An external field enhanced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material and application thereof

Abstract

The present application relates to the field of electrochemical materials, in particular to a kind of field enhancement type NiCo2S4@NiFe LDH / N-rGO heterostructure composite material and its application.The present application successfully synthesizes field enhancement type NiCo2S4@NiFe LDH / N-rGO nanoparticles as catalyst, which shows excellent performance in ORR, OER electrochemical performance and ZABs battery performance.Near-infrared light is used as an external field to further improve the performance of electrocatalytic materials.Through the auxiliary effect of external field, the dual-function performance of NiCo2S4@NiFe LDH / N-rGO nanoparticles is improved, and it shows superior performance in liquid phase and flexible devices.The present application provides a powerful platform for further improving the performance and flexibility of ZABs using photothermal effect, thereby laying a foundation for the future development of its catalytic process and device development.

Description

Technical Field

[0001] This invention relates to the field of electrochemical materials, specifically to an externally reinforced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material and its applications. Background Technology

[0002] The pursuit of green and renewable energy and the adoption of innovative energy storage technologies are of paramount strategic importance. Currently, lithium-ion batteries dominate the energy storage market, particularly in consumer applications. However, existing lithium-ion battery technologies face challenges due to insufficient energy density (50-260 Wh / kg). -1 High operating costs and potential safety issues have hindered the further development and utilization of zinc-air batteries. Therefore, developing next-generation energy conversion and storage systems is imperative. Zinc-air batteries (ZABs) possess exceptional theoretical energy density (1086 Wh / kg⁻¹). -1 Zinc-air batteries (ZABs) are promising candidates due to their strong safety and cost-effectiveness. Therefore, exploring ZABs as a next-generation energy conversion and storage solution holds significant research potential. However, the slow kinetics of ORR and OER in ZABs hinder their practical application.

[0003] This problem is further exacerbated by flexible equipment and extreme temperature conditions, thus highlighting the necessity for extensive research and development of electrocatalytic materials and their modification. The development and utilization of bifunctional electrocatalysts are crucial for solving the kinetic retardation problem in these reactions and thus advancing the practical application of ZABs. However, the development of bifunctional electrocatalysts has now reached a bottleneck. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide an external field reinforced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material and its application.

[0005] The technical solution adopted in this invention is as follows: an external field reinforced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material, the preparation process of which includes the following steps:

[0006] (1) Preparation of NiCo2S4 hollow spheres;

[0007] (2) Synthesis of NiCo2S4@NiFe LDH: Iron source, nickel source and alkali are dissolved in water, NiCo2S4 hollow spheres are added, and NiCo2S4@NiFe LDH is synthesized by hydrothermal method;

[0008] Then, NiCo2S4@NiFe LDH was combined with graphene to obtain NiCo2S4@NiFe LDH / N-rGO heterostructure composite material.

[0009] Preferably, in step (1), the preparation process of NiCo2S4 hollow spheres is as follows: CoSO4·7H2O is dispersed in a mixed solvent of EG and DMF, and gradually heated to 130-160℃ in an argon atmosphere. Then, thiourea is slowly added, and the reaction is carried out under reflux conditions for 4-6 hours. Ni(OAc)2·4H2O is dispersed in a mixed solvent of EG and DMF, and then the mixture is added dropwise to the reaction solution and reacted at 160-180℃ for 4-6 hours. The dark precipitate obtained by centrifugation is washed multiple times with deionized water and ethanol, and finally dried in a vacuum oven.

[0010] Preferably, the molar ratio of CoSO4·7H2O to Ni(OAc)2·4H2O is 2:1.

[0011] Preferably, in the mixed solvent of EG and DMF, the volume ratio of EG to DMF is 1:4.

[0012] Preferably, in step (2), the iron source is Fe(NO3)3·9H2O, the nickel source is Ni(NO3)2·6H2O, and the alkali is urea.

[0013] Preferably, in step (2), the reaction system is placed in a high-pressure reactor and heated in a continuous rotating oven for a reaction temperature of 110℃-130℃ and a reaction time of 8-12 hours.

[0014] Preferably, in step (3), NiCo2S4@NiFe LDH, graphene dispersed in ethanol, NH3·H2O and ethanol are added to a high-pressure reactor and reacted for 4-6 hours. After ultrasonic centrifugation and washing three times, the final product NiCo2S4@NiFe LDH / N-rGO is obtained.

[0015] The NiCo2S4@NiFe LDH / N-rGO heterostructure composite material described above is used as an electrocatalytic material, and the electrocatalytic material is enhanced under photothermal conditions.

[0016] The application of the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material for electrode fabrication, as described above.

[0017] The application of the above-mentioned field-enhanced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material in the preparation of zinc-air batteries, wherein the zinc-air battery is a liquid-phase zinc-air battery or a flexible zinc-air battery, and the zinc-air battery is enhanced under photothermal conditions.

[0018] A battery device includes an electrode prepared from the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material as described above, and a near-infrared light source, wherein the near-infrared light source irradiates the electrode prepared from the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material.

[0019] In this invention, NiCo2S4@NiFe LDH / N-rGO nanoparticles were successfully synthesized as catalysts, exhibiting excellent performance in ORR, OER electrochemical properties, and battery performance in ZABs. Near-infrared light was used to further enhance the performance of the electrocatalytic material. Through external field assistance, the bifunctional properties of NiCo2S4@NiFe LDH / N-rGO nanoparticles were improved, demonstrating superior performance in liquid phase and flexible devices. This research provides a powerful platform for further improving the performance and flexibility of ZABs using photothermal effects, thus laying the foundation for future advancements in their catalytic processes and device development. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0021] Figure 1 A schematic diagram of the synthesis of field-enhanced NiCo2S4@NiFe LDH / N-rGO;

[0022] Figure 2 In the figure, (a) is a TEM image of NiCo2S4@NiFe LDH / N-rGO; (b) is a HRTEM image of NiCo2S4 and NiFe LDH, with the figure showing the corresponding magnified HRTEM images.

