Molecular sieve-based photoanode, preparation method thereof and photo-assisted near-neutral zinc-air battery

Abstract

This invention relates to the field of electrochemical technology, specifically to a molecular sieve-based photoelectrode, its preparation method, and a light-assisted near-neutral zinc-air battery. A titanium source, a silicon source, and an organic template agent are mixed and subjected to a hydrothermal reaction. After centrifugation, a Ti-rich titanium-silicon molecular sieve precursor is obtained. The Ti-rich titanium-silicon molecular sieve precursor is carbonized to obtain a carbonized Ti-rich titanium-silicon molecular sieve. The carbonized Ti-rich titanium-silicon molecular sieve is impregnated in a ruthenium-containing solution and dried to obtain the precursor. The precursor is then subjected to high-temperature treatment in a mixed atmosphere of Ar and H2 to obtain a molecular sieve-based photoelectrocatalyst. The molecular sieve-based photoelectrocatalyst of this invention not only solves the problem of poor conductivity of the titanium-silicon molecular sieve itself but also overcomes the problem of high contact resistance caused by poor contact between the titanium-silicon molecular sieve and the current collector, thereby improving the charge-discharge efficiency, rate performance, and output power of the near-neutral zinc-air battery.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to a molecular sieve-based photoelectric cathode and its preparation method, and a light-assisted near-neutral zinc-air battery. Background Technology

[0002] With the rapid development of the global economy and people's increasing demands for quality of life, energy demand continues to grow. Zinc-air batteries, as a new type of green energy technology, have attracted widespread attention due to their advantages of high theoretical energy density (1360Wh / kg), low cost, and environmental friendliness.

[0003] Currently, alkaline zinc-air batteries (using 6 mol / L KOH as the electrolyte) have been applied in various fields, but they suffer from problems such as electrolyte carbonation, carbon corrosion of the air cathode, self-discharge of the zinc anode, and surface passivation, which severely affect battery life and long-term power supply capability. In contrast, neutral zinc-air batteries exhibit longer life and lower corrosivity, effectively avoiding various side reactions in traditional alkaline zinc-air battery electrolytes, reducing battery self-discharge, improving zinc anode utilization efficiency, and thus enhancing battery energy density and lifespan, making them a current research hotspot. However, due to the relatively low ionization degree of neutral salts in aqueous solutions, the ionic conductivity of neutral electrolytes is low, causing the catalytic activity of the air cathode in oxygen reduction and oxygen evolution reactions to be inferior to that under alkaline conditions, resulting in a larger charge / discharge overpotential in neutral zinc-air batteries.

[0004] Zeolite molecular sieve materials possess many advantages, and existing research has attempted to utilize the confinement effect of molecular sieves to design battery cathodes. However, most molecular sieves themselves have poor conductivity, a characteristic that becomes a limiting factor during battery charge-discharge cycles, hindering efficient electron transport, leading to increased battery polarization, decreased charge-discharge efficiency, and impacting the battery's rate performance and output power. In particular, insufficient and inadequate contact between molecular sieve particles and the current collector results in significant contact resistance, further impeding electron conduction and causing significant energy loss in neutral zinc-air batteries under high-current charge-discharge conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a molecular sieve-based photoelectrode, its preparation method, and a light-assisted near-neutral zinc-air battery. This invention uses a Ti-rich titanium-silicon molecular sieve precursor as raw material. The precursor is carbonized to obtain a carbonized Ti-rich titanium-silicon molecular sieve. Subsequently, the carbonized Ti-rich titanium-silicon molecular sieve is immersed in a ruthenium-containing solution, dried, and then subjected to high-temperature treatment in a reducing atmosphere to obtain a molecular sieve-based photoelectrocatalyst. This invention significantly improves the electronic conductivity of the molecular sieve-based photoelectrocatalyst by carbonizing the Ti-rich titanium-silicon molecular sieve precursor and loading it with ruthenium. This not only solves the problem of poor conductivity inherent in titanium-silicon molecular sieves but also overcomes the problem of high contact resistance caused by poor contact between the titanium-silicon molecular sieve and the current collector. Thus, while maintaining the advantages of long lifespan and low corrosion of neutral zinc-air batteries, it significantly improves the charge-discharge efficiency, rate performance, and output power of the battery.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first objective of this invention is to provide a method for preparing a molecular sieve-based photoelectrocatalyst, comprising the following steps:

[0008] S1. Mix titanium source, silicon source and organic template agent. The organic template agent is composed of structure directing agent and hexadecyltrimethylammonium bromide. Perform hydrothermal reaction and centrifuge to obtain Ti-rich titanium-silicon molecular sieve precursor.

[0009] Among them, hexadecyltrimethylammonium bromide, as a surfactant, can interact with the titanium source through its long-chain alkyl group, promoting the uniform dispersion of the titanium source in the Ti-rich titanium-silicon molecular sieve precursor framework; at the same time, it avoids the aggregation of the titanium source to form non-framework titanium, such as TiO2, thereby improving the effective utilization rate of titanium and enhancing catalytic activity; compared with other more expensive organic template agents, hexadecyltrimethylammonium bromide exhibits good structure-directing effect under different pH values, temperatures and synthesis conditions, and is inexpensive and widely applicable.

