A method for preparing a photo-assisted asymmetrically coordinated cobalt-based catalyst and applications thereof

Abstract

The application is suitable for the field of electrochemical energy storage technology, and provides a preparation method and application of a light-assisted asymmetric coordination cobalt-based catalyst, the preparation method comprising: adding cobalt nitrate hexahydrate, 2-methyl imidazole, triphenyl phosphine and 2,5-diamino terephthalic acid into an organic solvent, performing ultrasonic dispersion, solvothermal reaction, centrifugal separation, washing and drying to obtain Co-ONP-1142 catalytic material, and applying the Co-ONP-1142 catalytic material as an air positive electrode catalyst to a zinc-air battery under light conditions. The asymmetric coordination structure effectively breaks the Laporte inhibition, promotes the separation and migration of photo-generated carriers, significantly improves the rate performance, energy density and cycle stability of the zinc-air battery, and greatly reduces the cost of the positive electrode catalyst material.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, and particularly relates to a method for preparing a light-assisted asymmetric cobalt-based catalyst and its application. Background Technology

[0002] Against the backdrop of a global energy structure accelerating its transition towards low-carbon and renewable energy, the proportion of intermittent renewable energy sources such as wind and solar power in electricity supply continues to increase. Due to the significant volatility and uncertainty of these energy sources, large-scale grid connection poses greater challenges to grid frequency stability, voltage support, and power balance. Therefore, there is an urgent need to develop electrochemical energy storage technologies that combine high energy density, high power output, long cycle life, and low cost. Zinc-air batteries, using metallic zinc as the negative electrode, have a theoretical energy density of up to 1086 Wh·kg⁻¹. -1 It has advantages such as abundant raw materials, environmental friendliness, high safety and low manufacturing cost, and has good application prospects in large-scale stationary energy storage, distributed energy systems and emergency energy supply.

[0003] However, the actual energy density, power output, and cycle life of zinc-air batteries are still far below their theoretical levels, and their engineering applications are mainly limited by the slow reaction kinetics of the air cathode. The oxygen reduction reaction (ORR) during discharge and the oxygen evolution reaction (OER) during charging both involve complex multi-electron transfers and oxygen-containing intermediate conversions, leading to increased overpotentials, increased energy loss, and further limiting the battery's peak power density, rate performance, and cycle stability. Existing zinc-air battery air cathodes face the problem of different requirements for the electronic structure of active sites and the adsorption strength of intermediates in ORR and OER. Traditional catalysts struggle to simultaneously achieve effective O2 adsorption and activation, as well as timely conversion and desorption of oxygen-containing reaction intermediates such as *OH, *O, and *OOH, easily causing an imbalance in intermediate adsorption. This results in high charge-discharge reaction energy barriers and voltage differences, leading to a significant reduction in the battery's actual energy density.

[0004] Although noble metal-based catalysts (such as Pt / C and RuO2) exhibit benchmark activities for ORR and OER, respectively, their high cost, poor stability, and susceptibility to intermediates (CO, SO2) make them unsuitable for use. x Poisoning makes them unsuitable for large-scale deployment. Transition metal oxides and layered hydroxides (such as Co3O4, NiCo-LDH, etc.) have poor conductivity, resulting in high internal resistance of the battery positive electrode and severe polarization under high current density charge-discharge conditions. Transition metal nitrogen-carbon based catalysts (such as Fe-NC, Co-NC, etc.) have a simple M-N4 structure, which cannot effectively control the electronic structure of the catalyst metal center, resulting in a high electrochemical reaction energy barrier and slow electron transport rate.

[0005] To address these issues, existing technologies have proposed photo-assisted electrocatalysis strategies, introducing semiconductors, heterojunctions, or photosensitive components to enable photogenerated carriers to participate in ORR and OER processes. However, existing photo-assisted catalysis systems still suffer from limited photoresponse range, easy recombination of photogenerated electrons and holes, and low interfacial migration efficiency. Particularly when the metal active center is in a regularly symmetrical coordination environment, some d-orbital electron transitions are restricted by Laporte's selection law (Laporte's selection law states that under electric dipole transition conditions, transitions between electronic states with the same parity are usually forbidden transitions, while transitions between electronic states with different parities are usually allowed transitions), making it difficult to effectively convert absorbed light energy into active carriers participating in the electrode reaction. The highly symmetrical localized crystal field restricts the fine-tuning of the metal center's d-orbital energy levels, electron cloud distribution, and adsorption energy of oxygen-containing intermediates, resulting in insufficient orbital coupling and slow interfacial charge transport, making it difficult to further balance ORR / OER bifunctional activity with structural stability at high current densities.

[0006] In summary, existing zinc-air batteries have problems such as difficulty in achieving both ORR / OER dual-function catalytic activity, low utilization efficiency of photogenerated carriers, severe polarization during charge and discharge, and performance degradation under high current density. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a photo-assisted asymmetric cobalt-based catalyst and its application, thereby addressing the problems mentioned in the background art.

[0008] The present invention is implemented as follows: a method for preparing a photo-assisted asymmetric cobalt-based catalyst includes the following steps:

[0009] A cobalt source, a first ligand, a second ligand, and a third ligand are added to an organic solvent and dispersed by ultrasonication to obtain a mixed solution.

[0010] The mixed solution was transferred to a high-pressure reactor and heated under closed conditions to carry out a solvothermal reaction.

[0011] After the reaction was completed, the product was centrifuged, washed and dried to obtain an asymmetrically coordinated cobalt-based cathode catalyst.

[0012] The cobalt source is cobalt nitrate hexahydrate, the first ligand is 2-methylimidazole, the second ligand is triphenylphosphine, and the third ligand is 2,5-diaminoterephthalic acid.

[0013] In a further technical solution, the molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole and triphenylphosphine is 1:(1~2):(4~8):(1~2).

[0014] In a further technical solution, the molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole and triphenylphosphine is 1:1:4:2.

[0015] In a further technical solution, the organic solvent is N,N-dimethylformamide;

[0016] The ultrasonic dispersion treatment takes 20 to 30 minutes, the power is 200 to 300W, and the water temperature is controlled below 30℃.

[0017] The temperature of the solvothermal reaction is 100–140°C, and the constant temperature is maintained for 15–25 hours.

[0018] The washing process involves washing with anhydrous ethanol 3 to 5 times.

[0019] The drying temperature is 50–70°C, and the drying time is 8–12 hours.

[0020] Another objective of this invention is to provide an application of a light-assisted asymmetricly coordinated cobalt-based catalyst, which, based on the asymmetricly coordinated cobalt-based cathode catalyst prepared by the above method, is used as an air cathode catalyst in a metal-air battery under light irradiation conditions.

[0021] In a further technical solution, the metal-air battery is a zinc-air battery.

[0022] In a further technical solution, the zinc-air battery includes a zinc negative electrode, an electrolyte, an air positive electrode, and a casing, wherein the air positive electrode contains an asymmetrically coordinated cobalt-based positive electrode catalyst.

[0023] In a further technical solution, the air positive electrode includes a gas diffusion layer substrate and a catalyst layer supported on the gas diffusion layer substrate, wherein the catalyst layer comprises an asymmetrically coordinated cobalt-based positive electrode catalyst material, a conductive agent, and a binder;

[0024] The gas diffusion layer substrate is a hydrophobic carbon cloth that has been treated to be waterproof and breathable.