[0023] Figure 3 In the image, (a) XRD pattern of NiCo2S4@NiFe LDH / N-rGO; (b) Raman spectrum of NiCo2S4@NiFe LDH / N-rGO; (cf) High-resolution XPS spectra of C1s, Fe 2p, Co 2p, and Ni 2p in NiCo2S4@NiFe LDH / N-rGO;

[0024] Figure 4In the image, (a) S2p and (b) N 1s in NiCo2S4@NiFe LDH / N-rGO; (c) XPS full spectrum of NiCo2S4@NiFe LDH / N-rGO composite material;

[0025] Figure 5 In the figure, (a) the polarization curve of ORR, (b) the CV of NiCo2S4@NiFe LDH / N-rGO in 0.1M KOH solution saturated with O2 and Ar, (c) the methanol resistance test of NiCo2S4@NiFe LDH / N-rGO and Pt / C, (d) the electron transfer number and H2O2 production of NiCo2S4@NiFe LDH / N-rGO in NiCo2S4@NiFe test, (e) the Koutecky-Levich plots corresponding to different potentials, (f) the percentage of H2O2 in NiCo2S4@NiFe LDHN-rGO electrode at different potentials measured by RRDE, (g) the RRDE LSV polarization curve of NiCo2S4@NiFe LDH / N-rGO in 0.1M KOH at 1600 rpm, (h) the polarization curve of OER, and (i) the Tafel slope curve;

[0026] Figure 6 In the image, (a) the UV-Vis absorption spectrum of NiCo2S4@NiFe LDH / N-rGO, and (b) the UV-Vis absorption spectrum of NiCo2S4@NiFe LDH / N-rGO and Electrolyte under 808 nm near-infrared irradiation in 1 mol L... -1 Temperature changes in KOH and electrolyte over time; (c) NiCo2S4@NiFe LDH / N-rGO electrode under 808nm laser irradiation in 1mol L... -1 Temperature changes in KOH electrolyte over time;

[0027] Figure 7 In the figure, the temperature of (a, b) NiCo2S4 / N-rGO and (c, d) NiFe LDH / N-rGO electrodes in the electrolyte changes with time (10s, 50s, 100s and 200s) under 808nm laser irradiation.

[0028] Figure 8 In the image, (a) polarization curves, and (b) various electrodes at 1 mol L⁻¹. -1 10mA cm of OER in KOH -2 The corresponding potentials are shown below, where NiCo2S4@NiFe LDH / N-rGO-Light represents the condition of the NiCo2S4@NiFe LDH / N-rGO electrode under illumination, (c) NiCo2S4@NiFe LDH / N-rGO at 10 mA cm⁻¹-2 Stability tests of the catalyst in OER under both illumination and non-illumination conditions, and RuO2, (d) polarization curves, (e) various electrodes at 0.1 mol L. -1 The corresponding E of ORR in KOH 1 / 2 and J L (f) NiCo2S4@NiFe LDH / N-rGO at a fixed potential of 0.6V RHE Stability tests of catalysts under light and no light were conducted, with Pt / C catalysts under no light.

[0029] Figure 9 In the figures, (a) CV curves of the electrode at different scan rates: NiCo2S4@NiFe LDH / N-rGO; (b) CV curves of the electrode at different scan rates under illumination: NiCo2S4@NiFe LDH / N-rGO; (c) corresponding double-layer capacitance data obtained from CV measurements at different scan rates; (d) corresponding double-layer capacitance data obtained from CV measurements at different scan rates under illumination; (e) bifunctional curves of NiCo2S4@NiFe LDH / N-rGO and NiCo2S4@NiFe LDH / N-rGO catalysts under illumination and without illumination; (f) NiCo2S4@NiFe LDH / N-rGO, Pt / C+RuO2 and other reported 0.1 mol L... -1 Comparison of the performance of bifunctional groups in potassium hydroxide bifunctional electrocatalysts;

[0030] Figure 10 In the figure, (a) schematic diagram of rechargeable ZAB, (b) open-circuit voltage, (c) charge-discharge polarization curve, (d) power density polarization curve, (e) discharge curves of ZABs based on NiCo2S4@NiFe LDH / N-rGO and Pt / C+RuO2 at different current densities, and (f) discharge curves at a current density of 10 mA cm⁻¹. -2 The specific capacity of ZAB at that time;

[0031] Figure 11 The current density of a zinc-air battery based on a NiCo2S4@NiFe LDH / N-rGO air cathode under 5 min charging and 5 min discharging conditions with and without illumination is (a) 10 mA cm⁻¹. -2 (b) 25mA cm -2 (c)50mA cm -2 Long-term constant current charge-discharge curves at various times;

[0032] Figure 12In the image, (a) is a digital image of an LED powered by two series-connected NiCo2S4@NiFe LDH / N-rGO cells; (b) shows an assembled zinc-air battery that can be used to power an LED strip.

[0033] Figure 13 In the figure, (a) the electrical conductivity of PANa hydrogel at 25℃ and (b) -40℃;

[0034] Figure 14 In the middle, (a) a scheme for photothermal assisted FZABs; (b) a scheme based on NiCo2S4@NiFe LDH / N-rGO and Pt / C+RuO2, at a current density of 1 mA cm⁻¹ -2 (c) Specific capacity of FZABs based on NiCo2S4@NiFe LDH / N-rGO and Pt / C+RuO2; (d) Charge-discharge polarization curves of FZABs based on NiCo2S4@NiFe LDH / N-rGO and Pt / C+RuO2.

[0035] Figure 15 In the middle, (a) the performance curves of NiCo2S4@NiFe LDH / N-rGO and Pt / C+RuO2 at 25℃ (1 mA cm⁻¹) -2 (b) Cyclic current density; NiCo2S4@NiFeLDH / N-rGO and Pt / C+RuO2 at 25 °C at 5 mA cm⁻¹ -2 Performance curves at cyclic current density; (c) NiCo2S4@NiFe LDH / N-rGO at 25℃ and 1 mA cm⁻¹ -2 Performance curves of NiCo2S4@NiFe LDH / N-rGO before and after cyclic current density illumination; (d) Performance of NiCo2S4@NiFe LDH / N-rGO at 25℃ under 5 mA cm⁻¹ current density illumination. -2 Performance curves before and after cyclic current density illumination; (e) at a current density of 2 mA cm⁻¹ -2 Cyclic curves of NiCo2S4@NiFe LDH / N-rGO under various mechanical deformation conditions;

[0036] Figure 16 Discharge curves and power density plots of FZABs at different temperatures;

[0037] Figure 17 In the figures, (a) open-circuit voltage diagrams of FZABs before and after illumination at 25°C and -40°C using NiCo2S4@NiFe LDH / N-rGO as the air cathode; (b) discharge and power density diagrams before and after illumination at 25°C and -40°C; and (c) current density of 1 mA cm⁻¹ based on NiCo2S4@NiFe LDH / N-rGO at 25°C and -40°C.-2 (d) Specific capacity of FZABs; Discharge curves of NiCo2S4@NiFe LDH / N-rGO under different current densities before and after illumination at 25℃ and -40℃;

[0038] Figure 18 NiCo2S4@NiFe LDH / N-rGO 1mA cm -2 Cyclic current density performance curves before and after illumination at -40℃. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] In the following embodiments, the pharmaceuticals and instruments used in this invention are shown in Tables 1 and 2.