[0010] S2. In an inert atmosphere, the Ti-rich titanium-silicon molecular sieve precursor is carbonized. During the carbonization process, part of the organic template agent in the Ti-rich titanium-silicon molecular sieve is thermally decomposed into small molecule gas and removed, while the remaining part is thermally decomposed into carbonaceous residue and further carbonized, transforming into carbon deposits in the pores, thus obtaining carbonized Ti-rich titanium-silicon molecular sieve.

[0011] S3. The Ti-rich titanium-silicon molecular sieve is immersed in a ruthenium-containing solution. During immersion, ruthenium ions in the solution are uniformly dispersed within the pores of the Ti-rich titanium-silicon molecular sieve due to electrostatic adsorption by hydroxyl groups on its surface and pore size confinement. After drying, the precursor is obtained. The pore size of the Ti-rich titanium-silicon molecular sieve is approximately 0.7 nm, close to that of Ru. 3+ The dynamic diameter is approximately 0.6 nm, Ru 3+ Ions can only diffuse into the interior of the Ti-rich titanium-silicon molecular sieve through the pore openings, while large-diameter particles or aggregated precursors are physically blocked from the outside, thus avoiding disordered accumulation on the surface.

[0012] S4. In an atmosphere containing reducing gas, the precursor is subjected to high-temperature treatment. During the high-temperature treatment, the Ru adsorbed on the precursor... 3+ Ruthenium nanoparticles are reduced to ruthenium nanoparticles and uniformly dispersed in the pores of Ti-rich titanium silica molecular sieves to obtain a molecular sieve-based photoelectrocatalyst.

[0013] Preferably, the molar ratio of titanium source, silicon source, structure directing agent, and hexadecyltrimethylammonium bromide is 1:25 to 50:63:0.3. Among them, the titanium source is the key element for the catalytic effect of Ti-rich titanium-silicon molecular sieves, and its content needs to provide sufficient active sites. If there is too much titanium source, that is, the molar ratio of titanium source to silicon source is too high, it is easy to lead to the formation of non-framework titanium. These non-framework titanium not only cannot effectively participate in the catalytic reaction, but also block the pores of Ti-rich titanium-silicon molecular sieves, affecting the diffusion of ruthenium nanoparticles, and thus reducing the catalytic performance of molecular sieve-based photoelectrocatalysts.

[0014] Preferably, the carbonization treatment conditions are: calcination at 400℃~800℃ for 3h~6h; wherein, if the calcination time is too long, the internal pores of the carbonized Ti-rich titanium silicon molecular sieve will collapse.

[0015] Preferably, the high-temperature treatment conditions are: holding at 200℃~400℃ for 2h~4h; however, if the holding time is too long, the ruthenium nanoparticles will agglomerate. When the temperature is above 400℃, the diffusion rate of ruthenium atoms is significantly increased, the confinement effect of the channels in the Ti-rich titanium-silicon molecular sieve is broken, and the ruthenium nanoparticles undergo Ostwald ripening, resulting in an increase in particle size and a decrease in dispersibility. Conversely, when the temperature is too low, the H2 reduction capacity is insufficient, and Ru… 3+ Only partially reduced, not completely converted into metallic Ru 0 This leads to a decrease in the photoelectrocatalytic activity of molecular sieve-based catalysts.

[0016] Preferably, the hydrothermal reaction conditions are: crystallization at 170°C for 16 to 48 hours.

[0017] Preferably, the atmosphere containing the reducing gas is selected from a mixture of Ar and H2.

[0018] Preferably, in the mixed atmosphere of Ar gas and H2, the volume fraction of H2 accounts for 3% to 10% of the mixed atmosphere.

[0019] Preferably, Ru in the ruthenium-containing solution 3+ The concentration range is 0.1 mol / L to 0.2 mol / L; this concentration range ensures efficient anchoring and uniform distribution of ruthenium nanoparticles, thereby maximizing the catalytic activity and stability of the molecular sieve-based photoelectrocatalyst and avoiding the risk of inefficiency or failure. Specifically, when the concentration is lower than 0.1 mol / L, the adsorption amount of ruthenium nanoparticles in the precursor is low, and the density of active sites is low, which cannot effectively improve the catalytic activity of the molecular sieve-based photoelectrocatalyst; when the concentration is higher than 0.2 mol / L, Ru... 3+ The rapid adsorption and formation of an excessively thick liquid film on the surface of Ti-rich titanium-silicon molecular sieves, coupled with shrinkage stress during high-temperature treatment and drying, leads to the aggregation of ruthenium nanoparticles. This makes the pore structure of the Ti-rich titanium-silicon molecular sieves prone to blockage, affecting mass transfer efficiency.

[0020] Preferably, the ruthenium-containing solution is selected from ruthenium trichloride solution, ruthenium nitrate solution, or ruthenium acetylacetone solution; among them, ruthenium salts with smaller particle sizes are preferred. If the radius of the ruthenium salt is too large, the pores inside the Ti-rich titanium-silicon molecular sieve cannot adsorb it. During high-temperature processing, excessively large ruthenium salt particles are prone to agglomeration, resulting in uneven distribution of ruthenium nanoparticles on the Ti-rich titanium-silicon molecular sieve. This uneven distribution will reduce the effective exposure rate of ruthenium active sites and significantly reduce the utilization rate of molecular sieve-based photoelectrocatalysts and ruthenium.

