Pt / s-tio2-x@ti self-supporting electrode, preparation method thereof, application to ammonia production by nitrate electro-reduction and zn-no3- battery

Abstract

The application belongs to the field of batteries, and particularly relates to a Pt / S-TiO 2‑x @Ti self-supporting electrode and a preparation method thereof, nitrate electroreduction ammonia production application and Zn-NO3 ‑ Battery; the Pt / S-TiO 2‑x @Ti self-supporting electrode comprises a titanium substrate, an oxygen-defect titania array in-situ grown on the surface of the titanium substrate, and Pt nanoparticles and S atoms doped in the oxygen-defect titania array; wherein the oxygen defects and the S atoms construct a blocked Lewis acid-base pair; the Pt nanoparticles mediate the formation of a reverse hydrogen overflow channel. The electrode disclosed by the application can have excellent NO3 ‑ RR activity and selectivity, in addition, the material can effectively adapt to the characteristics of the Zn-NO3 ‑ Battery, and can exhibit excellent electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically relating to a Pt / S-TiO2 battery. 2-x @Ti self-supporting electrode and its preparation method, application of nitrate electroreduction to ammonia production and Zn-NO3 - Battery industry. Background Technology

[0002] Ammonia (NH3) is not only a core raw material for the production of fertilizers and industrial chemicals, but also a highly promising carbon-free energy carrier. Currently, ammonia production mainly relies on the traditional Haber-Bosch process, which requires high temperature and pressure conditions, resulting in high energy consumption and significant carbon emissions. Electrocatalytic nitrate reduction (NO3)... - RR can utilize nitrate pollutants in industrial wastewater and agricultural runoff as raw materials to convert them into ammonia under normal temperature and pressure. It is a technical route that combines the value of pollutant resource utilization and green ammonia synthesis.

[0003] In recent years, based on NO3 - Zn-NO3 based on the RR principle - Batteries have attracted attention. These batteries typically use zinc as the anode and a nitrate reduction electrode as the cathode. During discharge, zinc oxidation provides electrons, while nitrate reduction occurs at the cathode, coupling electrical energy output with ammonia synthesis. Therefore, Zn-NO3... - The battery can not only realize the resource conversion of nitrate pollutants, but also simultaneously obtain electrical energy output, and has application prospects in the fields of energy conversion, wastewater treatment and ammonia synthesis.

[0004] However, Zn-NO3 - Battery performance is highly dependent on cathode NO3 - The activity, selectivity, and stability of the RR catalytic electrode. NO3 - RR involves multi-electron and multi-proton transfer processes, requiring a continuous and sufficient supply of active hydrogen ( (Also known as adsorbed hydrogen) supply; however, most catalysts have slow water splitting kinetics, leading to Insufficient formation limits the reaction rate. Furthermore, the formed hydrogen is prone to complex hydrogen evolution reactions, causing severe hydrogen evolution side reactions (HER), reducing ammonia selectivity and Faraday efficiency. For Zn-NO3... - For batteries, the aforementioned issues will further affect the battery's discharge voltage, power density, ammonia production efficiency, and cycle stability.

[0005] Although strategies such as defect engineering, heteroatom doping, and single-atom catalysis have been used to enhance NO3 - RR performance, but how to simultaneously achieve efficient generation and orientation? Utilizing and effectively inhibiting HER remains a constraint on NO3. - RR catalytic electrode and Zn-NO3 - Key issues in improving battery performance.

[0006] To address the aforementioned issues, existing technologies have disclosed several processes for the electrocatalytic synthesis of ammonia from nitrate. For example, patent document CN122079262A discloses a high-entropy perovskite hydroxide, its preparation method, and its application in the electrocatalytic synthesis of ammonia from nitrate. The high-entropy perovskite hydroxide is ASn(OH)6, where A is one or more of Zn, Mn, Co, Ni, and Cu. Patent document CN121896660A discloses a method for preparing a cobalt-based catalyst for the electrocatalytic synthesis of ammonia from nitrate. This method involves placing melamine upstream of ZIF-67 powder and performing a two-step programmed pyrolysis treatment under a high-purity nitrogen protective atmosphere. After natural cooling, a cobalt-based catalyst with rhombic carbon as a substrate and Co-NC nanoparticles anchored thereon is obtained. Patent document CN122082023A discloses a silver-cobalt composite oxide catalyst, its preparation method, and its application in the electrocatalytic reduction of ammonia from nitrate, specifically disclosing the calcination of a metal complex in an air atmosphere.

[0007] In summary, although there are many types of existing electrocatalytic materials, different types of electrocatalytic materials have different principles and requirements. For example, for materials used in the electrocatalytic production of ammonia from nitrate, it is necessary to reasonably suppress the hydrogen evolution reaction (HER). However, existing electrocatalytic materials still have many shortcomings: on the one hand, they are difficult to effectively suppress the hydrogen evolution reaction (HER), and on the other hand, they cannot reasonably and directionally optimize the electrocatalytic production of ammonia from nitrate, leading to the nitrate reduction reaction (NO3)... - The performance of RR needs further improvement; on the other hand, its catalytic stability under high current conditions also has shortcomings, making it difficult to meet the requirements for the commercial application of zinc-nitrate batteries. Summary of the Invention

[0008] To address the problems existing in the prior art, the primary objective of this invention is to provide a Pt / S-TiO₂ solution. 2-x @Ti self-supporting electrode (also known as self-supporting electrode, composite electrode or Pt,S-TiO) 2-x @Ti) aims to provide an electrode suitable for nitrate electroreduction with hindered Lewis acid-base pair-reverse hydrogen overflow synergy.

