A method for enhancing TiO2 surface photovoltage

Abstract

The present invention relates to the field of materials chemistry, and specifically to a method for enhancing the surface photovoltage of TiO2. The method comprises the following steps: taking a certain amount of fluorinated polyimide powder and mixing it with ethanol, then adding tetrabutyl titanate to form a suspension, adding deionized water dropwise, stirring, and transferring to a hydrothermal reactor for hydrothermal reaction. After the hydrothermal reaction is completed, the powder is filtered, washed, dried, and ground, and an appropriate amount of powder is placed in a quartz boat of a tubular furnace and heated in an ammonia atmosphere. After cooling, the powder is taken out and ground to obtain TiO2 with enhanced surface photovoltage. The present application can effectively improve the surface photovoltage signal of TiO2 by adding fluorinated polyimide during preparation and treating it in an ammonia atmosphere. This research has practical significance for promoting the practical application of TiO2 photocatalytic materials. In addition, the present invention is simple to operate and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of material chemistry, in particular to the field of photocatalytic materials, and specifically to a method for enhancing the photovoltage of a TiO2 surface. Background Art

[0002] Photocatalysis, due to its environmental friendliness, low cost, recyclability, and applicability, has become a promising catalytic technology, widely used to address environmental issues and promote sustainable development. A key research focus is the use of photocatalysts to achieve efficient energy conversion. Among various photocatalysts, titanium dioxide (TiO2) is a common photocatalytic material.

[0003] TiO2 has a large band gap of approximately 3.2 eV, which makes TiO2 have high photocatalytic activity in the ultraviolet light range and is suitable for photocatalytic reactions under sunlight. At the same time, TiO2 has strong stability and still has reliable photocatalytic ability at high temperatures. In practical applications, nano-titanium dioxide P25 occupies a certain market share as a photocatalyst, and as people continue to deepen their research and application of photocatalytic technology, P25's position in the market will continue to be consolidated and developed. However, the low mobility of photogenerated charge pairs seriously limits the photocatalytic performance of TiO2. In order to solve this problem, using simple and effective preparation methods to improve the separation and migration efficiency of photogenerated carriers has become a research hotspot.

[0004] Fluorinated polyimide is a high-performance polymer with unique properties and a wide range of applications. It is obtained by polymerizing imide monomers containing fluorine atoms. Fluorinated polyimide exhibits high-temperature stability and excellent chemical inertness, making it widely used in aerospace, electronics, chemicals, pharmaceuticals, and other fields. Summary of the Invention

[0005] The present invention aims to provide a method for enhancing the surface photovoltage of TiO2 that is simple to operate and easy to implement. The method involves adding fluorinated polyimide powder during the TiO2 preparation process to alter the physical properties of TiO2, thereby improving the separation and migration efficiency of photogenerated carriers. Furthermore, surface photovoltage technology can visualize the separation rate of photogenerated carriers in photocatalysts. A stronger surface photovoltage signal generated after light irradiation indicates a higher rate of photogenerated carrier separation, providing a basis for verifying whether the photocatalytic activity of the catalyst prepared using this strategy has been significantly enhanced.

[0006] In order to achieve the above object of the invention, the specific technical solution of the present invention is:

[0007] A method for enhancing (improving) the surface photovoltage of TiO2 comprises the following steps:

[0008] In the first step, a certain amount of fluorinated polyimide powder is mixed with ethanol, and then tetrabutyl titanate is added to form a suspension, and deionized water is added and stirred;

[0009] The second step is to transfer the suspension into a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the suspension is filtered, washed, dried and ground.

[0010] The third step is to place the powder into a quartz boat in a tube furnace, heat it in an ammonia atmosphere, and grind it after cooling to obtain TiO2 with enhanced surface photovoltage signal.

[0011] As a better preferred method in the present application, the mass ratio of the fluorinated polyimide added in the first step to the generated TiO2 is 0.5%-2.0%, specifically 0.5%, 1%, 1.5%, 2.0%, etc.

[0012] As a better preferred embodiment of the present application, the stirring time in the first step is 1-3 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0013] As a better preferred method in this application, the volume ratio of deionized water to tetrabutyl titanate added in the first step is 1.5-2.5, specifically 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, etc.

