Method for generating hydrogen using Bi.SUB.2.O.SUB.3.@SiO.SUB.2 .nanocomposite catalyst

Abstract

A method of hydrogen (H.sub.2) generation includes hydrolyzing a borohydride salt in an aqueous solution including a catalyst to form gaseous hydrogen. The catalyst is a bismuth(III) oxide-doped silicon dioxide with an amount of bismuth(III) oxide from 2 wt. % to 12 wt. % based on a total weight of the bismuth(III) oxide-doped silicon dioxide. The bismuth(III) oxide is dispersed in silicon dioxide in the catalyst. The weight ratio of the catalyst to the borohydride salt present in the aqueous solution is from 0.1:2 to 7:1 and a rate of hydrolysis of the borohydride salt in the presence of the catalyst is 2 to 3 times greater than a rate of hydrolysis of the borohydride salt in the absence of the catalyst.

Claims

1. A method of hydrogen generation, comprising: hydrolyzing a borohydride salt in an aqueous solution comprising a catalyst to form gaseous hydrogen, wherein the catalyst is a bismuth(III) oxide-doped silicon dioxide, wherein the amount of bismuth(III) oxide is from 2 to 12 wt. % based on a total weight of the bismuth(III) oxide-doped silicon dioxide, wherein the bismuth(III) oxide is dispersed in silicon dioxide in the catalyst, wherein a weight ratio of the catalyst to the borohydride salt present in the aqueous solution is from 0.1:2 to 7:1, wherein a rate of hydrolysis of the borohydride salt in the presence of the catalyst is 2 to 3 times greater than a rate of hydrolysis of the borohydride salt in the absence of the catalyst.

2. The method of claim 1, wherein the borohydride salt is sodium borohydride.

3. The method of claim 1, wherein the amount of bismuth(III) oxide is from 2 to 3 wt. % based on a total weight of the bismuth(III) oxide-doped silicon dioxide.

4. The method of claim 1, wherein the amount of bismuth(III) oxide is from 4 to 6 wt. % based on a total weight of the bismuth(II) oxide-doped silicon dioxide.

5. The method of claim 1, wherein the amount of bismuth(III) oxide is from 9 to 10 wt. % based on a total weight of the bismuth(II) oxide-doped silicon dioxide.

6. The method of claim 1, wherein the hydrolyzing occurs at a temperature of 25 to 50 C.

7. The method of claim 1, wherein a hydrogen generation rate is from 100 to 2200 mL/minute per gram of the borohydride salt.

8. The method of claim 4, wherein the hydrolyzing occurs at a temperature of 30 C. and a hydrogen generation rate is from 480 to 500 mL of hydrogen/minute per gram of the borohydride salt.

9. The method of claim 4, wherein the hydrolyzing occurs at a temperature of 35 C. and a hydrogen generation rate is from 1100 to 1120 mL of hydrogen/minute per gram of the borohydride salt.

10. The method of claim 4, wherein the hydrolyzing occurs at a temperature of 40 C. and a hydrogen generation rate is from 1420 to 1440 mL of hydrogen/minute per gram of the borohydride salt.

11. The method of claim 4, wherein the hydrolyzing occurs at a temperature of 45 C. and a hydrogen generation rate is from 1990 to 2010 mL of hydrogen/minute per gram of the borohydride salt.

12. The method of claim 1, wherein the catalyst is made by a process comprising: milling a bismuth salt, silica, and a sugar to form a mixture; calcinating the mixture at 400 to 600 C. for 3 to 5 hours; and milling the calcinated mixture to form the catalyst.

13. The method of claim 12, wherein the sugar is glucose.

14. The method of claim 12, wherein the milling occurs at a rate of 300 to 400 rounds per minute.

15. The method of claim 12, wherein the milling occurs for 5 to 60 minutes.

16. The method of claim 1, wherein the gaseous hydrogen is formed in 0.1 to 30 minutes.

17. The method of claim 1, wherein the amount of the borohydride salt present in the aqueous solution is 0.1 to 2 grams.

18. The method of claim 3, wherein the hydrolyzing occurs at a temperature of 30 C. and a hydrogen generation rate is from 125 to 150 mL of hydrogen/minute per gram of the borohydride salt.

