Full solid solution S-type heterojunction catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of inorganic nano catalytic materials, and provides a full solid solution S-type heterojunction catalyst as well as a preparation method and application thereof. According to the invention, two continuous solid solutions are respectively used as a reductive semiconductor and an oxidative semiconductor, a full solid solution S-type heterojunction with a controllable built-in electric field is constructed, effective absorption of sunlight, rapid separation of photon-generated carriers and collaborative optimization of oxidation-reduction potential are realized, and the photocatalytic performance of the catalyst is obviously improved. Results of the embodiment show that the all-solid-solution S-type heterojunction catalyst constructed by the invention has efficient catalytic activity and excellent stability on degradation of ethylene under the conditions of normal temperature, normal pressure and visible light.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic nanocatalytic materials, and in particular to a full solid solution S-type heterojunction catalyst and a preparation method and application thereof. Background Art

[0002] In 1972, Fujishima discovered the phenomenon of photocatalytic water decomposition by titanium dioxide electrodes. This pioneering work opened the door to the field of semiconductor photocatalysis. At present, semiconductor photocatalysis has become one of the most promising technologies for solving energy crises and environmental pollution problems. Although a large number of photocatalysts (such as inorganic semiconductor TiO 2 、SrTiO 3 、BiVO 4 、Ag 3 PO 4 and organic semiconductor gC 3 N 4 , MOFs, COFs), but due to the rapid recombination of photogenerated carriers, the mutual limitations between the light absorption range and the redox capacity (e.g. Figure 1 As shown in (a), the activity of single-component photocatalysts is poor, which greatly limits the application prospects of photocatalytic technology.

[0003] Heterojunction photocatalysts have emerged as a potential solution to this problem. Heterojunction photocatalysts integrate the light absorption and redox properties of single-component semiconductor photocatalysts, and generate an electric field at the interface of the heterojunction that can effectively separate carriers. However, the relationship between light utilization and redox in heterojunction photocatalysts is still contradictory. When the band gap is narrow, the redox potential is low, while when the redox potential is high, the band gap tends to be wide and the light energy utilization is very low.

[0004] Inspired by the energy transfer method during photosynthesis in plants in nature, Bader constructed the first Z-scheme photocatalytic system in 1979. However, some inappropriateness of the Z-scheme photocatalytic mechanism has been recently discovered and reported. Subsequently, the concept of S-scheme heterojunction (i.e., S-type heterojunction) photocatalyst was further advanced in 2019. The S-scheme heterojunction is composed of two different semiconductor materials, and its band structure presents a unique staggered arrangement, like the shape of the letter "S", which makes the photogenerated carriers have a special transfer mechanism at the interface. Due to the unique migration pathway of photogenerated carriers, the S-type heterojunction achieves both effective absorption of sunlight and high redox ability. However, how to further regulate the built-in electric field of the S-type heterojunction to achieve effective absorption of sunlight, efficient separation of photogenerated carriers and coordinated optimization of redox potential, and achieve higher photocatalytic performance is still a huge challenge.

[0005] The plant hormone ethylene (C 2 H 4 ) can accelerate the ripening of fruits and vegetables. However, excessive ethylene can cause rapid decay of fruits, and the use of inert gases in refrigerated transportation will incur additional energy costs. Therefore, the development of a sustainable ethylene degradation technology to preserve fruits and vegetables is an urgent and arduous task. Currently, compared with physical adsorption, ozone oxidation and thermal catalytic oxidation, photocatalytic oxidation is a very attractive option. According to the current research on C 2 H 4 To understand the mechanism of photocatalytic degradation, an effective photocatalyst requires a high separation efficiency of photogenerated carriers. In addition, it must be able to simultaneously trigger the oxidation of OH - (OH - +h + → OH, +2.59 V vs. NHE) and reduced O 2 (O 2 +e - → ·O 2 - , -0.33V vs. NHE). Therefore, for a single-component photocatalyst, the band gap must be greater than 2.92eV to achieve effective catalysis. In summary, a highly efficient visible light photocatalytic degradation of C 2 H 4 The development of photocatalysts remains a formidable challenge. Summary of the invention

[0006] In view of this, the present invention provides a full solid solution S-type heterojunction catalyst and its preparation method and application. The present invention uses a continuous solid solution as a reducing and oxidizing semiconductor to construct a solid solution S-type heterojunction with a controllable built-in electric field, which can effectively improve the carrier separation efficiency and improve the photocatalytic performance. The obtained full solid solution S-type heterojunction catalyst can efficiently catalyze and degrade ethylene gas under normal temperature and pressure and visible light conditions.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A full solid solution S-type heterojunction catalyst comprises a reductive semiconductor and an oxidative semiconductor, wherein the reductive semiconductor and the oxidative semiconductor are both continuous solid solutions.

