A z-type co2 reduction full reaction system and a preparation method and application thereof

Abstract

The application provides a Z-type CO2 reduction full reaction system, a preparation method and application thereof, the Z-type CO2 reduction full reaction system comprising a CO2 reduction photocatalyst, an H2O oxidation photocatalyst and an oxidation-reduction electron mediator; the CO2 reduction photocatalyst comprises Bi4NbO8X or Bi4TaO8X loaded with double noble metals on the surface, and X comprises Cl and / or Br; the H2O oxidation photocatalyst comprises a surface modified WO3; the oxidation-reduction electron mediator comprises I ‑ / IO3 ‑ ; the CO2 reduction photocatalyst and the H2O oxidation photocatalyst are coupled by the oxidation-reduction electron mediator to form the Z-type CO2 reduction full reaction system. The Z-type full reaction system constructed in the application has the characteristics of wide visible light response range and high interface charge transport efficiency, can realize efficient conversion of CO2 and H2O into CO and O2 under the condition of no sacrificial agent, and has the potential for industrial large-scale production.

Description

Technical Field

[0001] This application belongs to the field of photocatalysis technology, and relates to a Z-type CO2 reduction total reaction system, its preparation method and application. Background Technology

[0002] Photocatalytic CO2 reduction technology utilizes solar energy to convert CO2 into high-value-added chemicals such as CO, CH4, and CH3OH, which is one of the important ways to achieve carbon resource recycling and mitigate the greenhouse effect. In the photocatalytic process, the semiconductor photocatalyst absorbs sunlight to generate photogenerated electrons and holes. Electrons drive the CO2 reduction reaction, while holes drive the oxidation reaction (usually water oxidation), thereby realizing the conversion of solar energy into chemical energy.

[0003] Currently, photocatalytic CO2 reduction systems mainly include single photocatalyst systems and Z-type photocatalyst systems. Single photocatalyst systems are simple to construct, but they suffer from severe recombination of photogenerated electrons and holes. The redox capacity of a single material is insufficient to meet the thermodynamic requirements of both CO2 reduction and water oxidation, resulting in low overall photocatalytic efficiency.

[0004] Z-type photocatalytic systems, by coupling CO2 reduction photocatalysts with water oxidation photocatalysts and utilizing electron mediators for interfacial charge transfer, can effectively promote the spatial separation of photogenerated carriers, thus attracting widespread attention. Existing Z-type photocatalytic CO2 reduction systems mainly employ metal oxides, metal sulfides, nitrides, and graphitic carbon nitrides as photocatalysts, combined with Fe... 3+ / Fe 2+ I - / IO3 - The redox pairs construct electron transport channels. However, the above systems still suffer from problems such as insufficient visible light utilization, limited CO2 adsorption and activation capacity, low interfacial charge transport efficiency, and poor redox energy level matching between the two photocatalysts. In addition, many systems still require the addition of sacrificial agents to consume holes to maintain the reaction, making it difficult to achieve a complete reaction process coupling CO2 reduction and water oxidation.

[0005] Therefore, developing a Z-type full-reaction system that combines excellent visible light response, efficient carrier separation, and good redox matching is of great practical significance for improving solar energy utilization efficiency and promoting CO2 resource utilization. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application aims to provide a Z-type CO2 reduction complete reaction system, its preparation method, and its applications. The Z-type complete reaction system constructed in this application features a wide visible light response range and high interfacial charge transport efficiency, enabling efficient conversion of CO2 and H2O to CO and O2 without sacrificial agents. Furthermore, the system offers flexible combinations, broad applicability, and a simple preparation process, possessing the potential for large-scale industrial production. This system effectively solves the problems of low charge separation efficiency, insufficient visible light utilization, and difficulty in achieving complete CO2-H2O conversion in existing carbon dioxide photocatalytic systems, providing an efficient, stable, and sustainable technical solution for solar-driven CO2 resource utilization.

[0007] To achieve the purpose of this application, the following technical solution is adopted: In a first aspect, this application provides a Z-type CO2 reduction total reaction system, which includes a CO2 reduction photocatalyst, an H2O oxidation photocatalyst, and a redox electron mediator; The CO2 reduction photocatalyst includes Bi4NbO8X or Bi4TaO8X with two noble metals supported on its surface, where X includes Cl and / or Br. The H2O oxidation photocatalyst includes surface-modified WO3; The redox electron mediator includes I - / IO3 - ; The CO2 reduction photocatalyst and the H2O oxidation photocatalyst are coupled through the redox electron mediator to form a Z-type CO2 reduction complete reaction system.

[0008] It is understood that in this application, "full reaction" refers to the complete photocatalytic reaction process in which CO2 reduction and H2O oxidation are completed simultaneously without the addition of sacrificial agents and using only H2O as an electron donor.