19. The method of claim 5, wherein the hydrolyzing occurs at a temperature of 30 C. and a hydrogen generation rate is from 160 to 180 mL of hydrogen/minute per gram of the borohydride salt.

20. The method of claim 1, wherein generating hydrogen has an activation energy of 65 to 75 kJ/mol.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more complete appreciation of this disclosure (including alternatives and/or variations thereof) and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

(2) FIG. 1 is a flowchart illustrating a method of preparing a bismuth(III) oxide-doped silicon dioxide catalyst (catalyst), according to certain embodiments.

(3) FIG. 2A is a graph depicting a variation in the volume of liberated hydrogen (H.sub.2) versus reaction time, according to certain embodiments.

(4) FIG. 2B is a graph depicting hydrogen generation rates (HGR) versus weight percent of Bi.sub.2O.sub.3, according to certain embodiments.

(5) FIG. 3A is a graph depicting variation in the volume of liberated H.sub.2 versus reaction time over 5 wt. % Bi.sub.2O.sub.3SiO.sub.2 composite catalyst calcined at 500 C., according to certain embodiments.

(6) FIG. 3B is a graph depicting HGR with wt. % of NaBH.sub.4, over 5 wt. % Bi.sub.2O.sub.3/SiO.sub.2 composite catalyst calcined at 500 C., according to certain embodiments.

(7) FIG. 4A is a graph depicting volume of liberated H.sub.2 versus reaction time over 5 wt. % Bi.sub.2O.sub.3/SiO.sub.2 composite catalyst calcined at 500 C., according to certain embodiments.

(8) FIG. 4B is a graph depicting HGR as a function of reaction temperature for 5 wt. % Bi.sub.2O.sub.3/SiO.sub.2 composite catalyst calcined at 500 C., according to certain embodiments.

DETAILED DESCRIPTION

(9) In the following description, it is understood that other embodiments may be utilized, and structural and operational changes may be made without departure from the scope of the present embodiments disclosed herein.

(10) Reference will now be made to specific embodiments or features, examples of which are illustrated in the accompanying drawings. In the drawings, whenever possible, corresponding or like reference numerals will be used to designate identical or corresponding parts throughout the several views. Moreover, references to various elements described herein are made collectively or individually when there may be more than one element of the same type. However, such references are merely exemplary in nature. It may be noted that any reference to elements in the singular may also be constructed to relate to the plural and vice-versa without limiting the scope of the disclosure to the exact number or type of such elements unless set forth explicitly in the appended claims. Further, as used herein, the words a, an, and the like generally carry a meaning of one or more, unless stated otherwise.

(11) Furthermore, the terms approximately, approximate, about, and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween. Within the description of this disclosure, where a numerical limit or range is stated, the endpoints are included unless stated otherwise. Also, all values and subranges within a numerical limit or range are specifically included as if explicitly written out.

(12) As used herein, the term milling refers to a process of mechanical grinding or crushing in which materials are subjected to high-speed motion, often using a grinding media such as balls, rods, and/or blades, to reduce the particle size and/or to mix components of a mixture. This process can involve various types of milling equipment, such as ball mills, hammer mills, and/or planetary mills, and may be used to achieve uniformity in material composition, enhance surface area for chemical reactions, and/or facilitate synthesis of composite materials. In the context of this embodiment, milling is employed to combine and disperse the components of the catalyst mixture (i.e., bismuth(III) oxide and silica) and other ingredients (e.g., fuel and capping agents) to promote an effective and homogeneous reaction.

(13) As used herein, the term calcination refers to a thermal treatment process in which a material is heated to high temperatures in the presence or absence of air or oxygen, typically to bring about a chemical transformation or remove volatile components, such as moisture and/or organic matter.

(14) As used herein, the term hydrolyzing refers to a chemical process in which a substance reacts with water (H.sub.2O) to break down or decompose into less complex components. In this context, hydrolysis typically involves the reaction of a compound with water to form products such as acids, bases, and/or other derivatives, often resulting in the release of gases (i.e., hydrogen and/or oxygen) and/or the formation of new chemical bonds.