[0014] As a better preferred method in the present application, the volume ratio of ethanol to tetrabutyl titanate added in the first step is 2-2.5, specifically 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc.

[0015] As a better preferred method in this application, the hydrothermal time of the second step is 18-30h, specifically 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, etc.

[0016] As a better preferred method in this application, the hydrothermal temperature in the second step is 140-180°C, specifically 140°C, 150°C, 160°C, 170°C, 180°C, etc.

[0017] As a better preferred embodiment of the present invention, the second step drying temperature is 50-60°C, specifically 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, etc.

[0018] As a better preferred method in this application, the heating temperature in the tube furnace in the third step is 450-500°C, specifically 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, etc.

[0019] As a better preferred method in this application, the heating time in the third step tube furnace is 1h-3h, specifically 1h, 1.5h, 2h, 2.5h, 3h, etc.

[0020] Another object of the present invention is to protect TiO2 with increased surface photovoltage obtained by any of the above methods or a combination of methods.

[0021] As a better preferred method in the present application, the TiO2 prepared with the assistance of fluorinated polyimide has a significantly enhanced surface photovoltage signal in the range of 310 to 480 nm, and the surface photovoltage signal can reach 1.5 mV.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The method for preparing TiO2 with significantly enhanced surface photovoltage signal in the present invention is simple to operate, easy to implement and reliable.

[0024] (2) The surface photovoltage of TiO2 prepared with the aid of fluorinated polyimide in the present invention is significantly enhanced in the range of 310 to 480 nm, which has important practical significance for improving photocatalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD pattern of the TiO2 sample prepared without adding fluorinated polyimide.

[0026] Figure 2 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 1.

[0027] Figure 3 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 2.

[0028] Figure 4 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 3.

[0029] Figure 5 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 4.

[0030] Figure 6 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 5.

[0031] Figure 7Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 6.

[0032] Figure 8 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 7.

[0033] Figure 9 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding polyimide and the sample obtained in Example 8.

[0034] Figure 10 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding polyfluoroethylene and the sample obtained in Example 9.

[0035] Figure 11 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the sample obtained in Example 10.

[0036] Figure 12 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the samples obtained in Example 11 and Example 1.

[0037] Figure 13 Comparison of the surface photovoltage signals of the TiO2 sample prepared without adding fluorinated polyimide and the samples obtained in Example 12 and Example 3. DETAILED DESCRIPTION

[0038] A method for preparing a surface photovoltage-enhanced TiO2 photocatalytic material comprises the following steps:

[0039] The first step is to mix fluorinated polyimide (specifically 0.5%, 1.0%, 1.5%, 2.0%, etc.) with a mass ratio of 0.5% to 2.0% of TiO2 with ethanol (the volume ratio of ethanol added to tetrabutyl titanate is 2-2.5, specifically 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc.), and then add a certain amount of tetrabutyl titanate to form a suspension, add deionized water (the volume ratio of deionized water added to tetrabutyl titanate is 1.5-2.5, specifically 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, etc.) and stir for 1-3 hours.

[0040] In the second step, the suspension is transferred to a hydrothermal reactor and subjected to hydrothermal reaction at 140-180°C for 16-30 hours. After the reaction is completed, the suspension is filtered, washed, dried at 50-60°C and ground.

[0041] The third step is to place the powder into a quartz boat in a tube furnace, treat it at 450-500°C in an ammonia atmosphere for 1-3 hours, and then grind it after cooling to obtain TiO2 with enhanced surface photovoltage signal.

[0042] Preferably, the mass ratio of the total mass of the added fluorinated polyimide to the mass of TiO2 is 0.5%-2%.

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] In the following examples, XRD was conducted on a DX-2700BH X-ray diffractometer; the surface photovoltage test was conducted on a surface photovoltage spectrometer assembled at Jilin University. The light source was a 500W xenon lamp, and a lock-in amplifier was used to amplify the collected signal. The sample was pressed between conductive glass and a metallic copper base. The wavelength test range was 200 to 600 nm. Conventional technical means were used for the specific test methods and operations.

[0045] The raw materials used in the following examples are all commercially available products, such as fluorinated polyimide powder which can be purchased from Zigong Zhongtiansheng New Material Technology Co., Ltd.