[0009] In this application, Bi4NbO8X or Bi4TaO8X exhibits excellent visible light response and CO2 adsorption and activation capabilities; surface-modified WO3 possesses excellent water oxidation activity and stability, and can form a good redox matching relationship with Bi4NbO8X or Bi4TaO8X; - / IO3 - Electron mediators can promote directional electron transport, reduce the recombination probability of photogenerated carriers, and thus improve the overall efficiency of photocatalytic reaction.

[0010] Under visible light irradiation, this system achieves effective separation and directional transport of photogenerated electrons and holes, driving the synergistic process of CO2 reduction and H2O oxidation. The ratio of CO to O2 generated is close to the theoretical stoichiometry. This solves the problems of low visible light utilization, severe recombination of photogenerated electrons and holes, insufficient CO2 activation capacity, and difficulty in achieving complete CO2-H2O conversion in existing photocatalytic CO2 reduction systems. It has the advantages of high visible light utilization, high carrier separation efficiency, good CO selectivity, excellent system stability, and no need for sacrificial agents. It provides an efficient, stable, and industrially promising technical solution for solar-driven CO2 resource utilization.

[0011] In some embodiments, the CO2 reduction photocatalyst is Bi4NbO8Cl or Bi4TaO8Cl with two noble metals supported on its surface. 0.9 Br 0.1 The dual noble metals include Pt-Ag or Au-Ag.

[0012] And / or, the Bi4NbO8X surface is loaded with Ag or CoO. x -Ag, x>0.

[0013] In this application, the supported cocatalyst can further promote the spatial separation of photogenerated electrons and holes, improve the interfacial charge transport efficiency, and thus effectively enhance the CO2 reduction performance; after optimization of the cocatalyst, the CO selectivity in the system can reach 100%.

[0014] In some embodiments, the surface is loaded with a dual noble metal, Bi4TaO8Cl. 0.9 Br 0.1 In this context, the dual noble metals are Au-Ag, and the mass ratio of Au to Ag is 1:(2~5), such as 1:2, 1:3.3, 1:4 or 1:5, etc.

[0015] When the two noble metals are Au-Ag, both Au and Ag serve as reduction sites, forming an Au-Ag core-shell structure. (Bi4TaO8Cl) 0.9 Br 0.1 Au is preferentially loaded onto the surface, and then Ag is deposited further, so that Ag is mainly distributed in the outer region of Au particles, forming a bimetallic structure with Au as the core and Ag as the shell.

[0016] In this core-shell structure, Au and Bi4TaO8Cl 0.9 Br 0.1Upon contact, a Schottky junction forms at the interface, efficiently capturing photogenerated electrons. Simultaneously, interfacial interactions induce charge redistribution, shifting the Au Fermi level towards a more negative potential and reducing its effective work function, thereby promoting electron migration from the Au core to the outer Ag shell. The Ag shell, with its stronger CO2 adsorption capacity and abundant surface active sites, effectively promotes the capture and activation of CO2 molecules, as well as the formation and stabilization of the key intermediate ·COOH, accelerating subsequent reduction reactions. The functional division and synergistic effect of Au and Ag in electron transport and surface reactions optimizes the core-shell structure simultaneously at the thermodynamic driving force and reaction kinetics levels.

[0017] And / or, when the Bi4NbO8X surface is loaded with Ag, the Ag loading amount is 0.8wt%~1.2wt%, for example 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, or 1.3wt%, etc.; the Bi4NbO8X surface is loaded with CoO x When -Ag, CoO x The loading amount is 0.2wt%~0.4wt%, for example 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, or 0.4wt%, etc., CoO x The mass ratio of Ag to Ag is (0.2~0.4):1, for example, 0.2:1, 0.25:1, 0.3:1, 0.35:1 or 0.4:1, etc.

[0018] In some embodiments, the surface-modified WO3 comprises a load of PtO. x and through Cs + WO3 that has undergone exchange and acid treatment, x > 0.

[0019] In the surface-modified WO3, the PtO x The loading of Pt is 0.3wt%~0.7wt%, for example 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt% or 0.7wt%; the molar ratio of Cs to W is 1:(90~110), for example 1:90, 1:92, 1:95, 1:98 or 1:100.

[0020] In some embodiments, the mass ratio of the CO2 reduction photocatalyst to the H2O oxidation photocatalyst is 1:(0.8~1.2), for example, 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc.

[0021] Secondly, this application provides a method for preparing the Z-type CO2 reduction total reaction system as described in the first aspect, the preparation method comprising: S1. Bi4NbO8X or Bi4TaO8X is prepared by molten salt method, and two noble metals are loaded on the Bi4TaO8X to obtain a CO2 reduction photocatalyst. S2. Surface modification of WO3 yields H2O oxidation photocatalyst; S3. Mix the CO2 reduction photocatalyst, H2O oxidation photocatalyst and NaI aqueous solution to obtain a Z-type CO2 reduction complete reaction system.

