Photoelectric catalyst for photo-assisted metal-air seawater battery, heterojunction photoelectrode, battery and application of photo-assisted metal-air seawater battery

Abstract

The invention discloses a photoelectric catalyst for a photo-assisted metal-air seawater battery, a heterojunction photoelectrode, the battery and application thereof, and belongs to the technical field of conjugated organic polymer materials. The invention discloses a photoelectric catalyst for a photo-assisted metal-air seawater battery, which is a conjugated porous organic polymer with an A3-(D-Core) structure, that is, the catalyst is a conjugated porous polymer with a specific topological structure formed by three acceptor units surrounding a donor core, the donor in the polymer is benzotrithiophene, and the donor in the polymer is benzotrithiophene. And the acceptor is benzobithiazole. The photoelectric catalyst for the photo-assisted metal-air seawater battery has photo-response activity, can effectively drive OER / ORR reaction in a neutral medium, namely seawater, can obtain a remarkable light enhancement effect, and can produce H2O2.

Description

Technical Field

[0001] This invention relates to the field of conjugated organic polymer materials technology, and more specifically, to a photoelectrocatalyst, heterojunction photoelectrode, battery, and their applications for a light-assisted metal-air-seawater battery. Background Technology

[0002] Hydrogen peroxide (H2O2), as an important green oxidant and clean energy carrier, is widely used in industry, environmental protection, medical and energy fields. However, its mainstream production technologies, such as the anthraquinone process and traditional electrochemical synthesis methods, generally suffer from drawbacks such as high energy consumption, generation of toxic byproducts, and reliance on expensive purification processes.

[0003] Rechargeable metal-air battery systems, especially metal-air seawater batteries, are attracting attention because they can simultaneously output electrical energy and high-value-added chemicals (such as H2O2) during discharge by utilizing the oxygen reduction reaction.

[0004] Metal-air seawater batteries have a similar battery structure to traditional metal-air batteries, except that they use seawater as the electrolyte. Typically, a metal-air seawater battery mainly consists of an air cathode containing a catalyst and a gas diffusion layer, an active metal anode, and a seawater electrolyte.

[0005] Theoretically, by designing a cathode with bifunctional catalytic activity, combining the oxygen evolution reaction with the highly selective two-electron oxygen reduction reaction, H2O2 can be efficiently produced directly from seawater during discharge, and energy storage can be achieved, forming a value-added self-powered system. The reaction equation is as follows:

[0006] Discharge process: Cathode: O2 + 2H + +2e － →H2O2 Anode: Na → Na + +e － Na + +OH － →NaOH Charging process: Cathode: 2H₂O → O₂ + 4H₂O + +4e － Anode: NaOH → Na + +OH － Na + +e － →Na + Existing technologies use manganese tungstate as a bifunctional catalyst to prepare zinc-air batteries, using 6M potassium hydroxide and 0.2M zinc acetate as electrolytes, generating H2O2 during discharge.

[0007] However, metal-air batteries using manganese tungstate as a catalyst exhibit slow reaction kinetics in near-neutral seawater media, resulting in low H2O2 yield and energy efficiency. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a photocatalyst for a light-assisted metal-air seawater battery that addresses the defects and deficiencies of the prior art. This catalyst has photoresponsive activity and can effectively drive the OER / ORR reaction in a neutral medium such as seawater and achieve a significant light enhancement effect.

[0009] Another object of the present invention is to provide a heterojunction photoelectrode.

[0010] Another object of the present invention is to provide a light-assisted metal-air-seawater battery.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution: A photoelectrocatalyst for a light-assisted metal-air-seawater battery, wherein the catalyst is a conjugated porous organic polymer having repeating units with the structure shown in Formula I:

[0012] Formula I.

[0013] This invention discloses a photoelectrochemical catalyst for a light-assisted metal-air-seawater battery. The catalyst is a conjugated porous organic polymer with an A3-(D-Core) structure, which is a conjugated porous polymer with a specific topological structure consisting of three acceptor units surrounding a donor core. The donor in the polymer is benzotrithiophene, and the acceptor is benzobisthiazole.