[0009] The second objective of this invention is to provide the aforementioned Pt / S-TiO 2-x Preparation method of @Ti self-supporting electrode and its application in the electroreduction of nitrate to produce ammonia.

[0010] A third objective of this invention is to provide a product comprising the aforementioned Pt / S-TiO2-x @Ti self-supporting electrode Zn-NO3 - Battery.

[0011] In order to improve NO3 - RR activity, improve NO3 - The present invention, through in-depth research, provides the following solutions to address the selectivity of RR and HER, as well as long-term cycling stability under high current:

[0012] A Pt / S-TiO 2-x @Ti self-supporting electrode, including a titanium substrate, an oxygen-defective titanium dioxide array grown in situ on the surface of the titanium substrate, and Pt nanoparticles and S atoms doped in the oxygen-defective titanium dioxide array.

[0013] Among them, oxygen vacancies and S atoms hinder the construction of Lewis acid-base pairs; Pt nanoparticles mediate the formation of reverse hydrogen overflow channels.

[0014] This invention provides a Pt-S dual-doped oxygen-deficient titanium dioxide array electrode material, which can construct hindered Lewis acid-base pairs based on oxygen defects and S atoms in the structure, and form a reverse hydrogen overflow channel mediated by Pt nanoparticles. Based on the S-Ov FLP-Pt mediated reverse hydrogen overflow synergy, it achieves... The spatial decoupling of generation and utilization breaks the NO3 - The inherent trade-off between activity and selectivity in RR; thus significantly improving NO3 - RR activity, NO3 - The material exhibits selectivity for RR and HER, as well as long-term cycling stability under high current. Furthermore, it is effectively compatible with Zn-NO3. - The battery's characteristics enable it to exhibit excellent electrochemical performance.

[0015] Furthermore, the titanium substrate is a titanium sheet or titanium mesh with a thickness of 0.1~0.3mm and a purity of ≥99.9%.

[0016] In this invention, the oxygen-deficient titanium dioxide array is at least one of titanium dioxide nanowires and titanium dioxide nanosheets along the Z-axis (height direction) of the titanium substrate surface; preferably, titanium dioxide nanosheets; further, the thickness of a single nanosheet is 5~20 nm. This invention demonstrates that this array morphology helps to further enhance the synergistic mechanism of oxygen-deficient / S-constructed FLPs and reverse hydrogen overflow channels in the material of this invention, and helps to further improve NO3- - RR activity, NO3 - The selectivity of RR and HER and the long-term cycling stability under high current improve Zn-NO3. - Battery performance.

[0017] Furthermore, the TiO2-x The array is oriented along the Z-axis of the titanium substrate, with a directional growth uniformity of ≥90%, and the specific surface area of ​​the nanosheet array is ≥80m². 2 g -1 ;

[0018] The electrode of this invention has an oxygen-defect titanium dioxide array with a thickness of 2~5μm;

[0019] Furthermore, TiO 2-x It is an anatase phase with a band gap of 2.8~3.0 eV and the valence band edge is shifted upward relative to the Fermi level by 0.2~0.4 eV.

[0020] The valence state of Pt in the Pt nanoparticles is Pt 0 With Pt 4+ Coexistence, of which Pt 0 The Pt nanoparticles comprise 60-80% of the total Pt atoms; their particle size is 2-5 nm; and their loading is 0.1-0.5 wt.%, or more specifically, 0.15-4.5 wt.%.

[0021] S atoms are incorporated into the lattice of oxygen-deficient titanium dioxide by substituting for lattice oxygen, and the bond length of the Ti-S bond is 2.35~2.40 Å; the doping amount of the S atoms is 1~3 at.%, and the oxygen vacancy concentration is 5×10⁻⁶. 19 ~2×10 20 cm -3 .

[0022] Furthermore, in the hindered Lewis acid-base pair, the distance between the S atom and the oxygen vacancy is 0.3~0.5 nm, and the two do not form a neutral adduct, maintaining independent acid-base activity.

[0023] The Pt / S-TiO 2-x The charge transfer resistance of the @Ti self-supporting electrode is ≤15Ω, and the electrochemically active surface area at -0.6V vs. RHE is ≥7.5mFcm. -2 .

[0024] The present invention also provides the aforementioned Pt / S-TiO 2-x The preparation method of the @Ti self-supporting electrode includes the following steps:

[0025] Step 1:

[0026] TiO2@Ti was prepared by in-situ growth of a titanium dioxide array on a titanium substrate.

[0027] Step 2:

[0028] Oxygen-deficient TiO2@Ti was prepared by reducing TiO2@Ti.