[0021] Preferably, the structure-directing agent is selected from tetrapropylammonium hydroxide, tetraethylammonium hydroxide, or hexadecyltrimethylammonium bromide; wherein, the molecular size and shape of tetrapropylammonium hydroxide molecules, as well as suitable alkalinity and good thermal stability, make the preparation process more stable and controllable.

[0022] Preferably, the silicon source is selected from tetraethyl orthosilicate, silica sol, or water glass.

[0023] Preferably, the titanium source is selected from tetrabutyl titanate, titanium tetrachloride or titanium sulfate.

[0024] A second objective of this invention is to provide a molecular sieve-based photoelectrocatalyst prepared by the above-described method.

[0025] Preferably, the molecular sieve-based photoelectrocatalyst has a regular and uniform polyhedral structure with regular and orderly internal channels.

[0026] A third objective of this invention is to provide a molecular sieve-based photoelectric positive electrode, which is made of the aforementioned molecular sieve-based photoelectric catalyst, binder, conductive agent, and current collector.

[0027] The fourth objective of this invention is to provide a method for preparing a molecular sieve-based photoelectric positive electrode, comprising the following steps: mixing a molecular sieve-based photoelectric catalyst, a conductive agent, and a binder, coating the mixture onto a current collector, and drying it to obtain a molecular sieve-based photoelectric positive electrode.

[0028] Preferably, the conductive agent is selected from conductive carbon Super P, carbon nanotubes, or Ketjen black. Super P is an amorphous carbon black with a particle size typically between 40 nm and 50 nm. This relatively small and uniformly distributed particle size allows it to mix better with molecular sieve-based photoelectrocatalysts. In contrast, carbon nanotubes typically have a large aspect ratio and are prone to entanglement and aggregation. Although Ketjen black also has a small particle size, its aggregation tendency is more pronounced than that of Super P. Super P, on the other hand, can be uniformly dispersed on the surface and in the gaps between molecular sieve particles, forming a good conductive network.

[0029] Preferably, the binder is selected from Nafion solution, polyvinylidene fluoride, or polytetrafluoroethylene; compared with PVDF and PTFE, Nafion solution has good ion conductivity, which can significantly accelerate the proton transport process and effectively reduce internal resistance; at the same time, Nafion solution also has excellent chemical stability and bonding properties.

[0030] Preferably, the current collector is selected from carbon paper, carbon cloth or nickel foam.

[0031] The fifth objective of this invention is to provide a light-assisted near-neutral zinc-air battery, which is composed of the aforementioned molecular sieve-based photoelectric positive electrode, a separator, a negative electrode, and an electrolyte.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention provides a method for preparing a molecular sieve-based photoelectrocatalyst. In an inert atmosphere, a Ti-rich titanium-silicon molecular sieve precursor is carbonized. During the carbonization process, a portion of the organic template agent in the Ti-rich titanium-silicon molecular sieve is thermally decomposed into small molecule gases and removed. The remaining portion is thermally decomposed into carbonaceous residue and further carbonized, transforming into in-pore carbon deposits to obtain a carbonized Ti-rich titanium-silicon molecular sieve. The carbonized Ti-rich titanium-silicon molecular sieve is then impregnated in a ruthenium-containing solution. During the impregnation process, the Ru in the ruthenium-containing solution... 3+Under the electrostatic adsorption of hydroxyl groups on the surface of Ti-rich titanium-silicon molecular sieves and the confinement effect of pore size, the hydroxyl groups are uniformly dispersed within the pores of the Ti-rich titanium-silicon molecular sieves. After drying, a precursor is obtained. The precursor is then subjected to high-temperature treatment in a reducing atmosphere. During the high-temperature treatment, the Ru adsorbed on the precursor... 3+ Ruthenium nanoparticles are reduced to Ti and uniformly dispersed within the pores of a Ti-rich titanium-silicon molecular sieve, yielding a molecular sieve-based photocatalyst. This invention significantly enhances the electronic conductivity of the molecular sieve-based photocatalyst by carbonizing the Ti-rich titanium-silicon molecular sieve precursor and loading it with ruthenium. This not only solves the problem of poor conductivity inherent in titanium-silicon molecular sieves but also, due to the small particle size (approximately 200 nm) of the molecular sieve-based photocatalyst, reduces the packing voids between the particles, thereby increasing the contact point density with the current collector. This overcomes the problem of high contact resistance caused by poor contact between the titanium-silicon molecular sieve powder and the current collector. Thus, while maintaining the advantages of long lifespan and low corrosion in near-neutral zinc-air batteries, this significantly improves the battery's charge / discharge efficiency, rate performance, and output power.

