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CN-121972219-A - Donor-acceptor type carbon nitride photocatalyst and preparation method and application thereof

CN121972219ACN 121972219 ACN121972219 ACN 121972219ACN-121972219-A

Abstract

The invention discloses a donor-acceptor type carbon nitride photocatalyst, a preparation method and application thereof, wherein the preparation method of the donor-acceptor type carbon nitride photocatalyst comprises the steps of mixing a carbon nitride precursor with molten salt and calcining to obtain cyano-modified carbon nitride; and mixing the cyano-modified carbon nitride with 4,4' -biphenyl dicarboxylic acid, and calcining to realize covalent bonding reaction, thus obtaining the donor-acceptor type carbon nitride photocatalyst. According to the carbon nitride photocatalyst, an asymmetric donor-acceptor structure is constructed, a strong built-in electric field is induced, and simultaneously cyano is used as a proton/electron storage library, so that the charge separation efficiency and the proton transmission capacity are remarkably improved, and the hydrogen peroxide preparation by photocatalysis is efficiently realized.

Inventors

  • YUAN YUPENG
  • SHEN QIAO
  • WANG YULING
  • TIAN CHONG
  • ZHANG QIAOYU
  • SONG XIAOLIN
  • LI DACHENG

Assignees

  • 安徽大学

Dates

Publication Date
20260505
Application Date
20260107

Claims (10)

  1. 1. A method for preparing a donor-acceptor type carbon nitride photocatalyst, which is characterized by comprising the following steps: S1, mixing a carbon nitride precursor with molten salt and calcining to obtain cyano-modified carbon nitride; S2, mixing the cyano-modified carbon nitride with 4,4' -biphenyl dicarboxylic acid, and calcining to realize covalent bonding reaction, thereby obtaining the donor-acceptor type carbon nitride photocatalyst.
  2. 2. The method for preparing a donor-acceptor type carbon nitride photocatalyst according to claim 1, wherein in step S1, the carbon nitride precursor is at least one of dicyandiamide, melamine or urea, preferably dicyandiamide, and the molten salt is at least one of sodium chloride, potassium chloride or lithium chloride, preferably sodium chloride; preferably, the mass ratio of the carbon nitride precursor to the molten salt is 1:2-4.
  3. 3. The method for preparing a donor-acceptor type carbon nitride photocatalyst according to claim 1 or 2, wherein in step S1, before the mixing, the method further comprises grinding the carbon nitride precursor and the molten salt to a particle size of 100-200 mesh.
  4. 4. A method for preparing a donor-acceptor carbon nitride photocatalyst according to any one of claims 1 to 3 wherein in step S1, the calcination temperature is 550 to 650 ℃ for 4 to 6 hours at a rate of 1 to 10 ℃ per minute; preferably, the calcination is performed under an air atmosphere.
  5. 5. The method for preparing a donor-acceptor type carbon nitride photocatalyst according to any one of claims 1 to 4, wherein in step S2, the mass ratio of the cyano carbon nitride to 4,4' -biphenyl dicarboxylic acid is 80 to 120:1.
  6. 6. The method of preparing a donor-acceptor type carbon nitride photocatalyst according to any one of claims 1 to 5, wherein in step S2, the mixing comprises ultrasonic dispersion of cyano-modified carbon nitride with 4,4' -biphenyl dicarboxylic acid; preferably, the ultrasonic dispersion power is 100-300W, and the ultrasonic dispersion time is 20-40min.
  7. 7. The method for preparing a donor-acceptor type carbon nitride photocatalyst according to any one of claims 1 to 6, wherein in step S2, the calcination temperature is 350 to 450 ℃, the calcination time is 1 to 3 hours, and the temperature rise rate is 1 to 10 ℃ per minute; preferably, the calcination is performed under an air atmosphere.
  8. 8. A donor-acceptor type carbon nitride photocatalyst prepared by the preparation method according to any one of claims 1 to 7.
  9. 9. The donor-acceptor type carbon nitride photocatalyst according to claim 8, wherein the donor-acceptor type carbon nitride photocatalyst has a donor unit of a biphenyl ring and an acceptor unit of a cyano group, the cyano group is modified at a carbon nitride edge, and the biphenyl ring is connected with the carbon nitride edge amino group through an amide bond to form an asymmetric donor-acceptor structure.
  10. 10. Use of the donor-acceptor type carbon nitride photocatalyst of claim 9 in the photocatalytic production of hydrogen peroxide.

