Water photovoltaic thin film device based on titanium dioxide and preparation method and application of water photovoltaic thin film device

Abstract

The invention relates to a water photovoltaic thin film device based on titanium dioxide and a preparation method and application thereof, and the preparation method comprises the following steps: transversely coating two conductive carbon pastes on a flexible substrate through a blade coating method, and drying to form two parallel wires to obtain a substrate with a wire layer; longitudinally coating a layer of titanium dioxide slurry on the substrate with the wire layer, wherein the titanium dioxide slurry is formed by mixing titanium dioxide nano powder, a binder and an organic solvent; and drying to form a titanium dioxide film, thereby obtaining the water photovoltaic film device based on titanium dioxide. The water photovoltaic thin film device based on titanium dioxide can generate continuous water photovoltaic electric energy through water evaporation driving, a self-driving signal source is provided for the device, so that dependence on an external power supply is avoided, meanwhile, as an N-type semiconductor, the conductivity of the device is highly sensitive to the environmental oxygen concentration, and by measuring an electric signal spontaneously generated by the device, the oxygen concentration of the environment can be accurately measured. The oxygen concentration of the environment can be indirectly sensed with high sensitivity without an external power supply.

Description

Technical Field

[0001] This invention relates to the field of water-voltaic technology, specifically to a water-voltaic thin-film device based on titanium dioxide, its preparation method, and its application. Background Technology

[0002] Oxygen detection technology is crucial in many fields, especially in mining, geological exploration, and even archaeology, where it is a vital safeguard for life. However, traditional oxygen detection methods, including fixed monitoring points or handheld portable devices, heavily rely on external power sources, resulting in heavy operational burdens, low coordination efficiency, and the inability to perform long-term real-time monitoring. Therefore, there is a need to introduce more portable devices with real-time detection capabilities.

[0003] The water voltage effect is a phenomenon where a potential difference is generated by the interaction between water and a solid surface. Its main mechanism is that the surface of a solid material often carries an electric charge. When it comes into contact with water, the charges in the water cause the charges on the material surface to rearrange, forming an electric double layer and thus generating a potential difference. If the water also evaporates, the evaporation process carries away ions (such as H+) from the water. + OH - The materials move in a directional manner, carrying with them the electrical charges within the material. Some materials may even react slightly with water, generating additional mobile charges. These separated charges can be connected by wires to form an electric current, thus achieving continuous power generation.

[0004] However, the amount of electricity generated by the photovoltaic effect is often too small, making it almost impossible to apply in the field of power generation. At the same time, the structure of the thin film and its special power generation method also greatly limit its application as a power source for microelectronic devices such as sensors. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a titanium dioxide-based water-voltaic thin film device, its preparation method and application, solving the technical problems in the prior art where electrochemical or semiconductor oxygen sensors need to rely on external power sources and the traditional water-voltaic effect is difficult to utilize.

[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing a water-voltaic thin-film device based on titanium dioxide, comprising the following steps: S1, coating two conductive carbon pastes laterally on a flexible substrate by a blade coating method, and drying them to form two parallel wires, thereby obtaining a substrate with a wire layer; S2, coating a layer of titanium dioxide slurry longitudinally on the substrate with the wire layer, wherein the titanium dioxide slurry is composed of titanium dioxide nanopowder, a binder and an organic solvent; and then drying it to form a titanium dioxide thin film, thereby obtaining a water-voltaic thin-film device based on titanium dioxide.

[0007] Secondly, the present invention provides a water-voltaic thin-film device prepared by the above-described preparation method.

[0008] Thirdly, the present invention provides an application of the above-mentioned water-voltaic thin-film device in oxygen concentration detection.

