US 12275881 B1Patent grantUnited States

Surfactant-Controlled Bismuth Oxyhalide Quantum Dots

Official patent title

Method for making bismuth oxyhalide quantum dots

Arabic title: طريقة تصنيع نقاط كمومية من أوكسي هاليد البزموت

Invention

Problem

Bismuth oxyhalide quantum dots are commonly produced through solvothermal or other heat-intensive, time-consuming routes. Their optical and photocatalytic properties are sensitive to pH, temperature, morphology, and surface chemistry, complicating repeatable scale-up.

Why it matters

A short, ambient-temperature formation route could lower synthesis complexity for visible-light semiconductor nanomaterials that are being investigated for photocatalysis, sensing, solar-energy, and optoelectronic applications.

Approach

A bismuth salt in glycol solvent is mixed with an aqueous alkali-metal halide, then introduced into an aqueous polyoxyethylene sorbitan surfactant solution. Quantum dots form without added heat, are filtered, and may subsequently be dried at 100–115 °C.

Who may benefit

Potential beneficiaries include quantum-dot and photocatalyst manufacturers, water-remediation researchers, optical-sensor developers, solar-material laboratories, and organizations seeking cadmium-, lead-, or mercury-free semiconductor alternatives.

Potential value

The one-pot formation step runs at 15–25 °C without added heat and provides surfactant-controlled bismuth oxyhalide dots with claimed 59–82 m²/g surface area, 1.80–2 eV band gap, and a preferred 1:1 bismuth-to-iodine ratio.

Background

Quantum dots exhibit size-dependent electronic and optical behavior, making repeatable control of composition and dimensions important. Bismuth oxyhalides avoid reliance on cadmium-, lead-, or mercury-based semiconductor systems, and bismuth oxyiodide has a comparatively low band gap suitable for visible-light response. Conventional BiOI preparation frequently uses reflux, microwave, autoclave, or solvothermal treatment, and product properties vary with synthesis conditions. The patent seeks a simpler wet-chemical route that forms the quantum dots at room temperature with surfactant control.

Technology overview

Bi(NO3)3 is dissolved in ethylene glycol or another listed glycol, while an alkali-metal halide—preferably KI—is dissolved in water. The solutions are combined and stirred for 5–10 minutes at 15–25 °C, then mixed with an aqueous polyoxyethylene sorbitan ester surfactant for 10–15 minutes at the same temperature. Vacuum filtration isolates the dots; drying may follow. Claimed products have 59–82 m²/g surface area and a 1.80–2 eV band gap, with a preferred Bi:I molar ratio of 1:1.

Potential applications

Visible-light photocatalyst research for organic-pollutant degradation.
Optical and chemical sensor material development.
Solar-energy and photoactive-semiconductor research.
Colloidal quantum-dot platforms for nanomaterial-based devices.

Evidence-supported advantages

Forms the quantum dots at 15–25 °C without added process heat.
Uses a short one-pot wet-chemical sequence before filtration.
Avoids cadmium-, lead-, and mercury-based quantum-dot compositions.
Defines surface-area, band-gap, surfactant-content, and Bi:I ratio ranges.

Development stage

Room-temperature synthesis and SEM, surface, and optical characterization are described, with photocatalytic activity discussed; quantitative application performance and scaled production were not established in the supplied evidence. The development stage was not independently verified.

Commercial opportunity

The process may appeal to quantum-dot, photocatalyst, and optical-material developers seeking lower-temperature formation. Commercial development would need reproducible size distributions, optical and photocatalytic benchmarks, surfactant removal control, solvent recovery, stability and toxicity evaluation, scale-up, and application-specific device or reactor validation.

Patent classifications

WIPO IPC

C09K11/74Materials for applications not otherwise provided for; applications of materials not otherwise provided for
C01G29/00Compounds containing metals not covered by subclasses C01D or C01F

CPC

C09K11/7428Materials for applications not otherwise provided for; applications of materials not otherwise provided for
C01G29/00Compounds containing metals not covered by subclasses C01D or C01F

Inventors

First inventorBabiker Y. Abdulkhair
InventorFaisal K. Algethami
InventorMohamed R. Elamin

Keywords

bismuth oxyhalide
bismuth oxyiodide
quantum dots
room-temperature synthesis
surfactant
visible light
photocatalysis
band gap

Patent document and drawings

The patent publication is mapped to this record. Patent drawings remain within that publication; no separately cleared public media package has been supplied.