[0046] Comparative Example 1

[0047] 1) Ethanol and tetrabutyl titanate were mixed in a volume ratio of 2:1, and deionized water and tetrabutyl titanate were added in a volume ratio of 2, and stirred for 2 hours.

[0048] 2) The suspension was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 180°C for 24 hours. After the reaction was completed, the suspension was filtered, washed, dried at 60°C, and ground.

[0049] 3) The powder was placed in a quartz boat in a tube furnace, treated at 500°C for 2 hours in an ammonia atmosphere, and then ground after cooling to obtain TiO2.

[0050] Test photovoltage signal and XRD, Figure 1 The XRD spectrum of the prepared TiO2 is shown in Figure 2. Figure 1 It can be seen that the sample has obvious diffraction peaks only at 2θ=25.7° and 37.8°, which is consistent with the TiO2 diffraction peaks reported in the literature, indicating that the prepared sample is pure TiO2.

[0051] Example 1

[0052] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0053] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 0.5%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2, and the stirring time was 2 hours.

[0054] 2) The final suspension in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 180° C. for 24 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0055] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated in an ammonia atmosphere at 500° C. for 2 h, cooled, and ground to obtain TiO2.

[0056] Compared with Comparative Example 1, Example 1 is added with 0.5% by mass of fluorinated polyimide to TiO2 for auxiliary preparation.

[0057] Figure 2 Surface photovoltage signal comparison diagram of the samples obtained in Example 1 and Comparative Example 1. Figure 2 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly improved in the range of 310-480nm compared with that of TiO2 prepared without the assistance of fluorinated polyimide. The preparation of TiO2 with the assistance of an appropriate amount of fluorinated polyimide can enhance the surface photovoltage signal of TiO2.

[0058] Example 2

[0059] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0060] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.0%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 1.8, and the stirring time was 2 hours.

[0061] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 160° C. for 22 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0062] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 500° C. for 2 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0063] Compared with Comparative Example 1, Example 2 was prepared by adding fluorinated polyimide in a mass ratio of 1.0% to TiO2; the volume ratio of deionized water to tetrabutyl titanate was 1.8; the hydrothermal temperature was 160°C, and the hydrothermal time was 22h.

[0064] Figure 3 Surface photovoltage signal comparison diagram of the samples obtained in Example 2 and Comparative Example 1. Figure 3 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly improved in the range of 310-480nm compared with that of TiO2 prepared without the assistance of fluorinated polyimide. The preparation of TiO2 with the assistance of an appropriate amount of fluorinated polyimide can enhance the surface photovoltage signal of TiO2.

[0065] Example 3

[0066] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0067] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.5%; the volume ratio of ethanol to tetrabutyl titanate was 2.1:1; the volume ratio of deionized water to tetrabutyl titanate was 2, and the stirring time was 2 hours.

[0068] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 180° C. for 22 h. After the reaction was completed, the suspension was filtered, washed, dried at 55° C., and ground.

[0069] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 500° C. for 2 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0070] Compared with Comparative Example 1, Example 3 is prepared by adding fluorinated polyimide in a mass ratio of 1.5% to TiO2; the volume ratio of ethanol to tetrabutyl titanate is 2.1:1; the stirring time is 3 hours; the hydrothermal time is 22 hours; and the drying temperature is 55°C.

[0071] Figure 4 The surface photovoltage signal comparison diagram of the samples obtained in Example 3 and Comparative Example 1. Figure 4 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly improved in the range of 310-480nm compared with that of TiO2 prepared without the assistance of fluorinated polyimide. The preparation of TiO2 with the assistance of an appropriate amount of fluorinated polyimide can enhance the surface photovoltage signal of TiO2.

[0072] Example 4

[0073] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0074] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 2.0%; the volume ratio of deionized water to tetrabutyl titanate was 2.0, and the stirring time was 2 hours.

[0075] 2) The suspension was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 170° C. for 25 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0076] 3) The powder was placed in a quartz boat in a tube furnace, treated at 480°C for 2 hours in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0077] Compared with Comparative Example 1, Example 4 was prepared by adding fluorinated polyimide in a mass ratio of 2.0% to TiO2; the hydrothermal temperature was 170°C, the hydrothermal time was 25h; and the ammonia atmosphere heat treatment temperature was 480°C.

