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CN-122006751-A - CO reduction method for photocatalysis2Methanogenic Bi2O2S@Ag2S composite photocatalyst and preparation method thereof

CN122006751ACN 122006751 ACN122006751 ACN 122006751ACN-122006751-A

Abstract

The invention belongs to the technical field of photocatalysis nano materials, and relates to a Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 and a preparation method thereof. The method comprises the steps of dispersing Bi 2 O 2 S nano-sheets in deionized water by ultrasonic, adding AgNO 3 , stirring for at least 2 hours under high force, repeatedly washing and centrifuging, and drying to obtain a target product Bi 2 O 2 S@Ag 2 S, wherein the molar ratio of Bi to Ag is 1:1.2-2.89. The Bi 2 O 2 S@Ag 2 S is creatively prepared by the method, wherein Ag 2 S and Bi 2 O 2 S share a sulfur source and grow on the surface of the Bi 2 O 2 S nanosheets to form a nanoparticle morphology. The problems of rapid recombination of Bi 2 O 2 S photo-generated electrons and poor stability of a silver-based semiconductor are solved, and the prepared catalyst can efficiently catalyze carbon dioxide to obtain methane and has good catalytic stability.

Inventors

  • LI ZHONGYU
  • WU YUEHAN
  • XU SONG
  • LIU XUAN
  • CAI ZEMING
  • ZHOU MAN
  • LIN LIWEI
  • LI HAN

Assignees

  • 常州大学

Dates

Publication Date
20260512
Application Date
20260115

Claims (7)

  1. 1. A preparation method of a Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 is characterized by comprising the following steps of dispersing Bi 2 O 2 S nano-sheets in deionized water in an ultrasonic mode, adding AgNO 3 , stirring for at least 2 hours with great force, repeatedly washing and centrifuging, and drying to obtain a target product Bi 2 O 2 S@Ag 2 S, wherein the molar ratio of Bi to Ag is 1:1.2-2.89.
  2. 2. The method for preparing the Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 according to claim 1, characterized in that the preparation method of the Bi 2 O 2 S nanosheets comprises the steps of mixing bismuth nitrate pentahydrate with thiourea in a molar ratio of 1.9-2.1:1 in water until the reagent is completely dispersed in water, then adding excessive lithium hydroxide monohydrate, continuing stirring until all the reagent is uniformly dispersed in water, transferring to an autoclave and maintaining at 200 ℃ for 72 hours.
  3. 3. The method for preparing the Bi 2 O 2 S@Ag 2 S composite photocatalyst for photocatalytic reduction of CO 2 to methane according to claim 2, wherein the method for mixing bismuth nitrate pentahydrate with thiourea comprises using magnetic stirring for more than 60 minutes.
  4. 4. The method for preparing the Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 according to claim 2, wherein the mass ratio of bismuth nitrate converted from bismuth nitrate pentahydrate to thiourea is 10:1.
  5. 5. The method for preparing the Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 according to claim 2, wherein the mass ratio of lithium hydroxide monohydrate to bismuth nitrate pentahydrate is more than 8:1.
  6. 6. The preparation method of the Bi 2 O 2 S@Ag 2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 , according to claim 1, is characterized in that the preparation of the Bi 2 O 2 S@Ag 2 S composite photocatalyst further comprises the steps of firstly dispersing prepared Bi 2 O 2 S nanosheets in 60mL of deionized water by ultrasonic, then adding AgNO 3 , stirring the mixture uniformly, repeatedly washing and centrifuging the mixture, and drying the mixture at 60 ℃ to obtain a target product Bi 2 O 2 S@Ag 2 S.
  7. 7. A Bi 2 O 2 S@Ag 2 S composite photocatalyst for photocatalytic reduction of CO 2 to methane, characterized in that it is produced by the process according to any one of claims 1 to 6.

