A carbon-modified metal oxide additive-TiO2 photocatalytic material, its preparation method and application

Abstract

This invention discloses a carbon-modified metal oxide auxiliary agent—TiO2 photocatalytic material, its preparation method, and its application. It is prepared by in-situ pyrolysis of a metal ion-coordinated organic polymer on the surface of a TiO2 semiconductor. The photocatalytic auxiliary agent exhibits close contact between the carbon material and the metal oxide nanoparticles, enabling rapid transfer of charge carriers from TiO2 to the hydrogen evolution active sites of the metal oxide, significantly improving the hydrogen production efficiency of the photocatalytic system (up to 156.13 mmol / h). ‑ 1 g ‑1 Furthermore, carbon-modified metal oxide cocatalysts can be obtained by in-situ pyrolysis of metal-coordinated organic polymers. This synthesis method is inexpensive, widely applicable, easy to prepare on a large scale, and facilitates the control of the cocatalyst's surface and interface, which is expected to promote the practical application of TiO2 photocatalytic hydrogen production systems.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to a carbon-modified metal oxide additive-TiO2 photocatalytic material, its preparation method, and its application. Background Technology

[0002] The overexploitation and consumption of traditional fossil fuels by humankind has triggered a severe energy crisis, making the development of environmentally friendly renewable energy a global focus. Hydrogen energy, with its extremely high calorific value and clean, pollution-free products, is one of the most promising renewable energy sources. Among these, the process of converting solar energy into high-calorific-value hydrogen energy through semiconductor photocatalytic water splitting has significant research value.

[0003] The core of photocatalytic hydrogen production research lies in the development of highly efficient photocatalysts. TiO2, due to its suitable band structure and relatively negative conduction band position, has become the most widely studied semiconductor material in this field. Although TiO2 possesses high photocatalytic hydrogen production activity, the rapid recombination of photogenerated electron-hole pairs and its own photolithography problems severely limit its large-scale application. Therefore, further improving the photocatalytic hydrogen evolution activity and stability of TiO2 is urgently needed. Currently, methods such as constructing solid solutions, building heterojunctions, or supporting co-catalysts have effectively improved the hydrogen evolution activity and stability of TiO2 photocatalysts. Among these, co-catalyst loading, which can both accelerate the migration of photogenerated carriers and reduce the activation energy required for hydrogen evolution, has been proven to significantly enhance the hydrogen evolution activity of TiO2 photocatalysts.

[0004] In recent years, Ni, Co, and Fe-based cocatalysts have attracted widespread attention due to their low cost, high activity, high stability, and excellent hydrogen evolution promoting ability. However, the Ni, Co, and Fe-based cocatalysts have too many defects at the heterojunction interface with TiO2 and the charge transfer kinetics are relatively slow, which easily leads to recombination quenching of photogenerated carriers. If the carrier separation problem at the Ni, Co, and Fe-based cocatalyst-TiO2 heterojunction interface can be solved, it is expected to promote the practical application of TiO2 photocatalytic hydrogen production system. Summary of the Invention

[0005] To address the problem of poor interfacial charge separation in existing metal oxide-based TiO2 photocatalytic materials, this invention provides a carbon-modified metal oxide-based TiO2 photocatalytic material, its preparation method, and its applications. It also presents a highly active hybrid TiO2 photocatalytic material for water splitting to produce hydrogen, along with its preparation method and applications. This invention proposes a strategy of obtaining carbon-modified metal oxide-based TiO2 photocatalytic materials through in-situ pyrolysis derivatization of metal coordination polymers on the TiO2 surface, achieving complete separation of photogenerated carriers within the catalyst.

[0006] The main technical principles of this invention are as follows:

[0007] Using nitrogen-containing polymers as the carbon material source (choosing dopamine as the nitrogen-containing polymer monomer), the nitrogen-containing functional groups on the surface of the polymer monomer are first used to coordinate metal ions, and then the metal-coordinated polymer is grown in situ on the surface of commercial TiO2. Finally, a highly active carbon-modified metal oxide auxiliary - TiO2 photocatalytic material is prepared through a heat treatment process.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a carbon-modified metal oxide auxiliary TiO2 photocatalytic material includes the following steps:

[0010] 1) Mix commercial TiO2 powder with distilled water at a mass ratio of 1:(30-50) to obtain a TiO2 solution. Then, add dopamine and metal ion nitrate to the TiO2 solution in sequence and stir for 30 minutes to obtain a mixed solution.