[0041] Table 1. Main Chemicals Used

[0042]

[0043] Table 2 Main Instruments Used

[0044]

[0045] Example 1:

[0046] The preparation of NiCo2S4@NiFe LDH / N-rGO, the synthetic route is as follows: Figure 1 As shown. The specific steps are as follows:

[0047] (1) First, dissolve 2 mmol CoSO4·7H2O (0.562 g) in a solution containing 80 mL of V EG (16mL) / V DMF NiCo₂S₄ hollow spheres (NiCo₂S₄ HSs) were synthesized in a 250 mL three-necked flask containing a 1:4 volume ratio mixed solvent (64 mL). The mixture was gradually heated to 145 °C under argon atmosphere. Subsequently, a solution containing 10 mmol of thiourea (0.7612 g) was slowly added to the flask in 10 mL of the mixed solvent, and the mixture was kept under reflux for 5 hours. Then, 10 mL of a mixed solvent containing 1 mmol of Ni(OAc)₂·4H₂O (0.6167 g) was carefully added dropwise to the reaction solution, and the mixture was kept at 170 °C for 5 hours.

[0048] (2) The dark precipitate obtained by centrifugation was washed multiple times with deionized water and ethanol, and finally dried in a vacuum oven at 60°C for 12 hours.

[0049] (3) NiCo2S4@NiFe LDH nanocomposite material was synthesized by a single-step hydrothermal method. First, a solution containing 0.1346 g Fe(NO3)3·9H2O, 0.2 g urea, and 0.291 g Ni(NO3)2·6H2O was dissolved in 34 mL of distilled water and magnetically stirred for 10 minutes. Then, 0.219 g NiCo2S4 hollow spheres were added to the solution, and the mixture was stirred continuously for 1 hour. The resulting solution was transferred to a 50 mL autoclave and kept at 120 °C for 10 hours in a continuous rotating oven. The solid product was then washed with water and ethanol and dried.

[0050] (4) The synthesized NiCo2S4@NiFe LDH was then combined with N-rGO. For this purpose, 16 mg NiCo2S4@NiFeLDH, 8 mg graphene (dissolved in 1.8 mg / mL ethanol), 1 mL NH3·H2O, and 24 mL ethanol were added to a high-pressure reactor and reacted at 150 °C for 5 hours. The resulting suspension was subjected to ultrasonic centrifugation and washing three times to obtain the final product NiCo2S4@NiFe LDH / N-rGO.

[0051] The phase and morphology of NiCo2S4@NiFe LDH / N-rGO were characterized as follows:

[0052] (1) Transmission electron microscopy (TEM, HRTEM)

[0053] An appropriate amount of nanoparticle sample was taken, dispersed in anhydrous ethanol, and ultrasonically distributed. Subsequently, the dispersion was deposited on a microgrid support film, dried, and its morphology was observed under a transmission electron microscope (TEM) using a JEOL-2100F.

[0054] (2) X-ray diffractometer (XRD)

[0055] The nanoparticle samples on the sample holder were compressed with a cover glass and then placed in a Bruker D 8 instrument for analysis of their crystal structure by scanning from different angles.

[0056] (3) Raman characterization

[0057] The in-situ Raman test was performed by pressing a small piece of nanoparticle powder sample flat onto a silicon wafer using a Renishaw Invia Raman spectrometer. The excitation wavelength was set to 532 nm and the objective lens was 50×.

[0058] (4) X-ray photoelectron spectroscopy (XPS)

[0059] The chemical composition and valence state of the synthesized nanoparticle electrocatalyst were determined by X-ray photoelectron spectroscopy (XPS) under vacuum conditions.

[0060] (5) Ultraviolet UV

[0061] A certain amount of nanoparticle sample was dissolved in anhydrous ethanol and transferred to a cuvette (no more than 2 / 3 of the height) for subsequent analysis.

[0062] The test results are as follows:

[0063] The final target product, NiCo2S4@NiFe LDH / N-rGO, was obtained through solvothermal and hydrothermal methods. The overall morphology of the material was first determined using transmission electron microscopy. Figure 2 Transmission electron microscopy (TEM) images of NiCo2S4@NiFeLDH / N-rGO in graphene substrate a reveal clearly defined, uniformly sized, cactus-like hollow spheres, approximately 1.2 μm in diameter, composed of numerous interconnected nanowires and nanosheets. These nanowires, approximately 15 nm to 25 nm in diameter, extend outwards to form specific nanosheets and surfaces close to the NiCo2S4 substrate. The entire NiCo2S4@NiFeLDH structure is attached to the graphene substrate. Figure 2 b provides insights into the different sizes of different components in the heterostructure. Further observation using high-resolution transmission electron microscopy (HRTEM) revealed that the interplanar spacing of NiCo2S4 in the NiCo2S4@NiFe LDH / N-rGO heterostructure is 0.232 nm, which corresponds to the (311) crystal plane of NiCo2S4. The interplanar spacing of NiFe LDH is 0.246 nm, corresponding to the (101) crystal plane.

[0064] The synthesis of NiCo2S4@NiFe LDH / N-rGO was verified by X-ray diffraction (XRD), and detailed structural information was provided. The XRD patterns indicate that the nanocomposite catalyst consists of NiCo2S4 (JCPDS No. 20-0782) and NiFe LDH (JCPDS No. 40-0215), as shown in the image. Figure 3 As shown in Figure a, the peaks at 26.8°, 31.6°, 50.5°, and 55.3° correspond to the (220), (311), (511), and (440) planes of NiCo2S4, respectively, while the remaining peaks belong to NiFe LDH.