[0022] In some embodiments, the method for preparing Bi4NbO8X in step S1 includes: using BiOCl, Bi2O3, and Nb2O5 as raw materials, mixing them with a first molten salt to obtain a first mixture, and then sequentially grinding and calcining to obtain the Bi4NbO8X.

[0023] The method for preparing Bi4TaO8X in step S1 includes: using BiOCl, BiOBr, Bi2O3, and Ta2O5 as raw materials, mixing them with a second molten salt to obtain a second mixture, and then sequentially grinding and calcining them to obtain Bi4TaO8X.

[0024] The preparation method further includes: loading Ag or CoO onto the surface of Bi4NbO8X. x -Ag.

[0025] In some embodiments, the first molten salt includes any one or a combination of at least two of NaCl, CsCl, or KCl; the content of the first molten salt in the first mixture is 0.3 mol% to 1.0 mol%, for example, 0.3 mol%, 0.4 mol%, 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.8 mol%, or 1 mol%.

[0026] And / or, the second molten salt comprises NaCl and KCl.

[0027] And / or, the temperatures of the first calcination and the second calcination are each independently 823K~905K, such as 823K, 853K, 873K, 883K, 893K, 903K or 905K, etc.; the holding times are each independently 5h~15h, such as 5h, 8h, 10h, 12h or 15h, etc.

[0028] And / or, the method of loading Pt-Ag or Au-Ag on the Bi4TaO8X includes: first loading Pt or Au by impregnation hydrogenation, and then loading Ag by photodeposition. And / or, the method of loading Ag onto the Bi4NbO8X surface includes photodeposition to load CoO onto the Bi4NbO8X surface. xThe methods for loading CoO with Ag include: firstly, using photodeposition to load CoO. x Ag is then loaded using photodeposition. The impregnation hydrogenation method includes: mixing Bi4TaO8X with a Pt salt solution or an Au salt solution, drying the mixture, and then heating it in a hydrogen-containing atmosphere. The photodeposition method includes: mixing Bi4TaO8X or Bi4NbO8X with a salt solution of the metal to be deposited, and then performing a photoreaction under an Xe lamp.

[0029] In some embodiments, the method for surface modification of WO3 in step S2 includes: immersing WO3 in a Pt salt solution, and after the immersion is completed, calcining it for the fourth time in an air atmosphere to obtain PtO-loaded WO3. x WO3, then proceed with Cs in sequence. + The surface-modified WO3 was obtained by exchange and acid exchange.

[0030] The Cs + The exchange method includes: loading the PtO x WO3 was impregnated in a Cs2CO3 solution and then subjected to a fifth calcination.

[0031] The acid exchange method includes: [the acid exchange method is described in the context of] Cs. + The exchanged products were soaked in H2SO4 solution, and then stirred, washed and dried in sequence.

[0032] And / or, the concentration of the NaI aqueous solution in step S3 is 0.5mM to 10mM, for example, 0.5mM, 1mM, 3mM, 5mM, 8mM or 10mM.

[0033] Thirdly, this application also provides an application of the Z-type CO2 reduction total reaction system as described in the first aspect, the application including solar-driven CO2 reduction.

[0034] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0035] Compared with the prior art, this application has the following advantages: (1) This application constructs a photocatalyst for carbon dioxide reduction composed of Bi-Ta / Nb-based oxyhalide carbon dioxide reduction, a photocatalyst for water oxidation composed of surface-modified WO3, and I - / IO3 -The Z-type total reaction system, composed of redox electron mediators, achieves effective coupling of CO2 reduction and H2O oxidation, enabling the synergistic conversion of CO2 and H2O without the need for sacrificial agents. The CO to O2 generation ratio is close to the theoretical stoichiometric ratio, allowing for stable operation over extended periods.

[0036] (2) The Bi-Ta / Nb-based oxyhalide photocatalyst, cocatalyst and surface-modified WO3 involved in this application are all prepared by mature processes. The system composition is flexible and the construction method is simple. It can be controlled according to different reaction requirements and has good scalability and application potential. Attached Figure Description

[0037] Figure 1 These are the XRD patterns of the catalysts provided in Examples 1 and 2.

[0038] Figure 2 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 2.

[0039] Figure 3 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 3.

[0040] Figure 4 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 4.

[0041] Figure 5 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 5.

[0042] Figure 6 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 6.

[0043] Figure 7 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 7.

[0044] Figure 8 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 8.

[0045] Figure 9 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 9.

[0046] Figure 10 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 10.

[0047] Figure 11 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 1 and 11.

[0048] Figure 12 These are the XRD patterns of the catalysts provided in Examples 12 and 13.

[0049] Figure 13 These are the UV-vis DRS spectra of the catalysts provided in Examples 12 and 13.

[0050] Figure 14 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 12 and 14.

[0051] Figure 15 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 12 and 15.