[0011] The molar ratio of dopamine to metal ion nitrate is (0.8-1.2):(0.12-0.16);

[0012] The molar ratio of the metal ions to TiO2 is (0.3-2):100;

[0013] 2) Heat the above mixture to boiling at 100-150℃ and maintain for 3 hours until the solution is completely evaporated. Recover the product obtained after drying.

[0014] 3) The dried product was transferred to a tube furnace and calcined at 350-500℃ for 3 hours under an inert atmosphere to obtain carbon-modified metal oxide additive-TiO2 photocatalytic material.

[0015] In this invention:

[0016] Furthermore, the metal ion nitrate mentioned in step 1) is selected from one of nickel nitrate, cobalt nitrate, or ferric nitrate.

[0017] Furthermore, the molar ratios of the metal ions and TiO2 mentioned in step 1) are 0.3%, 0.6%, 1%, 1.5%, and 2%, respectively.

[0018] Furthermore, the calcination at 350-500℃ for 3 hours mentioned in step 3) is carried out in an Ar atmosphere with a heating rate of 5℃ / min, and is carried out at 350℃, 400℃, 450℃ and 500℃ respectively.

[0019] The present invention also relates to a carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material, which is obtained by the above-mentioned preparation method of a carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material, and is a highly active hybrid auxiliary agent-TiO2 photocatalytic material.

[0020] The present invention also relates to the application of a carbon-modified metal oxide additive - TiO2 photocatalytic material, which is used to simulate sunlight photocatalytic water splitting to produce hydrogen, with a hydrogen production rate of 113.83-156.13 mmol / h / g.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The present invention discloses a method for preparing a carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material, which utilizes the pyrolysis derivatization of metal coordination polymers to obtain the carbon-modified metal oxide auxiliary agent. This innovative synthesis method is inexpensive and easy to prepare on a large scale.

[0023] 2. The preparation method of the carbon-modified metal oxide promoter-TiO2 photocatalytic material described in this invention can be applied to the construction of various metal oxide hybrid promoters modified by carbon materials, and has universality; in addition, the preparation method facilitates the control of the catalyst's internal and external interfaces, and is expected to achieve the precise design and controllable preparation of highly active hydrogen production photocatalysts.

[0024] 3. The carbon-modified metal oxide additive-TiO2 photocatalytic material of the present invention can utilize the easy electron transport characteristics of carbon materials to accelerate the rapid transfer of photogenerated charge carriers in TiO2 to the hydrogen evolution active sites of metal oxides by modifying the metal oxide additive with carbon materials. Attached Figure Description

[0025] Figure 1 This is a scan image of the carbon-modified cobalt oxide auxiliary-TiO2 photocatalytic material obtained in Example 1 of this invention;

[0026] Figure 2 This is a transmission image of the carbon-modified cobalt oxide auxiliary-TiO2 photocatalytic material obtained in Example 1 of this invention;

[0027] Figure 3 These are graphs showing the hydrogen production activity of the photocatalytic materials obtained in Examples 1-3 and Comparative Examples 1-4 of this invention; Detailed Implementation

[0028] The following description, in conjunction with the accompanying drawings and specific examples, further illustrates the essence of the present invention. These embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0029] Example 1:

[0030] A specific preparation method for a highly active hybrid auxiliary agent-TiO2 photocatalyst material is as follows, comprising the following steps: First, 1g of TiO2 support is uniformly dispersed in 40g of distilled water. Then, appropriate amounts of dopamine and Co ion nitrate (molar ratio 1:0.14) are added sequentially to the mixture, wherein the molar ratio of Co ions to TiO2 is 1%. After magnetic stirring for approximately 30 minutes, the mixture is heated to 100℃ and boiled until the solution evaporates to dryness. The evaporated precursor is collected in a container. Subsequently, the obtained precursor is calcined and pyrolyzed at 400℃ under an inert atmosphere to finally obtain the carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalyst.

[0031] The performance of the photocatalytic reactor for hydrogen production was evaluated: 5 mg of sample was completely dispersed in 20 mL of Na₂S / Na₂SO₃ aqueous solution (Na₂S 0.25 M, Na₂SO₃ 0.35 M). Before visible light irradiation, the photocatalytic reaction cycle system was evacuated for 30 min to remove all gases. The amount of H₂ produced was detected by online gas chromatography. Detection was performed every 30 min for a total of 6 times (180 min).

[0032] The photocatalytic hydrogen production activity showed that the prepared carbon-modified cobalt oxide-TiO2 photocatalytic material had a hydrogen production rate of 156.13 mmol / h / g.