[0034] 2. The Ti-rich titanium-silicon molecular sieve precursor selected in this invention possesses photoresponsiveness and a high Ti content in its framework. Introducing the organic template agent hexadecyltrimethylammonium bromide to regulate the hydrolysis process of the reaction solution helps obtain the Ti-rich titanium-silicon molecular sieve precursor. This structure provides more photoactive centers, thereby accelerating the photocatalytic reaction rate. Furthermore, carbonizing the Ti-rich titanium-silicon molecular sieve precursor, under thermal drive, causes dehydration condensation reactions between adjacent Si-OH or Ti-OH groups in the precursor framework, forming Si-O-Si or Ti-O-Ti bonds, thus achieving structural reconstruction. This process not only enhances the framework structure of the Ti-rich titanium-silicon molecular sieve, improving its thermal and chemical stability, but also effectively opens up electron conduction pathways, significantly improving the conductivity of the Ti-rich titanium-silicon molecular sieve precursor. Simultaneously, carbonization increases the number of active sites in the carbonized Ti-rich titanium-silicon molecular sieve. These active sites become more sensitive to light capture and response, laying the foundation for improved battery performance.

[0035] 3. The molecular sieve-based photocatalyst of this invention exhibits tunable pore size and excellent catalytic performance in oxygen reduction and oxygen evolution reactions. This is because this invention uses a titanium-rich and highly conductive Ti-rich carbide titanium-silicon molecular sieve as the substrate material. Through an impregnation method, the ordered pore structure of the Ti-rich carbide titanium-silicon molecular sieve is utilized to confine ruthenium nanoparticles, ensuring that the ruthenium nanoparticles are uniformly loaded within the internal structure of the Ti-rich carbide titanium-silicon molecular sieve, effectively avoiding the agglomeration tendency of the ruthenium nanoparticles. Furthermore, the small-diameter ruthenium nanoparticles formed not only greatly promote the transfer of photogenerated electrons to ruthenium in the Ti-rich carbide titanium-silicon molecular sieve, significantly shortening the electron transport distance, but also accelerate the oxygen reduction and oxygen evolution kinetics under photoassisted conditions, achieving highly efficient photocatalytic performance.

[0036] 4. The molecular sieve-based photoelectrocatalyst of the present invention has a high specific surface area, high stability and abundant and ordered pore structure, such as countless tiny "high-speed channels", which significantly accelerates the diffusion of reactant molecules and shortens the time for reactants to reach the active site, thereby greatly improving the oxygen reduction reaction rate.

[0037] The molecular sieve-based photocatalyst of this invention is used to prepare a molecular sieve-based photocathode. When the molecular sieve-based photocathode is exposed to light, the Ti-rich titanium-silicon carbonized molecular sieve, with its unique pore structure and conductivity, creates an ideal "working environment" for ruthenium nanoparticles. This not only accelerates electron transfer but also precisely provides a transfer path for photogenerated electrons, effectively reducing carrier recombination efficiency. This allows for rapid photoelectric conversion within the battery, greatly improving the battery's charge-discharge performance.

[0038] 5. Combining the molecular sieve-based photoelectric cathode and photo-assisted technology obtained in this invention into a near-neutral zinc-air battery can not only improve the slow mass transfer process in the electrolyte and significantly improve the power density and energy utilization efficiency of the battery, but also exhibit a lower charge and discharge overpotential, thereby enhancing the charge and discharge efficiency of the battery. It also has excellent round-trip efficiency and cycle stability, providing strong support for obtaining a stable and rechargeable near-neutral zinc-air battery.

[0039] In a light-assisted near-neutral zinc-air battery, the molecular sieve-based photoelectron cathode of this invention exhibits extremely rapid photogenerated electron transfer kinetics and high photogenerated carrier separation efficiency. These two factors work synergistically to effectively enhance the oxygen reduction and oxygen evolution reaction kinetics at the molecular sieve-based photoelectron cathode, resulting in a significant reduction in the polarization overpotential during charge and discharge of the light-assisted near-neutral zinc-air battery, thereby significantly improving the power density of the battery. Specifically, during the catalytic oxygen reduction reaction, its ruthenium sites can precisely and efficiently adsorb oxygen molecules, accelerating the conversion of oxygen into products; while during the catalytic oxygen evolution reaction, it can promote the decomposition of products into oxygen, making the reaction faster and more efficient. Attached Figure Description

[0040] Figure 1 The image shows a scanning electron microscope image of the Ti-rich titanium-silicon molecular sieve prepared in Comparative Example 1.

[0041] Figure 2 The images are scanning electron microscope images of the Ti-rich titanium-silicon molecular sieves prepared in Examples 1 to 3, where a is Example 1, b is Example 2, and c is Example 3.

[0042] Figure 3 The steady-state fluorescence spectra of the Ti-rich titanium-silicon molecular sieves prepared in Examples 1 to 3 and the Ti-rich titanium-silicon molecular sieve prepared in Comparative Example 1 are shown.

[0043] Figure 4 The graph shows the charge-discharge plateau curves of a near-neutral zinc-air battery assembled with a molecular sieve-based photoelectric cathode prepared using TS@C-800 in Example 3, under both illumination and non-illumination conditions.

[0044] Figure 5 This is a transmission electron microscope image of the molecular sieve-based photoelectrocatalyst prepared in Example 3.

[0045] Figure 6 The image shows the current-time photoresponse curves of TS@C-800 and Ru@TS@C-800 obtained in Example 3 to ultraviolet light.