[0052] Figure 16 This is a graph showing the CO and O2 generation rates of the catalysts provided in Examples 12 and 16.

[0053] Figure 17 This is a graph showing the changes in CO generation rate and apparent quantum efficiency of the catalyst provided in Example 12 as a function of incident light wavelength.

[0054] Figure 18 This is a cyclic stability test diagram of the catalyst provided in Example 12 in the visible light-driven CO2 reduction Z-type full reaction. Detailed Implementation

[0055] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0056] "The scope of this application can be defined by a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower limit and upper limit values ​​can be arbitrarily combined to form a new range. That is, any lower limit value can be combined with any upper limit value to form a valid range. For example, if the ranges of 60~120 and 80~110 are listed for a specific parameter, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this application. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then 1~3, 1~4, and 2~5 can be defined as ranges of 1~3, 1~4, and 5~ ... All ranges 1~5, 2~3, 2~4, and 2~5 fall within the scope of this application. In this application, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only an abbreviation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, and 10. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0057] In this application, "at least two combinations" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or at least two combinations" means any one of the listed items, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this application. In this application, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this application, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0058] In this application, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond those listed unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this application, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this application. The term "embodiment" as used in this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments that do not conflict with existing technologies. The ordinal numbers "first," "second," "third," and "fourth," etc., used in this application in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect," are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0059] In this application, the order in which the steps are written in the methods described in the various embodiments does not imply a strict execution order. The actual execution order of each step should be determined according to its function and possible internal logic. Unless otherwise specified, all steps in this application can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0060] The term "embodiment" as used in this application means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0061] In this application, "room temperature" generally refers to 4℃~35℃, and may refer to 20℃±5℃. In some embodiments of this application, room temperature refers to 20℃~30℃.

[0062] Example 1 This embodiment provides a Z-type CO2 reduction total reaction system, including a CO2 reduction photocatalyst, an H2O oxidation photocatalyst, and a redox electron mediator; wherein, the CO2 reduction photocatalyst is Bi4NbO8Cl supported with Ag cocatalyst (Ag loading is 1wt%), and the H2O oxidation photocatalyst is PtO supported... x and through Cs + WO3 (PtO) exchanged and acid-treated x The loading of Pt is 0.5 wt%, the molar ratio of Cs to W is 1:100), and the redox electron mediator is I. - / IO3 - The mass ratio of CO2 reduction photocatalyst to H2O oxidation photocatalyst is 1:1, and the two form a Z-type CO2 reduction complete reaction system through redox electron coupling.

[0063] The preparation method is as follows: S1. Using BiOCl, Bi2O3, and Nb2O5 as starting materials and NaCl as molten salt, the two are mixed (NaCl content is 0.6 mol%) and thoroughly ground. Then, the mixture is heated in a tube furnace at 883 K for 10 K min. -1 The mixture was calcined at a heating rate of 10 h, cooled, washed with deionized water, and dried to obtain Bi4NbO8Cl. Then, the Bi4NbO8Cl powder catalyst was added to an AgNO3 aqueous solution, irradiated under a Xe lamp for 4 h, washed with deionized water, and vacuum dried.

[0064] S2. Impregnate WO3 powder with an aqueous solution of H2PtCl6·6H2O, and calcine in air at 823K for 0.5h to remove PtO. x The load is applied to WO3, and then the resulting load PtO is applied. xWO3 was immersed in Cs2CO3 solution and calcined in air at 773K for 10 min. After calcination, the obtained material was immersed in 1M H2SO4 solution and stirred vigorously for 1 h. Finally, it was washed with deionized water and dried to obtain surface-modified WO3 catalyst.

[0065] S3. Disperse 0.05g of Bi4NbO8Cl supported on Ag co-catalyst and 0.05g of surface-modified WO3 catalyst in 100mL of NaI aqueous solution (concentration of 1mM) without adjusting pH to obtain the Z-type CO2 reduction reaction system.

[0066] Example 2 The difference between this embodiment and Embodiment 1 is that Bi4NbO8Cl is replaced with Bi4NbO8Br and Bi4NbO8Cl, respectively. 0.9 Br 0.1 In step S1, BiOCl is replaced with combinations of BiOBr, BiOCl, and BiOBr, respectively. The remaining preparation methods and parameters are consistent with those in Example 1.

[0067] Example 3 The difference between this embodiment and Example 1 is that the reduction co-catalyst Ag is replaced with Au, Pt and Rh respectively; Au, Pt, and Rh were prepared using a chemical reduction method. Specifically, Bi4NbO8X was placed in aqueous solutions of HAuCl4·3H2O, H2PtCl6·6H2O, and RhCl3·3H2O, respectively. Then, 1.5 mL of fresh NaBH4 aqueous solution (0.1 mg / mL) was added dropwise to each mixture. After stirring for 30 min, the mixture was washed several times with deionized water to obtain Bi4NbO8X loaded with Au, Pt, and Rh, respectively.