[0025] In a further technical solution, the mass ratio of the asymmetrically coordinated cobalt-based cathode catalyst, the conductive agent, and the binder in the catalyst layer is (3-5):(0.5-1.5):(0.5-1.5).

[0026] In a further technical solution, the electrolyte is an alkaline electrolyte containing potassium hydroxide and zinc acetate.

[0027] The present invention provides a method for preparing a photo-assisted asymmetric cobalt-based catalyst and its application, which has the following beneficial effects:

[0028] (1) Significantly improves the specific capacity and energy density of zinc-air batteries: The zinc-air battery assembled with Co-ONP-1142 as the asymmetric coordination material as the air cathode achieves a specific capacity of 896.38 mAh·g under dark conditions. -1 Compared to the 689.98 mAh·g of Co-N based batteries -1 The specific capacity increased by approximately 29.91%; under simulated sunlight irradiation, the specific capacity further increased to 985.57 mAh·g. -1 The energy density under dark conditions reaches as high as 1027.44 Wh·kg⁻¹. -1 This represents an improvement of approximately 37.80% compared to Co-N-based batteries; under illumination conditions, it further increases to 1071.48 Wh·kg⁻¹. -1 .

[0029] (2) Significantly improves the power density and rate performance of zinc-air batteries: Co-ONP-1142-based zinc-air batteries achieve a peak power density of up to 138 mW·cm under illumination. -2 relatively dark conditions (120 mW·cm) -2 The rate capability improvement reached 15%. Under different current densities, Co-ONP-1142 exhibited the lowest overpotential and the weakest polarization, demonstrating excellent rate performance.

[0030] (3) Significantly reduces charge / discharge overpotential and improves cycle stability: at 10 mA·cm -2 At the given current density, the OER overpotential decreased from 215 mV in darkness to 140 mV under illumination; the battery charge-discharge voltage difference decreased from 0.8 V to 0.6 V. Under illumination, the battery voltage remained essentially constant during more than 220 hours of continuous cycling, without significant voltage drop.

[0031] (4) Significantly reduced cost of cathode catalyst materials: This invention uses cobalt nitrate hexahydrate as the cobalt source and 2-methylimidazolium, triphenylphosphine, and 2,5-diaminoterephthalic acid as multiple ligands, with a wide range of raw material sources. Based on a preliminary estimate of the equivalent mass of catalyst, the unit mass raw material cost of Co-ONP-1142 is reduced by more than 80% compared to 20 wt.% of commercial Pt / C catalyst.

[0032] (5) A novel asymmetric coordination and photo-assisted electrocatalysis synergistic strategy is provided: Through the N / O / P multi-element asymmetric coordination structure, the present invention simultaneously achieves local electronic structure regulation, Laporte forbidden relaxation, efficient separation and directional migration of photogenerated carriers, providing a novel technical approach for the design of catalytic systems for high-performance, long-life photo-assisted zinc-air batteries. Attached Figure Description

[0033] Figure 1A flowchart illustrating a method for preparing a photo-assisted asymmetric cobalt-based catalyst according to an embodiment of the present invention;

[0034] Figure 2 A conceptual model diagram of a Co-ONP-1142-based photovoltaic-assisted zinc-air battery;

[0035] Figure 3 The discharge current density is 5 mA·cm under different illumination conditions. -2 The specific capacity curves at different times (where (a) represents the dark condition and (b) represents the light condition).

[0036] Figure 4 The discharge current density is 5 mA·cm under different illumination conditions. -2 Energy density curves at different times (where (a) represents darkness and (b) represents illumination).

[0037] Figure 5 The power density curves are shown under different illumination conditions (where (a) represents the dark condition and (b) represents the illuminated condition).

[0038] Figure 6 The magnification performance curves are shown under different lighting conditions (where (a) represents the dark condition and (b) represents the lit condition).

[0039] Figure 7 Constant current charge-discharge cycle curves of zinc-air batteries assembled with different ligands under different illumination conditions (where (a) represents the dark condition and (b) represents the illuminated condition).

[0040] Figure 8 SEM images of Co-ONP-1142 (where (a) and (b) are low-magnification SEM images of Co-ONP-1142, and (c) is a high-magnification SEM image of Co-ONP-1142).

[0041] Figure 9 The TEM image of Co-ONP-1142 and the elemental distribution diagrams of P, N, O, and Co in Co-ONP-1142 are shown (where (a) is the TEM image and (b) is the elemental distribution diagram of P, N, O, and Co).

[0042] Figure 10 XRD patterns of Co-N and Co-ONP-1142;

[0043] Figure 11 XPS spectra of Co 2p and N 1s for Co-ONP-1142 and Co-N are compared (where (a) is Co 2p and (b) is N 1s).

[0044] Figure 12XPS spectra of O 1s and P 2p of Co-ONP-1142 and Co-O (where (a) is O 1s and (b) is P 2p).

[0045] Figure 13 The ultraviolet absorption spectra of Co-O, Co-P, Co-N, and Co-ONP-1142 are shown.

[0046] Figure 14 Infrared spectra of Co-O, Co-P, Co-N, and Co-ONP-1142;

[0047] Figure 15 The open-circuit voltage curves of Co-O, Co-N, Co-P and Co-ONP-1142 under different illumination conditions are shown (where (a) is under dark conditions and (b) is under illumination conditions).

[0048] Figure 16 The OER diagrams and corresponding overpotentials of Co-N, Co-P, Co-O and Co-ONP-1142 under dark conditions are shown (where (a) is the OER diagram and (b) is the overpotential).

[0049] Figure 17 The OER diagrams and corresponding overpotentials of Co-N, Co-P, Co-O and Co-ONP-1142 under illumination are shown (where (a) is the OER diagram and (b) is the overpotential).

[0050] Figure 18 Tafel slope plots of Co-N, Co-P, Co-O and Co-ONP-1142 under different illumination conditions (where (a) represents the dark condition and (b) represents the illuminated condition).

[0051] Figure 19 ORR diagrams and corresponding onset potentials of Co-N, Co-P, Co-O and Co-ONP-1142 under dark conditions (where (a) is the ORR diagram and (b) is the onset potential).

[0052] Figure 20 The ORR diagrams and corresponding onset potentials of Co-N, Co-P, Co-O and Co-ONP-1142 under illumination are shown (where (a) is the ORR diagram and (b) is the onset potential).

[0053] Figure 21EIS of Co-N, Co-P, Co-O and Co-ONP-1142 and EIS of Co-ONP with different ratios under dark conditions (where (a) is the EIS of Co-N, Co-P, Co-O and Co-ONP-1142, and (b) is the EIS of Co-ONP with different ratios).

[0054] Figure 22 The image shows the EIS of Co-N, Co-P, Co-O, and Co-ONP-1142 under illumination, as well as the EIS of Co-ONP with different ratios (where (a) is the EIS of Co-N, Co-P, Co-O, and Co-ONP-1142, and (b) is the EIS of Co-ONP with different ratios).

[0055] Figure 23 ECSA plots of Co-O, Co-N, Co-P, and Co-ONP-1142 under dark conditions (where (a) is Co-O, (b) is Co-N, (c) is Co-P, and (d) is Co-ONP-1142).