[0014] The photocatalyst for photo-assisted metal-air seawater batteries of the present invention has photoresponsive activity. In photo-assisted metal-air seawater batteries, it is a special photocathode material that simultaneously possesses excellent seawater stability, high efficiency bifunctional catalytic activity (for OER / ORR), high H2O2 selectivity, and strong photoelectric coupling capability. It can utilize photogenerated charge carriers to promote the cathode reaction, overcome the reaction kinetic limitations in near-neutral seawater media, effectively drive the OER / ORR reaction and obtain a significant light enhancement effect, thereby improving H2O2 yield and energy efficiency.

[0015] This invention also protects a heterojunction photoelectrode, comprising a substrate, an inner layer of a TiO2 nanorod array, and an outer layer of a catalyst, wherein the catalyst is the aforementioned photoelectrochemical catalyst for a light-assisted metal-air-seawater battery.

[0016] In a specific embodiment of the present invention, the substrate may be carbon paper or conductive glass.

[0017] The heterojunction photoelectrode of this invention uses a TiO2 nanorod array as the inner layer because rutile TiO2 nanorods possess excellent electronic transport properties, superior structural stability, and highly tunable physicochemical properties. Its band gap is approximately 3.0 eV, primarily absorbing ultraviolet light (wavelength <400 nm), and its visible light response can be moderately extended through doping or morphology modulation. Its regular one-dimensional nanostructure provides directional transport channels for photogenerated carriers, significantly suppressing electron-hole recombination; while the mainly exposed (110) crystal plane possesses a high density of catalytically active sites, facilitating surface redox reactions.

[0018] The heterojunction photoelectrode of this invention uses the aforementioned catalyst as the outer layer. This is because the unique topological structure in the conjugated porous polymer induces favorable electronic modulation. Its mechanism of action is as follows: on the one hand, it optimizes the adsorption of oxygen species and guides the oxygen reduction reaction toward the step 2e. - The ORR pathway is activated; on the other hand, it promotes electronic coupling with OER-active TiO2, thereby establishing an S-type charge transfer mechanism and enhancing the built-in electric field. These properties endow this polymer-based heterostructure with photo-promoted 4e-ionization in neutral media. - OER and 2e - ORR bifunctional catalytic capability.

[0019] Preferably, the conjugated porous organic polymer is obtained by a condensation reaction of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde.

[0020] This invention also protects a method for preparing the heterojunction photoelectrode, comprising the following steps: S1. Tetrabutyl titanate solution is coated on the substrate surface and calcined to obtain a substrate loaded with TiO2 seeds; S2. The substrate with TiO2 seed crystals obtained in step S1 is placed in a solution of hydrochloric acid and tetrabutyl titanate precursor, subjected to hydrothermal reaction, and calcined to obtain a substrate with TiO2 nanorod arrays. S3. 2,5-Diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde are mixed in an organic solvent to obtain a mixture. The substrate with the TiO2 nanorod array obtained in step S2 is immersed in the mixture, and a condensation reaction is carried out in an inert atmosphere to obtain the heterojunction photoelectrode. In step S3, the temperature of the condensation reaction is 120~170℃, and the time of the condensation reaction is 12~72 hours.

[0021] In step S1, the substrate is pretreated commercial carbon paper (CP); the pretreatment process is: ultrasonic cleaning of the commercial carbon paper with acetone, ethanol and deionized water and vacuum drying.

[0022] In step S1, the tetrabutyl titanate solution is a tetrabutyl titanate isopropanol solution.

[0023] In step S1, the calcination temperature is 400~550℃ and the time is 0.5~2h.

[0024] In step S2, the hydrothermal reaction temperature is 150~170℃ and the hydrothermal reaction time is 12~24h.

[0025] In step S2, the calcination temperature is 400~550℃, and the calcination time is 0.5~2h.

[0026] In step S3, the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde is (0.5-1):1.5.

[0027] In step S3, the concentration of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde is 0.1~0.25 mmol. For example, it can be 0.12 mmol, 0.14 mmol, 0.16 mmol, 0.18 mmol, 0.2 mmol, or 0.22 mmol.