[0046] Figure 7 The charge-discharge plateau curves are shown for the light-assisted near-neutral zinc-air battery assembled using molecular sieve-based photoelectric cathodes prepared with TS@C-800 and Ru@TS@C-800 from Example 3. Detailed Implementation

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods.

[0049] In existing technologies, although neutral zinc-air batteries have shown significant advantages in improving battery life and reducing corrosion, their performance is still limited by the low ionic conductivity of the neutral electrolyte and the insufficient catalytic activity of the air cathode. To address this issue, researchers have explored various methods to enhance the catalytic efficiency and electronic conductivity of the cathode, including the use of high-performance catalysts and improved electrode structures. However, these methods often face challenges such as high catalyst costs, complex preparation processes, or poor compatibility between the catalyst and electrode materials. In particular, for molecular sieve-based materials, although their unique pore structure and confinement effect provide favorable conditions for catalyst dispersion, their low conductivity and poor contact with the current collector limit their practical application in neutral zinc-air batteries.

[0050] This invention addresses the problems existing in the prior art by providing a method for preparing a molecular sieve-based photoelectrocatalyst, comprising the following steps: mixing a titanium source, a silicon source, and an organic template agent, wherein the organic template agent is composed of a structure-directing agent and hexadecyltrimethylammonium bromide, and performing a hydrothermal reaction, followed by centrifugation to obtain a Ti-rich titanium-silicon molecular sieve precursor; carbonizing the Ti-rich titanium-silicon molecular sieve precursor in an inert atmosphere, wherein during the carbonization process, part of the organic template agent in the Ti-rich titanium-silicon molecular sieve is thermally decomposed into small molecule gases and removed, and the other part is thermally decomposed into carbonaceous residue and further carbonized, transforming into in-pore carbon deposits to obtain a carbonized Ti-rich titanium-silicon molecular sieve; immersing the carbonized Ti-rich titanium-silicon molecular sieve in a ruthenium-containing solution, wherein during the immersion process, the Ru in the ruthenium-containing solution... 3+ Under the electrostatic adsorption of hydroxyl groups on the surface of Ti-rich titanium-silicon molecular sieves and the confinement effect of pore size, the hydroxyl groups are uniformly dispersed within the pores of the Ti-rich titanium-silicon molecular sieves. After drying, a precursor is obtained. The precursor is then subjected to high-temperature treatment in a reducing gas atmosphere. During the high-temperature treatment, Ru adsorbed on the precursor... 3+ Ruthenium nanoparticles are reduced to ruthenium nanoparticles and uniformly dispersed in the pores of Ti-rich titanium silica molecular sieves to obtain a molecular sieve-based photoelectrocatalyst.

[0051] This invention significantly improves the electronic conductivity of zeolite-based photoelectrocatalysts by carbonizing Ti-rich titanium-silicon molecular sieve precursors and loading them with ruthenium. This not only solves the problem of poor conductivity of titanium-silicon molecular sieves themselves, but also overcomes the problem of high contact resistance caused by poor contact between titanium-silicon molecular sieves and current collectors. Thus, while maintaining the advantages of long lifespan and low corrosion of neutral zinc-air batteries, it significantly improves the charge-discharge efficiency, rate performance, and output power of the batteries.

[0052] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0053] Example 1

[0054] A method for preparing a molecular sieve-based photoelectrocatalyst includes the following steps:

[0055] S1. Place 50 mL of isopropanol in a beaker, add 1.75 mL of tetrabutyl titanate and 20 mL of tetrapropylammonium hydroxide, and stir at room temperature for 1 h to obtain reaction solution I; separately, place 44 mL of tetrapropylammonium hydroxide in a beaker, add 0.58 g of hexadecyltrimethylammonium bromide, and then add 50 mL of tetraethyl orthosilicate dropwise, and stir vigorously for 1 h to obtain reaction solution II.

[0056] S2. Slowly add reaction solution I dropwise into reaction solution II, stir vigorously at room temperature for 2 hours, and then remove alcohol at 80°C for 30 minutes, replenishing with deionized water during the process; then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 170°C for 48 hours. After cooling to room temperature, wash the product three times with water and ethanol respectively; then dry the product at 100°C for 12 hours to obtain the Ti-rich titanium-silicon molecular sieve precursor.

[0057] S3. The Ti-rich titanium-silicon molecular sieve precursor was placed in a tube furnace and heated to 400°C at 3°C / min under a nitrogen atmosphere. After calcination for 3 hours, it was allowed to cool naturally to obtain the Ti-rich carbonized titanium-silicon molecular sieve, denoted as TS@C-400.

[0058] S4. Dissolve 60 mg of ruthenium trichloride in 2 mL of deionized water, then add 400 mg of TS@C-400, stir for 12 h, dry at 80 °C, then place in a tube furnace and linearly heat to 400 °C in a mixed atmosphere of Ar and H2, hold for 2 h, and then cool naturally to obtain a molecular sieve-based photoelectrocatalyst, denoted as Ru@TS@C-400.