[0056] Figure 24 ECSA diagrams of Co-O, Co-N, Co-P, and Co-ONP-1142 under illumination conditions (where (a) is Co-O, (b) is Co-N, (c) is Co-P, and (d) is Co-ONP-1142).

[0057] Figure 25 Ca of ECSA for Co-O, Co-N, Co-P, and Co-ONP-1142 under different illumination conditions dl (Where, (a) represents darkness and (b) represents light.)

[0058] Figure 26 Comparison of the d-band centers of Co-ONP-1142 and Co-N;

[0059] Figure 27 The ORR free energy step diagrams for Co-ONP-1142 and Co-N are shown. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0061] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0062] An embodiment of the present invention provides a method for preparing a photo-assisted asymmetric cobalt-based catalyst, comprising the following steps:

[0063] A cobalt source, a first ligand, a second ligand, and a third ligand are added to an organic solvent and dispersed by ultrasonication to obtain a mixed solution.

[0064] The mixed solution was transferred to a high-pressure reactor and heated under closed conditions to carry out a solvothermal reaction.

[0065] After the reaction was completed, the product was centrifuged, washed and dried to obtain an asymmetrically coordinated cobalt-based cathode catalyst.

[0066] The cobalt source is cobalt nitrate hexahydrate, the first ligand is 2-methylimidazole, the second ligand is triphenylphosphine, the third ligand is 2,5-diaminoterephthalic acid, and the organic solvent is N,N-dimethylformamide.

[0067] In a preferred embodiment of the present invention, the molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole, and triphenylphosphine is 1:(1-2):(4-8):(1-2). More preferably, the molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole, and triphenylphosphine is 1:1:4:2.

[0068] In a preferred embodiment of the present invention, the ultrasonic dispersion treatment time is 20 to 30 minutes, the power is 200 to 300W, and the water temperature is controlled below 30°C;

[0069] The temperature of the solvothermal reaction is 100–140°C, and the constant temperature is maintained for 15–25 hours.

[0070] The washing process involves washing with anhydrous ethanol 3 to 5 times.

[0071] The drying temperature is 50–70°C, and the drying time is 8–12 hours.

[0072] Another embodiment of the present invention provides an application of a light-assisted asymmetricly coordinated cobalt-based catalyst. Based on the asymmetricly coordinated cobalt-based cathode catalyst material prepared by the above method, the asymmetricly coordinated cobalt-based cathode catalyst material is used as an air cathode catalyst in a metal-air battery under light irradiation conditions.

[0073] In a preferred embodiment of the present invention, the metal-air battery is a zinc-air battery, which includes a zinc negative electrode, an electrolyte, an air positive electrode, and a casing. The air positive electrode contains an asymmetrically coordinated cobalt-based positive electrode catalyst.

[0074] In a preferred embodiment of the present invention, the air positive electrode includes a gas diffusion layer substrate and a catalyst layer supported on the gas diffusion layer substrate, wherein the catalyst layer comprises an asymmetricly coordinated cobalt-based positive electrode catalyst material, a conductive agent and a binder;

[0075] The gas diffusion layer substrate is a hydrophobic carbon cloth that has been treated to be waterproof and breathable.

[0076] In a preferred embodiment of the present invention, the mass ratio of the asymmetrically coordinated cobalt-based cathode catalyst, the conductive agent, and the binder in the catalyst layer is (3-5):(0.5-1.5):(0.5-1.5).

[0077] In a preferred embodiment of the present invention, the electrolyte is an alkaline electrolyte containing potassium hydroxide and zinc acetate.

[0078] The following specific examples verify the asymmetric cobalt-based cathode catalyst material prepared in this invention.

[0079] Example 1: Preparation of the catalytic material Co-ONP-1142;

[0080] The specific process is as follows: Figure 1As shown, 0.291 g of cobalt nitrate hexahydrate, 0.328 g of 2-methylimidazole, 0.524 g of triphenylphosphine, and 0.181 g of 2,5-diaminoterephthalic acid were weighed and added to 40 mL of N,N-dimethylformamide. The mixture was ultrasonically treated in a CNC ultrasonic cleaner for 25 minutes (power 250 W, water temperature controlled below 30℃) to completely dissolve or fully disperse the solids, resulting in a homogeneous gray-purple mixed solution. This mixed solution was directly transferred to a 50 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, sealed, and placed in an oven. It was heated to 120℃ and maintained at that temperature for 20 hours, then allowed to cool naturally to room temperature. Upon opening the reactor, a purplish-black suspension was obtained. The entire purplish-black suspension was transferred to 50 mL centrifuge tubes and centrifuged at 9000 r / min for 10 minutes to fully separate the solid and liquid. The supernatant was carefully discarded. Add 30 mL of anhydrous ethanol to the dark purple precipitate at the bottom of the centrifuge tube. Gently crush and shake with a clean glass rod for 1-2 minutes to completely disperse the precipitate from a clump into a homogeneous suspension. Centrifuge again at 9000 r / min for 10 minutes and discard the supernatant. Repeat the above procedure three times, using 30 mL of anhydrous ethanol each time to ensure sufficient contact between the precipitate and the washing solution. For the fourth wash, transfer the precipitate to a new clean centrifuge tube, add 30 mL of anhydrous ethanol, and centrifuge under the same conditions for 10 minutes. At this point, the supernatant should be colorless, transparent, and free of the pungent odor of N,N-dimethylformamide. If the supernatant still has color or odor, repeat the ethanol wash until it meets the requirements. The dark purple wet precipitate obtained from the last centrifugation was carefully removed and evenly spread in a clean glass petri dish, with a thickness not exceeding 2 mm. It was then placed in a drying oven and dried at 60°C for 10 hours. After the temperature dropped to room temperature, it was removed to obtain a loose, purplish-black powder, which is the asymmetrically coordinated cobalt-based cathode catalyst material, named Co-ONP-1142 catalyst material.

[0081] Figure 8 (a)- Figure 8(c) Scanning electron microscopy (SEM) images of the Co-ONP-1142 cathode catalyst are shown. SEM morphology reveals that Co-ONP-1142 exhibits a hexahedral framework with significant surface roughening, accompanied by numerous irregular pits and localized defects. The introduction of oxygen (O) and phosphorus (P) effectively interferes with the material's crystallization and growth behavior, inducing structural distortions and defect sites on the surface, breaking the inert characteristics of the original highly symmetrical structure. This asymmetric and roughened surface structure significantly increases the specific surface area of ​​the material, exposing more electrochemical active sites and directly improving the catalytic efficiency of ORR and OER. Furthermore, the abundant surface defects optimize the interfacial contact characteristics, promoting mass transfer and charge transfer between oxygen, electrolyte, and electrode, effectively reducing interfacial impedance and reaction overpotential. In summary, the roughened surface structure and abundant defect sites of Co-ONP-1142 not only effectively increase the specific surface area and active site exposure of the material but also promote reactant transport and interfacial charge transfer processes, providing an excellent reaction environment for the ORR / OER bifunctional catalytic reaction. Therefore, the Co-ONP-1142-based zinc-air battery exhibits superior catalytic activity and electrochemical performance, further demonstrating the important role of surface defect engineering and asymmetric structure regulation in improving photo-assisted electrocatalysis performance.