[0009] Preferably, the reductive semiconductor is Zn x Cd 1-x S, wherein 0<x≤1; the oxidized semiconductor is Bi 2 Mo y W 1-y O 6 or Sb 2 Mo z W1-z O 6 , where 0<y<1, 0≤z≤1.

[0010] Preferably, the Bi 2 Mo y W 1-y O 6 and Sb 2 Mo z W 1-z O 6 All of them are ultra-thin nanosheets, among which Bi 2 Mo y W 1-y O 6 The thickness of the ultra-thin nanosheets is 0.8 to 1.6 nm, Sb 2 Mo z W 1-z O 6 The thickness of the ultra-thin nanosheet is 0.7 to 1.4 nm; the Zn x Cd 1-x S is a quantum dot;

[0011] The value of x is 0.2, 0.4, 0.6, 0.8 or 1.0, the value of y is 0.2, 0.4, 0.6 or 0.8, and the value of z is 0.2, 0.4, 0.6, 0.8 or 1.0.

[0012] Preferably, the Bi 2 Mo y W 1-y O 6 The preparation method comprises:

[0013] A bismuth source, a tungsten source, a molybdenum source, a quaternary ammonium salt and deionized water are mixed for hydrothermal reaction to obtain the Bi 2 Mo y W 1-y O 6 ; The temperature of the hydrothermal reaction is 90-120°C and the time is 20-24h.

[0014] Preferably, the Sb 2 Mo z W 1-z O 6 The preparation method comprises:

[0015] The antimony source, tungsten source, molybdenum source, quaternary ammonium salt and deionized water are mixed for hydrothermal reaction to obtain the Sb 2 Mo z W 1-z O 6 ; The temperature of the hydrothermal reaction is 90-120°C and the time is 20-24h.

[0016] Preferably, the full solid solution S-type heterojunction catalyst is Zn x Cd 1-x S / Bi 2 Mo y W 1-y O 6 or Zn x Cd 1-x S / Sb 2 Mo z W 1-z O 6 ; The Zn x Cd 1-x S / Bi 2 Mo y W 1-y O 6 Medium Zn x Cd 1-x The mass fraction of S is 5 to 20%; the Zn x Cd 1-x S / Sb 2 Mo z W 1-z O 6 Medium Zn x Cd 1-x The mass fraction of S is 20 to 50%.

[0017] The present invention also provides a method for preparing the full solid solution S-type heterojunction catalyst described in the above scheme, comprising the following steps:

[0018] mixing an oxidative semiconductor and an alcohol solvent to obtain a suspension;

[0019] The suspension is mixed with raw materials for preparing a reducing semiconductor, and a full solid solution S-type heterojunction catalyst is prepared by an in-situ hydrothermal method.

[0020] Preferably, when the reductive semiconductor is Zn x Cd 1-x S, the in-situ hydrothermal method comprises: mixing the suspension with a cadmium source, a zinc source and a sulfur source for an in-situ hydrothermal reaction to obtain the full solid solution S-type heterojunction; the temperature of the in-situ hydrothermal reaction is 80 to 120° C., and the time is 10 to 12 hours.

[0021] The present invention also provides the use of the full solid solution S-type heterojunction catalyst described in the above scheme or the full solid solution S-type heterojunction catalyst prepared by the preparation method described in the above scheme in photocatalysis.

[0022] Preferably, the application includes: using the full solid solution S-type heterojunction catalyst to catalytically degrade ethylene.

[0023] The present invention provides a full solid solution S-type heterojunction catalyst, including a reductive semiconductor and an oxidative semiconductor, wherein the reductive semiconductor and the oxidative semiconductor are both continuous solid solutions. In order to solve the problem of low efficiency of separation of photogenerated carriers in the S-type heterojunction, the present invention proposes the concept of "full solid solution S-type heterojunction", adopts two continuous solid solutions as reductive and oxidative semiconductors respectively, and constructs a full solid solution S-type heterojunction with a controllable built-in electric field. Figure 1 As shown in (c), the built-in electric field strength is related to the conduction band valence band position between the two semiconductors, and the conduction band valence band position of the semiconductor can be adjusted by forming a solid solution. The continuous solid solution means the continuous and controllable adjustment of the conduction band valence band position. The present invention can adjust the content of the elements in the continuous solid solution to adjust the conduction band valence band position, and finally make the conduction band valence band position between the two solid solution semiconductors suitable, reaching the strongest, thereby achieving effective absorption of sunlight, rapid separation of photogenerated carriers and coordinated optimization of redox potential, and significantly improving the photocatalytic performance of the catalyst. In addition, the present invention constructs an S-type heterojunction through two continuous solid solutions, which removes the limitation of the band gap of a single-component catalyst. It only needs to satisfy the oxidation potential greater than +2.59V and the reduction potential less than -0.33V for the whole, and the redox reaction can be triggered to achieve efficient degradation of ethylene under visible light.