[0078] Figure 5 Surface photovoltage signal comparison diagram of the samples obtained in Example 4 and Comparative Example 1. Figure 5 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly improved in the range of 310-480nm compared with that of TiO2 prepared without the assistance of fluorinated polyimide. The preparation of TiO2 with the assistance of an appropriate amount of fluorinated polyimide can enhance the surface photovoltage signal of TiO2.

[0079] Example 5

[0080] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0081] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 2.5%; the volume ratio of ethanol to tetrabutyl titanate was 2.0:1; the volume ratio of deionized water to tetrabutyl titanate was 1.9, and the stirring time was 2 hours.

[0082] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 160° C. for 20 h. After the reaction was completed, the suspension was filtered, washed, dried at 58° C., and ground.

[0083] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 500° C. for 3 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0084] Compared with Comparative Example 1, Example 5 was prepared by adding fluorinated polyimide with a mass ratio of 5 to TiO2 of 2.5%; the volume ratio of deionized water to tetrabutyl titanate was 1.9; the hydrothermal temperature was 160°C, the hydrothermal time was 20h; the drying temperature was 58°C; and the heat treatment time under an ammonia atmosphere was 3h.

[0085] Figure 6 Surface photovoltage signal comparison diagram of the samples obtained in Example 5 and Comparative Example 1. Figure 6 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of fluorinated polyimide. Excessive fluorinated polyimide can weaken the surface photovoltage signal of TiO2.

[0086] Example 6

[0087] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0088] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.0%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2, and the stirring time was 2 hours.

[0089] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 190° C. for 24 h. After the reaction was completed, the suspension was filtered, washed, dried at 55° C., and ground.

[0090] 3) The powder obtained in step 2) is placed in a quartz boat in a tube furnace, treated at 500° C. for 2 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0091] Compared with Comparative Example 1, Example 6 is prepared by adding fluorinated polyimide in a mass ratio of 1.0% to TiO2; the volume ratio of ethanol to tetrabutyl titanate is 2:1; the hydrothermal temperature is 190°C; and the drying temperature is 55°C.

[0092] Figure 7 Surface photovoltage signal comparison diagram of the samples obtained in Example 6 and Comparative Example 1. Figure 7 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of fluorinated polyimide. The fluorinated polyimide-assisted TiO2 prepared at an excessively high hydrothermal reaction temperature can weaken the surface photovoltage signal of TiO2.

[0093] Example 7

[0094] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0095] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.0%; the volume ratio of ethanol to tetrabutyl titanate was 2.1:1; the volume ratio of deionized water to tetrabutyl titanate was 2.1, and the stirring time was 2 hours.

[0096] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 130° C. for 26 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0097] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 450° C. for 2 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0098] Compared with Comparative Example 1, Example 7 adds fluorinated polyimide with a mass ratio of 1.0% to TiO2 to assist in the preparation; the volume ratio of ethanol to tetrabutyl titanate is 2.1:1; the hydrothermal temperature is 130°C, the hydrothermal time is 26h; and the ammonia atmosphere heat treatment temperature is 450°C.

[0099] Figure 8 Surface photovoltage signal comparison diagram of the samples obtained in Example 7 and Comparative Example 1. Figure 8 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of fluorinated polyimide. TiO2 prepared with the assistance of fluorinated polyimide at too low a hydrothermal reaction temperature can weaken the surface photovoltage signal of TiO2.

[0100] Example 8

[0101] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0102] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.0%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2, and the stirring time was 2 hours.

[0103] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 140° C. for 30 h. After the reaction was completed, the suspension was filtered, washed, dried at 55° C., and ground.

[0104] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 480° C. for 1 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0105] Compared with Comparative Example 1, Example 8 is prepared by adding polyimide with a mass ratio of 1.0% to TiO2; the hydrothermal temperature is 140°C, the hydrothermal time is 30h; the drying temperature is 55°C; the heat treatment temperature under ammonia atmosphere is 480°C, and the time is 1h.