[0082] like Figure 9 (a) and Figure 9 As shown in (b), overall, the elements of the Co-ONP-1142 cathode catalyst exhibit a relatively uniform dispersion within the particle size, without obvious agglomeration or phase separation, indicating that the prepared Co-ONP-1142 has good elemental uniformity. In summary, these results strongly demonstrate that Co-ONP-1142 successfully constructed a uniformly dispersed multi-element asymmetric structure, which is also an important structural basis for its excellent electrocatalytic performance. This structure can effectively regulate the electronic environment of the cobalt center, optimize the adsorption behavior of reaction intermediates, thereby improving the reaction kinetics of ORR and OER, and enhancing the charge-discharge efficiency of the battery.

[0083] Figure 10 The XRD patterns of Co-N and Co-ONP-1142 cathode catalysts are shown in the figure. (The diffraction angle is not shown). Compared to Co-N, the XRD pattern of Co-ONP-1142 shows new diffraction peaks, indicating that the preparation process of this invention forms a new crystalline phase while simultaneously creating the Co-N porous framework, and successfully constructs an asymmetric coordination structure. The Co-N porous framework provides smooth channels for electrolyte permeation and oxygen diffusion, effectively shortening the path of reactants to active sites. Simultaneously, the formed asymmetric electronic structure induces charge redistribution at the interface, optimizing the adsorption free energy of oxygen intermediates, thereby significantly reducing the reaction energy barrier between ORR and OER, and improving the charge / discharge efficiency and rate performance of the battery. In summary, the XRD results demonstrate that the Co-ONP-1142 material successfully introduces a new crystalline phase and constructs a multifunctional active structure with asymmetric coordination characteristics while maintaining the Co-N porous framework structure. This structure not only provides a continuous channel for electrolyte transport and oxygen diffusion, but also promotes the redistribution of interfacial charges and optimizes the adsorption energy barrier of oxygen intermediates by regulating the local electronic environment of the Co center, thereby synergistically improving the ORR / OER reaction kinetics and providing a structural basis for the excellent photo-assisted zinc-air battery performance of the Co-ONP-1142 cathode catalyst.

[0084] like Figure 11 (a) Figure 11 (b) Figure 12 (a) and Figure 12 As shown in (b), the XPS spectra further demonstrate that the coordination structure and electronic state of the Co active center in the Co-ONP-1142 cathode catalyst were significantly reconstructed after the introduction of O, N, and P elements. In the Co2p spectrum, Co is present simultaneously in both Co-N and Co-ONP-1142. 2+ and Co 3+ The composition indicates that the Co site maintains a mixed valence state. The asymmetric coordination environment is conducive to enhancing Co... 2+ / Co 3+The reversible valence transitions between these phases provide a more flexible electron transfer channel for multi-electron redox reactions during charge and discharge. The presence of the Co-O peak in the O 1s spectrum indicates that O atoms can directly participate in the coordination of the Co center. The Co-O bond can further break the original symmetrical coordination field of the Co center, causing significant electronic polarization at the Co site. Meanwhile, the CO and OC=O groups can improve the polarity and chemical affinity of the material surface, enhancing the wetting of the electrode surface by the electrolyte and the adsorption and migration of ions at the interface. Therefore, the introduction of oxygen species not only changes the first coordination layer structure of the Co center but also improves the mass transfer process at the electrode / electrolyte interface by regulating the chemical environment of the carbon support surface. In the P 2p spectrum, the peaks at 129.2 and 133.4 eV are attributed to Co-P and PC bonds, respectively. The Co-P peak indicates that P can directly coordinate with the Co active center, while the PC peak indicates that some P atoms are covalently embedded in the carbon framework. Because the atomic radius and electronegativity of P atoms differ significantly from those of N and O, the formation of Co-P bonds further alters the bond length, coordination field strength, and charge distribution around the Co center, thus exacerbating the asymmetry of the local structure. Simultaneously, the PC structure modulates the electronic structure of the carbon skeleton, enhancing the electronic coupling between the active center and the conductive carrier. Therefore, Co-N, Co-O, and Co-P bonds collectively constitute a multi-element asymmetric coordination unit, resulting in a stronger local built-in electric field and richer electron transfer pathways around the Co site. In summary, the O, N, and P elements in Co-ONP-1142 do not exist as independent functional groups, but rather reconstruct the local coordination structure of the Co center through Co-N, Co-O, Co-P, and PC bonds. This asymmetric coordination structure can regulate the electron occupancy state and redox capacity of the Co active center, while preventing excessively strong or weak adsorption of intermediates by a single Co-N site. Furthermore, polar O, N, and P sites can enhance the chemisorption capacity of the electrode surface for ions and reaction intermediates, inhibiting the migration and loss of active species during charge and discharge. Adjustments to the electronic structure of the carbon framework help reduce interfacial charge transfer resistance and accelerate ion diffusion and redox reaction kinetics. The enhanced electronic coupling between the Co center and the heteroatom-doped carbon framework further accelerates interfacial charge transfer. In summary, the asymmetric structure improves the utilization rate of active sites and the reversibility of reactions, enabling the material to maintain fast reaction kinetics and high capacity output even at high current densities, and contributing to improved charge-discharge efficiency, rate performance, and long-term cycle stability.

[0085] Figure 13The UV absorption spectrum of the Co-ONP-1142 cathode catalyst is shown. The stronger dd transitions and LMCT (Ligand-to-Metal Charge Transfer) processes in the visible light region indicate a significant asymmetric reconstruction of the coordination environment of the Co metal center in Co-ONP-1142. This asymmetric coordination field induces the splitting of the 3d orbital energy levels of Co and the redistribution of electrons, optimizing the adsorption / desorption behavior of oxygen intermediates at the active sites. This reduces the overpotential of the ORR and OER reactions, improving the charge-discharge efficiency of the battery. The redshift of the absorption edge signifies enhanced light absorption, endowing Co-ONP-1142 with the ability to generate more photogenerated carriers under illumination. These photogenerated carriers can participate in electrocatalytic reactions, accelerating charge transfer and enabling the battery to achieve higher open-circuit voltage, specific capacity, and peak power density under illumination.

[0086] Figure 14 Infrared spectra of Co-O, Co-P, CO-N, and Co-ONP-1142 cathode catalysts are shown. Co-ONP-1142 retains the characteristic absorption peaks of multiple ligands, accompanied by some peak position shifts and intensity changes, proving that O, N, and P coordinating atoms successfully participate in coordination, forming an asymmetric structure. Simultaneously, the strong σ-electron-donating ability of the P ligand effectively increases the electron density of the Co center, accelerates the charge transfer rate, and reduces the battery's internal resistance, enabling the battery to maintain a high discharge voltage and power output even at high current densities. In summary, the Co-ONP-1142 prepared in this invention is an asymmetric material; the coexistence of multiple coordinating atoms in a strong and weak field asymmetric structure enhances the material's structural stability, enabling the Co-ONP-1142-based battery to maintain stable voltage output and a small voltage gap during long-term cycling.

