# US 12,766,481 B1 · Photocatalyst-free seawater hydrogen sulfide splitting for hydrogen production

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- Number: US 12,766,481 B1
- Document ID: US12766481B1
- Status: Granted
- Kind: B1
- Application number: 19/321,878
- Filed: 2025-09-08
- Granted: 2026-10-20
- Earliest claimed: 2025-09-08
- Assignees: United Arab Emirates University
- Applicants: United Arab Emirates University
- Inventors: Muhammad Tahir; Malaz Suliman
- Web page: https://patentgrep.com/patent/US12766481B1

## CPC

- B01J 19/127: {Sunlight; Visible light}
- B01D 53/007: {by irradiation}
- B01D 53/52: Hydrogen sulfide
- B01D 53/78: with gas-liquid contact
- B01F 23/233: using driven stirrers with completely immersed stirring elements
- B01F 33/45: Magnetic mixers; Mixers with magnetically driven stirrers
- B01J 19/0066: {Stirrers (mixing per se B01F)}
- C01B 3/042: Decomposition of water (by electrolysis of water C25B1/04)
- G01N 23/2209: using wavelength dispersive spectroscopy [WDS]
- G01N 30/88: Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- B01D 2257/304: Hydrogen sulfide
- B01D 2258/02: Other waste gases
- B01D 2259/802: Visible light
- B01J 2219/00164: controlling the flow
- B01J 2219/0869: Feeding or evacuating the reactor
- B01J 2219/0884: Gas-liquid
- B01J 2219/1203: Incoherent waves
- G01N 2030/025: {Gas chromatography}
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

The present disclosure provides a method for producing hydrogen comprising providing seawater containing dissolved sodium chloride (NaCl), introducing hydrogen sulfide (H2S) gas into the seawater to form a reaction mixture containing dissolved H2S and bisulfide ions (HS−), exposing the reaction mixture to solar irradiation in the absence of any photocatalyst, and generating hydrogen gas through photoexcitation of the bisulfide ions and seawater splitting facilitated by the dissolved H2S species. The seawater has a NaCl concentration of approximately 3.5 wt. %. The reaction mixture is maintained at ambient temperature during the solar irradiation. The hydrogen gas generation occurs through multiple reaction pathways comprising excimer formation, water interaction with excited bisulfide ions, and radical-mediated electron transfer. The H2S gas is continuously flowed through the reaction mixture. The dissolved H2S species induce morphological changes in NaCl crystals from smooth surfaces to fragmented, flake-like structures.

## Claims

### Claim 1

A method of producing hydrogen, comprising the steps of:
providing seawater containing dissolved sodium chloride (NaCl);
introducing hydrogen sulfide (H2S) gas into the seawater to form a reaction mixture containing dissolved H2S and bisulfide ions (HS−);
exposing the reaction mixture to solar irradiation in the absence of any photocatalyst;
generating hydrogen gas through photoexcitation of the bisulfide ions and seawater splitting facilitated by the dissolved H2S species, and maintaining the reaction mixture at ambient temperature during the solar irradiation.

### Claim 2 (depends on 1)

The method of claim 1, wherein the seawater has a NaCl concentration of approximately 3.5 wt. %.

### Claim 3 (depends on 1)

The method of claim 1, wherein the ambient temperature is approximately 18° C.

### Claim 4 (depends on 1)

The method of claim 1, wherein the solar irradiation is provided by a xenon lamp simulating solar light.

### Claim 5 (depends on 1)

The method of claim 1, wherein the hydrogen gas generation occurs through multiple reaction pathways comprising excimer formation, water interaction with excited bisulfide ions, and radical-mediated electron transfer.

### Claim 6 (depends on 1)

The method of claim 1, further comprising a step of continuously flowing the H2S gas through the reaction mixture at a flow rate of approximately 3 mL/min.

### Claim 7 (depends on 1)

The method of claim 1, wherein the method achieves a hydrogen production rate of 25.89 mol·L−1·min−1.

### Claim 8

A method for detoxifying hydrogen sulfide waste while producing hydrogen, comprising:
dissolving hydrogen sulfide (H2S) gas in seawater containing sodium chloride (NaCl) to form bisulfide ions (HS−);
irradiating the seawater with solar energy without using any photocatalyst;
photoexciting the bisulfide ions to generate hydrogen gas through multiple reaction pathways including excimer formation and radical-mediated electron transfer;
simultaneously facilitating seawater splitting through interaction of dissolved H2S species with seawater constituents, and
maintaining the seawater at ambient temperature during the solar irradiation to optimize hydrogen sulfide solubility.

### Claim 9 (depends on 8)

The method of claim 8, wherein the seawater comprises additional salts selected from the group consisting of MgCl2, Na2SO4, CaCl2, and KCl in concentrations representative of natural seawater composition.

### Claim 10 (depends on 8)

The method of claim 8, wherein the ambient temperature is maintained at approximately 18° C. through a cooling system.

### Claim 11 (depends on 8)

The method of claim 8, wherein the multiple reaction pathways further comprise water interaction with excited bisulfide ions to produce elemental sulfur and molecular hydrogen.