[0106] Figure 9 Surface photovoltage signal comparison diagram of the samples obtained in Example 8 and Comparative Example 1. Figure 9 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of polyimide is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of polyimide. If the hydrothermal time is too long, the surface photovoltage signal of TiO2 prepared with the assistance of polyimide can be weakened.

[0107] Example 9

[0108] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0109] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.5%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2, and the stirring time was 2 hours.

[0110] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 160° C. for 28 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0111] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 450° C. for 3 h in an ammonia atmosphere, cooled, and then ground to obtain TiO2.

[0112] Compared with Comparative Example 1, Example 9 is prepared by adding polyfluoroethylene in a mass ratio of 1.5% to TiO2; the hydrothermal temperature is 160°C, the hydrothermal time is 28h; the heat treatment temperature under ammonia atmosphere is 450°C, and the time is 3h.

[0113] Figure 10 Surface photovoltage signal comparison diagram of the samples obtained in Example 9 and Comparative Example 1. Figure 10It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of polyfluoroethylene is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of polyfluoroethylene. The preparation of TiO2 with the assistance of polyfluoroethylene can weaken the surface photovoltage signal of TiO2.

[0114] Example 10

[0115] The preparation process of the surface photovoltage signal attenuation type TiO2 in this embodiment is as follows:

[0116] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.5%; the volume ratio of ethanol to tetrabutyl titanate was 2.2:1; the volume ratio of deionized water to tetrabutyl titanate was 1.8, and the stirring time was 2 hours.

[0117] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 160° C. for 20 h. After the reaction was completed, the suspension was filtered, washed, dried at 58° C., and ground.

[0118] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 480° C. in an air atmosphere for 3 h, cooled, and then ground to obtain TiO2.

[0119] Compared with Comparative Example 1, the mass ratio of the embodiment to TiO2 is 1.5% of fluorinated polyimide as an auxiliary preparation; the volume ratio of ethanol to tetrabutyl titanate is 2.2:1; the volume ratio of deionized water to tetrabutyl titanate is 1.8; the hydrothermal temperature is 160°C, and the hydrothermal time is 20h; TiO2 is heat-treated in an air atmosphere; the air atmosphere heat treatment temperature is 480°C, and the time is 3h.

[0120] Figure 11 Surface photovoltage signal comparison diagram of the samples obtained in Example 10 and Comparative Example 1. Figure 11 It can be seen that the surface photovoltage signal of TiO2 prepared with the assistance of fluorinated polyimide is significantly lower in the range of 310-480nm than that of TiO2 prepared without the assistance of fluorinated polyimide. Heat treatment of TiO2 prepared with the assistance of fluorinated polyimide in air atmosphere can weaken the surface photovoltage signal of TiO2.

[0121] Example 11

[0122] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0123] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 0.5%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2.2, and the stirring time was 2 hours.

[0124] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 150° C. for 28 h. After the reaction was completed, the suspension was filtered, washed, dried at 55° C., and ground.

[0125] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 450° C. for 2 h in a nitrogen atmosphere, cooled, and then ground to obtain TiO2.

[0126] Compared with Comparative Example 1, Example 11 adds fluorinated polyimide in a mass ratio of 0.5% to TiO2 to assist in the preparation; the volume ratio of deionized water to tetrabutyl titanate is 2.2; the hydrothermal temperature is 150°C, and the hydrothermal time is 28h; TiO2 is heat-treated in a nitrogen atmosphere; the drying temperature is 55°C; and the heat treatment temperature in a nitrogen atmosphere is 450°C.

[0127] Figure 12 Surface photovoltage signal comparison diagram of the samples obtained in Example 11, Example 1 and Comparative Example 1. Figure 12 It can be seen that the surface photovoltage signal of TiO2 prepared by heat treatment in nitrogen atmosphere and assisted by fluorinated polyimide is improved in the range of 310-480nm compared with that of TiO2 prepared without fluorinated polyimide, but is significantly weakened compared with that of TiO2 prepared by heat treatment in ammonia atmosphere and assisted by fluorinated polyimide. TiO2 prepared with an appropriate amount of fluorinated polyimide and calcined in ammonia atmosphere can enhance the surface photovoltage signal of TiO2.