[0087] Example 2: Preparation of zinc anode;

[0088] First, select zinc sheets with a thickness of 0.1 mm to 0.5 mm as the base material and cut them to a shape suitable for the battery mold. Use a fine file to lightly trim the burrs on the cut edges. Use multi-grade silicon carbide sandpaper for gradient sanding, with sandpaper grits of 400 grit, 800 grit, and 1200 grit in sequence, to achieve a progressive surface treatment from coarse grinding to fine polishing. For the first stage of sanding, use 400 grit sandpaper, apply constant pressure (about 5N-10N) along the length of the zinc sheet, and sand back and forth at a uniform speed for 2 minutes. For the second stage of sanding, switch to 800 grit sandpaper, rotate the sanding direction 90 degrees, perpendicular to the scratches from the first stage, and sand along a single axis for 2 minutes. For the third stage of sanding, switch to 1200 grit sandpaper, return the sanding direction to the first stage direction, and gently sand for 1-2 minutes until the surface of the zinc sheet presents a uniform, delicate, bright metallic luster without any visible scratches. Then, immediately immerse the polished zinc sheet in a glass beaker containing anhydrous ethanol and clean it for 5 to 10 minutes at room temperature using a 60W ultrasonic cleaner. Next, remove the zinc sheet and transfer it to deionized water for another 3 to 5 minutes of ultrasonic cleaning. Repeat this process twice, and finally wipe the surface dry with absorbent paper.

[0089] Example 3: Preparation of a zinc-air battery cathode based on Co-ONP-1142 catalytic material;

[0090] A hydrophobic carbon cloth with a thickness of 0.2 mm to 0.5 mm, treated with waterproof and breathable technology, was selected as the substrate for the gas diffusion layer and cut into the same shape as the zinc anode. 0.01 g of Co-ONP-1142 catalyst, 0.0025 g of polyvinylidene fluoride, and 0.0025 g of conductive carbon black were weighed out. 2 mL to 3 mL of N,N-dimethylformamide was added to the mixed powder to dissolve it, and the mixture was simultaneously ultrasonically dispersed at 60 W for 10 to 15 minutes. Then, an appropriate amount of slurry was pipetted onto the carbon cloth surface in a grid or spiral pattern. The carbon cloth containing the slurry was placed horizontally in an oven and dried at 60°C to 80°C for 15 to 20 minutes to completely dry the solvent. This process was repeated five times to progressively add and firmly anchor the catalyst and auxiliary materials onto the carbon cloth substrate.

[0091] Example 4: Preparation of electrolyte for zinc-air batteries;

[0092] Accurately weigh 6.740 g of potassium hydroxide and 0.600 g of zinc acetate using a precision analytical balance, and place them in two separate beakers. Add 20 mL of deionized water to each beaker and stir until completely dissolved. Place the beaker containing the potassium hydroxide solution on a magnetic stirrer and adjust the speed to about 800 rpm. While stirring continuously at high speed, slowly pour the zinc acetate stock solution into the center of the vortex in a thin stream along the inner wall of the beaker using a glass rod. The addition process should last for more than 80 seconds. After mixing, continue stirring for 12 to 15 minutes until the initial white turbidity completely disappears and the solution returns to a colorless and transparent state.

[0093] Example 5: Assembling a Co-ONP-1142-based zinc-air battery;

[0094] The zinc-air battery encapsulation structure of this invention includes a sandwich-type clamp consisting of three square acrylic sheets (upper, middle, and lower) and four sets of butterfly locking components. The cleaned and polished zinc sheet negative electrode is placed on the bottom plate area without through holes. Next, carbon loaded with catalyst is arranged on the upper plate position with circular vents. Then, a 0.3mm thick expanded polytetrafluoroethylene (ePTFE) waterproof and breathable membrane is taken, cut to match the outline of the carbon cloth, and placed over the back of the carbon cloth to prevent electrolyte leakage from the vent side. After positioning all components, the three acrylic sheets are stacked neatly and tightened sequentially with four butterfly nuts in a diagonal, consistent torque to ensure even distribution of pressure between the three sheets. This ensures good sealing while preventing cracks or deformation of the acrylic sheets due to uneven stress. A conceptual model of a photo-assisted zinc-air battery using Co-ONP-1142 as the positive electrode catalyst material is shown below. Figure 2 As shown.

[0095] Example 6: Photoassisted reaction conditions;

[0096] The reaction conditions for the dark group zinc-air batteries in this invention were set as follows: the assembled zinc-air batteries were placed in a light-proof environment and charged and discharged at room temperature. The reaction conditions for the illuminated group zinc-air batteries were set as follows: a 300W xenon lamp (equipped with an AM 1.5G filter to simulate standard sunlight) was used as the light source, vertically illuminating the positive electrode window of the battery, with the light intensity set to 100 mW / cm². 2 Charge and discharge tests were conducted at the same room temperature.

[0097] Example 7: Electrochemical performance testing;

[0098] 1. Open circuit voltage test:

[0099] Open-circuit voltage is a crucial parameter for evaluating the activity of battery catalysts. It directly reflects the catalytic ability of the air cathode for ORR (Orbital Rate of Return) and serves as the basis for subsequent assessments of battery energy density and power output. Tests were conducted at room temperature, using an electrochemical workstation to record the potential difference between the positive and negative electrodes. Data was collected under both dark conditions and simulated sunlight irradiation. Figure 15 (a) and Figure 15 (b) The open-circuit voltage curves of batteries assembled with different catalytic materials under dark and light conditions are shown. The zinc-air battery assembled with Co-ONP-1142 as the air cathode achieved an open-circuit voltage of 1.45 V under dark conditions, an improvement of approximately 10.69% compared to the 1.31 V of the control material Co-N-based battery. This result indicates that even in a dark environment, the catalytic activity of Co-ONP-1142 for the oxygen reduction reaction is significantly superior to that of the control material Co-N. The asymmetric coordination structure improves the reaction kinetics, providing favorable conditions for improving the discharge voltage, power output, and operational stability of the air cathode in the zinc-air battery. Under simulated sunlight irradiation conditions, the open-circuit voltage of this battery further increased to 1.53 V, an improvement of approximately 5.52% compared to 1.45 V under dark conditions. In summary, the increased voltage obtained under illumination strongly confirms that the electron-hole pairs generated by Co-ONP-1142 under photoexcitation can effectively promote interfacial charge transfer during the oxygen reduction reaction, thereby further suppressing the reaction overpotential and increasing the open-circuit voltage of the battery.

[0100] 2. Specific capacity test:

[0101] Specific capacity is a key parameter measuring the ability of an electrode material to store and release charge per unit mass, directly reflecting the catalytic efficiency of the catalyst for ORR and OER, as well as the utilization rate of active sites. The experiment was conducted at room temperature, using a Blue Battery testing system to perform constant current discharge on the battery, with the discharge current density set at 5 mA·cm⁻¹. -2 The discharge capacity was recorded under both dark and simulated sunlight conditions, and the specific capacity was calculated based on the mass of the active material. Figure 3 (a) and Figure 3 (b) shows that the zinc-air battery assembled with Co-ONP-1142 as the air cathode has a specific capacity of 896.38 mAh·g under dark conditions. -1 Compared to the 689.98 mAh·g of Co-N based batteries -1 The increase of approximately 29.91% fully demonstrates that its unique ligand-doped structure optimizes the electron distribution and reaction kinetics of active sites, exhibiting charge storage and release capabilities far exceeding those of symmetric materials like Co-N. Under simulated sunlight irradiation, the specific capacity further increases to 985.57 mAh·g. -1The capacity improvement was approximately 9.95% compared to dark conditions. In summary, the capacity increase induced by illumination confirms the significant photo-assisted catalytic effect of Co-ONP-1142. The asymmetric structure in Co-ONP-1142 expands the light absorption range of the material, increases the carrier concentration near the active sites, and optimizes the adsorption / desorption energy barrier of oxygen intermediates at the active sites by adjusting the d-orbital electron occupancy state of cobalt ions, thereby effectively improving the specific capacity performance of the battery.