[0024] Furthermore, the present invention adopts Zn x Cd 1-x S (0<x≤1) is a reducing semiconductor, using Bi 2 Mo y W 1-y O 6 (0<y<1) or Sb 2 Mo z W 1-z O 6 (0≤z≤1) is an oxidizing semiconductor, and the obtained heterojunction catalyst has excellent photocatalytic performance. The results of the embodiment show that the full solid solution S-type heterojunction catalyst constructed by the present invention has high catalytic activity and excellent stability for the degradation of ethylene under normal temperature and pressure and visible light conditions. The full solid solution S-type heterojunction catalyst of the present invention is applied to the storage of fruits and vegetables, which can significantly extend the shelf life of fruits and vegetables. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the photocatalytic principle of a single-component semiconductor, a traditional S-type heterojunction, and a full solid solution S-type heterojunction of the present invention;

[0026] Figure 2 Bi prepared in Example 1 2 Mo 0.2 W 0.8 O 6SEM images (left) and AFM images (right) of the nanosheets;

[0027] Figure 3 The Sb prepared in Example 1 2 Mo 0.6 W 0.4 O 6 SEM image (left), AFM image (middle) and height profile image (right) of the nanosheet;

[0028] Figure 4 The Zn prepared in Example 1 x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O 6 XRD pattern of solid solution;

[0029] Figure 5 Zn x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O 6 Test results of photocatalytic performance of solid solution;

[0030] Figure 6 X%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 Photocatalytic performance test results of S-type heterojunction catalysts;

[0031] Figure 7 Y%-Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 Photocatalytic performance test results of S-type heterojunction catalysts;

[0032] Figure 8 Zn under visible light 0.4 Cd 0.6 Performance cycle diagram of S catalytic degradation of ethylene;

[0033] Fig. 9 10%-Zn under visible light 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 Performance cycle diagram for catalytic degradation of ethylene;

[0034] Fig.10 30%-Zn under visible light 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 Performance cycle diagram for catalytic degradation of ethylene;

[0035] Fig.11 These are the test results of the fruit and vegetable preservation experiment. DETAILED DESCRIPTION

[0036] The invention provides a full solid solution S-type heterojunction catalyst, comprising a reductive semiconductor and an oxidative semiconductor, wherein the reductive semiconductor and the oxidative semiconductor are both continuous solid solutions.

[0037] In the present invention, the reducing semiconductor is preferably Zn x Cd 1-x S, wherein 0<x≤1, specifically, the value of x is 0.2, 0.4, 0.6, 0.8 or 1.0; the oxidized semiconductor is Bi 2 Mo y W 1-y O 6 or Sb 2 Mo z W 1-z O 6 , wherein 0<y<1, 0≤z≤1, specifically, the value of y is 0.2, 0.4, 0.6 or 0.8, and the value of z is 0.2, 0.4, 0.6, 0.8 or 1.0.

[0038] In the present invention, the Bi 2 Mo y W 1-y O 6 and Sb 2 Mo z W 1-z O 6 All of them are ultra-thin nanosheets, among which Bi 2 Mo y W 1-y O 6 The thickness of the ultra-thin nanosheet is 0.8 to 1.6 nm, preferably 0.8 nm.2 Mo z W 1-z O 6 The thickness of the ultra-thin nanosheet is 0.7-1.4 nm, preferably 0.7 nm; the Zn x Cd 1-x S is a quantum dot; in a specific embodiment of the present invention, Zn x Cd 1-x S quantum dots are grown in situ on Bi 2 Mo y W 1-y O 6 or Sb 2 Mo z W 1-z O 6 Ultrathin nanosheet surface.

[0039] In the present invention, the Bi 2 Mo y W 1-y O 6 The preparation method preferably comprises: mixing a bismuth source, a tungsten source, a molybdenum source, a quaternary ammonium salt and deionized water to perform a hydrothermal reaction (referred to as the first hydrothermal reaction) to obtain the Bi 2 Mo y W 1-y O 6 The bismuth source is preferably bismuth nitrate, specifically Bi(NO 3 ) 3 ·5H 2 O, the tungsten source is preferably sodium tungstate, specifically Na 2 WO 4 ·2H 2 O, the molybdenum source is preferably sodium molybdate, specifically Na 2 MoO 4 ·2H 2 O, the molar ratio of the bismuth source, tungsten source and molybdenum source is based on the Bi 2 Mo y W 1-y O 6 The chemical formula of can be determined, and no further details are given here; the quaternary ammonium salt is preferably hexadecyltrimethylammonium bromide (CTAB, chemical formula is C 19 H 42BrN). The total molar amount of the bismuth source, tungsten source and molybdenum source and the mass ratio of the quaternary ammonium salt are preferably 3-6mmol:0.05-1g, more preferably 3mmol:0.05g; the dosage ratio of the bismuth source and deionized water is preferably 2mmol:80mL; the present invention preferably first disperses the bismuth source, tungsten source, molybdenum source and quaternary ammonium salt with deionized water, stirs the obtained mixed solution for 3h, and then pours it into a high-pressure reactor, and puts the high-pressure reactor into an oven for the first hydrothermal reaction; the temperature of the first hydrothermal reaction is preferably 90-120°C, more preferably 100°C, and the time is preferably 20-24h, more preferably 24h. After the first hydrothermal reaction, the present invention preferably rinses the obtained product with deionized water and ethanol, and then freeze-dries it to obtain the Bi 2 Mo y W 1-y O 6 , specifically Bi 2 Mo y W 1-y O 6 Ultrathin nanosheets. The present invention can prepare Bi with ultrathin nanosheet morphology by the above method. 2 Mo y W 1-y O 6 , which is beneficial to increase light absorption, increase specific surface area, and have more surface active sites.