[0009] Compared with the prior art, the beneficial effects of the present invention include: This invention relates to a titanium dioxide-based water-voltaic thin-film device that generates continuous water-voltaic power through water evaporation, providing a self-driven signal source and thus avoiding dependence on an external power supply. Furthermore, as an N-type semiconductor, its conductivity is highly sensitive to ambient oxygen concentration; oxygen adsorption captures surface charge carriers, effectively modulating its Fermi level and carrier transport capability. This modulation is directly reflected in the output intensity of the water-voltaic signal. Therefore, by measuring the spontaneously generated electrical signal of this device, it is possible to indirectly and with high sensitivity sense ambient oxygen concentration without an external power source. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the water-voltaic thin-film device of the present invention; Figure 2 The results are the open-circuit voltage test results of the water-volt thin-film device in Embodiment 1 of the present invention under different oxygen content environments. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] To address the shortcomings of current electrochemical or semiconductor oxygen sensors that rely on external power sources, this invention provides a titanium dioxide-based water-voltaic thin-film device, its fabrication method, and its applications. Utilizing the unique material properties of titanium dioxide, the invention achieves an intrinsic coupling between oxygen-sensing characteristics and water-voltaic power generation, thereby enabling oxygen monitoring based on the water-voltaic effect. Specifically, nanostructured titanium dioxide, due to its excellent specific surface area and hydrophilicity, can generate continuous water-voltaic power through water evaporation, providing a self-driven signal source for the device. Simultaneously, as an N-type semiconductor, its conductivity is highly sensitive to ambient oxygen concentration; oxygen adsorption captures surface charge carriers, effectively modulating its Fermi level and carrier transport capability. This modulation is directly reflected in the output intensity of the water-voltaic signal: as oxygen concentration increases, the water-voltaic current / voltage decreases, and vice versa. Therefore, by measuring the spontaneously generated electrical signal of this device, it is possible to indirectly and with high sensitivity sense ambient oxygen concentration without an external power source. This integrated "sensing-power generation" design completely eliminates the dependence of traditional electrochemical or semiconductor oxygen sensors on external power sources, opening up new avenues for miniaturized, low-power, and even passive oxygen monitoring solutions.

[0013] In a first aspect, the present invention provides a method for preparing a water-voltaic thin-film device based on titanium dioxide, comprising the following steps: S1, two conductive carbon pastes are horizontally coated on a flexible substrate by a scraping method, and after drying, two parallel wires are formed, resulting in a substrate with a wire layer. S2, a layer of titanium dioxide slurry is longitudinally coated on a substrate with a conductive layer. The titanium dioxide slurry is composed of titanium dioxide nanopowder, binder and organic solvent. After drying, a titanium dioxide thin film is formed, and a water-voltaic thin film device based on titanium dioxide is obtained.

[0014] Preferably, in step S1, the flexible substrate includes polyvinyl chloride (PVC). This invention uses a non-conductive and flexible PVC material as the substrate to avoid the formation of charge leakage channels on the conductive substrate, which would lead to rapid recombination of interface charges generated by the water voltaic effect, thus reducing the open-circuit voltage.

[0015] Preferably, in step S1, the flexible substrate undergoes pretreatment before use. The pretreatment specifically includes: ultrasonic cleaning with anhydrous ethanol for 10–20 min, ultrasonic cleaning with deionized water for 5–15 min, and then drying at 50–70 °C for 15–25 min. This invention removes oil stains from the surface of the flexible substrate through ultrasonic cleaning with anhydrous ethanol, removes residual ethanol with deionized water, and ensures the substrate surface is free of impurities after drying, thus improving the adhesion between subsequent conductive lines and thin film layers.

[0016] Preferably, in step S1, the solid content of the conductive carbon paste is 50-60%; the conductive carbon paste is of the JELCON CH-8 type. This invention improves conductivity and water resistance by using conductive carbon paste to make the wires; and avoids the direct use of metal wires (metal wires directly exposed to the outside are extremely prone to oxidation and failure).

[0017] Preferably, in step S1, the coating speed of the scraping method is controlled at 3–6 cm / s. This invention avoids the formation of air bubbles by controlling the coating speed.

[0018] Preferably, the drying in step S1 is carried out at 50–70 °C for 20–40 min.

[0019] Preferably, in step S1, the width of the wire is 0.3 to 0.8 cm.