[0028] In step S3, the specific temperature of the condensation reaction can be 120℃, 130℃, 140℃ or 150℃.

[0029] In step S3, the condensation reaction time can be 12h, 24h, 30h, 48h, or 72h.

[0030] In step S3, after the condensation reaction, a purification process is also included. The purification process is as follows: the mixed solution obtained after the condensation reaction is added to dichloromethane for precipitation and filtration. The obtained solid is washed several times with N,N-dimethylformamide. Then, the collected product is subjected to Soxhlet extraction with dichloromethane for 3 days and then dried in a vacuum drying oven.

[0031] The method for preparing heterojunction photoelectrodes of the present invention involves in-situ growth of a conjugated porous polymer generated by a condensation reaction onto a TiO2 nanorod array to form a heterojunction photoelectrode.

[0032] Preferably, the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde is (0.8–1):1.5. The two reactive monomers can react fully to form bonds, resulting in the conjugated porous polymer with the highest yield.

[0033] Preferably, in step S3, the catalyst for the condensation reaction is acetic acid. The molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride to acetic acid is 1:15.5.

[0034] Preferably, in step S3, the organic solvent is one or more of N-methylpyrrolidone (NMP), toluene, or methanol.

[0035] This invention also protects a liquid flow type photo-assisted metal-air seawater battery, comprising a photoelectrode, a sodium electrode, a solid electrolyte and a seawater electrolyte disposed between the photoelectrode and the sodium electrode, wherein the photoelectrode is the heterojunction photoelectrode described above.

[0036] In this system, the photoelectrode serves as the positive electrode, the sodium electrode as the negative electrode, and the superconducting solid electrolyte only allows Na ions to pass through.

[0037] The above-mentioned sodium-air seawater battery is prepared by: sealing the photoelectrode, sodium electrode and solid electrolyte in a glove box and letting it stand, then adding real seawater as the electrolyte to assemble the sodium-air seawater battery.

[0038] The liquid flow photo-assisted metal-air seawater battery of the present invention is a rechargeable photochemical seawater battery that achieves efficient photoelectrochemical energy storage and high round-trip efficiency without the need for external power supply and oxygen input during photodischarge.

[0039] Preferably, the solid electrolyte is Na3Zr2Si2PO4. 12 .

[0040] This invention also protects the application of the above-described liquid flow photo-assisted metal-air seawater battery in the preparation of H2O2.

[0041] The liquid flow photo-assisted metal-air seawater battery of the present invention integrates a battery chemical system for the production of hydrogen peroxide. It can utilize natural seawater and sunlight to promote the in-situ synthesis of hydrogen peroxide, which is an economical and renewable method to realize the added value of the product from water to hydrogen peroxide.

[0042] In summary, the liquid-flow photo-assisted metal-air seawater battery of this invention employs a photoelectrocatalyst with excellent seawater stability, highly efficient bifunctional catalytic activity (for OER / ORR), high H2O2 selectivity, and strong photoelectric coupling capability. By combining the oxygen evolution reaction with the highly selective two-electron oxygen reduction reaction through a bifunctional cathode, H2O2 can be efficiently produced directly from seawater during discharge, achieving energy storage and forming a value-added self-powered system. The introduction of photo-assisted metal-air seawater battery system utilizes photogenerated carriers to promote the cathode reaction, improving reaction kinetics and energy efficiency even in near-neutral seawater media.

[0043] Compared with the prior art, the beneficial effects of the present invention are: This invention discloses a photocatalyst for a light-assisted metal-air-seawater battery. The catalyst is a conjugated porous organic polymer with an A3-(D-Core) structure, meaning it is a conjugated porous polymer with a specific topological structure consisting of three acceptor units surrounding a donor core. The donor in the polymer is benzotrithiophene, and the acceptor is benzobisthiazole. This photocatalyst for a light-assisted metal-air-seawater battery exhibits photoresponsive activity and can effectively drive the OER / ORR reaction in a neutral medium like seawater, achieving a significant light enhancement effect. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the chemical structure of the polymer in Example 1 and Comparative Example 1.