[0029] Step 3:

[0030] A composite solution containing oxygen-deficient TiO2@Ti and platinum and sulfur sources was subjected to pressure holding under negative pressure, followed by photoreduction to obtain a reduction product. The reduction product was then annealed to obtain Pt / S-TiO2. 2-x @Ti self-supporting electrode.

[0031] This invention pre-generates oxygen-deficient TiO2@Ti in situ on a titanium substrate; subsequently, it performs dual doping treatment with platinum and sulfur sources, combined with a dual doping method involving negative pressure-photoreduction and annealing. This achieves synergy, enabling the material to improve NO3- performance based on a novel oxygen-deficient / S-based free-floating polymerase chain (FLPs) and reverse hydrogen overflow channel synergistic mechanism. - RR activity, improve NO3 - The selectivity of RR and HER and the long-term cycling stability under high current improve Zn-NO3. - Battery performance.

[0032] In this invention, in step 1, the titanium substrate is subjected to hydrothermal treatment in an alkaline solution, followed by acid treatment and calcination in an oxygen-containing atmosphere to obtain the TiO2@Ti;

[0033] And / or, the alkaline solution is a 3-5M NaOH solution, the hydrothermal temperature is 160-200℃, and the hydrothermal time is 10-14h; preferably, the alkaline solution is a 3.5-4.5M NaOH solution, the hydrothermal temperature is 170-190℃, and the hydrothermal time is 11-13h; the preferred temperature is conducive to the construction of titanium dioxide nanosheets, which helps to further synergize with subsequent processes and further improve NO3. - RR activity and selectivity.

[0034] And / or, the acid solution for acid treatment is a 0.8~1.2M HCl solution;

[0035] And / or, the calcination temperature is 400~500℃, and the calcination time is 0.5~1.5h.

[0036] The preparation method described in this invention helps to form a suitable NO3 on the surface of a titanium substrate. - The array of RR nanosheet morphology facilitates synergistic effects with other processes to further enhance NO3. - The activity and selectivity of RR.

[0037] In this invention, in step 2, the reducing atmosphere for the reduction treatment is a hydrogen-containing atmosphere. Besides hydrogen, the hydrogen-containing atmosphere may also contain a diluent gas comprising at least one of nitrogen and rare gases. The hydrogen content in the hydrogen-containing atmosphere can be 3-7% vol%.

[0038] And / or, the reduction treatment temperature is 450~550℃, more preferably 480~520℃; under these preferred conditions, it is helpful to further improve the prepared NO3. - RR activity and selectivity.

[0039] And / or, the reduction process takes 0.5 to 1.5 hours.

[0040] In this invention, oxygen-deficient TiO2@Ti is doped with a platinum-sulfur dual source, further combined with a negative pressure holding-photoreduction and annealing process. This achieves synergy, enabling the material to improve NO3- based on a novel oxygen-deficient / S-based FLPs and reverse hydrogen overflow channel synergistic mechanism. - RR activity, NO3 - The selectivity of RR and HER and the long-term cycling stability under high current improve Zn-NO3. - Battery performance.

[0041] In step 3, the platinum source is at least one of chloroplatinic acid, chloroplatinate, platinum chloride, and platinum acetylacetonate;

[0042] The sulfur source is at least one of thiourea, thioacetamide, sodium sulfide, and sodium thiosulfate.

[0043] In the composite solution, the concentration of the platinum source is 0.003~0.007M, and the molar ratio of the sulfur source to the platinum source is 15~25:1;

[0044] The pressure for negative pressure treatment is -0.09 to -0.07 MPa;

[0045] The pressure holding time under negative pressure is 20~40 minutes.

[0046] In this invention, the photoreduction treatment is performed using a 250-350W xenon lamp for 10-20 minutes, more preferably 14-16 minutes; under these preferred conditions, it helps to further improve the prepared NO3. - RR activity and selectivity.

[0047] And / or, the annealing atmosphere includes at least one of nitrogen and rare gases;

[0048] And / or, the annealing temperature is 300~400℃;

[0049] The annealing time is 0.5~1.5 hours.

[0050] The present invention also provides the aforementioned Pt / S-TiO 2-x The application of the @Ti self-supporting electrode for the electroreduction of nitrate to ammonia is demonstrated by using it as an electrocatalytic electrode to catalyze the electrocatalytic reduction of nitrate to ammonia.

[0051] The Pt / S-TiO of the present invention 2-x @Ti self-supporting electrode, compatible with NO3 - The RR characteristic can improve its activity and selectivity, and help improve its catalytic stability.

[0052] The application described in this invention is to use it to prepare Zn-NO3 based on the principle of electrocatalytic reduction of nitrate to ammonia. - Battery. This invention can be used to assemble Zn-NO3 based on the characteristics of the electrodes. - This improves the battery's electrochemical performance.

[0053] This invention also provides Zn-NO3 - The battery contains the aforementioned Pt / S-TiO 2-x @Ti self-supporting electrode.

[0054] The Zn-NO3 of this invention - The battery, in addition to containing the aforementioned Pt / S-TiO 2-x Apart from the Ti self-supporting electrode, the other components and structural relationships can all be known.