[0128] Example 12

[0129] The preparation process of the surface photovoltage signal enhanced TiO2 in this embodiment is as follows:

[0130] 1) Fluorinated polyimide powder was mixed with ethanol, tetrabutyl titanate was added to form a suspension, and deionized water was added and stirred; the mass ratio of the fluorinated polyimide to the subsequently generated TiO2 was 1.5%; the volume ratio of ethanol to tetrabutyl titanate was 2:1; the volume ratio of deionized water to tetrabutyl titanate was 2.1, and the stirring time was 2 hours.

[0131] 2) The suspension obtained in step 1) was transferred to a hydrothermal reactor and subjected to a hydrothermal reaction at 140° C. for 18 h. After the reaction was completed, the suspension was filtered, washed, dried at 60° C., and ground.

[0132] 3) The powder obtained in step 2) was placed in a quartz boat in a tube furnace, treated at 480°C for 3 h in a nitrogen-hydrogen mixed gas (5% H2 + 95% N2) atmosphere, and then ground after cooling to obtain TiO2.

[0133] Compared with Comparative Example 1, Example 12 adds fluorinated polyimide in a mass ratio of 1.5% to TiO2 to assist in the preparation; the volume ratio of ethanol to tetrabutyl titanate is 2:1; the volume ratio of deionized water to tetrabutyl titanate is 2.1; the hydrothermal temperature is 140°C, and the hydrothermal time is 18 hours; TiO2 is heat-treated in a nitrogen-hydrogen mixed gas (5% H2 + 95% N2) atmosphere; the heat treatment temperature in the nitrogen-hydrogen mixed gas atmosphere is 480°C, and the time is 3 hours.

[0134] Figure 13 Surface photovoltage signal comparison diagram of the samples obtained in Example 12, Example 3 and Comparative Example 1. Figure 13 It can be seen that the surface photovoltage signal of TiO2 prepared by nitrogen-hydrogen mixed heat treatment and assisted by fluorinated polyimide is improved in the range of 310-480nm compared with that of TiO2 prepared without the assistance of fluorinated polyimide, but is significantly weakened compared with that of TiO2 prepared by ammonia atmosphere heat treatment and assisted by fluorinated polyimide. The preparation of TiO2 with the assistance of an appropriate amount of fluorinated polyimide can enhance the surface photovoltage signal of TiO2.

[0135] The above descriptions are merely typical embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for enhancing the surface photovoltage of TiO2, characterized in that The following steps are involved: In the first step, a certain amount of fluorinated polyimide powder is mixed with ethanol, and then tetrabutyl titanate is added to form a suspension, and finally deionized water is added and stirred; the mass ratio of the added fluorinated polyimide powder to the generated TiO2 is 0.5%-2.0%; the volume ratio of ethanol to tetrabutyl titanate is 2-2.5; In the second step, the material obtained in the first step is transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, it is filtered, washed, dried and ground to obtain a powder; the hydrothermal temperature is 140-180°C and the hydrothermal time is 18-30 hours; The third step is to place the powder into a quartz boat in a tube furnace, heat it in an ammonia atmosphere, and grind it after cooling to obtain TiO2 with enhanced surface photovoltage signal; the heating temperature in the tube furnace is 450-500℃; the heating time is 1 h-3 h; the surface photovoltage signal of TiO2 with enhanced surface photovoltage signal is significantly enhanced in the range of 310-480 nm, and the surface photovoltage signal can reach 1.5 mV.

2. A method for enhancing TiO2 surface photovoltage according to claim 1, characterized in that: The stirring time described in the first step is 4-8 h.

3. A method for enhancing TiO2 surface photovoltage according to claim 1, characterized in that: In the first step, the volume ratio of deionized water to tetrabutyl titanate is 1.5-2.

5.

4. A method for enhancing TiO2 surface photovoltage according to claim 1, characterized in that: The second step is drying at a temperature of 50-60°C; the particle size after grinding is 100-120 mesh.

5. The method for enhancing the surface photovoltage of TiO2 according to claim 1, wherein: After the third step of grinding, the particle size is 100-120 mesh.

6. TiO2 with enhanced surface photovoltage obtained by the method according to any one of claims 1 to 5.

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