[0020] Preferably, in step S2, the preparation step of titanium dioxide slurry includes: mixing titanium dioxide nanopowder and organic solvent at a ratio of 0.4 to 0.6 g / mL to obtain a suspension; then adding a binder to the suspension at a ratio of 8 to 12 μL / mL, stirring for 20 to 40 min, and then ultrasonically vibrating for 4 to 6 min, repeating 2 to 4 times to obtain titanium dioxide slurry.

[0021] Preferably, in step S2, the organic solvent includes anhydrous ethanol; the binder includes a 4-6 wt% Nafion solution. This invention improves the overall bonding strength by adding Nafion.

[0022] Preferably, the drying in step S2 is carried out at 50–70 °C for 20–40 min.

[0023] Preferably, in step S2, the width of the titanium dioxide film is 0.8 to 1.2 cm.

[0024] Secondly, the present invention provides a water-voltaic thin-film device prepared by the above-described preparation method.

[0025] See Figure 1 The water-voltaic thin-film device obtained by the present invention includes a substrate 1, two horizontally arranged wires 2 on the substrate 1, and a carbon dioxide thin film 3 arranged vertically above the wires.

[0026] Thirdly, the present invention provides an application of the above-mentioned water-voltaic thin-film device in oxygen concentration detection.

[0027] Preferably, the steps for detecting oxygen concentration include: The water-voltaic thin-film device is placed in a closed space, and part of the titanium dioxide thin film of the water-voltaic thin-film device is located in water; Then, mixed gases with different oxygen contents were introduced into the sealed space, and the open-circuit voltage of the water volt effect under different oxygen contents was measured. By fitting a power function to the oxygen content and open-circuit voltage, the relationship between open-circuit voltage and oxygen concentration is obtained. Substitute the open-circuit voltage of the gas to be measured into the open-circuit voltage-oxygen concentration relationship to obtain the oxygen concentration of the gas to be measured.

[0028] It should be noted that during the actual testing process, a portion of the titanium dioxide film is ensured to be submerged in water, and the position of the wires is not critical; in the testing of this invention, neither wire is submerged. The open-circuit voltage of this invention was measured using an electrochemical workstation (Chi660E).

[0029] A further preferred expression for the relationship between open-circuit voltage and oxygen concentration is: V=6.0852C -0.608 Where C is the oxygen concentration and V is the open-circuit voltage.

[0030] The present invention will be further described in detail below through specific embodiments. The substrate is a 4 cm × 10 cm PVC to accommodate the layout requirements of the subsequent thin film layer and wires. The substrate needs to be pretreated before use: ultrasonically cleaned with anhydrous ethanol for 15 min (to remove surface oil), ultrasonically cleaned with deionized water for 10 min (to remove residual ethanol), and then dried in a 60 ℃ oven for 20 min.

[0031] Example 1 A method for fabricating a water-voltaic thin-film device based on titanium dioxide includes the following steps: S1. On the pretreated PVC substrate, apply tape longitudinally, leaving two parallel rectangular conductor areas, each measuring 4 cm × 0.5 cm with a spacing of 4 cm, to serve as the positive and negative conductors, respectively. Using a scraper, evenly apply conductive carbon paste (JELCON CH-8) to the reserved areas at a scraping speed of 5 cm / s. After removing the tape, place the substrate in a forced-air drying oven and heat at 60 ℃ for 30 min until the conductive carbon paste is completely dry. Cool to room temperature to form two parallel conductors, resulting in a substrate with a conductor layer.

[0032] S2, using anatase phase titanium dioxide nanopowder and anhydrous ethanol as raw materials, mixed into a suspension at a ratio of 0.5 g / mL, then adding nafion at a ratio of 10 μL / mL to the suspension to improve the overall binding force, stirring for 30 min and then ultrasonically vibrating for 5 min, repeating three times to ensure thorough and uniform mixing, to obtain titanium dioxide slurry. A 1 cm × 8 cm rectangular pattern is longitudinally pre-defined on a substrate with a conductive layer using adhesive tape. A smooth layer of titanium dioxide slurry is then applied to the rectangular pattern using a scraping method. After removing the tape, the substrate is placed in an oven and heated at 60 °C for 30 min until all organic solvents have completely evaporated, forming a titanium dioxide thin film and thus obtaining a titanium dioxide-based water-voltaic thin-film device.

