CN113145156A - Preparation of NiO-based Z-type heterojunction photoelectric catalytic material - Google Patents

Abstract

The invention discloses a synthesis method of a novel Z-type heterojunction photoelectric catalytic material, and belongs to the technical field of photoelectric catalysis. The method comprises the following steps: growing a NiO nano sheet on the foamed nickel in situ, electroplating silver, synthesizing a sulfhydryl acetic acid polypyrrole composite material, and modifying a substrate material with the sulfhydryl acetic acid polypyrrole. The invention is characterized in that the nickel oxide with wide forbidden band and the polypyrrole with good conductivity with narrow forbidden band are compounded together by taking silver as an electron transfer medium, and a synthetic method of a novel Z-type heterojunction photocatalytic material is researched. The synthesized catalytic material has the advantages of wide spectrum absorption range, large specific surface area, high stability, simple synthesis method and the like, and the Z-type heterojunction structure better retains the oxidation-reduction capability of a photoproduction electron hole compared with the traditional II-type heterojunction structure, so that the catalytic activity is high, and the efficient degradation of methyl orange in a water body is realized.

Description

Preparation of NiO-based Z-type heterojunction photoelectric catalytic material

Technical Field

The invention relates to the technical field of photoelectrocatalysis, in particular to a synthesis method of a novel Z-type heterojunction structure photoelectrocatalysis material.

Background

Photocatalytic degradation is a viable method for removing organic matter from water sources. Due to the advantages of low cost, multiple functions, high efficiency, mild reaction conditions, etc., photocatalysis is increasingly applied to the degradation of organic pollutants.

Researchers have also been working on the design and synthesis of a wide variety of highly efficient photocatalysts that convert inexhaustible solar energy into the driving force for photodegradation. In various heterojunction structures, more active substances are generated because the Z-type heterojunction system retains the stronger reducibility and oxidizability of electrons and holes. These active substances produced (^·O₂ ^-、^·OH and h⁺) Can effectively degrade organic substances.

Methyl orange is a commonly used indicator in analytical chemistry. Methyl orange is also an azo dye and can be used for printing and dyeing textiles. The discharge of dye wastewater such as methyl orange and the like can cause visual pollution, when the color of the water body is deepened, sunlight is prevented from irradiating the water body to a great extent, and then the growth of animals and plants in the water is influenced. Meanwhile, the natural decomposition of the organic dye in the environment consumes a large amount of oxygen, and the water body can smell due to oxygen deficiency, thereby further causing the pollution of water resources.

Disclosure of Invention

The invention provides a synthesis method of a novel Z-type heterojunction structure photoelectrocatalysis material, which can be easily realized in most laboratories without complex and fussy large-scale equipment support. The specific preparation scheme is as follows:

(1) growing NiO nano-sheets on the foamed nickel in situ: 1.2488 g of nickel acetate tetrahydrate (C) were weighed out₄H₁₄NiO₈) 3 g Urea (CH)₄N₂O) and 0.74 g of ammonium fluoride (NH)₄F) Dissolved in 100 mL of deionized water and magnetically stirred for 20 min. 17 mL of the solution was measured and transferred to a 50 mL stainless steel autoclave lined with Teflon, and a piece of pre-cleaned Nickel Foam (NF) was placed in the autoclave in advance and reacted for 5 hours at 130 ℃ under hydrothermal reaction. Naturally cooling the high-pressure autoclave to room temperature, taking out the NF sheet, washing with deionized water, and then heating at 80 deg.CDrying in vacuum for 10 h to obtain Ni (OH)₂Modified NF (Ni (OH)₂/NF) and calcining for 3 hours at 400 ℃ to obtain NF/NiO.

(2) Silver electroplating: and (2) placing the NF/NiO sheet prepared in the step (1) into 3 mL of silver ammonia solution, 2 mL of H2O and 1 mL of electrolyte mixed with KNO3 by adopting a traditional three-electrode system electrochemical deposition method, depositing for 1200 s at minus 0.2V, and finally washing with ultrapure water to obtain the NF/NiO/Au.