(15) As used herein, the term hydrogen generation rate (HGR) refers to the amount of hydrogen gas (H.sub.2) produced per unit of time during a chemical reaction. A hydrogen generation rate is typically expressed in milliliters of hydrogen per minute per gram of a reactant or catalyst per unit of time. In the context of hydrogen production, the HGR is a parameter used to evaluate the efficiency and effectiveness of the reaction, especially in processes like the hydrolysis of sodium borohydride (NaBH.sub.4) or other hydrogen-producing reactions.

(16) Aspects of this disclosure describe a method of hydrogen production using a bismuth(III) oxide-doped silicon dioxide (Bi.sub.2O.sub.3@SiO.sub.2) composite catalyst. Efficiently generating hydrogen through a catalytic process with the composite catalyst of the current disclosure provides a clean, sustainable, and rapid solution for hydrogen production, which assists in advancing renewable energy technologies and reducing reliance on non-renewable fuels.

(17) According to a first aspect of the present disclosure, a catalyst is described. The catalyst is a bismuth(III) oxide-doped silicon dioxide. Bismuth(III) oxide is dispersed in silicon dioxide in the catalyst. The amount of bismuth(III) oxide ranges from 2 to 12 weight percent (wt. %) based on the total weight of the bismuth(III) oxide-doped silicon dioxide. In some embodiments, the amount of bismuth(III) oxide ranges from 2 to 12 wt. %, preferably 2.5 to 11 wt. %, preferably 3 to 10 wt. %, preferably 4 to 9 wt. %, preferably 5 to 8 wt. %, and preferably 6 to 7 wt. % based on the total weight of the bismuth(II) oxide-doped silicon dioxide. In a preferred embodiment, the amount of bismuth(III) oxide is about 2.5 wt. % based on the total weight of the bismuth(III) oxide-doped silicon dioxide. In another preferred embodiment, the amount of bismuth(III) oxide is about 5 wt. % based on the total weight of the bismuth(III) oxide-doped silicon dioxide. In yet another preferred embodiment, the amount of bismuth(III) oxide is about 10 wt. % based on the total weight of the bismuth (III) oxide-doped silicon dioxide. In a most preferred embodiment, the amount of bismuth (III) oxide is 5 wt. % based on the total weight of the bismuth (III) oxide-doped silicon dioxide

(18) Referring to FIG. 1A, a second aspect of the present disclosure describes a method 50 of synthesizing the catalyst. The order in which the method 50 is described is not intended to be construed as a limitation, and any number of the described method steps can be combined in any order to implement the method 50. Additionally, individual steps may be removed or skipped from the method 50 without departing from the spirit and scope of the present disclosure.

(19) At step 52, the method 50 includes milling a bismuth salt, silica, and a sugar to form a mixture. This step may be highly exothermic and may be preferred to be performed in an inert atmosphere to prevent any unwanted side reactions, such as oxidations and/or explosions.

(20) In some embodiments, the bismuth salt may include, but is not limited to, bismuth nitrate, bismuth subnitrate, bismuth oxychloride, bismuth subsalicylate, bismuth oxide, bismuth vanadate, bismuth acetate, bismuth citrate, bismuth hydroxide, bismuth carbonate, bismuth sulfide, bismuth subcarbonate, bismuth tartrate, bismuth phthalate, bismuth bromide, bismuth iodide, bismuth chloride, bismuth sulfate, bismuth phosphate, bismuth aluminate, bismuth titanate, bismuth ferrite, bismuth molybdate, bismuth tungstate, bismuth telluride, bismuth selenide, bismuth antimonide, bismuth arsenide, bismuth silicate, bismuth oxide chloride, bismuth dimethylglyoximate, bismuth propionate, bismuth malate, bismuth gluconate, bismuth fumarate, bismuth acetylacetonate, bismuth lactate, bismuth butyrate, bismuth tartrates, a combination thereof, and the like. In some embodiments, the bismuth salt may be hydrated. In a preferred embodiment, the bismuth salt is bismuth nitrate.