[0033] Application Example 1 An application of a water-voltaic thin-film device in oxygen concentration detection includes the following steps: (1) The water-voltaic thin-film device obtained in Example 1 was placed in a sealed space with dimensions of 1 m (length, width, and height), and filled with a mixture of high-purity nitrogen and oxygen in known proportions. The oxygen content in the mixture was 5%, 10%, 15%, and 21%, respectively. The open-circuit voltage of the water-voltaic thin-film device under different oxygen content environments was tested. During the test, approximately 2 cm of the bottom portion of the titanium dioxide thin film in the water-voltaic thin-film device was submerged in water, while the remaining portion was exposed to the gas environment. The test results are as follows: Figure 2 As shown.

[0034] (2) Take Figure 2 The average value of the open-circuit voltage test results for each segment was used to fit the oxygen content and open-circuit voltage. Since the change in titanium dioxide resistance with oxygen follows a power law relationship, a power function was used for fitting, resulting in the open-circuit voltage-oxygen concentration relationship: V = 5.5297C -0.602 Where C is the oxygen concentration and V is the open-circuit voltage.

[0035] (3) Test the open circuit voltage V1 of the gas to be tested. Substitute V1=2.1 into the open circuit voltage-oxygen concentration relationship to obtain the oxygen concentration C1=4.998% of the gas to be tested. It was verified that it was basically the same as the actual oxygen concentration in the gas to be tested.

[0036] Comparative Example 1 (Examining the impact of different sensitive materials) The only difference from Example 1 is that the titanium dioxide nanopowder in step S2 is replaced with an equal amount of zinc oxide (ZnO) nanopowder, while the other steps and conditions are the same as in Example 1.

[0037] Comparative Example 2 The only difference from Example 1 is that the ratio of titanium dioxide to ethanol in step S2 is adjusted to prepare a suspension of 0.2 g / mL. The other steps and conditions are the same as in Example 1.

[0038] Comparative Example 3 The only difference from Example 1 is that the ratio of titanium dioxide to ethanol in step S2 is adjusted to prepare a suspension of 0.8 g / mL. The other steps and conditions are the same as in Example 1.

[0039] Comparative Example 4 (Effect of no Nafion binder) The only difference from Example 1 is that Nafion solution is not added in step S2, while the other steps and conditions are the same as in Example 1.

[0040] Comparative Example 5 (The effect of using a conductive substrate) The only difference from Example 1 is that the PVC substrate in step S1 is replaced with a conductive ITO / PET film.

[0041] The open-circuit voltage of the devices obtained in Comparative Examples 1-5 above was tested for the water-volt effect. The specific conditions and test results are shown in Table 1.

[0042] Table 1. Test conditions and results of open-circuit voltage of the devices obtained in Comparative Examples 1-5.

[0043] As shown in Table 1, replacing the sensitive material in Comparative Example 1 changed the type of slurry, resulting in a very small change in output voltage, making it impossible to perform the corresponding fitting. Similarly, replacing titanium dioxide nanopowder with an equal amount of graphene yielded the same effect as Comparative Example 1. Therefore, titanium dioxide nanomaterials are preferred in this invention.

[0044] Different slurry concentrations were used in Comparative Examples 2-3. The results showed that if the titanium dioxide concentration was too low, it would easily lead to structural discontinuity, and if the concentration was too high, the internal transport resistance would be large and the titanium dioxide film would easily fall off. Therefore, the present invention preferably mixes titanium dioxide nanopowder and organic solvent at a ratio of 0.4 to 0.6 g / mL to obtain a suspension, and more preferably 0.5 g / mL.

[0045] Comparative Example 4 removed the Nafion binder, which affected the adhesion and made the film easy to fall off; Comparative Example 5 used a conductive substrate, which formed a charge leakage channel, causing the interface charge generated by the water voltaic effect to recombine rapidly, reducing the open circuit voltage and making it impossible to achieve an effective fit between open circuit voltage and oxygen concentration.