[0068] The remaining preparation methods and parameters are consistent with those in Example 1.

[0069] Example 4 The difference between this embodiment and Example 1 is that the loading of the co-catalyst Ag is changed to 0.5wt%, 0.8wt%, 1.2wt%, and 1.5wt%, respectively; and the concentration of the AgNO3 aqueous solution is adaptively changed in step S1. The remaining preparation methods and parameters are consistent with those in Example 1.

[0070] Example 5 The difference between this embodiment and Example 1 is that the co-catalyst Ag is replaced with Au-Ag, Pt-Ag, Rh-Ag, Ru-Ag, and IrO, respectively. x -Ag, CoO x -Ag, and MnOx -Ag; The preparation methods for Au-Ag, Pt-Ag, Rh-Ag, and Ru-Ag are as follows: Au, Pt, Rh, and Ru are first loaded using photodeposition, respectively, and then Ag is loaded using photodeposition. Specifically, the two-step photodeposition method involves placing Bi4NbO8X in aqueous solutions of HAuCl4·3H2O, H2PtCl6·6H2O, RhCl3·3H2O, and RuCl3·3H2O, respectively, and performing the photodeposition reaction under a Xe lamp for 4 hours. Then, an aqueous solution of AgNO3 is added, and the photodeposition reaction continues under a Xe lamp for another 4 hours.

[0071] The preparation method of IrOx-Ag is as follows: IrO is loaded using an adsorption method. x Then, Ag was loaded using photodeposition; the adsorption method specifically involved placing Bi4NbO8X in an IrO2 solution, stirring for 2 hours, and washing thoroughly with deionized water to obtain loaded IrO2. x Bi4NbO8X; CoO x -Ag, MnO x -Ag was prepared by photodeposition. Specifically, Bi4NbO8X was placed in Co(NO3)2·6H2O and Mn(NO3)2·4H2O solutions, respectively, and irradiated under Xe lamp for 4 h. Then, AgNO3 aqueous solution was added to the solution, and the reaction was carried out under Xe lamp for another 4 h. After washing with deionized water, it was dried under vacuum.

[0072] Example 6 The difference between this embodiment and Embodiment 1 is that the co-catalyst Ag is replaced with CoO. x -Ag, and the Ag loading remains constant, CoO x The loading amounts were 0.1wt%, 0.2wt%, 0.3wt%, 0.35wt%, 0.4wt%, and 0.5wt%, respectively; in step S1, Bi4NbO8Cl powder catalyst was added to Co(NO3)2 aqueous solution of different concentrations; The remaining preparation methods and parameters are consistent with those in Example 1.

[0073] Example 7 The difference between this embodiment and Embodiment 1 is that the first molten salt NaCl is replaced with a combination of KCl, NaCl and CsCl. The remaining preparation methods and parameters are consistent with those in Example 1.

[0074] Example 8 The difference between this embodiment and Example 1 is that the content of the first molten salt NaCl is adjusted to 0.3 mol%, 0.5 mol%, 0.8 mol%, 1 mol%, 5 mol%, and 10 mol%, respectively. The remaining preparation methods and parameters are consistent with those in Example 1.

[0075] Example 9 The difference between this embodiment and Embodiment 1 is that the calcination temperatures are adjusted to 803K, 823K, 853K, 873K, 893K, 903K, 923K and 973K respectively; The remaining preparation methods and parameters are consistent with those in Example 1.

[0076] Example 10 The difference between this embodiment and Embodiment 1 is that the heat preservation time is adjusted to 5h, 8h, 12h and 15h respectively; The remaining preparation methods and parameters are consistent with those in Example 1.

[0077] Example 11 The difference between this embodiment and Embodiment 1 is that the method of loading Ag is changed to chemical reduction (CR) and impregnation (IMP) methods, respectively. The CR method involves impregnating Bi4NbO8Cl powder catalyst in AgNO3 aqueous solution, adding 1.5 mL of fresh NaBH4 aqueous solution (0.1 mg / mL) dropwise, stirring for 30 min, and then washing several times with deionized water to obtain the catalyst. The IMP method involves impregnating Bi4NbO8Cl powder catalyst in AgNO3 aqueous solution, and after impregnation, stirring at 473 K with 20 mL of H2 (min)... -1 ) and N2 (200 mL min) -1 Calcination was carried out for 1 hour under a flowing mixed atmosphere.

[0078] The remaining preparation methods and parameters are consistent with those in Example 1.

