Hydrophilic gel platform of photocatalytic water splitting, method for making thereof and use thereof

Abstract

This invention provides a hydrophilic gel platform for photocatalytic water splitting, its preparation method, and its application. The hydrophilic gel platform includes a hydrogel support and multiple photocatalytic regions uniformly dispersed therein. The photocatalytic regions contain metal nanoparticles coordinated and connected to a metal-organic framework. By solidifying the photocatalyst on the hydrogel support, its stability is improved. Furthermore, by controlling the crosslinking density of the hydrogel support, the accessibility of water molecules to the photocatalyst is increased, and the electron and proton transfer efficiency of the photocatalytic interface is enhanced, thereby significantly promoting the photocatalytic water splitting reaction and increasing the hydrogen yield.

Claims

1. A hydrophilic gel platform for photocatalytic water splitting, comprising: A hydrogel support comprising multiple hydrogel polymer chains polymerized from multiple hydrogel monomers, wherein the hydrogel polymer chains are interconnected and interwoven with multiple cross-linking nodes to form a microporous structure; and a photocatalytic region uniformly dispersed in the hydrogel support and embedded between any of the hydrogel polymer chains, wherein the photocatalytic region comprises metal nanoparticles coordinated to a metal-organic framework, wherein the metal-organic framework includes any member of the M-PGTP series, the preparation method comprising: Step A: mixing trialdehyde resorcinol and 2,3,6,7,10,11-hexaminobenzophenanthrene to prepare an organic ligand precursor; Step B: subjecting the organic ligand precursor to an acid-catalyzed reaction to form an organic framework PGTP; and Step C: forming a coordination covalent bond between the organic framework PGTP and a metal ion to obtain the metal-organic framework M-PGTP, wherein the metal ion is selected from the group consisting of magnesium ions, copper ions, and ferrous ions.

2. The hydrophilic gel platform as described in claim 1, wherein, The molar ratio of these hydrogel monomers and these cross-linking nodes is 1:(0.0012~0.0052).

3. The hydrophilic gel platform as described in claim 1, wherein, The pore size of this multi-microporous structure ranges from 0.1 to 25 micrometers.

4. The hydrophilic gel platform as claimed in claim 1, wherein the hydrogel monomer comprises at least one of the following: acrylamide, acrylonitrile, acryloxyethyltrimethylammonium chloride, methacryloxyethyltrimethylammonium chloride, dimethyl diallyl ammonium chloride, sodium acrylate, or 2-alkylamino-2-methylpropanesulfonic acid; the metal nanoparticles comprise: Gold nanoparticles (AuNPs) with an average particle size of 10 to 40 nanometers.

5. The hydrophilic gel platform as described in any one of claims 1 to 4, wherein the preparation method comprises: A photocatalyst is obtained by coordinating the metal nanoparticles with the metal-organic framework; a gel precursor is obtained by mixing the hydrogel monomers, the photocatalyst, and a crosslinking agent; and the gel precursor is then subjected to a gelation reaction in a humid environment by contacting an initiator to obtain the hydrophilic gel platform. During the gelation reaction, the hydrogel monomers polymerize to form hydrogel polymer chains, and the crosslinking agent generates crosslinking nodes between the hydrogel polymer chains. The hydrogel polymer chains interweave to form a multi-microporous structure to capture the photocatalyst, wherein the photocatalyst is embedded between any of the hydrogel polymer chains to form the photocatalytic region.

6. The hydrophilic gel platform as described in claim 5, wherein, The gelation reaction occurs in an aqueous solution, wherein, based on the total volume of the aqueous solution, the weight percentage of the metal nanoparticles is 0.25–0.32 wt%, the weight percentage of the metal-organic framework is 0.01–0.2 wt%, the volume molar concentration of the hydrogel monomer is 1.1 M–1.5 M, and the volume molar concentration of the crosslinking agent is 0.0013 M–0.0080 M.

7. The hydrophilic gel platform as described in claim 6, wherein, The initiator includes a free radical initiator and a thermal initiator, wherein the free radical initiator includes 0.1 to 0.5 wt% potassium persulfate and the thermal initiator includes 0.5 to 2.0 wt% N,N,N',N'-tetramethylethylenediamine.

8. A method for producing hydrogen, comprising: The hydrophilic gel platform as described in any one of claims 1 to 4 is immersed in a body of water, such that water molecules contained in the water come into contact with the photocatalytic region; an irradiation light is passed through the photocatalytic region to drive the photocatalytic reaction of the water molecules to decompose them into hydrogen and oxygen; and the hydrogen is collected.

9. The hydrogen production method as described in claim 8, wherein, The water molecules include free water molecules and bound water molecules. The free water molecules are dispersed in the pores of the microporous structure, and the bound water molecules are bound to the surface of the microporous structure. The molar ratio of the free water molecules to the bound water molecules is (70~80):(20~30).

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