(21) In some embodiments, the silica may include, but is not limited to, fumed silica, silica gel, precipitated silica, colloidal silica, crystalline silica, amorphous silica, silica aerogel, silica sand, silica powder, silicon dioxide, fused silica, synthetic silica, silica sol, hydrated silica, diatomaceous earth, microcrystalline silica, silica nanofibers, silica nanoparticles, silicate minerals, montmorillonite silica, silicon carbide, silica glass, silica gel beads, silica microspheres, silica spheres, silica-rich clay, silicon oxide, porous silica, silica-based zeolites, silica aerogel particles, silica aerogel composites, silica microsilica, high-purity silica, a combination thereof, and the like. In a preferred embodiment, the silica is fumed silica.

(22) In a preferred embodiment, the sugar is glucose. In other embodiments, sugars such as sucrose, maltose, dextrose, arabinose, fructose, galactose, fucose, xylose, lactose, mannose, a combination thereof, and the like may be used in place of or in combination with glucose. The sugar acts as a capping agent and is added to prevent the uncontrolled growth of the particles and to help maintain their size, shape, and dispersion. Capping agents can also protect the surface of reactive species, preventing them from undergoing undesirable reactions and/or aggregations. In some embodiments, citric acid, polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sodium citrate, starch, ascorbic acid, dextran, sodium polyacrylate, polyacrylic acid, oleic acid, lauric acid, stearic acid, hexadecyltrimethylammonium bromide (CTAB), polyethylenimine (PEI), thiol compounds, mercaptosuccinic acid, dodecylbenzene sulfonic acid, triethanolamine, ammonium citrate, lignin, chitosan, tannic acid, tartaric acid, polyethyleneglycol dimethacrylate (PEGDMA), hexadecylamine, octylamine, butylamine, sodium dodecyl sulfate (SDS), cetyltrimethylammonium chloride (CTAC), formic acid, acetic acid, lactic acid, mixtures thereof, and the like may also be used as capping agents.

(23) At step 54, the method 50 includes calcinating the mixture at 400 to 600 C., preferably 410 to 590 C., preferably 420 to 580 C., preferably 430 to 570 C., preferably 440 to 560 C., preferably 450 to 550 C., preferably 460 to 540 C., preferably 470 to 530 C., preferably 480 to 520 C., more preferably 490 to 510 C., and yet more preferably about 500 C. for 3 to 5 hours, preferably 3.1 to 4.9 hours, preferably 3.2 to 4.8 hours, preferably 3.3 to 4.7 hours, preferably 3.4 to 4.6 hours, preferably 3.5 to 4.5 hours, preferably 3.6 to 4.4 hours, preferably 3.7 to 4.3 hours, preferably 3.8 to 4.2 hours, more preferably 3.9 to 4.1 hours, and yet more preferably about 4 hours. In a preferred embodiment, the mixture is calcinated at 500 C. for 4 hours.

(24) The product of calcination may retain a carbonaceous residue obtained from carbonization of the sugar, preferably glucose, and the subsequent calcination of a carbonized product. As the calcination of the present disclosure will conventionally occur in the absence of activators or templating agents for the carbonized product, it is considered that the retained carbonaceous residue will comprise amorphous carbon. In certain embodiments, the catalyst may comprise amorphous carbon in an amount up to about 2 wt. %, based on the weight of the catalyst. For example, the catalyst may comprise amorphous carbon in an amount up to about 1 wt. % or up to about 0.5 wt. %, based on the weight of the catalyst.

(25) At step 56, the method 50 includes milling the calcinated mixture to form the catalyst. In some embodiments, the calcinated mixture is milled at a rate ranging from 300 to 400 rounds per minute (rpm), preferably 310 to 390 rpm, preferably 320 to 380 rpm, preferably 330 to 370 rpm, more preferably 340 to 360 rpm, and yet more preferably about 350 rpm. In a preferred embodiment, the calcined mixture is milled at a rate of 350 rpm.