[0059] Example 2

[0060] A method for preparing a molecular sieve-based photoelectrocatalyst is the same as that in Example 1, except that the calcination temperature in S3 is replaced by 600°C instead of 400°C, and includes the following steps:

[0061] S1. Place 50 mL of isopropanol in a beaker, add 1.75 mL of tetrabutyl titanate and 20 mL of tetrapropylammonium hydroxide, and stir at room temperature for 1 h to obtain reaction solution I; separately, place 44 mL of tetrapropylammonium hydroxide in a beaker, add 0.58 g of hexadecyltrimethylammonium bromide, and then add 50 mL of tetraethyl orthosilicate dropwise, and stir vigorously for 1 h to obtain reaction solution II.

[0062] S2. Slowly add reaction solution I dropwise into reaction solution II, stir vigorously at room temperature for 2 hours, and then remove alcohol at 80°C for 30 minutes, replenishing with deionized water during the process; then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 170°C for 48 hours. After cooling to room temperature, wash the product three times with water and ethanol respectively; then dry the product at 100°C for 12 hours to obtain the Ti-rich titanium-silicon molecular sieve precursor.

[0063] S3. The Ti-rich titanium-silicon molecular sieve precursor was placed in a tube furnace and heated to 600°C at 3°C / min under a nitrogen atmosphere. After calcination for 3 hours, it was allowed to cool naturally to obtain the Ti-rich carbonized titanium-silicon molecular sieve, denoted as TS@C-600.

[0064] S4. Dissolve 60 mg of ruthenium trichloride in 2 mL of deionized water, then add 400 mg of TS@C-600, stir for 12 h, dry at 80 °C, then place in a tube furnace and linearly heat to 400 °C in a mixed atmosphere of Ar and H2, hold for 2 h, and then cool naturally to obtain a molecular sieve-based photoelectrocatalyst, denoted as Ru@TS@C-600.

[0065] Example 3

[0066] A method for preparing a molecular sieve-based photoelectrocatalyst is the same as that in Example 1, except that the calcination temperature in S3 is replaced by 800°C instead of 400°C, and includes the following steps:

[0067] S1. Place 50 mL of isopropanol in a beaker, add 1.75 mL of tetrabutyl titanate and 20 mL of tetrapropylammonium hydroxide, and stir at room temperature for 1 h to obtain reaction solution I; separately, place 44 mL of tetrapropylammonium hydroxide in a beaker, add 0.58 g of hexadecyltrimethylammonium bromide, and then add 50 mL of tetraethyl orthosilicate dropwise, and stir vigorously for 1 h to obtain reaction solution II.

[0068] S2. Slowly add reaction solution I dropwise into reaction solution II, stir vigorously at room temperature for 2 hours, and then remove alcohol at 80°C for 30 minutes, replenishing with deionized water during the process; then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 170°C for 48 hours. After cooling to room temperature, wash the product three times with water and ethanol respectively; then dry the product at 100°C for 12 hours to obtain the Ti-rich titanium-silicon molecular sieve precursor.

[0069] S3. The Ti-rich titanium-silicon molecular sieve precursor was placed in a tube furnace and heated to 800°C at 3°C / min under a nitrogen atmosphere. After calcination for 3 hours, it was naturally cooled to obtain the Ti-rich carbonized titanium-silicon molecular sieve, denoted as TS@C-800.

[0070] S4. Dissolve 60 mg of ruthenium trichloride in 2 mL of deionized water, then add 400 mg of TS@C-800, stir for 12 h, dry at 80 °C, then place in a tube furnace and linearly heat to 400 °C in a mixed atmosphere of Ar and H2, hold for 2 h, and then cool naturally to obtain a molecular sieve-based photoelectrocatalyst, denoted as Ru@TS@C-800.

[0071] Example 4

[0072] A method for preparing a molecular sieve-based photoelectrocatalyst includes the following steps:

[0073] S1. Place 50 mL of isopropanol in a beaker, add 1.75 mL of tetrabutyl titanate and 20 mL of tetrapropylammonium hydroxide, and stir at room temperature for 1 h to obtain reaction solution I; separately, place 44 mL of tetrapropylammonium hydroxide in a beaker, add 0.58 g of hexadecyltrimethylammonium bromide, and then add 25 mL of tetraethyl orthosilicate dropwise, and stir vigorously for 1 h to obtain reaction solution II.

[0074] S2. Slowly add reaction solution I dropwise into reaction solution II, stir vigorously at room temperature for 2 hours, and then remove alcohol at 80°C for 30 minutes, replenishing with deionized water during the process; then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 170°C for 48 hours. After cooling to room temperature, wash the product three times with water and ethanol respectively; then dry the product at 100°C for 12 hours to obtain the Ti-rich titanium-silicon molecular sieve precursor.

[0075] S3. The Ti-rich titanium-silicon molecular sieve precursor was placed in a tube furnace and heated to 800°C at 3°C / min under a nitrogen atmosphere. After calcination for 3 hours, it was naturally cooled to obtain the Ti-rich carbonized titanium-silicon molecular sieve, denoted as TS@C-800.