[0040] In the present invention, the Sb 2 Mo z W 1-z O 6 The preparation method preferably comprises: mixing an antimony source, a tungsten source, a molybdenum source, a quaternary ammonium salt and deionized water to perform a hydrothermal reaction (referred to as the second hydrothermal reaction) to obtain the Sb 2 Mo z W 1-z O 6 In the present invention, the antimony source is preferably antimony chloride (SbCl 3 ), the tungsten source is preferably sodium tungstate, specifically Na 2 WO 4 ·2H 2 O, the molybdenum source is preferably sodium molybdate, specifically Na 2 MoO 4 ·2H 2 O, when z=0, the addition of molybdenum source is omitted, and when z=1, the addition of tungsten source is omitted; the quaternary ammonium salt is preferably hexadecyltrimethylammonium bromide (CTAB, chemical formula C 19 H 42BrN). The total molar amount of the bismuth source, tungsten source and molybdenum source and the mass ratio of the quaternary ammonium salt are preferably 3-6 mmol: 0.05-1 g; more preferably 3 mmol: 0.05 g. The temperature of the second hydrothermal reaction is preferably 90-120 ° C, more preferably 100 ° C, and the time is preferably 20-24 h, more preferably 24 h; the specific operation mode and post-treatment mode of the second hydrothermal reaction are consistent with the first hydrothermal reaction, which will not be repeated here. The present invention can prepare Sb with ultra-thin nanosheet morphology through the above method. 2 Mo z W 1-z O 6 , which is beneficial to increase light absorption, increase specific surface area, and have more surface active sites.

[0041] In the present invention, the full solid solution S-type heterojunction catalyst is Zn x Cd 1-x S / Bi 2 Mo y W 1-y O 6 or Zn x Cd 1-x S / Sb 2 Mo z W 1-z O 6 , preferably Zn 0.4 Cd 0.6 S / Bi 2 Mo 0.2 W 0.8 O 6 or Zn 0.4 Cd 0.6 S / Sb 2 Mo 0.6 W 0.4 O 6 ; The Zn x Cd 1-x S / Bi 2 Mo y W 1-y O 6 Medium Zn x Cd 1-x The mass fraction of S is preferably 5-20%, specifically 5%, 7%, 10%, 15% or 20%, more preferably 10%; the Zn x Cd 1-x S / Sb 2 Mo z W 1-z O 6 Medium Zn x Cd 1-xThe mass fraction of S is preferably 20-50%, specifically 20%, 25%, 30%, 35%, 40% or 50%, more preferably 30%.

[0042] The present invention adopts two continuous solid solutions as an oxidizing semiconductor and a reducing semiconductor respectively, and constructs a full solid solution S-type heterojunction catalyst. Based on the continuously adjustable energy band structure of the continuous solid solution, the full solid solution S-type heterojunction with controllable built-in electric field can realize the coordinated optimization of effective absorption of sunlight (ηabs), rapid photogenerated carrier separation (ηsep) and redox potential (ηrec). The carrier separation efficiency is positively correlated with the built-in electric field strength. The finally obtained full solid solution S-type heterojunction catalyst has excellent photocatalytic performance.

[0043] The present invention also provides a method for preparing the full solid solution S-type heterojunction catalyst described in the above scheme, comprising the following steps:

[0044] mixing an oxidative semiconductor and an alcohol solvent to obtain a suspension;

[0045] The suspension is mixed with raw materials for preparing a reducing semiconductor, and a full solid solution S-type heterojunction catalyst is prepared by an in-situ hydrothermal method.

[0046] The present invention mixes an oxidative semiconductor and an alcohol solvent to obtain a suspension. In the present invention, the alcohol solvent is preferably ethanol, and the oxidative semiconductor is preferably Bi 2 Mo y W 1-y O 6 or Sb 2 Mo z W 1-z O 6 , the Bi 2 Mo y W 1-y O 6 or Sb 2 Mo z W 1- z O 6 The preparation method is not described in detail. The dosage ratio of the oxidative semiconductor and the alcohol solvent is preferably 0.3-0.6 g:75-85 mL, more preferably 0.4 g:80 mL; the present invention preferably adds the oxidative semiconductor to ethanol and stirs for 1 hour to form a uniform suspension.