(3) Synthesis of a sulfhydryl acetic acid polypyrrole (PPy/MAA) composite material: at 25 deg.C, 0.8 mL of pyrrole (Py) monomer was injected into 60 mL of aqueous solution containing 1.6 mL of thioglycolic acid (MAA). The above mixed solution was stirred for 30 min to ensure complete dissolution, and then 20 mL of 6.8 g Ammonium Persulfate (APS) solution was added dropwise as an oxidizing agent to initiate polymerization. During the polymerization, the solution changed from colorless to dark gray, indicating the formation of polypyrrole (Ppy). The mixed solution obtained by the reaction was left at room temperature for 6 hours to complete the polymerization, the obtained precipitate was washed with ultrapure water and then with acetone several times (about 10 times), and the finally obtained PPy/MAA composite material was subsequently dried under vacuum at 60 ℃.

(4) PPy/MAA modified substrate material: the resulting PPy/MAA composite was ground to a powder and sonicated to form a 2 mg/mL homogeneous solution. And (3) uniformly dripping 1 mL of the homogeneous solution on the NF/NiO/Au substrate prepared in the step (2), repeatedly dripping and coating for many times, and drying at 60 ℃ to finally obtain the photoelectric material with the Z-type heterojunction structure of NF/NiO/Au/PPy/MAA.

(5) Application of photoelectrocatalysis: immersing the NF/NiO/Au/PPy/MAA electrode in 60-80 mL of 1 g/L Methyl Orange (MO) solution, and magnetically inducing and stirring the suspension in the dark for 20-30 min to establish the absorption and desorption balance of the dye and the electrode surface under normal atmospheric conditions. And (3) using a xenon lamp as sunlight, irradiating the sunlight by using the xenon lamp to perform photocatalytic degradation reaction, and collecting the mixed solution every 3-6 min. The residual concentration of the dye was determined using a uv-vis spectrometer.

The invention has the beneficial effects that:

(1) the method has the advantages of low cost, simple experimental operation and easily controlled reaction conditions;

(2) the prepared NF-NiO/Ag/MAA-PPy catalytic material has the advantages of wide spectrum absorption range, large specific surface area, high stability and the like.

(3) Compared with the traditional II type heterojunction structure, the Z type heterojunction structure better reserves the oxidation reduction capability of a photoproduction electron hole, so that the catalytic activity is high.

The following is a description of detailed embodiments of the present invention: a method for synthesizing a novel Z-shaped heterojunction structure photoelectric catalytic material.

Example 1

(1) Growing NiO nano-sheets on the foamed nickel in situ: 1.2488 g of nickel acetate tetrahydrate (C) were weighed out₄H₁₄NiO₈) 3 g Urea (CH)₄N₂O) and 0.74 g of ammonium fluoride (NH)₄F) Dissolved in 100 mL of deionized water and magnetically stirred for 20 min. 17 mL of the solution was measured and transferred to a 50 mL stainless steel autoclave lined with Teflon, and a piece of pre-cleaned Nickel Foam (NF) was placed in the autoclave in advance and reacted for 5 hours at 130 ℃ under hydrothermal reaction. Naturally cooling the autoclave to room temperature, taking out the NF sheets, washing with deionized water, and then drying in vacuum at 80 ℃ for 10 h to obtain Ni (OH)₂Modified Ni (OH)₂and/NF, and calcining for 3 hours at 400 ℃ to obtain NF/NiO.

(2) Silver electroplating: placing the NF/NiO sheet prepared in the step (1) in 3 mL of silver ammonia solution and 2 mL of H by adopting a traditional three-electrode system electrochemical deposition method₂O，1 mL KNO₃In the mixed electrolyte, the solution was deposited for 1200 s at-0.2V and finally rinsed with ultrapure water to obtain NF/NiO/Au.

(3) Synthesis of a sulfhydryl acetic acid polypyrrole (PPy/MAA) composite material: at 25 deg.C, 0.8 mL of pyrrole (Py) monomer was injected into 60 mL of aqueous solution containing 1.6 mL of thioglycolic acid (MAA). The above mixed solution was stirred for 30 min to ensure complete dissolution, and then 20 mL of 6.8 g Ammonium Persulfate (APS) solution was added dropwise as an oxidizing agent to initiate polymerization. During the polymerization, the solution changed from colorless to dark gray, indicating the formation of polypyrrole (Ppy). The mixed solution obtained by the reaction was left at room temperature for 6 hours to complete the polymerization, the obtained precipitate was washed with ultrapure water and then with acetone several times (about 10 times), and the finally obtained PPy/MAA composite material was subsequently dried under vacuum at 60 ℃.