[0045] Figure 2 The image shows the carbon NMR spectrum of the polymer in Example 1 and Comparative Example 1.

[0046] Figure 3 The infrared spectrum of the polymer in Example 1 and Comparative Example 1 is shown.

[0047] Figure 4 The specific surface area and pore size spectra of the polymer in Example 1 and Comparative Example 1 are shown.

[0048] Figure 5 This is the Tauc bandgap diagram of the polymer in Example 1 and Comparative Example 1.

[0049] Figure 6 The image shows the XRD pattern of the heterojunction photoelectrode in Example 2 and Comparative Example 2.

[0050] Figure 7 This is a scanning electron microscope (SEM) image and a transmission electron microscope (TEM) image of the heterojunction photoelectrode of Example 2 and Comparative Example 2.

[0051] Figure 8This is Example 3, and the charge / discharge rate performance diagram of Comparative Example 3 at different current densities.

[0052] Figure 9 The concentration of H2O2 generated during the discharge test of the battery in Example 3 at different current densities.

[0053] Figure 10 Cyclic stability test of the battery in Example 3. Detailed Implementation

[0054] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0055] 2,5-Diamino-1,4-Dithiophenyl dihydrochloride, CAS No. 75464-52-7.

[0056] Benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde, CAS number 2243590-42-1.

[0057] 2,5-Thiophene-dicarboxaldehyde, CAS number 932-95-6.

[0058] Hydrophilic carbon paper, manufactured by Toray Industries, Japan, model number LG13-704-1I.

[0059] Ceramic electrolyte (NASICON, Na3Zr2Si2PO) 12 The manufacturer is Mingta Laboratory.

[0060] The seawater was sourced from natural seawater in Qingdao, Shandong Province, China.

[0061] Example 1 A photoelectrochemical catalyst for a light-assisted metal-air-seawater battery, wherein the catalyst is a conjugated porous organic polymer having repeating units with the structure shown in Formula I:

[0062] Formula I.

[0063] The preparation method of the above-mentioned conjugated porous organic polymer includes the following steps: 27.7 mg, 4.52 mmol / L of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 55.8 mg, 6.75 mmol / L of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde (the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde is 1:1.5) are added to 20 mL of N-methyl-2-pyrrolidone, 5... A mixture of 100 μL of methanol and 100 μL of acetic acid catalyst in an organic solvent was placed in a pressure-resistant tube. Carbon paper was immersed in the mixture as a substrate. After three degassing treatments, the sealed pressure-resistant tube was subjected to a condensation reaction at 150 °C for 72 h under an inert atmosphere. The carbon paper was washed with dichloromethane (DCM) and anhydrous N,N-dimethylformamide (DMF). The collected carbon paper was continuously extracted with dichloromethane using a Soxhlet extraction method for 3 days and then dried in a vacuum drying oven to obtain the above-mentioned conjugated porous organic polymer catalyst.

[0064] Example 2 A heterojunction photoelectrode includes a carbon paper substrate, an inner layer of TiO2 nanorod array, and an outer layer of catalyst. The catalyst is the photoelectrochemical catalyst for a light-assisted metal-air-seawater battery as described in Example 1.

[0065] The fabrication method of the above heterojunction photoelectrode includes the following steps: S1. Commercial carbon paper is pretreated by ultrasonic cleaning with acetone, ethanol and deionized water and vacuum drying.