Description

Bi 2O2S@Ag2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 and preparation method thereof Technical Field The invention belongs to the technical field of photocatalysis nano materials, and relates to a Bi 2O2S@Ag2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 and a preparation method thereof. Background With the increasing severity of global climate change, the reduction and conversion of CO 2 has become a hotspot in current scientific research. Since Fujishima and Honda first demonstrated photocatalytic decomposition of water on a photoactive semiconductor catalyst in 1972, efforts have been made to develop efficient photocatalysts capable of collecting solar energy and converting it into chemical energy. The bismuth (Bi) based catalyst has application prospect of photocatalytic carbon dioxide reduction due to the abundant reserves, non-toxicity and special electronic structure. Bismuth oxysulfide (Bi 2O2 S) as a layered material has alternating layers of Bi 2O2]2+ and S 2- ions, and its open framework structure will create an internal electrostatic field between the layers, facilitating the separation of photogenerated carriers. However, the photo-generated electrons are easily and rapidly recombined, which results in a decrease in carrier separation efficiency, thereby limiting the catalytic performance of Bi 2O2 S. Methods of the prior art to improve the rapid recombination of Bi 2O2 S photo-generated electrons include the introduction of oxygen vacancies and the formation of heterojunctions. For example, the structure of the material comprises Bi 2O2 S, oxygen vacancies introduced into Bi 2O2 S and S-type heterojunction constructed by introducing Bi 4O5I2 into Bi 2O2 S, wherein the Bi 2O2 S-based photocatalytic material is disclosed in Chinese patent literature (application number 202411624158.6) and a preparation method and application thereof. The method has the main problems that the modification process of the composite material is complicated, and the method is not suitable for preparing methane from carbon dioxide. Disclosure of Invention The prior art has the problems that the carbon dioxide reduction performance of the pure Bi 2O2 S photocatalyst is low, and methane products serving as high-heat-value fuels cannot be produced. Aiming at the problems, the invention provides a preparation method of the Bi 2O2S@Ag2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2, which is simple to operate and easy to control, and the prepared Bi 2O2S@Ag2 S composite photocatalyst has good photocatalytic carbon dioxide methane production activity and has a certain application prospect. In order to achieve the purpose of the invention, the technical scheme adopted is as follows: A preparation method of a Bi 2O2S@Ag2 S composite photocatalyst for producing methane by photocatalytic reduction of CO 2 comprises the following steps of ultrasonically dispersing Bi 2O2 S nanosheets in deionized water, then adding AgNO 3, stirring for at least 2 hours, repeatedly washing and centrifuging, and drying to obtain a target product Bi 2O2S@Ag2 S, wherein the molar ratio of Bi to Ag is 1:1.2-2.89. Ag 2 S has excellent properties in photocatalytic applications, and the narrow bandgap structure (0.9-1.2 eV) of Ag 2 S facilitates the generation of photogenerated electron-hole pairs and the utilization of solar energy, which is commonly used as a photoactive material for the preparation of composite photocatalytic materials. However, since Ag + can be reduced to Ag 0 by high-energy photo-generated electrons, the silver-based semiconductor has poor stability, and thus its application in the field of photocatalysis is limited by this disadvantage. The Bi 2O2S@Ag2 S is creatively prepared by the method, wherein Ag 2 S and Bi 2O2 S share a sulfur source and grow on the surface of the Bi 2O2 S nanosheets to form a nanoparticle morphology. The problems of rapid recombination of Bi 2O2 S photo-generated electrons and poor stability of a silver-based semiconductor are solved, and the prepared catalyst can efficiently catalyze carbon dioxide to obtain methane and has good catalytic stability. There are various methods for preparing Bi 2O2 S nanoplatelets in the art, for example, a low-heat solid phase chemical method for preparing Bi 2O2 S nanoplatelets disclosed in chinese patent literature (application No. 202310611934.8), in which bismuth nitrate pentahydrate, sodium hydroxide and different sulfur source reactants react chemically in the solid phase grinding process, and then the mixture is heated in a water bath, washed and dried to obtain the Bi 2O2 S nanoplatelets. However, the method is a low-temperature reaction after solid-phase grinding, and uneven contact of reactants can lead to poor crystallinity, purity and regularity of a layered structure of a product, and can directly influence the basic performance of the product s