[0102] 3. Energy density test:

[0103] Energy density is a key indicator for measuring the energy storage capacity of a battery, directly determining the total charge and energy output during a single discharge cycle, reflecting the overall catalytic efficiency of the catalyst for ORR and OER. By comparing the changes in energy density under dark conditions and simulated sunlight irradiation conditions, the impact of photo-assisted effects on the energy output performance of zinc-air batteries can be further verified. The tests were conducted at room temperature, using the Blue Battery testing system to perform constant current discharge on the batteries, with the discharge current density set at 5 mA·cm⁻¹. -2 Discharge curves were recorded under both dark and simulated sunlight conditions, and the mass energy density was calculated based on the discharge plateau voltage and discharge capacity. Figure 4 (a) and Figure 4 (b) Energy density curves of batteries assembled with different catalytic materials under dark and light conditions are shown. Under dark conditions, the energy density of the Co-ONP-1142-based battery reaches 1027.44 Wh·kg⁻¹. -1 Compared to the 745.61 Wh·kg of Co-N based batteries -1 This represents an increase of approximately 37.80%. After incorporating simulated sunlight irradiation, the battery's energy density further increased to 1071.48 Wh·kg⁻¹. -1 Compared to 1027.44 Wh·kg under dark conditions -1 The increase was approximately 4.29%. In summary, the asymmetric coordination structure is beneficial for regulating the electron distribution around the active center, enabling photogenerated carriers to participate more effectively in the oxygen reduction reaction, thereby reducing discharge polarization, increasing the average operating voltage of the battery, and maintaining a relatively stable discharge platform, ultimately improving the actual energy output of the zinc-air battery.

[0104] 4. Power density test:

[0105] Power density is a crucial indicator for evaluating the power output capability of zinc-air batteries per unit effective area. It characterizes the energy output rate of the battery at different discharge current densities and the kinetic performance of the air electrode. Furthermore, it reflects the catalytic activity of the catalyst in the ORR process and the overall polarization characteristics of the battery. The Blue Battery testing system was used to conduct discharge polarization tests on the batteries. By gradually increasing the discharge current density, the operating voltage corresponding to different current densities was recorded under both dark environments and simulated sunlight conditions. The results were then analyzed based on the power density. Calculate the power density at various current densities, where This is the battery operating voltage. The discharge current density is used. The maximum power density of the battery is determined based on the obtained power density versus current density curve, and this is used to compare the power output performance of zinc-air batteries under different illumination conditions.

[0106] like Figure 5 (a) and Figure 5 As shown in (b), the Co-ONP-1142 zinc-air battery achieves a peak power density of up to 138 mW·cm⁻¹ under illumination. -2 relatively dark conditions (120 mW·cm) -2 The improvement reached 15%, significantly outperforming single-ligand materials. In summary, the photo-assisted asymmetric coordination strategy effectively promoted the separation and utilization of photogenerated carriers, simultaneously enhanced the bifunctional catalytic activity of ORR and OER, and suppressed polarization losses during the electrode reaction process, thereby significantly enhancing the energy output capability of the battery.

[0107] 5. Ratio Performance Test:

[0108] To evaluate the adaptability of Co-ONP-1142 as the air cathode in zinc-air batteries under real-world operating conditions, it was assembled into a complete zinc-air battery, and rate performance testing was conducted. Rate performance is a key indicator of a battery's ability to maintain voltage stability at different current densities, directly reflecting the charge transport kinetics, polarization, and structural stability of the electrode materials. By gradually increasing and then decreasing the current density, the overpotential change and recovery ability of the catalyst under high load conditions can be used to determine its potential for long-term stable operation under high current density conditions. Tests were conducted at room temperature using a Blue Battery testing system for constant current charge-discharge, with current density gradients set to 1, 2, 4, 8, 15, and 20 mA·cm⁻¹. -2 Discharge for a certain period of time at each current density, then gradually reduce the current to 1 mA·cm at the same gradient. -2 Record the voltage response curve throughout the entire process. For example... Figure 6 (a) and Figure 6 As shown in (b), when the current density increases from 1 mA·cm-2 Gradually increase to 20 mA·cm -2 At this point, the voltage continues to decrease, indicating that the polarization of the system increases at higher current densities. And when the current density increases from 20 mA·cm⁻¹... -2 Reset to 1 mA·cm -2 Upon further observation, the voltage recovered somewhat, and Co-ONP-1142 consistently exhibited the lowest voltage value throughout the entire process. In summary, at the same current density, Co-ONP-1142 exhibits the lowest overpotential, the weakest polarization, and more stable electrochemical performance. Furthermore, this material maintains good voltage response and structural stability under different current loads, demonstrating superior electrochemical stability and rate performance, which is beneficial for the practical application of zinc-air batteries under high current density conditions.

[0109] 6. Cyclic stability test:

[0110] To evaluate the long-term reliability of Co-ONP-1142 as the air cathode in zinc-air batteries, it was assembled into a complete zinc-air battery for cycle stability testing. Cycle stability is a key indicator measuring the voltage plateau maintained by the battery during repeated charge-discharge cycles, directly determining the battery's actual lifespan and application value. By monitoring the change trend of charge-discharge voltage during long-term cycling, the degree of activity decay and stability of the catalyst during repeated charge-discharge processes can be determined. The test was conducted at room temperature, using a Blue Battery testing system to perform constant current charge-discharge cycles on the battery, with the current density set at 5 mA·cm⁻¹. -2 Each charging and discharging cycle lasts for a certain period of time, and the charging and discharging voltage curves are recorded throughout the process. For example... Figure 7 (a) and Figure 7As shown in (b), under dark conditions, the voltage of the Co-ONP-1142-based zinc-air battery fluctuated between 1 V and 1.8 V and remained essentially constant during continuous cycling for over 165 hours, without any significant voltage collapse or plateau abrupt changes, indicating high stability and reversibility during charge-discharge cycles. Compared to the single-ligand material Co-N (whose charge-discharge voltage fluctuates between 0.7 V and 2.3 V), Co-ONP-1142 maintains a smaller voltage gap. The asymmetric structure not only enhances catalytic activity but also fundamentally improves the reversibility and cycle stability of the electrode reaction. Under illumination, the charge-discharge voltage of the zinc-air battery using Co-ONP-1142 mainly remained within the range of 1.0–1.6 V, corresponding to a charge-discharge voltage gap of approximately 0.6 V, and did not significantly widen during continuous cycling. In summary, illumination further improves the charge-discharge reaction kinetics of the Co-ONP-1142 air cathode. Photogenerated carriers generated after the catalyst is photoexcited can participate in the electrode interface reaction. Photogenerated electrons promote the oxygen reduction reaction during discharge, while photogenerated holes help the oxygen evolution reaction during charging. This accelerates the interfacial charge transfer, reduces electrode polarization, and lowers the charge-discharge voltage difference, thereby further enhancing the charge-discharge reversibility and long-term cycle stability of the battery.