[0047] After obtaining the suspension, the present invention mixes the suspension with raw materials for preparing a reducing semiconductor, and prepares a full solid solution S-type heterojunction catalyst by an in-situ hydrothermal method. In the present invention, when the reducing semiconductor is Zn x Cd 1-xS, the in-situ hydrothermal method comprises: mixing the suspension with a cadmium source, a zinc source, and a sulfur source for an in-situ hydrothermal reaction to obtain the full solid solution S-type heterojunction; the cadmium source is preferably cadmium acetate, specifically Cd(CH 3 COO 2 ·2H 2 O, when x=1, the addition of cadmium source is omitted; the zinc source is preferably zinc acetate, specifically Zn(CH 3 COO 2 ·2H 2 O, the sulfur source is preferably thiourea (CH 4 N 2 S); the molar ratio of the cadmium source, the zinc source and the sulfur source is based on Zn x Cd 1-x The chemical formula of S can be determined and will not be elaborated here; the present invention preferably adds the cadmium source and the zinc source to the suspension first, stirs for 2 hours and then adds thiourea, and then transfers the resulting mixture to an autoclave for in-situ hydrothermal reaction. The temperature of the in-situ hydrothermal reaction is preferably 80-120°C, more preferably 120°C, and the time is preferably 10-12h, more preferably 12h. After the in-situ hydrothermal reaction is completed, the present invention preferably collects the solid sample and washes it with deionized water, and then freeze-dries it to obtain the full solid solution S-type heterojunction catalyst. In the present invention, the ultra-thin oxidizing semiconductor is Zn x Cd 1-x S quantum dots (Zn x Cd 1-x S QDs) provide a stable nucleation surface, enabling heterogeneous nucleation and growth, thereby enabling the in-situ generation of Zn on the surface of ultrathin nanosheet-like oxidized semiconductors. x Cd 1-x SQDs are beneficial for capturing more light in photocatalytic reactions and providing more surface active sites.

[0048] The present invention also provides the full solid solution S-type heterojunction catalyst described in the above scheme or the use of the full solid solution S-type heterojunction catalyst described in the above scheme in photocatalysis.

[0049] In the present invention, the application preferably includes: using the full solid solution S-type heterojunction catalyst to catalytically degrade ethylene; the temperature for catalytically degrading ethylene is preferably 15 to 50°C, specifically room temperature, the pressure is preferably normal pressure, and the illumination condition is full light or visible light irradiation; in a specific embodiment of the present invention, ethylene is preferably catalytically degraded under normal temperature and pressure and visible light conditions. The full solid solution S-type heterojunction catalyst provided by the present invention has efficient catalytic activity and excellent stability for the degradation of ethylene, and its application in fruit and vegetable storage can effectively extend the shelf life of fruits and vegetables.

[0050] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Example 1

[0052] Zn x Cd 1-x S (0<x≤1) solid solution, Bi 2 Mo y W 1-y O 6 Solid solution (0<y<1), Sb 2 Mo z W 1-z O 6 Preparation of (0≤z≤1) solid solution:

[0053] Zn was obtained by hydrothermal method x Cd 1-x S (0<x≤1) powder. Taking x=0.4 as an example, the preparation method is as follows: 0.3810g thiourea (CH 4 N 2 S, 5 mmol), 0.4390 g Zn(CH 3 CO 2 ) 2 ·2H 2 O (2 mmol) and 0.7997 g Cd (CH 3 COO 2 ·2H 2 O (3 mmol) was dissolved in ethanol (80 mL). The resulting solution was transferred to a high-pressure reactor (100 mL) and reacted at 120 ° C for 10 h. The resulting solid product was collected, washed with deionized water, and freeze-dried for 24 h to obtain Zn 0.4 Cd 0.6 S.

[0054] Change Zn(CH 3 CO 2 ) 2 ·2H 2 O and Cd(CH 3 COO 2 ·2H 2 O molar ratio, Zn was prepared by the same preparation method 0.2 Cd 0.8 S, Zn 0.6 Cd 0.4 S and Zn 0.8Cd 0.2 S. In addition, Zn(CH 3 CO 2 ) 2 ·2H 2 O was added to prepare CdS, omitting Cd(CH 3 COO 2 ·2H 2 O was added to prepare ZnS.