[0066] Tetrabutyl titanate isopropanol solution was drop-coated onto the substrate surface in three portions, dried, and then calcined at 500℃ for 1 hour to obtain a substrate carbon paper loaded with TiO2 seeds. S2. The substrate carbon paper with TiO2 seed crystals obtained in step S1 was placed in a solution of 6M hydrochloric acid and 0.4mL tetrabutyl titanate precursor, and hydrothermally reacted at 150°C for 12h in a high-pressure reactor with a polytetrafluoroethylene liner. After washing, drying, and calcining at 500°C for 2h, the substrate carbon paper with TiO2 nanorod array was obtained. S3. 27.7 mg, 4.52 mmol / L of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 55.8 mg, 6.15 mmol / L of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde (the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride to benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde was 1:1.5) were added to 20 mL of N-methyl-2-pyrrolidone and 5... A mixture of 1 mL methanol and 100 μL acetic acid catalyst in an organic solvent was placed in a pressure-resistant tube. The substrate carbon paper with a TiO2 nanorod array supported obtained in step S2 was immersed in the mixture. After three degassing treatments, the sealed pressure-resistant tube was subjected to a condensation reaction at 150 °C for 72 h in an inert atmosphere. The carbon paper was washed with dichloromethane (DCM) and anhydrous N,N-dimethylformamide (DMF). The collected carbon paper was continuously extracted with dichloromethane using Soxhlet extraction for 3 days and then dried in a vacuum drying oven to obtain the above heterojunction photoelectrode.

[0067] Example 3 A liquid flow type photo-assisted metal-air seawater battery includes a photoelectrode, a sodium electrode, a solid electrolyte and a seawater electrolyte disposed between the photoelectrode and the sodium electrode, as described in Example 2.

[0068] The solid electrolyte is a ceramic electrolyte (NASICON, Na3Zr2Si2PO4). 12 ).

[0069] The above-mentioned liquid flow type photo-assisted metal-air seawater battery preparation method is as follows: the photoelectrode of Example 2 is used as the positive electrode, the sodium electrode is used as the negative electrode and the solid electrolyte are sealed and left to stand in a glove box, and 50 mL of seawater is added as the electrolyte to assemble the sodium-air seawater battery.

[0070] Comparative Example 1 A conjugated linear polymer having repeating units with the structure shown in Formula II:

[0071] Formula II.

[0072] The difference between the preparation method of the above-mentioned conjugated linear polymer and that of Example 1 is as follows: The 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde in Example 1 were replaced with 27.7 mg, 4.52 mmol / L of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 15.8 mg, 4.51 mmol / L of 2,5-thiophene-dicarboxaldehyde, i.e., the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 2,5-thiophene-dicarboxaldehyde was 1:1, to obtain the above-mentioned conjugated linear polymer.

[0073] Comparative Example 2 A photoelectrode, differing from Example 2 in step S3: S3. 27.7 mg, 4.52 mmol / L of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 15.8 mg, 4.51 mmol / L of 2,5-thiophene-dicarboxaldehyde (i.e., the molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and 2,5-thiophene-dicarboxaldehyde is 1:1) were mixed in an organic solvent containing 20 mL of N-methyl-2-pyrrolidone, 5 mL of methanol, and 100 μL of acetic acid catalyst. The mixture was placed in a pressure-resistant tube, and the substrate carbon paper with TiO2 nanorod arrays obtained in step S2 was immersed in the mixture. After three degassing treatments, the sealed pressure-resistant tube was subjected to a condensation reaction at 150 °C for 72 h in an inert atmosphere. The carbon paper was washed with dichloromethane (DCM) and anhydrous N,N-dimethylformamide (DMF), and then continuously extracted with dichloromethane for 3 days using Soxhlet extraction. The carbon paper was then dried in a vacuum drying oven to obtain the heterojunction photoelectrode described above.

[0074] Comparative Example 3 A liquid flow type photo-assisted metal-air-seawater battery differs from Example 3 in that the photoelectrode of Example 2 is replaced with the photoelectrode of Comparative Example 2.

[0075] Result detection Photo-assisted battery performance test: A xenon lamp with an AM 1.5 filter was used as the light source to simulate sunlight, maintaining an output power of 100 mW / cm². 2 The photoelectrode was illuminated by a light source, and the photovoltage characteristics of the solar seawater battery, i.e., the charge and discharge voltage generated under light irradiation, were recorded by an electrochemical workstation.

[0076] H2O2 production test of photo-assisted battery: The photo-assisted seawater battery test method during photodischarge includes the following steps: (1) Control the temperature during the photoreaction process through a liquid circulation device to ensure that H2O2 does not decompose; (2) Extract 1 mL of seawater electrolyte every 10 minutes to determine the H2O2 production.