[0111] 7. OER catalytic performance test:

[0112] The OER catalytic activity of each sample was evaluated using linear sweep voltammetry (LSV) in a standard three-electrode system. The tests were performed on a Chenhua electrochemical workstation using 1 M KOH solution as the electrolyte, a glassy carbon electrode with the catalyst supported as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode. The LSV scan rate was 5 mV·s. -1 The potential range is set according to the open circuit potential, and all test potentials are converted into reversible hydrogen electrode (RHE) potentials through the Nernst equation. Figure 16 (a) and Figure 16 (b) Shows the OER diagrams and corresponding overpotentials of Co-N, Co-P, Co-O, and Co-ONP-1142 under dark conditions at 10 mA·cm⁻¹. -2 At current density, the overpotentials of Co-N, Co-O, and Co-P are approximately 290, 320, and 300 mV, respectively, while Co-ONP-1142 has the lowest overpotential at only 215 mV. The significantly reduced overpotential indicates that the asymmetric structure effectively lowers the OER reaction barrier. Figure 17 (a) and Figure 17(b) demonstrates that under illumination, the OER overpotential of Co-ONP-1142 further decreases to 140 mV, compared to 215 mV under dark conditions. Illumination reduces the overpotential by approximately 75 mV, a reduction of 34.9%. In summary, Co-ONP-1142 exhibits a significantly reduced overpotential under illumination, indicating that its electrocatalytic reaction kinetics are effectively promoted, demonstrating superior photo-assisted electrocatalytic performance.

[0113] Figure 18 (a) and Figure 18 (b) (in the figure) The graph (representing current density) shows the Tafel slopes (Tafel slope: a kinetic parameter; a smaller slope indicates a faster increase in current density with potential) for Co-N, Co-P, Co-O, and Co-ONP-1142 under illumination and darkness. Under darkness, the Tafel slopes for Co-N, Co-P, and Co-O are 262.53, 341.39, and 299.47 mV·dec, respectively. -1 All exhibited significant reaction kinetic resistance; however, the Tafel slope of Co-ONP-1142 decreased significantly to 100.43 mV·dec -1 This indicates that it possesses faster reaction kinetics and a lower energy barrier. This significant improvement is attributed to the asymmetric coordination environment of Co-ONP-1142, which introduces local electronic structure differences around the Co active center, effectively modulating the adsorption energy of the reaction intermediate and promoting interfacial charge transfer. The Tafel slope under Co-ONP-1142 illumination is as low as 43.4 mV·dec -1 This indicates that the Co-ONP-1142-based battery exhibits extremely fast charge-discharge reaction rates under illumination, requiring minimal overpotential increment to reach the same current density. This results in lower charging voltage and higher discharging voltage during charging and discharging, significantly reducing the voltage gap and improving round-trip energy efficiency. In summary, the rapid reaction kinetics of the asymmetric material under light assistance enable the battery to maintain low polarization even under high current density charge-discharge conditions, effectively improving its rate performance and power output capability, thus adapting it to high-power demand scenarios.

[0114] 8. ORR catalytic performance test:

[0115] The ORR catalytic performance of each sample was evaluated using linear sweep voltammetry (LSV) in a standard three-electrode system. The tests were performed on a Chenhua electrochemical workstation, using 0.1 M KOH solution as the electrolyte, a glassy carbon electrode with the catalyst supported as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode. The LSV scan rate was 5 mV·s. -1The potential range is set according to the open circuit potential, and all test potentials are converted into reversible hydrogen electrode (RHE) potentials through the Nernst equation. Figure 19 (a) and Figure 19 (b) The ORR plots and corresponding onset potentials of Co-N, Co-P, Co-O, and Co-ONP-1142 under dark conditions are shown. -2 At the given current density, the onset potentials of Co-O, Co-N, and Co-P are approximately 0.50 V, 0.67 V, and 0.55 V, respectively, while the onset potential of Co-ONP-1142 increases significantly to 0.71 V. For example... Figure 20 (a) and Figure 20 As shown in (b), under illumination, the onset potential further increases to 0.98 V. This higher ORR onset potential indicates that Co-ONP-1142 effectively promotes the adsorption, activation, and electron transfer processes of oxygen molecules, thereby promoting the ORR reaction dominated by the four-electron pathway. This results in a higher discharge voltage plateau for the battery, directly improving its output voltage and energy density. In summary, the higher limiting current density of Co-ONP-1142 indicates a faster ORR reaction rate, enabling the reduction of more oxygen per unit time. This allows the battery to provide a greater current output under the same discharge conditions, thus improving its power density.

[0116] 9. Electrochemical Impedance Spectroscopy (EIS) Test:

[0117] Electrochemical impedance spectroscopy (EIS) was performed on the electrodes of each sample using a Chenhua electrochemical workstation. The tests were conducted in a 1 MKOH alkaline electrolyte using a standard three-electrode system: a glassy carbon electrode with a supported catalyst as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum wire electrode as the counter electrode. The frequency range of the impedance test was 0.01 Hz to 100 kHz, the AC amplitude was set to 5 mV, and the test potential was the open-circuit potential. The obtained impedance data were fitted to the equivalent circuit using ZView software to obtain relevant electrochemical parameters such as charge transfer resistance (Rct) and solution resistance (Rs). Simultaneously, while maintaining consistent synthesis conditions, the molar ratios of cobalt nitrate hexahydrate, diaminoterephthalic acid, dimethylimidazole, and triphenylphosphine were systematically adjusted to prepare four triligand materials with ratios of 1:1:4:1, 1:2:4:1, 1:1:8:1, and 1:1:4:2, respectively. Figure 21 (a) Figure 21 (b) Figure 22 (a) and Figure 22 (b) is shown in the figure. The real part of the impedance. (The negative imaginary part of the impedance) The single-ligand materials Co-N, Co-P, and Co-O all exhibit large semicircular radii, indicating that their interfacial charge transfer process is significantly restricted, and the electron transport efficiency between the catalyst layer and the reaction interface is low. In contrast, the impedance curve of the optimally proportioned Co-ONP-1142 under dark conditions shows a significantly contracted semicircle, and its Rct is significantly lower than that of all single-ligand samples. This significant reduction in Rct can be attributed to the precisely constructed asymmetric coordination structure of Co-ONP-1142. While retaining the hexahedral framework conductive network of Co-N, the introduction of O and P ligands effectively modulates the local electronic environment of the Co active center, optimizes the electron transport path between the active site and the reactant, and thus promotes rapid electron transfer at the interface. In summary, the lower Rct results in less charge transfer resistance during the charging and discharging process of the Co-ONP-1142-based battery, allowing electrons to be transferred from the active sites to the reaction interface more quickly. This effectively reduces the overpotential caused by charge accumulation, enabling the battery to exhibit a higher discharge voltage and a lower charging voltage at the same current density. At the same time, the rapid charge transfer also helps to improve the rate performance of the battery, allowing it to maintain a high power output even at high current densities.