(26) In some embodiments, the calcinated mixture is milled for 5 to 60 minutes, preferably 10 to 55 minutes, preferably 15 to 50 minutes, preferably 20 to 40 minutes, more preferably 25 to 35 minutes, and yet more preferably about 30 minutes. In a preferred embodiment, the calcinated mixture is milled for 30 minutes.

(27) The catalyst of the present disclosure may be used for hydrogen production. Accordingly, a third aspect of the present disclosure describes a method of hydrogen generation using the catalyst. The method includes hydrolyzing a borohydride salt in an aqueous solution including the catalyst to form gaseous hydrogen.

(28) In some embodiments, the borohydride salt may include, but is not limited to, sodium borohydride, lithium borohydride, potassium borohydride, calcium borohydride, magnesium borohydride, aluminum borohydride, zinc borohydride, barium borohydride, cesium borohydride, rubidium borohydride, strontium borohydride, tetrabutylammonium borohydride, ammonium borohydride, trimethylammonium borohydride, benzyltrimethylammonium borohydride, potassium tetraphenylborate, lithium tetrafluoroborate, potassium tetrafluoroborate, sodium tetrafluoroborate, copper borohydride, nickel borohydride, iron borohydride, lead borohydride, copper borohydride, thallium borohydride, gold borohydride, silver borohydride, rhodium borohydride, palladium borohydride, antimony borohydride, a combination thereof, and the like. In a preferred embodiment, the borohydride salt is sodium borohydride.

(29) The weight ratio of the catalyst to the borohydride salt present in the aqueous solution ranges from 0.1:2 to 7:1, preferably 0.5:2 to 6:1, preferably 0.7:2 to 5:1, preferably 1:2 to 4:1, preferably 1.2:2 to 3:1, and preferably 1.5:2 to 2:1.

(30) In some embodiments, the amount of the borohydride salt in the aqueous solution may range from 0.1 to 2 grams, preferably 0.2 to 1.6 grams, preferably 0.3 to 1.4 grams, preferably 0.4 to 1.2 grams, preferably 0.5 to 1 gram, more preferably 0.6 to 0.8 grams, and yet more preferably about 0.7 grams. In some embodiments, the amount of the borohydride salt in the aqueous solution may be greater than 2 grams.

(31) In some embodiments, the borohydride salt is contacted with the catalyst for 0.1 to 30 minutes, preferably 1 to 25 minutes, preferably 5 to 20 minutes, and preferably 10 to 15 minutes. In some embodiments, the borohydride salt may be contacted with the catalyst for more than 30 minutes.

(32) The rate of hydrolysis of the borohydride salt in the presence of the catalyst is 2 to 3 times greater than a rate of hydrolysis of the borohydride salt in the absence of the catalyst. In some embodiments, the rate of hydrolysis of the borohydride salt in the presence of the catalyst is 2 to 3 times greater, preferably 2.1 to 2.9 times greater, preferably 2.2 to 2.8 times greater, preferably 2.3 to 2.7 times greater, and preferably 2.4 to 2.6 times greater than a rate of hydrolysis of the borohydride salt in the absence of the catalyst. In some embodiments, the rate of hydrolysis of the borohydride salt in the presence of the catalyst may be greater than 3 times greater than a rate of hydrolysis of the borohydride salt in the absence of the catalyst.

(33) The concentration of bismuth(III) oxide concentration in the catalyst effects hydrogen production. In some embodiments, when the borohydride salt is in contact with the catalyst having bismuth(III) oxide at a concentration ranging from 2 to 3 wt. %, preferably about 2.5 wt. %, based on the total weight of the catalyst at a temperature of 30 C., the hydrogen generation rate (HGR) is 125 to 150 mL of hydrogen per minute per gram of the borohydride salt, preferably 130 to 145 mL of hydrogen per minute per gram of the borohydride salt, and preferably 135 to 140 mL of hydrogen per minute per gram of the borohydride salt. In some embodiments, increasing the concentration of bismuth(III) oxide to 9 to 11 wt. %, preferably 9.5 to 10.5 wt. %, and more preferably about 10 wt. %, in the catalyst at the same temperature (30 C.) results in a HGR of 160 to 180 mL of hydrogen per minute per gram of the borohydride salt, preferably 165 to 175 mL of hydrogen per minute per gram of the borohydride salt. In another embodiment, when the borohydride salt is in contact with the catalyst having 4 to 6 wt. %, preferably 4.5 to 5.5 wt. %, and more preferably about 5 wt. %, of bismuth(III) oxide based on the total weight of the catalyst, at a temperature of 30 C., the HGR is 480 to 500 mL of hydrogen per minute per gram of the borohydride salt, preferably 485 to 495 mL of hydrogen per minute per gram of the borohydride salt.

