The particles of  claim 132 , wherein the etching is done by HF solution. 
     
     
         134 . The particles of  claim 132 , wherein the etching is done by NaOH solution. 
     
     
         135 . The particles of  claim 131 , wherein the particles are prepared by an aerosol-based method. 
     
     
         136 . The particles of  claim 135 , wherein the aerosol-based method comprises the steps of:
 a) preparing a precursor solution comprising a silica source, a titania source, ferric chloride and a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the ferric chloride binds with the surfactant in the interior of the droplet and the silica source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles under the flow of nitrogen gas for pyrolysis.   
     
     
         137 . The particles of  claim 136 , wherein the silica source is tetraethyl orthosilicate (TEOS). 
     
     
         138 . The particles of  claim 136 , wherein the titania source is titanium isopropoxide. 
     
     
         139 . The particles of  claim 136 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         140 . The particles of  claim 136 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         141 . The particles of  claim 131  or  132 , wherein the particles are used for photocatalysis. 
     
     
         142 . The particles of  claim 131  or  132 , wherein the particles are used in oil spill mitigation technologies. 
     
     
         143 . A method of making hollow shelled particles, comprising:
 a) forming a silica shell due to a silica condensation reaction along a gas-liquid interface of an aerosol droplet; and   b) forming an iron-surfactant rich core by coagulation of ferric species in the presence of a surfactant.   
     
     
         144 . A method of producing thin shelled cage-like particles by an aerosol-based method, comprising the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source, (2) a carbon source, (3) an iron source, and (4) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the iron source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for calcination.   
     
     
         145 . The method of  claim 144 , wherein the ceramic is from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and the ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof. 
     
     
         146 . The method of  claim 144 , wherein the iron source is from the group consisting of ferric halides, and mixtures thereof. 
     
     
         147 . The method of  claim 144 , wherein the inert gas is from the group consisting of nitrogen, argon, and mixtures thereof. 
     
     
         148 . The method of  claim 144 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         149 . The method of  claim 144 , wherein the carbon source is a monosaccharide or polysaccharide. 
     
     
         150 . The method of  claim 144 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         151 . The method of  claim 150 , wherein the carbon source is sucrose. 
     
     
         152 . The method of  claim 144 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         153 . The method of  claim 144 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         154 . The method of  claim 144 , wherein the thickness of outer shell is 5 nm to 20 nm. 
     
     
         155 . A method of producing hollow double shelled particles with an outer layer of ceramic from the group consisting of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, and silica in combination with titania, zirconia, alumina, yttria, or ceria, and mixtures thereof, and an inner layer of carbon by an aerosol-based method, comprising the steps of:
 a) preparing a precursor solution comprising (1) a ceramic source from the group consisting of a source of silica, titania, zirconia, alumina, yttria, ceria, and mixtures thereof, (2) a carbon source, (3) a source of magnetic metal, such as an iron source from the group consisting of ferric halides, and mixtures thereof, and (4) a surfactant;   b) passing the precursor solution through a nozzle for atomization to form aerosol droplets;   c) passing the aerosol droplets through a heating zone and a drying zone for evaporation, wherein the magnetic metal source binds with the surfactant in the interior of the droplet and the ceramic source is on the surface of the droplet;   d) collecting the particles on a filter; and   e) passing the particles for pyrolysis under the flow of an inert gas from the group consisting of nitrogen, argon, and mixtures thereof, wherein the carbon source located in the interior of the particle generates an inner layer from the inside of the particle.   
     
     
         156 . The method of  claim 155 , wherein the ceramic source is tetraethyl orthosilicate (TEOS). 
     
     
         157 . The method of  claim 155 , wherein the carbon source is a monosaccharide or polysaccharide. 
     
     
         158 . The method of  claim 155 , wherein the carbon source is from the group consisting of sucrose, glucose, cellulose, and cyclodextrins, and mixtures thereof. 
     
     
         159 . The method of  claim 158 , wherein the carbon source is sucrose. 
     
     
         160 . The method of  claim 155 , wherein the surfactant is from the group consisting of cetyltrimethyl ammonium bromide (CTAB), cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium iodide (CTAI), cetyltrimethyl ammonium fluoride (CTAF), and cetyltrimethyl ammonium astatide (CTAA), and mixtures thereof. 
     
     
         161 . The method of  claim 155 , wherein the surfactant is cetyltrimethyl ammonium bromide (CTAB). 
     
     
         162 . The method of  claim 155 , wherein 0.8 g-1.9 g of the iron source is added, 0.1 g-2.2 g of the surfactant is added, 1.0 mL-9 mL of the ceramic source is added, and 0.01 g-3 g of the carbon source is added. 
     
     
         163 . The method of  claim 155 , wherein 0.95 g of the iron source is added, 1.1 g of the surfactant is added, 4.5 mL of the ceramic source is added, and 1.0 g of the carbon source is added. 
     
     
         164 . The method of  claim 155 , wherein silica condensation and sucrose dehydration occur in step “c”. 
     
     
         165 . The method of  claim 155 , wherein the particles are 50 nm to 5000 nm in diameter. 
     
     
         166 . The method of  claim 155 , wherein the particles are 100 nm to 1000 nm in diameter. 
     
     
         167 . The method of  claim 155 , wherein the outer layer is 5 nm to 100 nm thick. 
     
     
         168 . The method of  claim 155 , wherein the inner layer is 5 nm to 100 nm thick. 
     
     
         169 . The method of  claim 155 , wherein the inner layer is 50 nm to 5000 nm in diameter. 
     
     
         170 . The method of  claim 155 , wherein the inner layer is 100 nm to 1000 nm in diameter. 
     
     
         171 . The method of  claim 155 , wherein the outer layer is hydrophilic. 
     
     
         172 . The method of  claim 155 , wherein the inner layer is hydrophobic. 
     
     
         173 . The method of  claim 155 , wherein the outer layer is nonporous after step “e”. 
     
     
         174 . The method of  claim 155 , wherein during step “e” the carbon source forms said inner layer adjoining the silica outer layer and leaving a fully hollow interior. 
     
     
         175 . The method of  claim 155 , further comprising the step of etching out the outer silica layer. 
     
     
         176 . The method of  claim 175 , wherein the etching is done by a highly acidic solution. 
     
     
         177 . The method of  claim 176 , wherein the highly acidic solution is from the group consisting of HE HCl, and sulfuric acid. 
     
     
         178 . The method of  claim 175 , wherein the etching is done by a highly basic solution. 
     
     
         179 . The method of  claim 178 , wherein the highly basic solution is from the group consisting of NaOH and ammonium hydroxide. 
     
     
         180 . The method of  claim 155 , further comprising the step of removing the inner carbon layer by calcination. 
     
     
         181 . The method of  claim 155 , wherein the precursor solution further comprises a second metal. 
     
     
         182 . The method of  claim 181 , wherein the second metal is from the group consisting of tin, copper, palladium, chromium, zinc, rhodium, ruthenium, molybdenum, manganese, nickel, and aluminum.