[0055] As an optional solution, Zn-NO3 - The battery has a zinc anode and a Pt / S-TiO2 cathode. 2-x @Ti self-supporting electrode, the electrolyte can be an aqueous solution of 5~7M KOH + 0.4~0.6M NaNO3.

[0056] Beneficial effects

[0057] (1) This invention will use SO V The hindered Lewis acid-base pair and the Pt-mediated reverse hydrogen overflow channel are integrated in the same self-supporting TiO2. 2-x Nanosheet arrays have achieved generate, Spatial decoupling of migration and nitrate hydrogenation utilization can simultaneously solve Supply shortage and The problem of hydrogen evolution through recombination.

[0058] (2) SO V The sites can polarize and activate water molecules, reducing the water dissociation barrier; Pt nanoparticles can optimize... Adsorption free energy and its role as a "high-speed channel" for hydrogen migration enable... Directed transfer from hydrogen production centers to nitrate reduction centers improves ammonia selectivity and Faraday efficiency.

[0059] (3) In-situ grown TiO 2-xThe nanosheet array forms an integrated self-supporting structure with the titanium substrate, avoiding the introduction of binders and conductive agents, reducing interfacial resistance, and enhancing mechanical stability and long-term operational stability.

[0060] (4) The combined process of negative pressure holding-photoreduction-annealing can make Pt and S in oxygen-deficient TiO2. 2-x The surface is uniformly distributed, and platinum nanoparticles are anchored through defect sites, reducing the amount of precious metals used and the risk of agglomeration.

[0061] (5) The electrode can realize the resource-based production of ammonia from nitrates using water as a hydrogen source at normal temperature and pressure without the need for external hydrogen; it can also be extended to zinc-nitrate batteries for coupling power generation and ammonia production. Attached Figure Description

[0062] Figure 1 XRD patterns of electrodes prepared in Example 1, Comparative Example 3, and Comparative Example 4; wherein, PSTO is the electrode prepared in Example 1; STO is the electrode prepared in Comparative Example 3; and T is the electrode prepared in Comparative Example 4.

[0063] Figure 2 Raman spectra of the electrodes prepared in Example 1, Comparative Example 3 and Comparative Example 4;

[0064] Figure 3 The images shown are SEM-EDS images of the PSTO electrode prepared in Example 1, where (a) is an SEM image, (b) is an EDS image of Pt, (c) is an EDS image of S, (d) is an EDS image of Ti, and (e) is an EDS image of O.

[0065] Figure 4 Active sites of the PSTO electrode prepared in Example 1 Adsorption free energy diagram;

[0066] Figure 5 The energy barrier diagram for the hydrolysis reaction of each active site of the PSTO electrode prepared in Example 1 is shown.

[0067] Figure 6 Electrocatalytic NO3 production of electrodes prepared in Examples 1 and Comparative Examples 1-4 - RR performance comparison chart; Detailed Implementation

[0068] The present invention is further illustrated by specific embodiments, but is not limited to the following embodiments.

[0069] The present invention may use Pt / S-TiO 2-x The preparation method of the @Ti self-supporting electrode includes the following steps:

[0070] Step 1: Fabrication of TiO2 nanosheet arrays

[0071] The titanium substrate was ultrasonically cleaned sequentially with ethanol, acetone, and ultrapure water for 10-15 min each, and then vacuum dried at 60-80℃ for 20-40 min for later use. The treated titanium substrate was then placed in 3-5M NaOH solution and hydrothermally treated at 160-200℃ for 10-14 h. After cooling to room temperature, it was washed with deionized water until neutral, and then placed in 0.8-1.2M HCl solution for ion exchange for 2-4 h. After removal, it was washed with deionized water, dried at 60-80℃, and then annealed in air at 400-500℃ for 0.5-1.5 h with a heating rate of 1-3℃ / min to obtain TiO2 nanosheet arrays.

[0072] Step 2: Introduction of oxygen vacancies

[0073] The TiO2 nanosheet array obtained in step 1 was placed in a tube furnace, and an H2 / Ar mixed gas with a volume fraction of 3-7% was introduced. Annealing was carried out at 450-550℃ for 0.5-1.5 h with a heating rate of 1-3℃ / min. The mixture was then naturally cooled to room temperature to obtain oxygen-deficient TiO2. 2-x Nanosheet array;

[0074] Step 3: Pt, S co-doping

[0075] Prepare a mixed aqueous solution containing 0.003~0.007M H2PtCl6・6H2O and 0.08~0.12M thiourea; Add the TiO2 obtained in step 2... 2-x The nanosheet array was placed in the above mixed solution and subjected to negative pressure treatment under vacuum conditions of -0.09 to -0.07 MPa for 20 to 40 minutes. After removal, it was irradiated with a 300W xenon lamp for 10 to 20 minutes for photoreduction. It was then washed with deionized water 3 to 5 times and vacuum dried at 60 to 80°C for 1 to 2 hours. Finally, it was annealed in a nitrogen atmosphere at 300 to 400°C for 0.5 to 1.5 hours with a heating rate of 1 to 3°C / min to obtain the Pt,S-TiO. 2-x @Ti composite electrode.