(34) Temperature is another factor affecting the HGR with the method of present disclosure. In some embodiments, the borohydride salt is contacted with the catalyst at a temperature ranging from 25 to 50 C., preferably 30 to 45 C., and preferably 35 to 40 C. In a preferred embodiment, the borohydride salt is contacted with the catalyst at a temperature of about 30 to 45 C.

(35) In some embodiments, when the borohydride salt is contacted with the catalyst having a bismuth(III) oxide concentration of 4 to 6 wt. %, preferably about 5 wt. % based on the total weight of the catalyst, the HGR ranges from 480 to 500 mL of hydrogen per minute per gram of the borohydride salt, preferably 485 to 495 mL of hydrogen per minute per gram of the borohydride salt, and preferably 488 to 492 mL of hydrogen per minute per gram of the borohydride salt at a temperature 30 C. In some embodiments, when the borohydride salt is contacted with the catalyst having a bismuth(III) oxide concentration of 4 to 6 wt. %, preferably about 5 wt. % based on the total weight of the catalyst, the HGR ranges from 1100 to 1120 mL of hydrogen per minute per gram of the borohydride salt, preferably 1105 to 1115 mL of hydrogen per minute per gram of the borohydride salt, and more preferably about 1111 mL of hydrogen per minute per gram of the borohydride salt at a temperature of 35 C. In some embodiments, when the borohydride salt is contacted with the catalyst having a bismuth(III) oxide concentration of 4 to 6 wt. %, preferably about 5 wt. % based on the total weight of the catalyst, the HGR ranges from 1420 to 1440 mL of hydrogen per minute per gram of the borohydride salt, preferably 1425 to 1430 mL of hydrogen per minute per gram of the borohydride salt, and more preferably about 1428 mL of hydrogen per minute per gram of the borohydride salt at a temperature of 40 C. In some embodiments, when the borohydride salt is contacted with the catalyst having a bismuth(III) oxide concentration of 4 to 6 wt. %, preferably about 5 wt. % based on the total weight of the catalyst, the HGR ranges from 1990 to 2010 mL of hydrogen per minute per gram of the borohydride salt, preferably 1995 to 2005 mL of hydrogen per minute per gram of the borohydride salt, and more preferably about 2000 mL of hydrogen per minute per gram of the borohydride salt at a temperature of 45 C.

(36) In some embodiments, the activation energy required to generate hydrogen ranges from 65 to 75 kJ/mol, preferably 66 to 74 kJ/mol, preferably 67 to 73 kJ/mol, preferably 68 to 72 kJ/mol, more preferably 69 to 71 kJ/mol, and yet more preferably 69 to 70 kJ/mol. In a preferred embodiment, the activation energy required to generate hydrogen is about 69.2 kJ/mol.

EXAMPLES

(37) The disclosure will now be illustrated with working examples, which are intended to illustrate the working of the disclosure and not intended to restrictively imply any limitations on the scope of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure. The following examples demonstrate a sunscreen formulation. The following examples demonstrate a method of hydrogen (H.sub.2) generation. The examples are provided solely for illustration and are not to be construed as limitations of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure.