[16] .also, Figure 3 b gives the vibrational signals in the Raman spectrum; the Ni-O vibrational peak of NiCo2S4@NiFe LDH / N-rGO is at 476 cm⁻¹. -1 Co-O vibration signal at 550cm -1 The Fe-O signal peak is at 671 cm⁻¹ -1This confirmed the Ni-O, Co-O, and Fe-O vibrations in the NiCo2S4@NiFe LDH / N-rGO material. X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical state of the samples. The C 1s spectrum indicated the presence of C=C, with binding energies of 284.4-284.5 eV. The higher binding energy peaks observed in all samples are attributed to carbon oxides such as O=C or OC=O. Figure 3 c). In NiCo2S4@NiFe LDH, the Fe 2p XPS peaks are 724.5 eV and 715.9 eV, respectively, corresponding to Fe 2p 1 / 2 and Fe 2p 3 / 2 Fe of the signal 3+ The other peak is at 711.7 eV, corresponding to Fe 2p. 3 / 2 Fe of the signal 2+ state( Figure 3 d). The Co2p XPS spectrum shows four peaks at 780.4 / 795.9 eV and 782.2 / 797.6 eV, representing Co, respectively. 3+ State and Co 2+ state( Figure 3 e). The Ni 2p XPS spectrum of NiCo2S4@NiFe LDH shows two distinct peaks at 855.5 eV and 873.1 eV, corresponding to Ni 2p... 3 / 2 and Ni 2p 1 / 2 Ni 2+ state( Figure 3 f), Furthermore, the presence of satellite peaks with higher binding energies indicates the presence of Ni. 3+ Ni2p state 3 / 2 and Ni 2p 1 / 2 The binding energies of the orbitals are 857.6 eV and 879.0 eV, respectively. These results provide strong evidence for the successful synthesis of NiCo2S4@NiFe LDH / N-rGO.

[0065] For the S2p spectrum of NiCo2S4@NiFe LDH / N-rGO, the peaks at 163.0 eV and 161.6 eV are S 2- The peak at 168.0 eV originates from sulfate ( Figure 4 a). The high-resolution N1s spectrum can be further divided into three peaks centered at 397.78 eV (pyridine N), 398.91 eV (pyrrole N), and 399.79 eV (graphite N). Studies show that pyridine nitrogen and graphite nitrogen have good electron-accepting capabilities, which can promote oxygen adsorption and thus reduce the overpotential of the ORR. Pyridine N and pyrrole N can act as metal coordination (…). Figure 4 b). Figure 4c confirmed the presence of Ni, Co, Fe, S, O and N in the NiCo2S4@NiFe LDH / N-rGO composite material, and confirmed the successful synthesis of the NiCo2S4@NiFe LDH heterostructure.

[0066] Example 2:

[0067] The NiCo2S4@NiFe LDH / N-rGO working electrode is prepared by the following steps:

[0068] (1) Pretreatment of glassy carbon electrode:

[0069] Before polishing, clean the electrode surface thoroughly. Then, apply alumina polishing powder to 1μm, 0.3μm, and 0.05μm chamois sandpaper, respectively, and add a small amount of deionized water. Next, polish the electrode with sandpaper for about three minutes, using a figure-eight pattern or circular motions in one direction. After every three minutes of polishing, ultrasonically clean the electrode for about 15 seconds in a 1:1 mixture of anhydrous ethanol and ultrapure water, and then dry it with nitrogen gas.

[0070] (2) Preparation of the working electrode:

[0071] First, weigh 8 mg of the catalyst sample and 3 mg of Ketjen black into a 5 mL centrifuge tube. Then, add 1 mL of anhydrous ethanol to the centrifuge tube, followed by 40 μL of 5% Nafion solution. Place the tube in an ultrasonicator and sonicate for 40-60 minutes, shaking the tube while sonicating to facilitate dispersion. After sonication, use a pipette to evenly drop 20 μL of the catalyst ink onto the polished glassy carbon electrode surface. Before conducting relevant electrocatalytic performance tests, allow the electrode to air dry naturally or be dried in a 60°C oven.

[0072] In addition, a working electrode of a commercially available 20 wt% Pt / C and RuO2 catalyst was prepared using the same method as a comparative example.

[0073] Example 3:

[0074] The electrochemical performance of the NiCo2S4@NiFe LDH / N-rGO working electrode prepared in Example 2 and the working electrode of the commercial 20wt% Pt / C and RuO2 catalyst were tested. The test procedure is as follows:

[0075] Electrochemical performance tests of OER and ORR were performed using a conventional three-electrode system. The device has a geometric area of ​​0.196 cm². -2A catalyst-supported rotating disk electrode (RDE) was used as the working electrode, and a carbon rod as the counter electrode. ORR measurements used an Ag / AgCl electrode under saturated KCl conditions as the reference electrode, while OER measurements used a 1 mol L... -1 Hg / HgO electrode under KOH conditions. ORR was measured using linear sweep voltammetry (LSV) at 0.1 mol L⁻¹. -1 The scan rate in the KOH solution was 5 mV / s. -1 OER testing at 1 mol L -1 90% iR compensation was used in the KOH solution. The slope of the resulting curve was calculated according to the Tafel equation η = log(j / j0).

[0076] Electrochemical impedance spectroscopy (EIS) analysis was performed in the frequency range of 0.01–100 kHz, and the effective catalyst surface area (ECSA) was determined by measuring the double-layer capacitance (Cdl). Catalyst stability was assessed by iterative testing, and potential calibration was performed using the Nernst equation for a reversible hydrogen electrode (RHE). RHE =E Ag / AgCl +0.0591×pH+0.197, E RHE =E Hg / HgO +0.0591×pH+0.098-iR. RRDE measurements were performed using equations (1) and (2) to calculate the percentage of H2O2 and the number of transferred electrons (n):

[0077]

[0078] The current collection efficiency N of the Pt ring was determined to be 0.40 by reducing K3Fe[CN]6, where I d For disk current, I r It is the loop current.