[0046] In summary, unlike existing technologies, this invention has the following characteristics: (1) The present invention provides a design concept for a novel oxygen detection technology. By utilizing the gas-sensitive properties of materials, the oxygen content in the environment is visualized as an electrical signal through the water voltaic effect. The device designed according to the present invention does not require an external power source and can achieve a certain degree of self-driving.

[0047] (2) Based on the related technologies in this invention, various wearable flexible devices can be designed, which greatly improves the mobility of oxygen detection devices.

[0048] (3) Based on the technical concept of the present invention, the detection of other types of gases can be achieved by replacing materials with different gas sensitivities.

[0049] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for fabricating a water-voltaic thin-film device based on titanium dioxide, characterized in that, Includes the following steps: S1, two conductive carbon pastes are horizontally coated on a flexible substrate by a scraping method, and after drying, two parallel wires are formed, resulting in a substrate with a wire layer. S2, a layer of titanium dioxide slurry is longitudinally coated on a substrate with a conductive layer. The titanium dioxide slurry is composed of titanium dioxide nanopowder, binder and organic solvent. After drying, a titanium dioxide thin film is formed, and a water-voltaic thin film device based on titanium dioxide is obtained.

2. The method for fabricating a titanium dioxide-based water-voltaic thin-film device according to claim 1, characterized in that, In step S1, the flexible substrate includes polyvinyl chloride; The flexible substrate undergoes pretreatment before use. The pretreatment specifically includes: ultrasonic cleaning with anhydrous ethanol for 10-20 min, ultrasonic cleaning with deionized water for 5-15 min, and then drying at 50-70 ℃ for 15-25 min.

3. The method for fabricating a titanium dioxide-based water-voltaic thin-film device according to claim 1, characterized in that, In step S1, the solid content of the conductive carbon paste is 50-60%.

4. The method for fabricating a titanium dioxide-based water-voltaic thin-film device according to claim 1, characterized in that, In step S1, the scraping speed of the scraping method is controlled to be 3-6 cm / s; The drying in step S1 is performed at 50–70 °C for 20–40 min; The width of the conductor is 0.3 to 0.8 cm.

5. The method for fabricating a titanium dioxide-based water-voltaic thin-film device according to claim 1, characterized in that, In step S2, the preparation step of the titanium dioxide slurry includes: mixing titanium dioxide nanopowder and organic solvent at a ratio of 0.4 to 0.6 g / mL to obtain a suspension; then adding a binder to the suspension at a ratio of 8 to 12 μL / mL, stirring for 20 to 40 min, and then ultrasonically vibrating for 4 to 6 min, repeating 2 to 4 times to obtain the titanium dioxide slurry; The organic solvent includes anhydrous ethanol; The adhesive includes Nafion.

6. The method for fabricating a titanium dioxide-based water-voltaic thin-film device according to claim 1, characterized in that, The drying in step S2 is performed at 50–70 °C for 20–40 min; The width of the titanium dioxide film is 0.8 to 1.2 cm.

7. A water-voltaic thin-film device prepared by the preparation method according to any one of claims 1-6.

8. The application of the water-voltaic thin-film device as described in claim 7 in oxygen concentration detection.

9. The application of the water-voltaic thin-film device according to claim 8 in oxygen concentration detection, characterized in that, The steps for oxygen concentration detection include: The water-voltaic thin-film device is placed in a closed space, and part of the titanium dioxide thin film of the water-voltaic thin-film device is located in water; Then, mixed gases with different oxygen contents were introduced into the sealed space, and the open-circuit voltage of the water volt effect under different oxygen contents was measured. By fitting a power function to the oxygen content and open-circuit voltage, the relationship between open-circuit voltage and oxygen concentration is obtained. Substitute the open-circuit voltage of the gas to be measured into the open-circuit voltage-oxygen concentration relationship to obtain the oxygen concentration of the gas to be measured.

10. The application of the water-voltaic thin-film device according to claim 9 in oxygen concentration detection, characterized in that, The relationship between open-circuit voltage and oxygen concentration is as follows: V=5.5297C -0.602 Where C is the oxygen concentration and V is the open-circuit voltage.

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