Example 1: Synthesis of Bi.SUB.2.O.SUB.3.@SiO.SUB.2 .Composite Catalyst

(38) According to the present disclosure, Bi.sub.2O.sub.3@SiO.sub.2 was synthesized with Bi.sub.2O.sub.3 in an amount of 2.5 wt. %, 5 wt. %, and 10 wt. % by milling bismuth nitrate (Bi(NO.sub.3).sub.3.Math.5H.sub.2O). The bismuth nitrate was milled with a fumed silica alongside with 2.0 grams (g) of glucose as a fuel and capping agent. The resultant mixture was milled at 350 rounds per minute (rpm) for 30 minutes, with 5 stainless steel balls with a diameter of about 1.0 cm, in a stainless-steel milling crucible with a 100 mL capacity. The obtained mixture was calcined in a porcelain crucible at 500 C. for 4.0 hours. The product was milled at the same pre-identified conditions for 15 minutes and collected thereafter.

(39) In accordance with the present disclosure, the composite catalyst produced herein may generate clean and pure hydrogen effectively and efficiently. FIG. 2A depicts hydrolysis of NaBH.sub.4 with and without a Bi.sub.2O.sub.3@SiO.sub.2 catalyst. Further, the catalytic actions of Bi.sub.2O.sub.3-loaded catalysts were observed where all catalysts showed a catalytic activity higher than the self-hydrolysis process, as seen in FIG. 2A. Furthermore, the results depict that among the catalysts loaded with 2.5 wt. % to 10 wt. % bismuth(II) oxide (Bi.sub.2O.sub.3), the 5 wt. % Bi.sub.2O.sub.3 catalyst exhibited the highest activity, with a hydrogen generation rate (HGR) of 198 milliliter per minute per grams (mL min.sup.1 g.sup.1) at a room temperature of about 30 C., as shown in FIG. 2B.

(40) The influence of temperature and NaBH.sub.4 mass on the catalytic hydrolysis of NaBH.sub.4 over a 5 wt. % Bi.sub.2O.sub.3/SiO.sub.2 catalyst was evaluated, as depicted in FIGS. 3A-3B and FIGS. 4A-4B. FIGS. 3A-3B depict that as the weight of NaBH.sub.4 increases, the hydrolysis rate rises correspondingly. At around 30 C., HGR reaches about 195 mL min.sup.1 g.sup.1, 245 mL min.sup.1 g.sup.1, 370.4 mL min.sup.1 g.sup.1, 488 mL min.sup.1 g.sup.1, and 600 mL min.sup.1 g.sup.1, for NaBH.sub.4 amounts of 0.2 g, 0.3 g, 0.5 g, 0.7 g, and 1.0 g, respectively. Further, the influence of reaction temperature on the catalytic hydrolysis process was examined at a temperature range of 30 C. to 45 C. using 0.7 g of 5 wt. % Bi.sub.2O.sub.3/SiO.sub.2, as shown in FIGS. 4A-4B. HGR values of 488 mL min.sup.1 g.sup.1, 1111 mL min.sup.1 g.sup.1, 1428 mL min.sup.1 g.sup.1, and 2000 mL min.sup.1 g.sup.1 were obtained at reaction temperatures of 30 C., 35 C., 40 C., and 45 C., respectively. The activation energy for this reaction was about 69.2 kilojoules per mole (kJ/mol).

(41) Aspects of the present disclosure describe a Bi.sub.2O.sub.3@SiO.sub.2 catalyst that may be used to generate clean and pure hydrogen efficiently at a high hydrogen generation rate. The method as described herein provides an efficient process for the hydrolysis of NaBH.sub.4, applicable with the catalyst, as shown in FIGS. 2A-2B. Catalytic performance of Bi.sub.2O.sub.3@SiO.sub.2 was evaluated with Bi.sub.2O.sub.3 loadings of 2.5 wt. %, 5 wt. %, and 10 wt. %. Catalysts examined in the present disclosure showed enhanced activity compared to the self-hydrolysis process. Particularly, 0.7 g of 5 wt. % Bi.sub.2O.sub.3@SiO.sub.2 achieves hydrogen generation rates of 488 mL min.sup.1 g.sup.1, 1111 mL min.sup.1 g.sup.1, 1428 mL min.sup.1 g.sup.1, and 2000 mL min.sup.1 g.sup.1 at reaction temperatures of 30 C., 35 C., 40 C., and 45 C., respectively.

(42) Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the disclosure may be practiced otherwise than as specifically described herein.