[0055] Ultrathin Bi was synthesized by hydrothermal method. 2 Mo y W 1-y O 6 Taking y = 0.2 as an example, the preparation method is as follows: 2 mmol Bi(NO 3 ) 3 ·5H 2 O (0.9701 g), 0.8 mmol Na 2 WO 4 ·2H 2 O (0.2639 g), 0.2 mmol Na 2 MoO 4 ·2H 2 O (0.0484 g), 0.05 g CTAB (C 19 H 42 BrN) was dispersed with 80 mL of fresh deionized water. The mixed solution was then stirred for 3 h and poured into a high-pressure reactor (100 mL). It was kept in an oven at 100 °C for 24 h. After the reaction was rinsed with deionized water and ethanol, it was freeze-dried for 24 h to obtain Bi 2 Mo 0.2 W 0.8 O 6 Nanosheets. The obtained Bi 2 Mo 0.2 W 0.8 O 6 The SEM image (left) and AFM image (right) of the nanosheets are shown in Figure 2 As shown, according to Figure 2 It can be seen that the Bi prepared in this embodiment 2 Mo 0.2 W 0.8 O 6 It has an ultra-thin nanosheet morphology with a thickness of about 0.8nm.

[0056] Change Na 2 WO 4 ·2H 2 O and Na 2 MoO 4 ·2H 2 O molar ratio, and Bi2 Mo 0.4 W 0.6 O 6 、Bi 2 Mo 0.6 W 0.4 O 6 and Bi 2 Mo 0.8 W 02 O 6 In addition, Na is omitted 2 MoO 4 ·2H 2 Addition of O to prepare Bi 2 WO 6 , omit Na 2 WO 4 ·2H 2 Addition of O to prepare Bi 2 MoO 6 .

[0057] Ultrathin Sb was synthesized by hydrothermal method. 2 Mo z W 1-z O 6 Solid solution. Taking z = 0.6 as an example, the preparation method is as follows: 2 mmol SbCl 3 (0.456 g), 0.4 mmol Na 2 WO 4 ·2H 2 O (0.1320 g), 0.6 mmol Na 2 MoO 4 ·2H 2 O (0.1452 g), 0.0500 g CTAB (C 19 H 42 BrN) was dispersed with 80 mL of fresh deionized water. The mixed solution was then stirred for 3 h and poured into a high-pressure reactor (100 mL). The hydrothermal reaction was carried out in an oven at 100 °C for 24 h. After the reaction was rinsed with deionized water and ethanol, it was freeze-dried for 24 h to obtain Sb 2 Mo 0.6 W 0.4 O 6 Nanosheets. The obtained Sb 2 Mo 0.6 W 0.4 O 6 The SEM image (left), AFM image (middle) and height profile image (right) of the nanosheets are shown in Figure 2. Figure 3 As shown, according to Figure 3 It can be seen that the Sb prepared in this example 2 Mo 0.6 W 0.4 O6 It has an ultra-thin nanosheet morphology with a thickness of about 0.7nm.

[0058] Change Na 2 WO 4 ·2H 2 O and Na 2 MoO 4 ·2H 2 O molar ratio, Sb was prepared by the same preparation method 2 Mo 0.2 W 0.8 O 6 , Sb 2 Mo 0.4 W 0.6 O 6 and Sb 2 Mo 0.8 W 0.2 O 6 In addition, Na is omitted 2 WO 4 ·2H 2 O addition to prepare Sb 2 MoO 6 , omit Na 2 MoO 4 ·2H 2 O addition to prepare Sb 2 WO 6 .

[0059] Figure 4 The Zn prepared in this example x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O 6 The XRD pattern of the solid solution, according to Figure 4 It can be seen that this embodiment achieves effective preparation of the above solid solution.

[0060] Example 2

[0061] In a sealed container, the Zn prepared in Example 1 was x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O6 The solid solution acts as a catalyst to degrade ethylene gas.

[0062] The photocatalytic performance test of the present invention is carried out in a closed container. The specific implementation process is as follows:

[0063] Weigh Zn x Cd 1-x 0.2 g of S solid solution was evenly dispersed in a watch glass with an inner diameter of 60 mm. The watch glass was placed in a closed container with a volume of 250 mL. The air generator was used to generate flowing clean air to purge the container. 25 μL of ethylene was filled in. Samples were taken at appropriate intervals and the concentration change of ethylene gas in the reactor was detected by gas chromatograph. x Cd 1-x S solid solution replaced by Bi 2 Mo y W 1-y O 6 Solid solution or Sb 2 Mo z W 1-z O 6 Solid solution, the same method is used to test the performance. 2 MoO 6 、Bi 2 WO 6 、ZnS、CdS、Sb 2 WO 6 and Sb 2 MoO 6 The ethylene catalytic performance test was carried out under the same conditions.

[0064] Zn x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O 6 The catalytic performance test results of the solid solution are as follows Figure 5 As shown. Figure 5 It can be seen that Zn x Cd 1-x S solid solution, Bi 2 Mo y W 1-y O 6 Solid solution and Sb 2 Mo z W 1-z O 6 The catalytic performance of solid solutions is higher than that of single materials.

