# US 12,110,434 B1 · Bismuth oxyhalide-based quantum dots and method of synthesis thereof

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- Number: US 12,110,434 B1
- Document ID: US12110434B1
- Status: Granted
- Kind: B1
- Application number: 18/665,855
- Filed: 2024-05-16
- Granted: 2024-10-08
- Earliest claimed: 2024-05-16
- Assignees: Imam Mohammad Ibn Saud Islamic University
- Applicants: Imam Mohammad Ibn Saud Islamic University
- Inventors: Babiker Y. Abdulkhair; Faisal K. Algethami; Mohamed R. Elamin
- Web page: https://patentgrep.com/patent/US12110434B1

## CPC

- C09K 11/7428: {Halogenides (C09K11/7407 takes precedence)}
- C01G 29/00: Compounds of bismuth
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)

## Abstract

A method of producing bismuth oxyhalide quantum dots without heat. The method is a one-pot method that includes synthesizing bismuth oxyhalide quantum dots at room temperature. The method results in quantum dots preferably having bismuth and halide in a molar ratio of 1:1. Further, the bismuth oxyhalide quantum dots produced demonstrate excellent photocatalytic activity in the visible light spectrum and possess improved surface characteristics.

## Claims

### Claim 1

A method of producing bismuth oxyhalide quantum dots without added heat, comprising:
forming a first solution by dissolving a bismuth salt in an organic solvent;
forming a second solution by dissolving an alkali metal salt in water;
combining the first solution and the second solution to obtain a dual mixture;
combining the dual mixture with an aqueous surfactant solution comprising a surfactant to obtain a final mixture comprising the bismuth oxyhalide quantum dots; and
filtering the final solution to obtain the bismuth oxyhalide quantum dots,
wherein the alkali metal salt is selected from the group consisting of LiI, NaI, KI, RbI, CsI, LiBr, NaBr, KBr, RbBr, CsBr, LiCl, NaCl, KCl, RbCl, and CsCl.

### Claim 2 (depends on 1)

The method of claim 1, wherein the bismuth salt is Bi(NO3)3, and wherein the first solution, the second solution, the dual mixture and the final mixture are maintained at a temperature of ±5° C. during the forming and the combining.

### Claim 3 (depends on 1)

The method of claim 1, wherein the dual mixture is added to the surfactant solution such that the ratio of dual mixture to surfactant solution is 1:4 wt %.

### Claim 4 (depends on 1)

The method of claim 1, wherein the organic solvent is selected from the group consisting of polyethylene glycol, methylene glycol, tri-ethylene glycol, and ethylene glycol.

### Claim 5 (depends on 1)

The method of claim 1, wherein the surfactant is selected from the group consisting of an octyl phenol ethoxylate, a polyoxyethylene sorbitan monolaurate, and a polyoxyethylene sorbitan monooleate.

### Claim 6 (depends on 1)

The method of claim 1, wherein the dual mixture is stirred for 5 to 10 minutes at a temperature of 15 to 25° C.

### Claim 7 (depends on 1)

The method of claim 1, wherein the final mixture is stirred for 10 to 15 minutes at a temperature of 15 to 25° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the final solution is filtered by a vacuum.

### Claim 9 (depends on 1)

The method of claim 1, wherein the bismuth quantum dots are dried for 2 to 4 hours at a temperature of 100 to 115° C.

### Claim 10 (depends on 1)

The method of claim 1, wherein the surfactant in the final mixture is present in an amount between 0.5 to 2.2 wt %.

### Claim 11 (depends on 1)

The method of claim 1, wherein the alkali metal salt is KI.

### Claim 12 (depends on 1)

The method of claim 1, wherein the bismuth oxyhalide quantum dots have a surface area of 59 to 82 m2/g.

### Claim 13 (depends on 1)

The method of claim 1, wherein the bismuth oxyhalide quantum dots have a band gap energy (Eg) of 1.80 to 2 eV.

### Claim 14 (depends on 1)

The method of claim 1, wherein the bismuth oxyhalide quantum dots have an average crystal size of 10 nm or less.

### Claim 15 (depends on 1)

The method of claim 1, wherein the organic solvent is ethylene glycol.

### Claim 16 (depends on 1)

The method of claim 1, wherein the surfactant is an octyl phenol ethoxylate.

### Claim 17 (depends on 1)

The method of claim 1, wherein the bismuth oxyhalide quantum dots have a Bi:I ratio of 1:1.

### Claim 18 (depends on 1)

The method of claim 1, wherein the bismuth oxyhalide quantum dots are in the form of nanosheets having a thickness of 22 to 51 nm.