[0079] To calculate the number of transferred electrons, this invention tested LSV curves at different speeds, and the number of transferred electrons n can be calculated using the following KL equation.

[0080]

[0081] B = 0.62nFC0D0 2 / 3 ν -1 / 6 Formula (4)

[0082] Equations (3) and (4) represent the measured current density (j) and kinetic density (j), respectively. K ) and limiting current density (j L The angular velocity of the RDE is represented by ω, the number of transferred electrons by n, and the Faraday constant F = 96485 C mol. -1C0 represents the volume concentration of O2 in the electrolyte (1.2 × 10⁻⁶). -3 mol L -1 D0 represents the diffusion coefficient of O2 in the electrolyte (1.2 × 10⁻⁶). -3 mol L -1 ),υ represents the kinematic viscosity of the electrolyte in 0.01 cm⁻¹ 2 s -1 .

[0083] The bifunctional performance of the obtained NiCo2S4@NiFe LDH / N-rGO electrocatalyst was tested to assess its electrochemical properties. These tests were performed in an oxygen-saturated potassium hydroxide electrolyte using a three-electrode system, with all potentials calibrated to a reversible hydrogen electrode (RHE) as a reference. The performance of this electrocatalyst was compared with that of a noble metal-based Pt / C+RuO2 benchmark catalyst.

[0084] At 0.1 mol L -1 The performance of ORR was evaluated in a saturated aqueous potassium hydroxide solution. Figure 5 In this study, the heterostructure NiCo2S4@NiFe LDH / N-rGO exhibits superior ORR activity, with an onset potential of 0.90 V and a half-Position potential (E0). 1 / 2 The value is 0.809V, which is superior to NiCo2S4 HSs / N-rGO(E) 1 / 2 =0.763V), FeNi LDH NWs / N-rGO(E 1 / 2 =0.695V), close to that of commercial Pt / C catalysts (E 1 / 2 The performance (V=0.834V) is shown. The incorporation of the hollow structure composed of NiFe LDH and NiCo2S4 plays an important role in promoting the ORR activity of the material, thereby greatly improving the ORR performance of NiCo2S4@NiFe LDH. This enhancement is attributed to the optimization of the electronic structure of the non-uniform interface after the addition of NiFe LDH to NiCo2S4. This optimization promotes the adsorption / desorption of intermediates during the ORR process, thus improving the overall catalytic performance. Figure 5 The cyclic voltammetry (CV) curves shown in Figure b clearly demonstrate a distinct cathode peak at 0.702 V in the presence of O2, compared to the case with N2. This observation strongly suggests that the reduction of NiCo2S4@NiFe LDH / N-rGO is primarily attributed to the catalytic effect of this material on O2. The methanol tolerance of NiCo2S4@NiFe LDH / N-rGO was assessed, as shown in Figure b. Figure 5 As shown in c, even with the introduction of methanol (3 mol L) into the electrolyte... -1The current density of NiCo2S4@NiFe LDH / N-rGO remained largely unaffected, while the current density of Pt / C decreased significantly. This highlights the superior methanol resistance of NiCo2S4@NiFe LDH / N-rGO, surpassing that of Pt / C. To elucidate the kinetics of ORR, Koutecky-Levich analysis was performed. The calculated number of transferred electrons in NiCo2S4@NiFe LDH / N-rGO is approximately 4.0 (…). Figure 5 d、 Figure 5 e). This is very consistent with the value of approximately 3.98 obtained from measurements using the rotating ring disk electrode (RRDE). Figure 5 f、 Figure 5 g). Furthermore, it is noteworthy that the yield of the catalytic product, hydrogen peroxide, is less than 1% ( Figure 5 f) This may be due to the direct generation of hydroxide ions and water during the oxygen reduction process of NiCo2S4@NiFe LDH / N-rGO. These results collectively indicate a significant synergistic effect between NiCo2S4 and NiFe LDH, which, combined with the well-defined nanostructure of NiCo2S4@NiFe LDH / N-rGO, ultimately enhances the activity of ORR.

[0085] In a standard linear sweep voltammetry (LSV) experiment, this invention measures the current density at a current density of 10 mA cm⁻¹. -2 (E j＝10 The potential at which the synthesized catalyst was tested was used to evaluate and compare the OER activity of the synthesized catalyst and the benchmark noble metal catalyst. Figure 5 The LSV curve shown in h indicates that NiCo2S4@NiFe LDH / N-rGO(E j＝10 =311mV), FeNi LDH / N-rGO(E j＝10 =320mV), even exceeding the widely used RuO2 (E j＝10 =312mV). Furthermore, in Figure 5 In the figure, the Tafel slopes of NiCo2S4@NiFeLDH / N-rGO (99.9 mV / decade) and RuO2 (154 mV / decade) show a significant contrast. NiCo2S4@NiFeLDH / N-rGO exhibits excellent OER characteristics, which can be attributed to its inherently high catalytic activity and unique layered hollow heterostructure. Incorporating NiFeLDH into NiCo2S4 optimizes the electronic structure of the non-uniform interface, enhances the adsorption / desorption of intermediates during the OER process, and thus improves catalytic performance.

[0086] Example 4:

[0087] The photothermal cell performance was tested on the NiCo2S4@NiFe LDH / N-rGO working electrode prepared in Example 2 and the working electrode of a commercial 20wt% Pt / C and RuO2 catalyst.

[0088] To investigate the photothermal assisted performance of the supported catalyst, the electrode was placed in a solution containing 0.1 mol L... -1 or 1 mol L -1 The KOH solution was irradiated with an 808 nm laser (MDL-H-808-5W) in an electrolytic cell. The electrode temperature was monitored using an infrared thermal imager (FLIR E50), and temperature-time curves were recorded until a stable temperature was reached. The irradiation power could range from 0 to 5.0 W / cm². -2 Within the range of adjustment, laser irradiation was performed for 2 minutes before each test, followed by the corresponding electrochemical test.