[0076] This invention constructs SO V A hindered Lewis acid-base pair synergistically forms a catalytic interface with Pt-mediated reverse hydrogen spillover. In this system, the S atom acts as an electron-rich Lewis base, and the adjacent oxygen vacancy acts as an electron-deficient Lewis acid. These two atoms form spatially separated FLP sites, which can efficiently polarize H2O molecules and cause their dissociation to generate… Pt nanoparticles optimize the hydrogen adsorption free energy. This directs the H generated at the FLP site to the nitrate reduction center, ensuring a sufficient H supply while effectively inhibiting [the growth of H+]. The combined hydrogen evolution process achieves NO3. - RR's high activity and high selectivity.

[0077] The present invention also provides the aforementioned Pt,S-TiO 2-x The Ti composite electrode is used as a working electrode for the electrocatalytic reduction of nitrate to ammonia, or as a cathode for rechargeable Zn-NO3. - Battery.

[0078] Furthermore, the electrocatalytic reduction of nitrate to ammonia utilizes a three-electrode system with Pt,S-TiO₂. 2-x @Ti is the working electrode, Ag / AgCl (saturated KCl) is the reference electrode, and platinum sheet is the counter electrode; the electrolyte is a mixed solution of 0.3~0.7M Na2SO4 + 0.05~0.15M NaNO3, with a pH of 6~8; the applied working potential is -0.4~-0.7V vs. RHE, and the reaction temperature is 20~30℃.

[0079] Furthermore, at -0.6V vs. RHE, the ammonia yield can reach 80 mgh. -1 cm -2 The Faraday efficiency can reach 97%, and the performance degradation after 200 hours of continuous operation is less than 5%.

[0080] Furthermore, the rechargeable Zn-NO3 - The battery uses zinc foil as the anode, and the Pt,S-TiO₂... 2-x The Ti composite electrode serves as the cathode, and the electrolyte is a mixed solution of 5~7M KOH + 0.4~0.6M NaNO3; the open-circuit voltage of the battery is ≥1.4V, and the peak power density is ≥6.5mWcm³. -2 .

[0081] Furthermore, the Zn-NO3 - The battery simultaneously achieves ammonia synthesis during discharge, at 50 mA / cm. -2 At the given current density, the ammonia yield can reach 7.93 mgh. -1 cm -2 The Faraday efficiency reaches over 90%, and the performance degradation is less than 8% after 50 cycles.

[0082] The present invention also provides a rechargeable Zn-NO3 - The battery includes an anode, a cathode, an electrolyte, and a battery casing, wherein the cathode is the aforementioned Pt,S-TiO. 2-x @Ti composite electrode.

[0083] Example 1

[0084] This embodiment prepares Pt,S-TiO 2-x @Ti composite electrode, the steps are as follows:

[0085] Step 1:

[0086] Take a size of 2.5 × 4.0 cm. 2 Titanium sheets with a thickness of 0.2 mm (purity ≥99.9%) were ultrasonically cleaned sequentially with ethanol, acetone, and ultrapure water for 12 min each, and then vacuum dried at 60℃ for 30 min. The treated titanium sheets were placed in a 50 mL PTFE-lined autoclave, and 40 mL of 4.0 M NaOH solution was added. The reaction was carried out hydrothermally at 180℃ for 12 h. After cooling to room temperature, the titanium sheets were washed with deionized water until neutral, and then placed in 1.0 M HCl solution for ion exchange for 3 h. After removal, the sheets were washed with deionized water, dried at 60℃, and then annealed in a muffle furnace at 450℃ in air for 1 h at a heating rate of 2℃ / min to obtain a TiO2 nanosheet array (denoted as T).

[0087] Step 2:

[0088] The TiO2 nanosheet array obtained in step 1 was placed in a tube furnace, and a 5% H2 / Ar mixed gas was introduced (flow rate 60 mL / min). It was annealed at 500 °C for 1 h with a heating rate of 2 °C / min, and then naturally cooled to room temperature to obtain oxygen-deficient TiO2. 2-x Nanosheet array (denoted as TO).

[0089] Step 3:

[0090] Prepare 30 mL of a mixed aqueous solution containing 0.005 M H₂PtCl₆·6H₂O and 0.1 M thiourea. Place the TO sample obtained in step 2 into the above mixed solution and treat under negative pressure at -0.08 MPa for 30 min. After removal, irradiate with a 300 W xenon lamp for 15 min for photoreduction. Wash four times with deionized water and dry under vacuum at 60 °C for 1.5 h. Finally, anneal in a tube furnace with nitrogen gas (flow rate 60 mL / min) at 350 °C for 1 h with a heating rate of 2 °C / min to obtain the Pt,S-TiO₂. 2-x @Ti composite electrode (denoted as PSTO).