[0076] S4. Dissolve 60 mg of ruthenium trichloride in 2 mL of deionized water, then add 400 mg of TS@C-800, stir for 12 h, dry at 80 °C, then place in a tube furnace and linearly heat to 200 °C in a mixed atmosphere of Ar and H2, hold for 4 h, and then cool naturally to obtain a molecular sieve-based photoelectrocatalyst.

[0077] Comparative Example 1

[0078] A method for preparing Ti-rich titanium-silicon molecular sieves includes the following steps:

[0079] S1. Place 50 mL of isopropanol in a beaker, add 1.75 mL of tetrabutyl titanate and 20 mL of tetrapropylammonium hydroxide, and stir at room temperature for 1 h to obtain reaction solution I; separately, place 44 mL of tetrapropylammonium hydroxide in a beaker, add 0.58 g of hexadecyltrimethylammonium bromide, and then add 50 mL of tetraethyl orthosilicate dropwise, and stir vigorously for 1 h to obtain reaction solution II.

[0080] S2. Slowly add reaction solution I dropwise into reaction solution II, stir vigorously at room temperature for 2 hours, then remove alcohol at 80°C for 30 minutes, replenishing with deionized water during this period; then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 170°C for 48 hours. After cooling to room temperature, wash the product three times with water and ethanol respectively; then dry the product at 100°C for 12 hours to obtain the Ti-rich titanium-silicon molecular sieve precursor.

[0081] S3. The Ti-rich titanium-silicon molecular sieve precursor was heated to 550℃ in a muffle furnace under air atmosphere at a rate of 3℃ / min, held at that temperature for 6 hours, and then cooled naturally to obtain the Ti-rich titanium-silicon molecular sieve, denoted as TS.

[0082] observe Figure 1 The Ti-rich titanium-silicon molecular sieve prepared in Example 3 of this invention exhibits a regular and uniform polyhedral structure. This regular polyhedral morphology provides a larger specific surface area, increasing the exposure of active sites and facilitating reactant adsorption and photocatalytic reactions. Furthermore, the polyhedral structure enhances light scattering and absorption, improving light energy utilization and thus increasing photocatalytic efficiency. Therefore, the Ti-rich titanium-silicon molecular sieve with its polyhedral morphology significantly improves photocatalytic performance by optimizing light absorption, mass transfer, charge separation, and active site distribution.

[0083] observe Figure 2 It was found that, with the change of calcination temperature, the carbonized molecular sieve-based photoelectrocatalysts prepared in Examples 1 to 3 did not show significant differences in morphology. They could still maintain the polyhedral structure characteristics of the original Ti-rich titanium-silicon molecular sieves, and the size remained consistent, showing good uniformity.

[0084] Depend on Figure 3 The results showed that TS@C-800 had the lowest fluorescence intensity, indicating that it can effectively reduce the recombination efficiency of photogenerated carriers, which is beneficial to the separation of photogenerated electrons and holes and can achieve a better photocatalytic process.

[0085] The TS@C-800 and Ru@TS@C-800 of Example 3 of the present invention and the TS and conductive carbon SuperP of Comparative Example 1 were dispersed in ethanol at a mass ratio of 7:3. A small amount of 5 wt% Nafion binder solution was added, and after ultrasonic dispersion, the mixture was uniformly coated on both sides of hydrophobic carbon paper. After drying, molecular sieve-based photoelectrodes were obtained, which were denoted as TS@C-800-ZJ, Ru@TS@C-800-ZJ, and TS-ZJ, respectively.

[0086] The following section uses TS@C-800-ZJ, Ru@TS@C-800-ZJ, and TS-ZJ as positive electrodes, applying them in the assembly of near-neutral zinc-air batteries and conducting research:

[0087] Using TS@C-800-ZJ, Ru@TS@C-800-ZJ, and TS-ZJ as catalytic cathodes, respectively, a near-neutral zinc-air battery was assembled in the following order: negative electrode plate, zinc negative electrode, aqueous membrane, electrolyte chamber, catalytic cathode, and nickel foam current collector. After adding 1 mol / L zinc trifluoromethanesulfonate electrolyte and allowing it to stand, a near-neutral zinc-air battery was obtained. Once the open-circuit voltage stabilized, an LED ultraviolet light source was turned on approximately 5 cm from the molecular sieve-based photoelectrode. After 20 minutes of illumination, battery performance was tested at a current density of 0.2 mA / cm². 2 The performance of the charge-discharge platform was tested under the specified conditions.

[0088] Depend on Figure 4 It was found that the molecular sieve-based photoelectrode prepared by TS@C-800 in Example 3 can effectively accelerate the oxygen reduction reaction and oxygen evolution reaction process by generating photo-generated electrons and holes under light irradiation, and obtain a lower charge and discharge overpotential.

[0089] Depend on Figure 5 The results show that the confinement effect of the Ti-rich titanium-silicon molecular sieve pore structure effectively restricts the growth of ruthenium nanoparticles and keeps them stable, avoiding significant particle aggregation. These ruthenium nanoparticles have a small average particle size of approximately 2 nm to 3 nm and exhibit good dispersion uniformity. This characteristic suggests that photo-assisted solar cells can accelerate the electron transfer process at the positive electrode, thereby improving the overall performance of the battery.