[0033] Figure 1 This is a scan image of the carbon-modified cobalt oxide auxiliary-TiO2 photocatalyst material obtained in Example 1;

[0034] from Figure 1 It can be seen that the surface of commercial TiO2 becomes rough after being loaded with carbon-modified cobalt oxide additive.

[0035] Figure 2 This is a transmission image of the carbon-modified cobalt oxide auxiliary-TiO2 photocatalytic material obtained in Example 1;

[0036] from Figure 2 It can be seen that cobalt oxide nanoparticles are embedded in amorphous carbon, and carbon-modified cobalt oxide additives are tightly wrapped on the TiO2 surface.

[0037] Figure 3 This is a graph showing the hydrogen production activity of the carbon-modified cobalt oxide auxiliary-TiO2 photocatalytic material obtained in Example 1;

[0038] from Figure 3 It can be seen that the carbon-modified cobalt oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 156.13 mmol / h / g.

[0039] Example 2:

[0040] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 2 and Example 1 is that Co ion nitrate is replaced by Ni ion nitrate. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified nickel oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 145.44 mmol / h / g.

[0041] Figure 3 This is a graph showing the hydrogen production activity of the carbon-modified nickel oxide auxiliary-TiO2 photocatalytic material obtained in Example 2;

[0042] from Figure 3 It can be seen that the carbon-modified nickel oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 145.44 mmol / h / g.

[0043] Example 3:

[0044] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 3 and Example 1 is that Co ion nitrate is replaced by Fe ion nitrate. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified iron oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 118.34 mmol / h / g.

[0045] Figure 3 This is a graph showing the hydrogen production activity of the carbon-modified iron oxide auxiliary agent-TiO2 photocatalytic material obtained in Example 3;

[0046] from Figure 3 It can be seen that the carbon-modified iron oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 118.34 mmol / h / g.

[0047] Example 4:

[0048] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 4 and Example 1 is that the relative molar ratio of Co ions to TiO2 is 0.3%. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 113.83 mmol / h / g.

[0049] Example 5:

[0050] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 5 and Example 1 is that the molar ratio of Co ions to TiO2 is 0.6%. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 129.62 mmol / h / g.

[0051] Example 6:

[0052] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 6 and Example 1 is that the molar ratio of Co ions to TiO2 is 1.5%. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the hydrogen production rate of the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material is 138.37 mmol / h / g.

[0053] Example 7:

[0054] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 7 and Example 1 is that the molar ratio of Co ions to TiO2 is 2%. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the hydrogen production rate of the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material is 119.69 mmol / h / g.

[0055] Example 8:

[0056] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 8 and Example 1 is that the precursor is calcined and pyrolyzed at 350℃ under an inert atmosphere. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 125.76 mmol / h / g.

[0057] Example 9:

[0058] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 9 and Example 1 is that the precursor is calcined and pyrolyzed at 450℃ under an inert atmosphere. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 141.48 mmol / h / g.

[0059] Example 10:

[0060] The specific preparation method of a highly active hybrid auxiliary agent-TiO2 photocatalytic material is as follows, the same as in Example 1. The difference between Example 10 and Example 1 is that the precursor is calcined and pyrolyzed at 500℃ under an inert atmosphere. The hydrogen production activity evaluation of the catalyst is the same as in Example 1. The hydrogen production activity shows that the prepared carbon-modified cobalt oxide auxiliary agent-TiO2 photocatalytic material has a hydrogen production rate of 133.62 mmol / h / g.

[0061] Comparative Example 1:

[0062] The difference between Comparative Example 1 and Example 1 is that Co ion nitrate was not added. The hydrogen production activity evaluation of the catalyst was the same as that of Example 1. The hydrogen production activity showed that the hydrogen production rate of the prepared carbon material-TiO2 photocatalytic hydrogen production rate was 15.11 mmol / h / g.

[0063] Figure 3 This is a graph showing the hydrogen production activity of the carbon material-TiO2 photocatalyst obtained in Comparative Example 1;

[0064] from Figure 3 It can be seen that the carbon material-TiO2 photocatalytic material has a hydrogen production rate of 15.11 mmol / h / g.

[0065] Comparative Example 2:

[0066] The difference between Comparative Example 2 and Example 1 is that dopamine was not added. The hydrogen production activity evaluation of the catalyst was the same as that of Example 1. The hydrogen production activity showed that the hydrogen production rate of the prepared cobalt oxide promoter-TiO2 photocatalyst was 47.25 mmol / h / g.