[0091] Characterization revealed that the average particle size of Pt nanoparticles in PSTO was 3.2 nm, with a loading of 0.3 wt.%; the S atom doping amount was 2.1 at.%; and the oxygen vacancy concentration was 1.2 × 10⁻⁶. 20 cm -3 TiO 2-x The nanosheet array has a thickness of 3.5 μm, and the individual nanosheets have a thickness of 12 nm; the charge transfer resistance is 12 Ω; and the electrochemically active surface area is 7.57 mF / cm². -2 .

[0092] Performance Test 1: Electrocatalytic Reduction of Nitrate to Ammonia

[0093] A standard three-electrode system was used, with PSTO as the working electrode and Ag / AgCl (saturated KCl) as the reference electrode, at a depth of 1 cm. 2 A platinum sheet was used as the counter electrode. The electrolyte was a mixed solution of 20 mL of 0.5 M Na₂SO₄ and 0.1 M NaNO₃, pH=7. A potential of -0.6 V vs. RHE was applied, the reaction temperature was 25 °C, and the reaction time was 1 h.

[0094] Results: Ammonia yield was 80.3 mgh -1 cm -2 The Faraday efficiency was 97.8%; after 200 hours of continuous operation, the ammonia yield remained at 76.5 mgh. -1 cm -2 Faraday efficiency remained at 92.3%.

[0095] Performance Test 2: Zn-NO3 - Battery performance

[0096] Using zinc foil as the anode, PSTO as the cathode, and a mixed solution of 6M KOH + 0.5M NaNO3 as the electrolyte, a rechargeable Zn-NO3 electrolyte was assembled. - Battery.

[0097] Results: The battery open-circuit voltage was 1.46V; the peak power density was 6.82mW / cm³. -2 ; at 50mAcm -2 Discharge at the specified current density yielded an ammonia yield of 7.93 mgh. -1 cm -2 The Faraday efficiency was 92.1%; after 50 cycles, the discharge voltage plateau retention rate was 94.2%, and the ammonia yield retention rate was 91.5%.

[0098] Example 2

[0099] Compared with Example 1, the only difference is that the concentration of H2PtCl6·6H2O in step 3 is changed to 0.003M, while the other parameters remain unchanged.

[0100] Example 3

[0101] Compared with Example 1, the only difference is that the concentration of H2PtCl6·6H2O in step 3 is changed to 0.007M, while the other parameters remain unchanged.

[0102] Example 4

[0103] Compared with Example 1, the only difference is that the hydrogen annealing temperature in step 2 is changed to 450°C, while the other parameters remain unchanged, resulting in an oxygen vacancy concentration of 6.8 × 10⁻⁶. 19 cm -3 PSTO electrode.

[0104] Example 5

[0105] Compared with Example 1, the only difference is that the hydrogen annealing temperature in step 2 is changed to 550°C, while the other parameters remain unchanged, resulting in an oxygen vacancy concentration of 1.8 × 10⁻⁶. 20 cm -3 PSTO electrode.

[0106] Example 6

[0107] Compared with Example 1, the only difference is that the hydrothermal treatment conditions in step 1 are adjusted to: NaOH solution concentration of 3.0M, hydrothermal temperature of 160℃, and hydrothermal time of 14h, while other conditions remain unchanged, thus preparing Pt,S-TiO2 with titanium dioxide nanowires as the main component. 2-x @Ti composite electrode.

[0108] Characterization revealed that the obtained titanium dioxide array exhibited a nanowire structure that was oriented along the surface of a titanium substrate.

[0109] Example 7

[0110] Compared with Example 1, the only difference is that in step 3, the platinum source is replaced with potassium chloroplatinate and the sulfur source is replaced with thioacetamide. The concentration of the platinum source and the molar ratio of the sulfur source to the platinum source remain unchanged, and all other conditions remain the same, to obtain Pt,S-TiO. 2-x @Ti composite electrode.

[0111] Example 8

[0112] Compared with Example 1, the only difference is that in step 3, the photoreduction time is adjusted to 10 min, the annealing temperature is adjusted to 300 °C, and the annealing time is adjusted to 1.5 h, while the other conditions remain unchanged, to obtain Pt,S-TiO. 2-x @Ti composite electrode.

[0113] Comparative Example 1

[0114] Compared with Example 1, the only difference is that the hydrogen annealing treatment in step 2 is not performed, while the other parameters remain unchanged, and a Pt,S-TiO2@Ti electrode (denoted as PST) without obvious oxygen defects is obtained.

[0115] Comparative Example 2

[0116] Compared with Example 1, the only difference is that thiourea is not added in step 3, while the other parameters remain unchanged, to obtain single Pt-doped TiO2. 2-x @Ti electrode (denoted as PTO).

[0117] Comparative Example 3

[0118] Compared with Example 1, the only difference is that chloroplatinic acid is not added in step 3, while the other parameters remain unchanged, to obtain single-S-doped TiO2.2-x @Ti electrode (denoted as STO).

[0119] Comparative Example 4

[0120] Compared with Example 1, the only difference is that the pure TiO2 nanosheet array electrode (denoted as T) prepared in step 1 is used as the electrode to be tested, and steps 2 to 3 are not performed.