[0079] Example 12 This embodiment provides a Z-type CO2 reduction total reaction system, including a CO2 reduction photocatalyst, an H2O oxidation photocatalyst, and a redox electron mediator; wherein, the CO2 reduction photocatalyst is Bi4TaO8Cl supported on Au-Ag cocatalyst. 0.9 Br 0.1 (Ag and Au loadings were 1 wt% and 0.3 wt%, respectively), and the H2O oxidation photocatalyst was PtO supported. x and through Cs + WO3 (PtO) exchanged and acid-treated xThe loading of Pt is 0.5 wt%, the molar ratio of Cs to W is 1:100), and the redox electron mediator is I. - / IO3 - The mass ratio of CO2 reduction photocatalyst to H2O oxidation photocatalyst is 1:1, and the two form a Z-type CO2 reduction complete reaction system through redox electron coupling.

[0080] The preparation method is as follows: S1. Using BiOCl, BiOBr, Bi2O3, and Ta2O5 as starting materials, and NaCl and KCl as molten salts (molar ratio of 1:1), with a total solute concentration of 10 mol%, after thorough grinding, the mixture was heated in a tube furnace at 923 K for 10 K min. -1 The mixture was heated for 14 hours, cooled, washed with deionized water, and dried to obtain Bi4TaO8Cl. 0.9 Br 0.1 Then, Bi4TaO8Cl 0.9 Br 0.1 The powder was placed in a HAuCl4·3H2O solution, ultrasonically mixed, and then dried in a hot water bath. The resulting powder was heated at 473K for 1 h under a flowing H2 / N2 atmosphere (H2: 20 mL / min). Subsequently, the powder was placed in an AgNO3 aqueous solution and irradiated under a Xe lamp for 4 h. After washing with deionized water, it was vacuum dried.

[0081] S2. Impregnate WO3 powder with an aqueous solution of H2PtCl6·6H2O, and calcine in air at 823K for 0.5h to remove PtO. x The load is applied to WO3, and then the resulting load PtO is applied. x WO3 was immersed in Cs2CO3 solution and calcined in air at 773K for 10 min. After calcination, the obtained material was immersed in 1M H2SO4 solution and stirred vigorously for 1 h. Finally, it was washed with deionized water and dried to obtain surface-modified WO3 catalyst.

[0082] S3, 0.05 g of Bi4TaO8Cl supported on Au-Ag co-catalyst 0.9 Br 0.1 0.05 g of surface-modified WO3 catalyst was dispersed in 100 mL of NaI aqueous solution (concentration of 1 mM) without adjusting the pH to obtain a Z-type CO2 reduction reaction system.

[0083] Example 13 The difference between this embodiment and Embodiment 12 is that Bi4TaO8Cl is used. 0.9 Br 0.1 Replace them with Bi4TaO8Cl and Bi4TaO8Br respectively; The remaining preparation methods and parameters are consistent with those in Example 12.

[0084] Example 14 The difference between this embodiment and Example 12 is that the cocatalyst Au-Ag is replaced with Rh-Ag and Pt-Ag respectively; and in step S1, HAuCl4·3H2O is replaced with RhCl3·3H2O and H2PtCl6·6H2O respectively. The remaining preparation methods and parameters are consistent with those in Example 12.

[0085] Example 15 The difference between this embodiment and Embodiment 12 is that the co-catalyst Au-Ag is replaced with Ag and CoO, respectively. x -Ag、RuO x -Ag and FeO x -Ag; Among them, Ag cocatalysts are produced using photodeposition, CoOx-Ag, RuO x Specifically, the preparation methods of -Ag and FeOx-Ag co-catalysts are as follows: Bi4TaO8Cl 0.9 Br 0.1 The powder was placed in solutions of Co(NO3)2·6H2O, RhCl3·3H2O, and Fe(NO3)3·9H2O, respectively, and ultrasonically mixed. The suspension was then dried in a hot water bath to obtain powder, which was heated at 673K ​​for 2 hours. Subsequently, the powder was placed in an aqueous solution of AgNO3 and reacted under Xe lamp for 4 hours. After washing with deionized water, it was vacuum dried.

[0086] The remaining preparation methods and parameters are consistent with those in Example 12.

[0087] Example 16 The difference between this embodiment and Example 12 is that the loading of the co-catalyst Au-Ag is adjusted to: (0.5wt%Au, 1.0wt%Ag), (0.1wt%Au, 1.0wt%Ag), (0.3wt%Au, 1.5wt%Ag), and (0.3wt%Au, 0.5wt%Ag); and the concentration of the metal salt solution is adaptively adjusted in step S1. The remaining preparation methods and parameters are consistent with those in Example 12.

[0088] Comparative Example 1 The difference between this comparative example and Example 1 is that WO3 was not surface modified; The remaining preparation methods and parameters are consistent with those in Example 1.

[0089] Performance testing The Z-type complete reaction systems provided in Examples 1-16 and Comparative Example 1 were respectively added to a gas flow system in a reaction cell with a heat-resistant glass (Pyrex) window. The reaction system was connected to a cooling water system to maintain the reactor at room temperature. Air in the reactor was purged using the protective gas argon, followed by a gas flow rate of 30 mL / min. -1 The CO2 gas reached saturation, and the reactor was irradiated with a 300W xenon lamp equipped with a cutoff filter (λ≥420nm). The reaction products were analyzed online by gas chromatography. Qualitative and quantitative analyses were performed using a thermal conductivity detector (TCD) and a flame ionization detector (FID), respectively. Specific CO2 reduction and water oxidation performance are as follows: Figures 2-11 , Figures 14-18 As shown.