[0067] Figure 3 The graph shows the hydrogen production activity of the cobalt oxide additive-TiO2 photocatalytic material obtained in Comparative Example 2.

[0068] from Figure 3 It can be seen that the cobalt oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 47.25 mmol / h / g.

[0069] Comparative Example 3:

[0070] The difference between Comparative Example 3 and Example 2 is that dopamine was not added. The hydrogen production activity evaluation of the catalyst was the same as that of Example 1. The hydrogen production activity showed that the hydrogen production rate of the prepared nickel oxide additive-TiO2 photocatalyst was 42.07 mmol / h / g.

[0071] Figure 3 The graph shows the hydrogen production activity of the nickel oxide additive-TiO2 photocatalytic material obtained in Comparative Example 3.

[0072] from Figure 3 It can be seen that the nickel oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 42.07 mmol / h / g.

[0073] Comparative Example 4:

[0074] The difference between Comparative Example 4 and Example 3 is that dopamine was not added. The hydrogen production activity evaluation of the catalyst was the same as that of Example 1. The hydrogen production activity showed that the hydrogen production rate of the prepared iron oxide promoter-TiO2 photocatalyst was 33.14 mmol / h / g.

[0075] Figure 3 The graph shows the hydrogen production activity of the iron oxide auxiliary agent-TiO2 photocatalytic material obtained in Comparative Example 4.

[0076] from Figure 3 It can be seen that the iron oxide additive-TiO2 photocatalytic material has a hydrogen production rate of 33.14 mmol / h / g.

[0077] Summary and discussion:

[0078] Analysis of the photocatalytic water splitting hydrogen production performance in the above examples and comparative examples shows that carbon-modified metal oxide additives can significantly enhance the photocatalytic water splitting hydrogen production activity of TiO2 semiconductors, with a hydrogen production rate of 113.83-156.13 mmol / h / g. In contrast, simple carbon materials or metal oxide additives have limited effect on improving the photocatalytic water splitting hydrogen production activity of TiO2 semiconductors, with a hydrogen production rate of 15.11-47.25 mmol / h / g. This comparison further confirms that the carbon-modified metal oxide additives in this invention play a unique and significant role in improving the photocatalytic water splitting hydrogen production performance of TiO2.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a carbon-modified metal oxide auxiliary-TiO2 photocatalytic material, characterized in that: Includes the following steps: 1) Mix commercial TiO2 powder with distilled water at a mass ratio of 1:(30-50) to obtain a TiO2 solution. Then, add dopamine and metal ion nitrate to the TiO2 solution in sequence and stir for 30 min to obtain a mixed solution. The molar ratio of dopamine to metal ion nitrate is (0.8-1.2):(0.12-0.16); The molar ratio of the metal ions to TiO2 is (0.3-2):100; The metal ion nitrate is selected from one of nickel nitrate, cobalt nitrate, or ferric nitrate; 2) Heat the above mixture to boiling at 100-150 °C and maintain for 3 h until the solution is completely evaporated. Recover the product obtained after drying. 3) The dried product was transferred to a tube furnace and calcined at 350-500 °C for 3 h in an Ar atmosphere to obtain carbon-modified metal oxide additive-TiO2 photocatalytic material. The photocatalytic material was used to simulate sunlight photocatalytic water splitting to produce hydrogen, with a hydrogen production rate of 113.83-156.13 mmol / h / g.

2. The preparation method of a carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material according to claim 1, characterized in that: The molar ratios of the metal ions and TiO2 mentioned in step 1) are 0.3%, 0.6%, 1%, 1.5%, and 2%, respectively.

3. The preparation method of a carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material according to claim 1, characterized in that: Step 3) describes calcining at 350-500 ℃ for 3 h, with a heating rate of 5 ℃ / min, and calcining at 350 ℃, 400 ℃, 450 ℃, and 500 ℃ respectively.

4. A carbon-modified metal oxide additive-TiO2 photocatalytic material, characterized in that: The material was obtained by the preparation method of the carbon-modified metal oxide additive-TiO2 photocatalytic material according to any one of claims 1-3.

5. The application of the carbon-modified metal oxide auxiliary agent-TiO2 photocatalytic material according to claim 4, characterized in that: The aforementioned photocatalytic material is used to simulate sunlight photocatalytic water splitting to produce hydrogen, with a hydrogen production rate of 113.83-156.13 mmol / h / g.

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