[0089] To demonstrate that the photothermal effect promotes the electrocatalytic reaction activity, the photothermal effect of NiCo2S4@NiFe LDH / N-rGO in the external field response was systematically investigated. The UV-VIS spectrum of the NiCo2S4@NiFe LDH / N-rGO solution was used as a basis for this investigation. Figure 6 a) Strong absorption was observed in the 700-850 nm range, indicating that NiCo2S4@NiFe LDH / N-rGO may convert light into heat under near-infrared (NIR) illumination. The photothermal effect of the material was investigated by irradiating 1.0 mol L... with 808 nm near-infrared light. -1 KOH solution adhered to the NiCo2S4@NiFe LDH / N-GO nanomaterial electrode. From Figure 6 b、 Figure 6 In study c, it was found that the electrode temperature rose rapidly, reaching 56.7℃ within 20 seconds of illumination and stabilizing at 83℃ after 65 seconds. In stark contrast, the electrolyte temperature remained almost constant. The NiCo2S4@NiFe LDH / N-GO nanomaterials can effectively convert 808nm laser energy into heat, demonstrating that near-infrared light heating of the electrode is localized. These findings provide strong support for improving ORR and OER performance. Notably, the final equilibrium temperature of the NiCo2S4@NiFe LDH / N-rGO electrode (87.0℃) is significantly higher than that of the NiCo2S4 (46.8℃) and FeNi LDH / N-rGO (53.5℃) electrodes. Figure 7This demonstrates that the electrocatalyst formed by combining NiCo2S4 with FeNiLDH / N-rGO exhibits a superior photothermal response. These results collectively reflect the ultrasensitive photothermal response of the NiCo2S4@NiFeLDH / N-rGO catalyst, paving the way for further improvements in its electrocatalytic performance by leveraging its profound photothermal effects.

[0090] To evaluate the enhancement of catalytic activity by the photothermal effect, the OER / ORR performance of the catalyst with and without 808 nm near-infrared irradiation was systematically evaluated by linear sweep voltammetry (LSV). Figure 8 The LSV curves of the OER shown in a and b indicate that the potential of the NiCo2S4@NiFe LDH / N-rGO electrode decreased significantly after exposure to NIR irradiation, from 1.492V to 1.456V. Figure 8 In the c-phase, NiCo2S4@NiFe LDH / N-rGO exhibited significantly more stable performance, with the current density decreasing by only 12.7% after maintaining a stable potential for 10 hours, a stark contrast to the commercial RuO2 catalyst (23.7%). Simultaneously, NiCo2S4@NiFe LDH / N-rGO possessed excellent bifunctional activity, with NiCo2S4 and N-rGO providing excellent active sites for the ORR reaction. The effect of photothermal effect on ORR performance was evaluated in 0.1M saturated potassium hydroxide aqueous solution. Figure 8 d、 Figure 8 In this study, the heterostructure NiCo2S4@NiFe LDH / N-rGO exhibits superior ORR activity, with an onset potential of 0.90 V and a half-wave potential (E0). 1 / 2 The half-wave potential (E) is 0.809V. Under illumination, the half-wave potential (E) is... 1 / 2 The voltage was further increased to 0.82V. Figure 8 In the first step, the current density of NiCo2S4@NiFe LDH / N-rGO exhibited significant stability, decreasing by only 6.8% from the initial value after 10 hours of ORR processing, a stark contrast to commercial ORR catalysts (which showed a significant decrease of 27.5%). This phenomenon can be attributed to the external NiFe LDH acting as a protective layer for the internal NiCo2S4, thus mitigating its corrosion and ensuring sustained electrochemical activity stability. Under photothermal effects, the material's current density showed even better stability, decreasing by only 6.12% from the initial value after 10 hours. This demonstrates that NiCo2S4@NiFe LDH / N-rGO possesses superior ORR performance aided by photothermal effects.

[0091] Theoretically, the improvement in catalytic activity is usually associated with a large exposed electrochemical active surface area (ECSA), and therefore can be evaluated based on the sample's double-layer capacitance (Cdl). Figure 9 The ad shows that the Cdl of NiCo2S4@NiFe LDH / N-rGO is 10 mF cm⁻¹. -2 Under near-infrared illumination, the Cdl further increases to 15 mF cm⁻¹. -2 This can be attributed to the increased temperature on the surface of the NiCo2S4@NiFe LDH / N-rGO electrode, which promotes the activation and effective collision of reactive species, resulting in more active sites being accessible to the electrolyte. Therefore, NiCo2S4@NiFe LDH / N-rGO exhibits excellent photothermal conversion performance, which enhances the electrocatalytic process of ORR / OER. As a bifunctional catalyst, NiCo2S4@NiFe LDH / N-rGO provides an excellent potential difference of 0.683V (ΔE = E) under non-light illumination. j＝10 -E 1 / 2 The value further decreases to only 0.636V under near-infrared irradiation. Figure 9 e) demonstrates that this bifunctional electrocatalyst possesses excellent reversible catalytic activity and outstanding stability. This achievement makes it one of the most promising catalysts among recently reported noble metal-free bifunctional electrocatalysts, such as... Figure 9 As shown in f.

[0092] Example 5:

[0093] The performance of rechargeable ZABs batteries was tested on the NiCo2S4@NiFe LDH / N-rGO working electrode prepared in Example 2 and the working electrode of a commercial 20wt% Pt / C and RuO2 catalyst.

[0094] Zinc-air batteries were tested using a CHI 760e electrochemical workstation. Polished zinc sheets were used as the anode, and carbon paper loaded with NiCo2S4@NiFe LDH / N-rGO was used as the cathode. The electrolyte consisted of 6 mol L... -1 KOH and 0.2 mol L -1 The composition was Zn(CH3COO)2. For photoluminescence testing, a small rectangular aperture of 0.5 cm x 0.8 cm was engraved on a zinc sheet, and the zinc sheet was directly exposed to the illuminated air cathode when the near-infrared lamp was turned on. For photothermal assisted ZABs testing, near-infrared light was applied for 2 minutes to achieve temperature equilibrium before evaluating battery performance. All measurements were performed at room temperature, with a catalyst loading of 1.0 mg / cm³ on the air electrode. -2 .