(4) PPy/MAA modified substrate material: the resulting PPy/MAA composite was ground to a powder and sonicated to form a 2 mg/mL homogeneous solution. And (3) uniformly dripping 1 mL of the homogeneous solution on the NF/NiO/Au substrate prepared in the step (2), repeatedly dripping and coating for many times, and drying at 60 ℃ to finally obtain the photoelectric material with the Z-type heterojunction structure of NF/NiO/Au/PPy/MAA.

(5) Application of photoelectrocatalysis: immersing the NF/NiO/Au/PPy/MAA electrode in 60-80 mL of 1 g/L Methyl Orange (MO) solution, and magnetically inducing and stirring the suspension in the dark for 20-30 min to establish the absorption and desorption balance of the dye and the electrode surface under normal atmospheric conditions. And (3) using a xenon lamp as sunlight, irradiating the sunlight by using the xenon lamp to perform photocatalytic degradation reaction, and collecting the mixed solution every 3-6 min. The residual concentration of the dye was determined using a uv-vis spectrometer.

Claims (1)

1. The invention provides a synthesis method of a novel Z-type heterojunction structure photoelectric catalytic material, which comprises the following specific preparation scheme:

(1) growing NiO nano-sheets on the foamed nickel in situ: 1.2488 g of nickel acetate tetrahydrate (C) were weighed out₄H₁₄NiO₈) 3 g Urea (CH)₄N₂O) and 0.74 g of ammonium fluoride (NH)₄F) Dissolved in 100 mL of deionized water and magnetically stirred for 20 min. 17 mL of the solution was measured and transferred to a 50 mL stainless steel autoclave lined with Teflon, and a piece of pre-cleaned Nickel Foam (NF) was placed in the autoclave in advance and reacted for 5 hours at 130 ℃ under hydrothermal reaction. Naturally cooling the autoclave to room temperature, taking out the NF sheets, washing with deionized water, and then drying in vacuum at 80 ℃ for 10 h to obtain Ni (OH)₂Modified Ni (OH)₂and/NF, and calcining for 3 hours at 400 ℃ to obtain NF/NiO.

(2) Silver electroplating: placing the NF/NiO sheet prepared in the step (1) in 3 mL of silver ammonia solution and 2 mL of H by adopting a traditional three-electrode system electrochemical deposition method₂O，1 mL KNO₃In the mixed electrolyte, the solution was deposited for 1200 s at-0.2V and finally rinsed with ultrapure water to obtain NF/NiO/Au.

(3) Synthesis of a sulfhydryl acetic acid polypyrrole (PPy/MAA) composite material: at 25 deg.C, 0.8 mL of pyrrole (Py) monomer was injected into 60 mL of aqueous solution containing 1.6 mL of thioglycolic acid (MAA). The above mixed solution was stirred for 30 min to ensure complete dissolution, and then 20 mL of 6.8 g Ammonium Persulfate (APS) solution was added dropwise as an oxidizing agent to initiate polymerization. During the polymerization, the solution changed from colorless to dark gray, indicating the formation of polypyrrole (Ppy). The mixed solution obtained by the reaction was left at room temperature for 6 hours to complete the polymerization, the obtained precipitate was washed with ultrapure water and then with acetone several times (about 10 times), and the finally obtained PPy/MAA composite material was subsequently dried under vacuum at 60 ℃.

(4) PPy/MAA modified substrate material: the resulting PPy/MAA composite was ground to a powder and sonicated to form a 2 mg/mL homogeneous solution. And (3) uniformly dripping 1 mL of the homogeneous solution on the NF/NiO/Au substrate prepared in the step (2), repeatedly dripping and coating for many times, and drying at 60 ℃ to finally obtain the photoelectric material with the Z-type heterojunction structure of NF/NiO/Au/PPy/MAA.

(5) Application of photoelectrocatalysis: immersing the NF/NiO/Au/PPy/MAA electrode in 60-80 mL of 1 g/L Methyl Orange (MO) solution, and magnetically inducing and stirring the suspension in the dark for 20-30 min to establish the absorption and desorption balance of the dye and the electrode surface under normal atmospheric conditions. And (3) using a xenon lamp as sunlight, irradiating the sunlight by using the xenon lamp to perform photocatalytic degradation reaction, and collecting the mixed solution every 3-6 min. The residual concentration of the dye was determined using a uv-vis spectrometer.