[0090] Figure 1 These are the XRD patterns of the catalysts provided in Examples 1 and 2. Figure 12 These are the XRD patterns of the catalysts provided in Examples 12 and 13. As shown in the figures, Bi4NbO8X (X=Cl, Br) and Bi4TaO8X (X=Cl, Br, Cl) were successfully prepared using the preparation method of this application. 0.9 Br 0.1 The XRD diffraction peaks obtained from the material correspond one-to-one with the target phase, and there are no obvious impurity peaks, indicating that the prepared catalyst has good crystallinity and pure phase.

[0091] Figure 13 These are the UV-vis DRS spectra of the catalysts provided in Examples 12 and 14. As can be seen from the figures, the prepared Bi4TaO8Cl... 0.9 Br 0.1 The material exhibits strong light absorption in the visible light region, with the absorption edge located at approximately 480 nm, indicating that it possesses visible light response characteristics.

[0092] Depend on Figure 2 It can be seen that for Nb-based materials, when X is Cl, Bi4NbO8Cl exhibits the best catalytic effect, superior to its Br-doped system and the Cl / Br co-doped system; while for Ta-based materials, Bi4TaO8Cl... 0.9 Br 0.1 It exhibits the optimal CO and O2 generation rates, superior to those of pure Cl or pure Br phases. This indicates that appropriate Br doping can optimize the bandgap structure and photogenerated carrier separation efficiency of Ta-based materials. However, this optimization strategy cannot be simply extrapolated to Nb-based systems; Nb-based materials actually exhibit better catalytic performance in the pure chlorine phase.

[0093] Depend on Figure 3 , Figure 5 It can be seen that for Bi4NbO8X materials, when the co-catalyst is Ag or CoOx When -Ag is present, the catalyst works best; further from Figure 4 and Figure 6 It can be seen that when the Ag loading is 0.8wt%~1.2wt%, CoO x The catalytic effect is better when the loading is 0.2wt%~0.4wt%. And the catalytic effect is better when the loading is 0.2wt%~0.4wt%. Figure 14 and Figure 15 It can then be found that for Bi4TaO8Cl 0.9 Br 0.1 The material exhibits optimal catalytic performance only when the co-catalyst is Pt-Ag or Au-Ag; Figure 16 It can be further found that when the mass ratio of Au to Ag is 1:(2~5), the performance of the catalyst can be further improved.

[0094] Depend on Figures 7-11 It is known that the type and content of molten salt, the calcination temperature and holding time, and the loading method of Ag will also affect the effect of the obtained catalyst. By controlling them within the preferred range of this application, better results can be achieved.

[0095] Depend on Figure 17 It is known that the Z-type system has obvious photocatalytic CO2 reduction activity in the visible light region (λ≥420nm). The trend of its apparent quantum efficiency with the incident light wavelength is consistent with the light absorption characteristics of the material, showing high quantum efficiency. This indicates that the Z-type system constructed in this application can effectively utilize photogenerated carriers to drive the CO2 reduction reaction under visible light.

[0096] Depend on Figure 18 As can be seen, the catalyst provided in Example 12 exhibits good cycling stability in the visible light-driven CO2 reduction Z-type overall reaction. After multiple consecutive cycle tests, the generation rates of CO and O2 did not show significant attenuation, indicating that the Z-type overall reaction system constructed in this application has excellent catalytic stability.

[0097] Furthermore, data from Comparative Example 1 show that without surface modification of WO3, the generation rates of CO and O2 are 0.05 μmol / h and 0.01 μmol / h, respectively, which is significantly lower than that of Example 1.

[0098] The applicant declares that the above description is only a specific implementation of this application, but the protection scope of this application is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application fall within the protection and disclosure scope of this application.

Claims

1. A Z-type CO2 reduction total reaction system, characterized in that, The Z-type CO2 reduction complete reaction system includes a CO2 reduction photocatalyst, an H2O oxidation photocatalyst, and a redox electron mediator. The CO2 reduction photocatalyst includes Bi4NbO8X or Bi4TaO8X with two noble metals supported on its surface, where X includes Cl and / or Br. The H2O oxidation photocatalyst includes surface-modified WO3; The redox electron mediator includes I - / IO3 - ; The CO2 reduction photocatalyst and the H2O oxidation photocatalyst are coupled through the redox electron mediator to form a Z-type CO2 reduction complete reaction system.