Description

Donor-acceptor type carbon nitride photocatalyst and preparation method and application thereof Technical Field The invention belongs to the technical field of hydrogen peroxide preparation by photocatalysis, and particularly relates to a donor-acceptor type carbon nitride photocatalyst, and a preparation method and application thereof. Background Hydrogen peroxide is used as a key green oxidant, an industrial core reagent and a clean energy carrier, and has irreplaceable application value in the fields of chemical industry, energy and the like. However, traditional industrial preparation is dependent on long-term development requirements. Among the numerous photocatalytic materials, carbon nitride has received increasing attention in the field of photocatalysis due to its environmentally friendly, nonmetallic properties, low cost of preparation and good physicochemical stability. Despite these advantages, the photo-generated charge is fast to combine,Low selectivity,Limited adsorption and scarce active centers, which severely restrict their photocatalytic productionEfficiency is improved. To overcome these limitations, researchers have explored a variety of optimization strategies including constructing molecular heterojunctions to regulate interfacial charge transport, introducing functional groups to improve surface reaction characteristics, and designing donor-acceptor (D-a) carbon nitride optimized electronic structures. The D-A type carbon nitride has unique advantages of accurate regulation and control, no metal toxicity hidden trouble and modularized and diversified constituent units by virtue of an electronic structure, is remarkable in a plurality of photocatalytic materials, and is regarded as a non-metal candidate system with the most application potential in the field of photocatalytic ORR. However, even with the above characteristics, the existing D-A type carbon nitride photocatalyst is still limited by four major core challenges, namely, low charge utilization rate and two electrons caused by too fast photo-generated charge carrier recombination rateLow selectivity causesYield loss,The adsorption capacity is limited by the supply of the reaction substrate, the problems of scarce number of active centers and difficulty in supporting efficient catalytic reaction are mutually interwoven, and the photocatalytic production is inhibited togetherThe efficiency makes it difficult to meet the requirements of practical application scenes. Disclosure of Invention Based on the technical problems, the invention provides a donor-acceptor type carbon nitride photocatalyst, a preparation method and application thereof, wherein the carbon nitride photocatalyst induces a strong built-in electric field by constructing an asymmetric donor-acceptor structure, and simultaneously cyano is used as a proton/electron storage library, so that the charge separation efficiency and the proton transmission capacity are obviously improved, and the hydrogen peroxide is prepared by photocatalysis with high efficiency. The invention provides a preparation method of a donor-acceptor type carbon nitride photocatalyst, which comprises the following steps: S1, mixing a carbon nitride precursor with molten salt and calcining to obtain cyano-modified carbon nitride; S2, mixing the cyano-modified carbon nitride with 4,4' -biphenyl dicarboxylic acid, and calcining to realize covalent bonding reaction, thereby obtaining the donor-acceptor type carbon nitride photocatalyst. According to the invention, cyano modified carbon nitride is prepared by calcining a carbon nitride precursor with the aid of molten salt, the pore structure of the carbon nitride can be optimized by adding the molten salt, cyano groups with strong electron withdrawing are introduced, and then, an amidation reaction is carried out between the carboxyl of 4,4' -biphenyl and the amino at the edge of the cyano modified carbon nitride, and biphenyl rings are grafted onto a carbon nitride frame as donor units, so that an asymmetric donor-acceptor (D-A) structure is formed. On one hand, the asymmetric structure can remarkably enhance dipole moment, further induce a stronger built-in electric field and accelerate separation and transmission of photo-generated charge carriers, on the other hand, the cyano group with polarity electron deficiency is used as a proton/electron storage library, photo-generated electrons and protons can be effectively captured and stably stored and are rapidly transferred to a catalytic active site (carbon atom adjacent to the cyano group), the photo-generated electrons and the protons react with adsorbed oxygen to generate hydrogen peroxide efficiently through 2e-ORR, the biphenyl ring with the electron enrichment is used as an electron donor to provide sufficient sources for continuous generation of photo-generated electrons in the reaction process, and compared with the benzene ring alone as the electron donor, the conjugated effect of the lat