[0121] Comparative Example 5

[0122] Compared with Example 1, the only difference is that the photoreduction treatment in step 3 is changed to chemical reduction, that is, no light is applied, and NaBH4 is used as the reducing agent, and the amount of reducing agent is 1.2 times the theoretical amount of reduction, while the other parameters remain unchanged.

[0123] Comparative Example 6

[0124] Compared with Example 1, the only difference is that in step 3, chloroplatinic acid is replaced with an equimolar amount of palladium chloride to prepare Pd,S-TiO. 2-x @Ti electrode.

[0125] Comparative Example 7

[0126] Compared with Example 1, the only difference is that in step 3, thiourea is replaced with an equimolar amount of urea to prepare Pt,N-TiO. 2-x @Ti electrode.

[0127] Comparative Example 8

[0128] Compared with Example 1, the only difference is that in step 3, negative pressure treatment is not performed, but treatment is carried out at normal pressure for 30 minutes, while other conditions remain unchanged, to obtain Pt,S-TiO. 2-x @Ti electrode.

[0129] Comparative Example 9

[0130] Compared with Example 1, the only difference is that annealing is not performed in step 3. After photoreduction, cleaning and drying, it is used directly as an electrode.

[0131] The test results of the electrodes prepared in each experimental group in performance test 1 are shown in Table 1.

[0132] Table 1: Performance Comparison Results of Electrodes in Electrocatalytic Nitrate Reduction to Ammonia Production

[0133]

[0134] Table 1 shows that the performance comparison results of each embodiment and comparative example indicate that only a PSTO electrode possessing both S-Ov FLP sites and a Pt reverse hydrogen overflow channel can achieve optimal NO3- concentration. -The RR performance verified the effectiveness of the synergistic mechanism designed in this invention. Furthermore, as shown in Examples 1 and 6, constructing a nanosheet array helps to further synergistically improve the ammonia production performance of nitrate.

[0135] To investigate the Pt,S-TiO prepared in Example 1 2-x The structural stability and catalytic durability of the @Ti composite electrode during long-term electrolysis were tested by continuous operation for 200 hours on the electrode of Example 1. The results are shown in Table 2.

[0136] Table 2: Pt, S-TiO 2-x @Long-term stability test results of Ti electrode

[0137]

[0138] As shown in Table 2, the electrode described in this invention has excellent stability in the production of ammonia from nitrate reduction.

[0139] Each embodiment and comparative example of Zn-NO3 assembly - The performance test results after battery testing are shown in Table 3. The test conditions were as follows: Zn foil was used as the anode, and the tested electrodes prepared in each case were used as the cathodes. A mixed electrolyte of 6 M KOH + 0.5 M NaNO3 was used, and the test was conducted at 25 °C. The peak power density was obtained from the polarization curve. Ammonia yield and Faraday efficiency were measured at 50 mA·cm⁻¹. -2 The measurements were taken under constant current discharge conditions. The results are shown in Table 3.

[0140] Table 3: Pt, S-TiO 2-x @Ti electrode assembly Zn-NO3 - Battery performance test results

[0141]

[0142] The test results in Tables 1-3 systematically verify the Pt,S-TiO2 of this invention. 2-x @Ti composite electrode in nitrate electroreduction for ammonia production and Zn-NO3 - The superior performance of the battery is shown in Table 1. Table 1 indicates that the PSTO electrode, which simultaneously constructs S-Ov hindered Lewis acid-base pair (FLP) sites and Pt-mediated reverse hydrogen overflow channels, exhibits the highest ammonia yield and Faradaic efficiency, significantly superior to the other pairs. This demonstrates that the synergistic effect of the two can effectively promote NO3- production. - The reduction reaction is enhanced, and the selectivity for ammonia production is improved. Table 2 shows that the composite electrode maintains a high ammonia yield and Faradaic efficiency after 200 h of continuous operation, demonstrating its excellent structural stability and long-term catalytic durability. Table 3 further shows that the Zn-NO3 assembled using this composite electrode as the cathode... -The battery has high open-circuit voltage, peak power density, ammonia yield, and cycle stability, enabling simultaneous power generation and ammonia production.

[0143] The above results fully demonstrate that the composite electrode of the present invention can significantly enhance NO3 - Efficiency of ammonia production by electroreduction and Zn-NO3 - The battery's overall performance suggests promising applications in ammonia synthesis and energy conversion.

Claims

1. A Pt / S-TiO 2-x @Ti self-supporting electrode, characterized in that, It includes a titanium substrate, an oxygen-deficient titanium dioxide array grown in situ on the surface of the titanium substrate, and Pt nanoparticles and S atoms doped in the oxygen-deficient titanium dioxide array. Among them, oxygen vacancies and S atoms hinder the formation of Lewis acid-base pairs; Pt nanoparticles mediate the formation of reverse hydrogen overflow channels; The Pt / S-TiO 2-x The fabrication steps for the @Ti self-supporting electrode include: Step 1: TiO2@Ti was prepared by in-situ growth of a titanium dioxide array on a titanium substrate. Step 2: Oxygen-deficient TiO2@Ti was prepared by reducing TiO2@Ti. Step 3: A composite solution containing oxygen-deficient TiO2@Ti and platinum and sulfur sources was subjected to pressure holding under negative pressure, followed by photoreduction to obtain a reduction product. The reduction product was then annealed to obtain Pt / S-TiO2. 2-x @Ti self-supporting electrode; The negative pressure ranges from -0.09 to -0.07 MPa. The pressure holding time under negative pressure is 20~40 minutes; The light reduction treatment is performed by irradiation with a 250-350W xenon lamp for 10-20 minutes. And / or, the annealing atmosphere includes at least one of nitrogen and rare gases; And / or, the annealing temperature is 300~400℃; The annealing time is 0.5~1.5 hours.