[0065] Example 3

[0066] Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 Preparation and catalytic performance test of S-type heterojunction catalyst:

[0067] In-situ hydrothermal method was used to prepare Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 . With Zn 0.4 Cd 0.6 Taking the mass fraction of S QDs as 10% as an example, the preparation method is as follows: First, Bi 2 Mo 0.2 W 0.8 O 6 Nanosheets (0.4000 g) were added to ethanol (80 mL) and stirred for 1 h to form a uniform suspension. Then, 0.0510 g of Cd(CH 3 COO 2 ·2H 2 O and 0.0280 g Zn(CH 3 CO 2 ) 2 ·2H 2 O and stirred for 2 h. Subsequently, 0.0242 g of CH 4 N 2 S was added to the solution. The obtained suspension was transferred to an autoclave (100 mL) and reacted at 120°C for 10 h. Finally, the collected samples were washed with deionized water and freeze-dried for 24 h.

[0068] Change Cd(CH 3 COO 2 ·2H 2 O、Zn(CH 3 CO 2 ) 2 ·2H 2 O and CH 4 N 2 S dosage, respectively, to prepare Zn 0.4 Cd 0.6 S QDs with mass fractions of 5%, 7%, 10%, 15% and 20% Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo0.2 W 0.8 O 6 S-type heterojunction catalyst, denoted as X%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 S-type heterojunction catalyst (X=5, 7, 10, 15, 20, abbreviated as X%-ZCS / BMWO).

[0069] Catalytic performance test: Take X%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 0.2 g of S-type heterojunction catalyst was evenly dispersed in a watch glass with an inner diameter of 60 mm. The watch glass was placed in a closed container with a volume of 250 mL. An air generator was used to generate flowing clean air to purge the container. 25 μL of ethylene was filled in and a gas chromatograph was used to detect the concentration change of ethylene gas in the reactor.

[0070] Test results such as Figure 6 As shown, according to Figure 6 It can be seen that Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 The S-type heterojunction catalysts all showed excellent catalytic performance for ethylene degradation, among which 10%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 The S-type heterojunction catalyst showed the best performance in ethylene degradation.

[0071] Example 4

[0072] Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 Preparation and catalytic performance testing of S-type heterojunction series catalysts:

[0073] In-situ hydrothermal method was used to prepare Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo0.6 W 0.4 O 6 . With Zn 0.4 Cd 0.6 Taking the mass fraction of S QDs as 20% as an example, the preparation method is as follows: first, 0.4000g Sb 2 Mo 0.6 W 0.4 O 6 The nanosheets were added to ethanol (80 mL) and stirred for 1 h to form a uniform suspension. Then, 0.1020 g of Cd(CH 3 COO 2 ·2H 2 O and 0.0560 g Zn(CH 3 CO 2 ) 2 ·2H 2 O and stirred for 2 h. Subsequently, 0.0484 g of CH 4 N 2 S was added to the solution. The obtained suspension was transferred to an autoclave (100 mL) and reacted at 120° C. for 10 h. Finally, the collected sample was washed with deionized water and freeze-dried for 24 h.

[0074] Change Cd(CH 3 COO 2 ·2H 2 O、Zn(CH 3 CO 2 ) 2 ·2H 2 O and CH 4 N 2 S dosage, respectively, to prepare Zn 0.4 Cd 0.6 S QDs with mass fractions of 20%, 25%, 30%, 35%, 40% and 50% Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 S-type heterojunction catalyst, denoted as Y%-Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 S-type heterojunction catalyst (Y=20, 25, 30, 35, 40, 50, abbreviated as Y%-ZCS / SMWO).

[0075] 0.2 g of Y%-ZCS / SMWO S-type heterojunction (Y=20, 25, 30, 35, 40, 50) catalyst was weighed respectively and evenly dispersed in a watch glass with an inner diameter of 60 mm. The watch glass was placed in a closed container with a volume of 250 mL. An air generator was used to generate flowing clean air to purge the container. 25 μL of ethylene was filled in and the concentration change of ethylene gas in the reactor was detected by gas chromatograph.

[0076] The test results are as follows Figure 7 As shown, according to Figure 7 It can be seen that Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 The S-type heterojunction catalysts all showed excellent catalytic performance for ethylene degradation, among which 30%-Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 The S-type heterojunction catalyst showed the best performance in ethylene degradation.

[0077] Example 5

[0078] Catalytic stability test: Under visible light conditions, the 0.4 Cd 0.6 S, 10%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 and 30%-Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 Carry out cyclic catalytic test, the specific test method is as follows:

[0079] Process 1: In the first test, 0.2 g of the catalyst was taken and evenly dispersed in a watch glass with an inner diameter of 60 mm. The watch glass was placed in a closed container with a volume of 250 mL. The air generator was used to generate flowing clean air to purge the container. 25 μL of ethylene was filled in. The concentration change of ethylene gas in the reactor was detected by gas chromatograph.

[0080] Process 2: After the ethylene gas in the sealed container is degraded, the catalyst is dried at 60°C for 8 hours, redispersed in a watch glass with an inner diameter of 60 mm, and process 1 is repeated;

[0081] Process 3: The method is the same as process 2.