[0077] The method for detecting H2O2 concentration was as follows: The sulfuric acid-N,N-diethyl-p-phenylenediamine (DPD) colorimetric method was used. Specifically, a certain concentration of DPD solution, peroxidase solution, and phosphate buffer solution were added to 1 mL of the electrolyte extracted in step (2), and the absorbance at a wavelength of 551 nm was measured using ultraviolet-visible spectrophotometry. The concentration of H2O2 in the sample was calculated based on the standard curve.

[0078] Performance test data are shown in Table 1-3 below. Figures 1-10 As shown.

[0079] (1) The photocharging voltage of the liquid flow-type photo-assisted metal-air seawater battery of Example 3 and Comparative Example 3 was tested at different current densities. The test results are shown in Table 1 below. Figure 8 As shown.

[0080] Table 1. Photocharging voltage of the liquid flow-type photo-assisted metal-air-seawater battery in Example 3 and Comparative Example 3

[0081] As can be seen from Table 1 above, compared with Comparative Example 3, the liquid flow type photo-assisted metal-air seawater battery of Embodiment 3 of the present invention has a lower photocharging voltage at different rates.

[0082] (2) The photodischarge voltages of the liquid flow-type photo-assisted metal-air seawater batteries of Example 3 and Comparative Example 3 were tested at different current densities. The test results are shown in Table 2 below. Figure 8 As shown.

[0083] Table 2. Photodischarge voltages of the flow-type photo-assisted metal-air-seawater batteries in Example 3 and Comparative Example 3

[0084] As can be seen from Table 2 above, compared with Comparative Example 3, the liquid flow type photo-assisted metal-air seawater battery of Embodiment 3 of the present invention has a higher photodischarge voltage at different rates.

[0085] As can be seen from Tables 1 and 2 above, the liquid flow-type photo-assisted metal-air seawater battery of the present invention achieves a current density of 0.01-0.5 mA / cm². 2 It exhibits excellent charge and discharge performance over a wide range.

[0086] (3) The temperature during the photoreaction process is precisely controlled by a circulating cooling flow pump device. Every 10 minutes, 1 mL of seawater electrolyte solution is taken to determine the hydrogen peroxide (H2O2) yield of the liquid flow photo-assisted metal-air seawater batteries of Example 3 and Comparative Example 3.

[0087] The test results of Example 3 are shown in Table 3 and Figure 9 As shown in Table 3, the test results of Comparative Example 3 are shown in Table 3.

[0088] Table 3

[0089] From Table 3 above and Figure 9 It can be seen that the liquid flow-type photo-assisted metal-air seawater battery of Embodiment 3 of the present invention can generate H2O2 during photodischarge at a current density of 0.1 mA / cm². 2 At this time, the yield of H2O2 is the highest, reaching 5.47 mmol / g / h.

[0090] During the synthesis of the materials in Example 1 and Comparative Example 1, the powders that were not loaded on carbon paper and dispersed in the solvent were subjected to the following performance tests.

[0091] Figure 1 The diagram shows the synthetic routes of the polymers in Example 1 and Comparative Example 1. Example 1 is a conjugated porous polymer with a specific topological structure, namely the A3-(D-Core) structure, consisting of three acceptor units surrounding a donor core. The donor in the polymer is benzotrithiophene, and the acceptor is benzobisthiazole. Comparative Example 1 is a conjugated linear polymer with an ADA structure. The donor in the polymer is thiophene, and the acceptor is benzobisthiazole.

[0092] Figure 2 (a) is the carbon NMR spectrum of the conjugated polymer in Example 1. Figure 2 (b) shows the carbon NMR spectrum of the conjugated polymer in Comparative Example 1. The measurements were performed using a Bruker Avance NEO 600 MHz 13C solid-state NMR spectrometer. The results indicate the successful synthesis of the DA-type conjugated organic polymers of Example 1 and Comparative Example 1.