2. The Z-type CO2 reduction total reaction system according to claim 1, characterized in that, The CO2 reduction photocatalyst is Bi4NbO8Cl or Bi4TaO8Cl with a surface supported by two noble metals. 0.9 Br 0.1 The dual noble metals include Pt-Ag or Au-Ag; And / or, the Bi4NbO8X surface is loaded with Ag or CoO. x -Ag, x>0.

3. The Z-type CO2 reduction total reaction system according to claim 2, characterized in that, The surface is loaded with a dual noble metal, Bi4TaO8Cl. 0.9 Br 0.1 In this context, the dual noble metals are Au-Ag, and the mass ratio of Au to Ag is 1:(2~5); And / or, when the Bi4NbO8X surface is loaded with Ag, the Ag loading is 0.8wt%~1.2wt%; when the Bi4NbO8X surface is loaded with CoO x When -Ag, CoO x The loading amount is 0.2wt%~0.4wt%, CoO x The mass ratio of Ag to Ag is (0.2~0.4):

1.

4. The Z-type CO2 reduction total reaction system according to any one of claims 1-3, characterized in that, The surface-modified WO3 includes a load of PtO. x and through Cs + WO3 that has undergone exchange and acid treatment, x > 0; In the surface-modified WO3, the PtO x The loading of Pt is 0.3wt%~0.7wt%, and the molar ratio of Cs to W is 1:(90~110).

5. The Z-type CO2 reduction total reaction system according to any one of claims 1-4, characterized in that, The mass ratio of the CO2 reduction photocatalyst to the H2O oxidation photocatalyst is 1:(0.8~1.2).

6. A method for preparing the Z-type CO2 reduction total reaction system as described in any one of claims 1-5, characterized in that, The preparation method includes: S1. Bi4NbO8X or Bi4TaO8X is prepared by molten salt method, and two noble metals are loaded on the Bi4TaO8X to obtain a CO2 reduction photocatalyst. S2. Surface modification of WO3 yields H2O oxidation photocatalyst; S3. Mix the CO2 reduction photocatalyst, H2O oxidation photocatalyst and NaI aqueous solution to obtain a Z-type CO2 reduction complete reaction system.

7. The preparation method according to claim 6, characterized in that, The method for preparing Bi4NbO8X in step S1 includes: using BiOX, Bi2O3, and Nb2O5 as raw materials, mixing them with a first molten salt to obtain a first mixture, and then performing grinding and first calcination sequentially to obtain Bi4NbO8X; The method for preparing Bi4TaO8X in step S1 includes: using BiOX, BiOBr, Bi2O3, and Ta2O5 as raw materials, mixing them with a second molten salt to obtain a second mixture, and then sequentially grinding and calcining them to obtain Bi4TaO8X; The preparation method further includes: loading Ag or CoO onto the surface of Bi4NbO8X. x -Ag.

8. The preparation method according to claim 7, characterized in that, The first molten salt comprises any one or a combination of at least two of NaCl, CsCl, or KCl; the content of the first molten salt in the first mixture is 0.3 mol% to 1.0 mol%. And / or, the second molten salt comprises NaCl and KCl; And / or, the temperatures of the first calcination and the second calcination are each independently 823K~905K, and the holding times are each independently 5h~15h; And / or, the method of loading Pt-Ag or Au-Ag on the Bi4TaO8X includes: first loading Pt or Au by impregnation hydrogenation, and then loading Ag by photodeposition. And / or, the method of loading Ag onto the Bi4NbO8X surface includes photodeposition to load CoO onto the Bi4NbO8X surface. x The methods for loading CoO with Ag include: firstly, using photodeposition to load CoO. x Ag is then loaded using photodeposition. The impregnation hydrogenation method includes: mixing Bi4TaO8X with a Pt salt solution or an Au salt solution, drying the mixture, and then heating it in a hydrogen-containing atmosphere. The photodeposition method includes: mixing Bi4TaO8X or Bi4NbO8X with a salt solution of the metal to be deposited, and then performing a photoreaction under an Xe lamp.

9. The preparation method according to any one of claims 6-8, characterized in that, The method for surface modification of WO3 in step S2 includes: impregnating WO3 powder in a Pt salt solution, and after the impregnation is completed, calcining it for the fourth time in an air atmosphere to obtain PtO loaded on the surface. x WO3, then proceed with Cs in sequence. + The surface-modified WO3 was obtained by exchange and acid exchange. The Cs + The exchange method includes: loading the PtO x WO3 was impregnated in a Cs2CO3 solution and then subjected to a fifth calcination. The acid exchange method includes: [the acid exchange method is described in the context of] Cs. + The exchanged products were soaked in H2SO4 solution, and then stirred, washed and dried in sequence. And / or, the concentration of the NaI aqueous solution in step S3 is 0.5 mM to 10 mM.

10. An application of the Z-type CO2 reduction total reaction system as described in any one of claims 1-5, characterized in that, The applications include solar-driven CO2 reduction.

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