[0090] Depend on Figure 6 The results show that the photocurrent of Ru@TS@C is significantly enhanced compared to TS@C-800, indicating that Ru, as an electron trapping agent, effectively traps photogenerated electrons, reduces the recombination probability of photogenerated carriers, and enables it to extract more photogenerated electrons, thereby enhancing the photoresponse signal.

[0091] Depend on Figure 7 The results show that, compared with TS@C-800-ZJ, Ru@TS@C-800-ZJ can further improve the reaction kinetics of the battery and effectively reduce the charge-discharge polarization potential of the photo-assisted near-neutral zinc-air battery. Furthermore, Ru loading on TS@C-800 provides additional active sites for the photocatalytic reaction process. These active sites can adsorb reactant molecules and promote the interaction between photogenerated carriers and reactants, thereby increasing the reaction rate and photoresponse intensity, effectively improving the round-trip efficiency of the near-neutral zinc-air battery.

[0092] The molecular sieve-based photoelectrode of this invention exhibits photoresponsiveness. It utilizes the unique pore structure of Ti-rich titanium-silicon molecular sieves to accelerate the mass transfer process of reactant molecules and ions in the battery. Simultaneously, it combines the pore confinement effect to obtain nanoscale ruthenium nanoparticles, constructing a rapid photogenerated electron transfer channel. During oxygen reduction, ruthenium sites can precisely and efficiently adsorb oxygen molecules, accelerating the conversion of oxygen to products. Conversely, during oxygen evolution, it can facilitate the decomposition of products into oxygen, making the entire reaction process faster and more efficient. Benefiting from these advantages, Ru@TS@C-800-ZJ exhibits a low charge-discharge overpotential in near-neutral zinc-air batteries, not only improving the charge-discharge efficiency of near-neutral zinc-air batteries but also enabling the acquisition of more stable and rechargeable near-neutral zinc-air batteries, potentially opening a new chapter in the development of near-neutral zinc-air batteries.

[0093] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0094] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for the preparation of a molecular sieve-based photoelectrocatalyst, characterized in that, Includes the following steps: Titanium source, silicon source and organic template agent are mixed. The organic template agent is composed of structure directing agent and hexadecyltrimethylammonium bromide. The mixture undergoes hydrothermal reaction and centrifugation to obtain Ti-rich titanium-silicon molecular sieve precursor. The molar ratio of titanium source, silicon source, structure directing agent and hexadecyltrimethylammonium bromide is 1:25~50:63:0.3; In an inert atmosphere, the Ti-rich titanium-silicon molecular sieve precursor is carbonized. During the carbonization process, part of the organic template agent in the Ti-rich titanium-silicon molecular sieve precursor is thermally decomposed into small molecule gas and removed, while the other part is thermally decomposed into carbonaceous residue and further carbonized, transforming into carbon deposits in the pores, thus obtaining carbonized Ti-rich titanium-silicon molecular sieve. The carbonization conditions are: calcination at 400℃~800℃ for 3h~6h. Ti-rich carbonized titanium-silicon molecular sieves were impregnated in a ruthenium-containing solution. During the impregnation process, the Ru in the ruthenium-containing solution... 3+ Under the electrostatic adsorption of hydroxyl groups on the surface of Ti-rich titanium-silicon molecular sieves and the confinement effect of pore size, ruthenium is uniformly dispersed in the channels of Ti-rich titanium-silicon molecular sieves. After drying, a precursor is obtained; Ruthenium-containing solution contains Ru... 3+ The concentration is 0.1 mol / L to 0.2 mol / L; the ruthenium-containing solution is selected from ruthenium trichloride solution, ruthenium nitrate solution or ruthenium acetylacetone solution; In an atmosphere containing a reducing gas, the precursor is subjected to high-temperature treatment. During the high-temperature treatment, Ru adsorbed on the precursor... 3+ Ruthenium nanoparticles are reduced to ruthenium nanoparticles and uniformly dispersed in the pores of Ti-rich titanium-silicon molecular sieves to obtain a molecular sieve-based photoelectrocatalyst. The high-temperature treatment conditions are: holding at 200℃~400℃ for 2h~4h.

2. The method of claim 1, wherein the method is characterized by: The hydrothermal reaction conditions are: crystallization at 170℃ for 16h~48h.

3. A molecularly sieving photoelectrocatalyst prepared by the method of any one of claims 1 to 2, characterized in that, Molecular sieve-based photoelectrocatalysts exhibit a regular and uniform polyhedral structure with orderly internal pores.

4. A molecular sieve-based photoanode, characterized in that, The molecular sieve-based photoelectrode is made from the molecular sieve-based photoelectrocatalyst, binder, conductive agent, and current collector as described in claim 3.

5. The method for preparing the molecular sieve-based photoelectric positive electrode according to claim 4, characterized in that, Includes the following steps: A molecular sieve-based photoelectrocatalyst, a conductive agent, and a binder are mixed and coated onto a current collector. After drying, a molecular sieve-based photoelectrode is obtained.

6. A light-assisted quasi-neutral zinc-air battery, characterized by, The light-assisted near-neutral zinc-air battery is composed of the molecular sieve-based photoelectric positive electrode, separator, negative electrode and electrolyte as described in claim 4.

Images