[0095] Given the impressive bifunctional activity and stability observed, this invention continues by assembling rechargeable ZABs to evaluate their feasibility in practical applications. These zinc plates are prepared using zinc sheets as the anode and a NiCo2S4@NiFe LDH / N-rGO catalyst as the air cathode, as shown below. Figure 10 As shown in a. From Figure 10 As can be seen from b, under NIR conditions, an open-circuit voltage (OCV) of 1.49V was achieved and remained stable for 10 hours, significantly exceeding the 1.439V of Pt / C and RuO2-based ZABs. Furthermore, across the entire current density range, NiCo2S4@NiFe LDH / N-rGO-ZABs exhibited a narrower charge / discharge voltage gap compared to Pt / C-RuO2-ZABs. Figure 10 c). Under NIR light irradiation, the charge-discharge voltage gap is further reduced. Figure 10 The polarization curves in d show that ZABs using NiCo2S4@NiFe LDH / N-rGO achieve an impressive 188 mW cm⁻¹. -2 It exceeds Pt / C+RuO2 (95.1 mW cm⁻¹) -2 Notably, the presence of light resulted in a significant enhancement of the maximum power density, reaching 206 mW / cm². -2 To evaluate the discharge rate capability, this invention monitors the discharge voltage over a current density range. For example... Figure 10 As shown in e, the control current is between 1 and 20 mA. -2 The discharge rate plateau changes rapidly between these plateaus, yet the assembled battery maintains a stable discharge. The results indicate that NiFe LDH / N-rGO, as an air cathode, exhibits a better discharge plateau than Pt / C-RuO2. Furthermore, the discharge rate stability of NiCo2S4@NiFe LDH / N-rGO is further enhanced with the aid of the photothermal effect. Figure 10 Experimental results show that ZAB based on NiCo2S4@NiFe LDH / N-rGO achieves a specific discharge capacity of 732 mA hg under no-light conditions. -1 It exceeds Pt / C-RuO2 (703 mA hg) -1 Furthermore, this invention observed that exposure to NIR light further enhanced the discharge capability, reaching 783 mA hg. -1 .

[0096] The long-term charge-discharge cycling of ZABs was evaluated, such as... Figure 11 As shown. At a current density of 10 mA cm⁻¹ -2 This lasted for 4010 cycles. Figure 11a) The introduction of the photothermal effect further improves the battery performance, enabling it to achieve 7437 cycles while maintaining an impressive round-trip efficiency of 51.25%. This exceptional stability can be attributed to localized heating of the cathode surface, which prevents potential electrolyte evaporation, leakage, and anode Faraday efficiency loss. When the current density increases to 25 mA cm⁻¹... -2 At that time, NiCo2S4@NiFe LDH / N-rGO exhibited consistent charge / discharge voltage behavior and round-trip efficiency over 3410 cycles. Figure 11 b). Subsequently, in cycling tests under NIR illumination, the NiCo2S4@NiFe LDH / N-rGO-based ZABs exhibited significant stability during 8285 cycles at high current densities, while maintaining a good initial round-trip efficiency of 51.48%. This highlights that the photothermal effect of the material at high current densities further enhances its rechargeable cycling stability. Figure 11 In c, the current level is raised to a higher 50mA cm. -2 Even under these conditions, ZABs still exhibited significant stability, maintaining cycling performance for approximately 255 cycles. Notably, the performance of ZABs tends to decline generally under these conditions, primarily due to accelerated zinc corrosion and simultaneous electrolyte deterioration. However, when exposed to NIR irradiation, the number of stable cycles significantly increased to 340 cycles. This observation highlights the ability of photothermal effects to improve the charge-discharge cycling stability of ZABs under high current density conditions.

[0097] Furthermore, the assembled ZABs can effectively power small light bulbs and LED strips. Figure 12 a, Figure 12 b). These applications highlight its excellent charge-discharge performance, consistent with the stability observed in ORR and OER tests.

[0098] Example 6:

[0099] The NiCo2S4@NiFe LDH / N-rGO working electrode prepared in Example 2 and the working electrode of a commercial 20wt% Pt / C and RuO2 catalyst were used to assemble and test a rechargeable flexible zinc-air battery.

[0100] Using a CHI 760e electrochemical workstation with a polished zinc sheet as the anode, a NiCo2S4@NiFe LDH / N-rGO catalyst was introduced into a fluid collector composed of carbon cloth and nickel foam as the air cathode. PANa hydrogel, serving as the solid electrolyte for all rechargeable FZABs, consisted of an air cathode and a zinc anode, with both sides of the hydrogel layer secured by breathable and waterproof tape. The FZABs were tested in a low-temperature stirred reaction bath (DHJF-4002) at a temperature range of -10°C to 25°C, similar to the procedure used for performance testing of rechargeable liquid zinc-air batteries. To prepare the PANa hydrogel, a sodium hydroxide solution (5 mL, 4 g) was added to an aqueous solution of acrylic acid (AA) monomer (7.2 mL AA added to 10 mL H2O), and the mixture was stirred at 0°C. The AA monomer was prepared by vacuum distillation. Using ammonium persulfate (APS, 0.11 g) as an initiator, N,N'-methylenebisacrylamide (MBAA) as a chemical crosslinking agent was added to the neutralization solution. The mixture was stirred at 0 °C for half an hour, and then O2 was removed with N2 gas. Free radical polymerization was carried out at 75 °C for 2 hours, and the mixture was completely dried at 50 °C. The mixture was then soaked in a mixture of KOH and Zn(Ac)2 for 12 hours. Finally, the filter paper was dried to prepare a polymer hydrogel as a rechargeable FZABs electrolyte for experimental use.

[0101] To address the growing demand for flexible electronic devices, this invention successfully fabricated flexible FZABs. Using NiCo2S4@NiFe LDH / N-rGO as the air cathode, PANa-based hydrogel as the solid electrolyte, and zinc foil as the anode, rechargeable FZABs were constructed. Figure 14 a) This invention evaluated the hydrogel's tolerance through conductivity tests at room temperature and low temperature, demonstrating its potential for practical applications in FZABs. Figure 13 a, Figure 13 As shown in Figure b, the PANa hydrogel exhibits good conductivity at 25°C, measured at 273.79 mS / cm. Impressively, it maintains a high conductivity of 72.07 mS / cm even at extremely low temperatures (-40°C). Hydrogels with excellent conductivity are an important prerequisite for fabricating high-performance flexible zinc-air batteries.