[0082] The test results are as follows Figures 8 to 10 As shown. Figures 8 to 10 It can be seen that and Zn 0.4 Cd 0.6 Compared with 10%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 and 30%-Zn 0.4 Cd 0.6 S QDs / Sb 2 Mo 0.6 W 0.4 O 6 It can not only rapidly catalyze the degradation of ethylene, but also has good stability, and its activity will not decrease after long-term catalysis.

[0083] Example 6

[0084] Using 10%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 Carry out the fruit and vegetable preservation experiment, the specific operation method is as follows:

[0085] Banana and 0.3g 10% -Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 The catalyst was placed in a 3000mL fully sealed transparent glass container, and the light source was a 10W LED lamp, and the changes in the banana were observed. Another control experiment was set up without using the catalyst.

[0086] The experimental results are as follows Fig.11 As shown. Fig.11 It can be seen that the 10%-Zn 0.4 Cd 0.6 S QDs / Bi 2 Mo 0.2 W 0.8 O 6 Catalysts can effectively extend the shelf life of fruits and vegetables.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A full solid solution S-type heterojunction catalyst, characterized in that: The invention comprises a reductive semiconductor and an oxidative semiconductor, wherein the reductive semiconductor and the oxidative semiconductor are both continuous solid solutions.

2. The full solid solution S-type heterojunction catalyst according to claim 1, characterized in that: The reducing semiconductor is Zn x Cd 1-x S, wherein 0<x≤1; the oxidizing semiconductor is Bi2Mo y W 1-y O6 or Sb2Mo z W 1-z O6, where 0<y<1, 0≤z≤1.

3. The all-solid solution S-type heterogeneous catalyst junction according to claim 2, characterized in that: The Bi2Mo y W 1-y O6 and Sb2Mo z W 1-z O6 are all ultra-thin nanosheets, among which Bi2Mo y W 1-y The thickness of the O6 ultra-thin nanosheets is 0.8 to 1.6 nm, and the Sb2Mo z W 1- z The thickness of the O6 ultra-thin nanosheet is 0.7-1.4 nm; the Zn x Cd 1-x S is a quantum dot; The value of x is 0.2, 0.4, 0.6, 0.8 or 1.0, the value of y is 0.2, 0.4, 0.6 or 0.8, and the value of z is 0, 0.2, 0.4, 0.6, 0.8 or 1.

0.

4. The full solid solution S-type heterojunction catalyst according to claim 2, characterized in that: The Bi2Mo y W 1-y The preparation method of O6 comprises: The bismuth source, tungsten source, molybdenum source, quaternary ammonium salt and deionized water are mixed for hydrothermal reaction to obtain the Bi2Mo y W 1-y O6; the temperature of the hydrothermal reaction is 90-120°C and the time is 20-24h.

5. The full solid solution S-type heterojunction catalyst according to claim 2, characterized in that: The Sb2Mo z W 1-z The preparation method of O6 comprises: The antimony source, tungsten source, molybdenum source, quaternary ammonium salt and deionized water are mixed for hydrothermal reaction to obtain the Sb2Mo z W 1-z O6; the temperature of the hydrothermal reaction is 90-120°C and the time is 20-24h.

6. The all-solid solution S-type heterojunction catalyst according to claim 3, characterized in that: The full solid solution S-type heterojunction catalyst is Zn x Cd 1-x S / Bi2Mo y W 1-y O6 or Zn x Cd 1-x S / Sb2Mo z W 1-z O6; Zn x Cd 1-x S / Bi2Mo y W 1-y Zn in O6 x Cd 1-x The mass fraction of S is 5 to 20%; the Zn x Cd 1-x S / Sb2Mo z W 1-z Zn in O6 x Cd 1-x The mass fraction of S is 20 to 50%.

7. The method for preparing the full solid solution S-type heterojunction catalyst according to any one of claims 1 to 6, characterized in that: The following steps are involved: mixing an oxidative semiconductor and an alcohol solvent to obtain a suspension; The suspension is mixed with raw materials for preparing a reducing semiconductor, and a full solid solution S-type heterojunction catalyst is prepared by an in-situ hydrothermal method.

8. The preparation method according to claim 7, characterized in that: When the reducing semiconductor is Zn x Cd 1-x S, the in-situ hydrothermal method comprises: mixing the suspension with a cadmium source, a zinc source and a sulfur source for an in-situ hydrothermal reaction to obtain the full solid solution S-type heterojunction; the temperature of the in-situ hydrothermal reaction is 80 to 120° C., and the time is 10 to 12 hours.

9. Use of the full solid solution S-type heterojunction catalyst according to any one of claims 1 to 6 or the full solid solution S-type heterojunction catalyst prepared by the preparation method according to claim 7 or 8 in photocatalysis.

10. The use according to claim 9, characterized in that: The application includes: using the full solid solution S-type heterojunction catalyst to catalytically degrade ethylene.

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