2. The Pt / S-TiO as described in claim 1 2-x @Ti self-supporting electrode, characterized in that, The oxygen-defect titanium dioxide array is at least one of titanium dioxide nanowires and titanium dioxide nanosheets along the Z-axis direction of the titanium substrate surface; The thickness of the oxygen-defect titanium dioxide array is 2~5μm; The valence state of Pt in the Pt nanoparticles is Pt 0 With Pt 4+ Coexistence, of which Pt 0 The total Pt atoms account for 60-80% of the total Pt atoms; the Pt nanoparticles have a particle size of 2-5 nm and a loading of 0.1-0.5 wt.%. S atoms are incorporated into the lattice of oxygen-deficient titanium dioxide by substituting for lattice oxygen, and the bond length of the Ti-S bond is 2.35~2.40 Å; the doping amount of the S atoms is 1~3 at.%, and the oxygen vacancy concentration is 5×10⁻⁶. 19 ~2×10 20 cm -3 .

3. A Pt / S-TiO as described in claim 1 or 2 2-x The method for preparing a Ti self-supporting electrode is characterized by the following steps: include: Step 1: TiO2@Ti was prepared by in-situ growth of a titanium dioxide array on a titanium substrate. Step 2: Oxygen-deficient TiO2@Ti was prepared by reducing TiO2@Ti. Step 3: A composite solution containing oxygen-deficient TiO2@Ti and platinum and sulfur sources was subjected to pressure holding under negative pressure, followed by photoreduction to obtain a reduction product. The reduction product was then annealed to obtain Pt / S-TiO2. 2-x @Ti self-supporting electrode; The negative pressure ranges from -0.09 to -0.07 MPa. The pressure holding time under negative pressure is 20~40 minutes; The light reduction treatment is performed by irradiation with a 250-350W xenon lamp for 10-20 minutes. And / or, the annealing atmosphere includes at least one of nitrogen and rare gases; And / or, the annealing temperature is 300~400℃; The annealing time is 0.5~1.5 hours.

4. The Pt / S-TiO as described in claim 3 2-x The method for preparing a Ti self-supporting electrode is characterized by, In step 1, the titanium substrate is subjected to hydrothermal treatment in an alkaline solution, followed by acid treatment and calcination in an oxygen-containing atmosphere to obtain the TiO2@Ti; And / or, the alkaline solution is a 3-5M NaOH solution, the hydrothermal temperature is 160-200℃, and the hydrothermal time is 10-14h; And / or, the acid solution for acid treatment is a 0.8~1.2M HCl solution; And / or, the calcination temperature is 400~500℃, and the calcination time is 0.5~1.5h.

5. The Pt / S-TiO as described in claim 3 2-x The method for preparing a Ti self-supporting electrode is characterized by, In step 2, the reducing atmosphere for the reduction treatment is a hydrogen-containing atmosphere; And / or, the reduction treatment temperature is 450~550℃; And / or, the reduction process takes 0.5 to 1.5 hours.

6. The Pt / S-TiO as described in claim 3 2-x The method for preparing a Ti self-supporting electrode is characterized by, In step 3, the platinum source is at least one of chloroplatinic acid, chloroplatinate, platinum chloride, and platinum acetylacetonate; The sulfur source is at least one of thiourea, thioacetamide, sodium sulfide, and sodium thiosulfate. In the composite solution, the concentration of the platinum source is 0.003~0.007M, and the molar ratio of the sulfur source to the platinum source is 15~25:

1.

7. The Pt / S-TiO as described in claim 3 2-x The method for preparing a Ti self-supporting electrode is characterized by, The photoreduction process takes 14-16 minutes.

8. A Pt / S-TiO as described in claim 1 or 2 2-x @Ti self-supporting electrode or Pt / S-TiO prepared by the preparation method according to any one of claims 3 to 7 2-x The application of a Ti self-supporting electrode in the electroreduction of nitrate to ammonia production is characterized by... It was used as an electrocatalytic electrode for the electrocatalytic reduction of nitrate to produce ammonia.

9. The application as described in claim 8, characterized in that, It was used to prepare Zn-NO3 based on the principle of electrocatalytic reduction of nitrate to ammonia. - Battery.

10. Zn-NO3 - The battery, characterized in that, Contains the Pt / S-TiO as described in claim 1 or 2 2-x @Ti self-supporting electrode or Pt / S-TiO prepared by the preparation method according to any one of claims 3 to 7 2-x @Ti self-supporting electrode.

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