[0093] Figure 3 (a) in the figure is the infrared spectrum corresponding to Example 1. Figure 3 (b) in the diagram is the infrared spectrum corresponding to Comparative Example 1. Figure 3 It can be seen that at 1658cm -1 The presence of a characteristic tensile vibration band of imine at this point confirms the reaction between the amino and aldehyde groups. (1113 cm) -1 and 964cm -1 The presence of C–S bonds indicates the success of the condensation reaction.

[0094] Figure 4 (a) in the figure is the nitrogen adsorption-desorption diagram of Example 1. Figure 4 Figure (b) in the diagram is a schematic diagram of nitrogen adsorption-desorption in Comparative Example 1. Figure 4 It can be seen that the benzotrithiophene conjugated polymer of Example 1 has a molecular weight of 1237.3 m.2 With a specific surface area of ​​ / g and a large number of porous structures, it meets the requirements for catalytic reactions; while the specific surface area of ​​the linear polymer of thiophene in Comparative Example 1 is only 30.44 m². 2 / g, no open pores.

[0095] Figure 5 (a) in the figure is the Tauc bandgap diagram corresponding to Example 1. Figure 5 Figure (b) shows the Tauc bandgap diagram corresponding to Comparative Example 1. This diagram was obtained through Kubelka-Munk function conversion of UV-Vis absorption spectra, and both polymers were identified as direct bandgap semiconductors. As shown in the figure, the conjugated porous polymer material of Example 1 has a narrower bandgap and better light absorption behavior, allowing for better utilization of visible light. This is because an intramolecular charge transfer (A3-(D-Core)) occurs between the electron-donating and acceptor groups. This intramolecular charge transfer can narrow the bandgap, thereby improving the solar light absorption capacity of the conjugated porous polymer.

[0096] Figure 6 The XRD pattern of the photoelectrode in Example 2 and Comparative Example 2 is shown below. Figure 6 It can be confirmed that rutile TiO2 and polymers were successfully synthesized on carbon paper, and the resulting conjugated polymer is an amorphous polymer.

[0097] Figure 7 For Example 2, the scanning electron microscope (SEM) image and transmission electron microscope (TEM) image of the photoelectrode of Comparative Example 2 are shown. Figure 7 As can be seen, a vertically oriented TiO2 nanorod array with an average diameter of approximately 223 nanometers and a length of approximately 1.70 micrometers is formed on the surface of the carbon fiber substrate of the present invention. Furthermore, the distinct bright and dark areas in the transmission electron microscopy image reveal the TiO2 nanorod array with an outer polymer coating on the inner layer.

[0098] Figure 8 This is a graph showing the charge / discharge rate performance of the battery in Example 3 and Comparative Example 3 at different current densities. From... Figure 8 As can be seen, the battery in Example 3 can achieve good photocharge and discharge performance over a wide current density range. This is because benzotrithiophene, as an electron-donating group, has a stronger electron-donating ability than thiophene, allowing the built-in electric field between the conjugated porous polymer and the heterojunction interface to be synergistically enhanced, thereby increasing the driving force for photogenerated carrier separation. During photo-assisted charging, photogenerated holes with strong oxidizing ability in the TiO2 valence band drive OH groups under the action of external bias. - Oxidation produces O2. The oxygen generated during charging can serve as a beneficial reactant for the subsequent reduction to H2O2 during photodischarge, thus eliminating the need for an external oxygen supply required for traditional H2O2 production. Simultaneously, photogenerated electrons migrate to the metal anode, converting Na... +It is reduced to Na, thus realizing the conversion and storage of solar energy in a chemical form. From the perspective of band structure matching, the theoretical charging voltage corresponds to the lowest point of the conduction band of the conjugated polymer material and the Na / Na ratio. + The difference between the redox potentials, due to the photovoltage compensation effect, is lower than the theoretical equilibrium potential of a conventional seawater sodium-air battery (relative to Na / Na). + (3.47 V).