[0118] 10. Electrochemical Active Area (ECSA) Test:

[0119] Double-layer capacitor (C dl The current density difference (CV) is a key parameter for evaluating the electrocatalyst's electrocatalyst potential (ECSA), and is typically determined by cyclic voltammetry (CV). The specific measurement method involves recording CV curves at different scan rates (20 mV / s, 40 mV / s, 60 mV / s, 80 mV / s, 100 mV / s, and 120 mV / s) within the non-Radidatic interval. The difference in current density at a fixed potential is then selected. ,in, This represents the difference in current density during anodic and cathode scans at the same potential. This represents the current density corresponding to the anodic sweep of the CV curve at a specific potential. To plot the current density corresponding to the cathode scan of the CV curve at a specific potential against the scan rate, the slope obtained by linear fitting is C. dl Value. For example... Figure 23 (a) Figure 23 (b) Figure 23 (c) Figure 23 (d) Figure 24 (a) Figure 24 (b) Figure 24 (c) Figure 24 (d) Figure 25 (a) and Figure 25 As shown in (b), the C of each material under illumination conditionsdl The values ​​all increased, with Co-ONP-1142 showing an improvement in C. dl From 8.77 mF·cm in the dark state -2 Significantly increased to 11.9 mF·cm -2 The increase reached 35.7%, far exceeding that of Co-N (7.23 mF·cm⁻¹). -2 ), Co-O (4.70 mF·cm -2 ) and Co-P (5.69mF·cm -2 Combined with UV-Vis absorption spectroscopy analysis, the synergistic introduction of O and P ligands constructs local electronic structure differences within the Co-N host framework, forming a local electric field conducive to the directional migration of photogenerated carriers. This promotes charge accumulation at the Co active centers, amplifying the double-layer capacitance response. In summary, under illumination, C... dl The significant improvement allows the Co-ONP-1142 cathode catalyst to expose more electrochemical active sites under light irradiation, providing a larger reaction interface for ORR and OER reactions, directly increasing the catalytic reaction rate, and enabling the battery to exhibit higher discharge voltage and power output under light conditions; in addition, the enrichment of photogenerated carriers in the Co active center effectively accelerates the charge transfer process, reduces the interfacial charge transfer resistance, and enables the battery to exhibit a smaller voltage gap during charge and discharge.

[0120] Example 8: Density Functional Theory (DFT) Calculation;

[0121] To further reveal the essence of the excellent photo-assisted catalytic performance of Co-ONP-1142 from the electronic structure level, the partial density of states (PDOS) of the d orbitals of cobalt atoms was calculated using density functional theory (DFT). Figure 26 The comparison of the d-band centers of Co-ONP-1142 and Co-N is shown. The spin-up d-band center of Co-ONP-1142 has shifted significantly from -2.733 eV in Co-N to -0.625 eV. The closer the d-band center is to the Fermi level means that the adsorption capacity of the cobalt center for oxygen-containing intermediates is greatly enhanced, thus optimizing the adsorption free energy. Figure 27 The ORR free energy step diagrams (U=1.23V) of Co-ONP-1142 and the control sample Co-N under alkaline conditions are shown. The results show that the rate-determining step energy barrier of Co-N is as high as 0.52 eV; while the asymmetric coordination structure of Co-ONP-1142 optimizes the interaction between the active site and the oxygen-containing intermediate, significantly reducing the rate-determining step energy barrier, resulting in a smoother overall free energy curve, effectively reducing the ORR reaction overpotential, and improving the reaction kinetics.

[0122] Furthermore, the density of states near the Fermi level in Co-ONP-1142 is significantly higher than that in Co-N, indicating that the introduction of phosphorus greatly enhances the electronic density of states of the cobalt active center. This significantly reduces the interfacial charge transfer resistance, decreases Joule heat loss due to resistance, and extends the cycle life of the battery. The spin-up and spin-down d-band centers exhibit a clear asymmetric distribution. This spin polarization characteristic allows Co-ONP-1142 to utilize photogenerated carriers more efficiently in photo-assisted catalysis, further reducing the reaction overpotential and thus achieving higher open-circuit voltage, specific capacity, and peak power density under illumination. In summary, the DFT theoretical calculations further reveal the regulatory effect of the N / O / P multi-element asymmetric coordination structure in Co-ONP-1142 on the electronic structure of the Co active center. By optimizing the d-band center position, enhancing the electronic density of states near the Fermi level, and promoting spin polarization, it effectively improves the adsorption / desorption balance of oxygen-containing intermediates, lowers the energy barrier of key ORR reaction steps, and provides a theoretical basis for achieving efficient photo-assisted electrocatalysis.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a photo-assisted asymmetric cobalt-based catalyst, characterized in that, Includes the following steps: A cobalt source, a first ligand, a second ligand, and a third ligand are added to an organic solvent and dispersed by ultrasonication to obtain a mixed solution. The mixed solution was transferred to a high-pressure reactor and heated under closed conditions to carry out a solvothermal reaction. After the reaction was completed, the product was centrifuged, washed and dried to obtain an asymmetrically coordinated cobalt-based cathode catalyst. The cobalt source is cobalt nitrate hexahydrate, the first ligand is 2-methylimidazole, the second ligand is triphenylphosphine, and the third ligand is 2,5-diaminoterephthalic acid.

2. The method for preparing the photo-assisted asymmetric cobalt-based catalyst according to claim 1, characterized in that, The molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole and triphenylphosphine is 1:(1-2):(4-8):(1-2).

3. The method for preparing the photo-assisted asymmetric cobalt-based catalyst according to claim 2, characterized in that, The molar ratio of cobalt nitrate hexahydrate, 2,5-diaminoterephthalic acid, 2-methylimidazole and triphenylphosphine is 1:1:4:

2.

4. The method for preparing the photo-assisted asymmetric cobalt-based catalyst according to claim 1, characterized in that, The organic solvent is N,N-dimethylformamide; The ultrasonic dispersion treatment takes 20 to 30 minutes, the power is 200 to 300W, and the water temperature is controlled below 30℃. The temperature of the solvothermal reaction is 100–140°C, and the constant temperature is maintained for 15–25 hours. The washing process involves washing with anhydrous ethanol 3 to 5 times. The drying temperature is 50–70°C, and the drying time is 8–12 hours.

5. An application of a photo-assisted asymmetricly coordinated cobalt-based catalyst, comprising an asymmetricly coordinated cobalt-based cathode catalyst prepared by the method for preparing the photo-assisted asymmetricly coordinated cobalt-based catalyst according to any one of claims 1-4, characterized in that, The asymmetrically coordinated cobalt-based cathode catalyst was used as an air cathode catalyst in a metal-air battery under illumination.

6. The application of the photo-assisted asymmetric coordination cobalt-based catalyst according to claim 5, characterized in that, The metal-air battery is a zinc-air battery.

7. The application of the photo-assisted asymmetric coordination cobalt-based catalyst according to claim 6, characterized in that, The zinc-air battery includes a zinc negative electrode, an electrolyte, an air positive electrode, and a casing. The air positive electrode contains an asymmetrically coordinated cobalt-based positive electrode catalyst.

8. The application of the photo-assisted asymmetric coordination cobalt-based catalyst according to claim 7, characterized in that, The air cathode includes a gas diffusion layer substrate and a catalyst layer supported on the gas diffusion layer substrate. The catalyst layer contains an asymmetrically coordinated cobalt-based cathode catalyst material, a conductive agent, and a binder. The gas diffusion layer substrate is a hydrophobic carbon cloth that has been treated to be waterproof and breathable.

9. The application of the photo-assisted asymmetric coordination cobalt-based catalyst according to claim 8, characterized in that, The mass ratio of the asymmetrically coordinated cobalt-based cathode catalyst, conductive agent, and binder in the catalyst layer is (3-5):(0.5-1.5):(0.5-1.5).

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