[0099] Figure 9 The H2O2 yield of the liquid flow photo-assisted metal-air seawater battery in Example 3 at different current densities is shown. Figure 9 As can be seen from the data, the liquid flow type light-assisted metal-air seawater battery of Example 3 can achieve a speed of 0.1 mA / cm² under illumination. 2 At a current density of 5.47 mmol / g / h, H2O2 can be generated, far exceeding that at other current densities and in darkness. This is likely because, during photo-assisted discharge, in addition to the electrons released from sodium anode oxidation, extra photogenerated electrons with strong reducing power in the conduction band of the benzotrithiophene conjugated porous polymer also participate in the two-electron oxygen reduction process, thus achieving simultaneous H2O2 production and power generation. Simultaneously, photogenerated holes retained in the TiO2 valence band are attracted to the sodium anode, promoting the formation of metal oxides. Therefore, the theoretical discharge voltage is determined by the TiO2 valence band and the Na / Na ratio. + The difference between the redox potentials determines the output voltage, which corresponds to the difference between the TiO2 valence band and the O2 / H2O2 redox potential. These mechanisms explain why the battery's charge / discharge performance and in-situ H2O2 generation are simultaneously enhanced under sunlight irradiation.

[0100] The stability of a flow-type photo-assisted metal-air-seawater battery was evaluated using a multi-channel battery testing system. Figure 10 The results show the cycle stability of the liquid-flow photo-assisted metal-air seawater battery in Example 3. From... Figure 10 It can be seen that at 0.1 mA / cm 2 At the specified current density, the battery was able to operate stably for 13.5 hours with a round-trip efficiency of 69.16%, proving that the in-situ generation of H2O2 under photodischarge does not affect the performance of the metal-air battery.

[0101] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A photoelectrocatalyst for a light-assisted metal-air-seawater battery, characterized in that, The catalyst is a conjugated porous organic polymer, which has repeating units with the structure shown in Formula I: Formula I.

2. A heterojunction photoelectrode, characterized in that, It includes a substrate, an inner layer of TiO2 nanorod array, and an outer layer of catalyst, wherein the catalyst is the photoelectrophotocatalyst for a light-assisted metal-air-seawater battery as described in claim 1.

3. The heterojunction photoelectrode according to claim 2, characterized in that, The conjugated porous organic polymer is obtained by condensation reaction of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde.

4. The method for preparing the heterojunction photoelectrode according to claim 2 or 3, characterized in that, Includes the following steps: S1. Tetrabutyl titanate solution is coated on the substrate surface and calcined to obtain a substrate loaded with TiO2 seeds; S2. The substrate with TiO2 seed crystals obtained in step S1 is placed in a solution of hydrochloric acid and tetrabutyl titanate precursor, subjected to hydrothermal reaction, and calcined to obtain a substrate with TiO2 nanorod arrays. S3. 2,5-Diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde are mixed in an organic solvent to obtain a mixture. The substrate with the TiO2 nanorod array obtained in step S2 is immersed in the mixture, and a condensation reaction is carried out in an inert atmosphere to obtain the heterojunction photoelectrode. In step S3, the temperature of the condensation reaction is 120~170℃, and the time of the condensation reaction is 12~72 hours.

5. The method for preparing the photoelectrode according to claim 4, characterized in that, The molar ratio of 2,5-diamino-1,4-dithiophenyl dihydrochloride and benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde is (0.5~1):1.

5.

6. The method for preparing the photoelectrode according to claim 4, characterized in that, In step S3, the catalyst for the condensation reaction is acetic acid.

7. The method for preparing the photoelectrode according to claim 4, characterized in that, In step S3, the organic solvent is one or more of N-methylpyrrolidone, toluene, or methanol.

8. A liquid flow type photo-assisted metal-air-seawater battery, characterized in that, It includes a photoelectrode, a sodium electrode, a solid electrolyte and a seawater electrolyte disposed between the photoelectrode and the sodium electrode, wherein the photoelectrode is the heterojunction photoelectrode according to claim 2 or 3.

9. The liquid flow type photo-assisted metal-air seawater battery as described in claim 8, characterized in that, The solid electrolyte is Na3Zr2Si2PO4. 12 .

10. The application of the liquid flow photo-assisted metal-air seawater battery of claim 8 or 9 in the preparation of H2O2.

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