[0102] Figure 14 bd compares the power density, charge-discharge polarization curves, and specific capacity plots of NiCo2S4@NiFe LDH / N-rGO and Pt / C-RuO2 as air cathodes in FZABs. At room temperature, the peak power density reaches 111 mW / cm². -2 It is higher than the 53.18 mW cm⁻¹ of Pt / C-RuO₂. -2 and advanced FZABs (typically <50mW cm) -2 ()( Figure 14 b). Furthermore, compared to Pt / C-RuO2, FZABs using NiCo2S4@NiFe LDH / N-rGO exhibited a significantly lower charge voltage and a narrower charge / discharge voltage gap (b). Figure 14 c). Meanwhile, the FZABs battery based on NiCo2S4@NiFe LDH / N-rGO exhibited a stronger discharge capacity, with a specific capacity of 761.04 mA hg. -1 It exceeds the 696.15 mA hg of Pt / C-RuO2. -1 Specific capacity ( Figure 14 d).

[0103] To demonstrate the superior battery performance of NiCo2S4@NiFe LDH / N-rGO applied to FZABs, it was compared with Pt / C-RuO2. At room temperature (25℃), the current density was 1 mA cm⁻¹. -2 At that time, the NiCo2S4@NiFe LDH / N-rGO-FZABs had a discharge voltage of 1.2305V, a charge voltage of 1.9645V, and a round-trip efficiency of 62.64%. Even after 1300 cycles, the battery maintained a high round-trip efficiency of 51.72%, with the charge / discharge voltage increasing only slightly by 168mV. In contrast, the voltage gap of Pt / C-RuO2-FZABs widened significantly after 516 cycles. Figure 15 a). And at high current density (5 mA cm⁻¹) -2 Under these conditions, the NiCo2S4@NiFe LDH / N-rGO-FZABs battery successfully underwent 807 charge-discharge cycles. In contrast, a control experiment using Pt / C-RuO2-FZABs showed that with increasing voltage gap, only 113 stable charge-discharge cycles were achieved. Figure 15 b). To investigate the impact of photothermal effects on material properties in battery applications, [further investigation was conducted]. Figure 15 c. Figure 15 Experiment d. At a current density of 1 mA cm⁻¹ -2 After NIR illumination, the results showed that the initial round-trip efficiency was 57.43% after 1300 cycles. Figure 15 c). At high current density (5 mA cm⁻¹) -2 Under illumination, the NiCo2S4@NiFe LDH / N-rGO-FZABs battery successfully underwent 807 charge-discharge cycles. The round-trip efficiency increased from 52.4% to 67.4% before and after illumination. Figure 15 d). More practically, zinc-air batteries exhibit stable charge-discharge voltages under constant current conditions after various deformation and failure cycles (such as bending, twisting, folding, and recovery), demonstrating their excellent flexibility. Figure 15 e).

[0104] The NiCo2S4@NiFe LDH / N-rGO-FZABs battery maintains a stable open-circuit voltage of approximately 1.44V at room temperature. Figure 17 a) The open-circuit voltage (OCV) remained at 1.327 V at extremely low temperatures (-40°C). To verify the enhancing effect of photothermal heating on FZABs, an NIR source was added in this invention. The results showed that the open-circuit voltage could reach 1.489 V at room temperature and 1.363 V at extremely low temperatures (-40°C). This indicates that under light irradiation, the heat generated by photothermal heating not only offset the adverse effects of the low-temperature environment but also improved the catalytic activity. The power density of the flexible zinc-air battery at different temperatures is as follows: Figure 16 At room temperature, the peak power density reaches 111 mW / cm². -2 The power density decreases with decreasing temperature, reaching 93.15 mW / cm² at -10℃, -20℃, -30℃, and -40℃. -2 74.5mW cm -2 58.16mW cm -2 and 46.47mW cm -2 Under illumination, FZABs based on NiCo2S4@NiFe LDH / N-rGO can reach 151.7 mW cm⁻¹ at 25 °C. -2 The power density can reach 49.95 mW cm⁻¹ at -40℃. -2 power density ( Figure 17 b).

[0105] Compared to NIR-free conditions, FZABs based on NiCo2S4@NiFe LDH / N-rGO exhibit superior discharge capability under NIR light, with a specific capacity of 780.95 mA hg. -1 (25℃) and 738.23 mA hg -1 (-40℃)( Figure 17 c). Figure 17 d shows the control current (0.1mA cm). -2 up to 2mA cm -2 Despite rapid changes in current, the assembled battery exhibited stable discharge characteristics. As the current decreased, the voltage plateau recovered, indicating that NiCo2S4@NiFe LDH / N-rGO, as an air cathode, possesses good discharge rate performance. Under illumination, the discharge voltage increased from 1.369V to 1.381V (0.1mA cm⁻¹) at room temperature. -2 Increased to 2mAcm -2Meanwhile, at -40°C, the discharge voltage increased from 1.260V to 1.320V, confirming that light irradiation increased the voltage at both temperatures.

[0106] FZABs exhibit excellent long-term stability at low temperatures. At -40°C, the battery cycled 1300 times with an initial round-trip efficiency of 46.8%, and under NIR illumination, it cycled up to 3480 times with an initial round-trip efficiency of 58.9%, demonstrating that illumination improves the charge-discharge cycle stability of FZABs. Figure 18 ).

[0107] In summary, this invention successfully synthesized NiCo2S4@NiFe LDH / N-rGO and applied it to ZABs and FZABs, exhibiting excellent performance. The significant photothermal effect enables immediate and localized heating of the working electrode, surpassing traditional heating strategies without requiring additional energy input. Under photothermal stimulation, ΔE increased to 0.636 V, exceeding most previously reported non-noble metal-based catalysts. The resulting photothermally assisted ZABs achieved a power density of 206 mW / cm² at 25 °C. -2 and 151mW cm -2 The liquid-phase device exhibits a long-term cycling stability of 8285 cycles, while the solid-state device demonstrates a long-term cycling stability of 1300 cycles. Under photothermal effects, FZABs exhibit excellent power density at sub-zero temperatures (49.95 mW cm⁻¹ at -40°C). -2 It exhibits excellent charge-discharge cycling performance (3480 cycles at -40°C) and excellent mechanical flexibility. This research provides a powerful platform for further improving the performance and flexibility of ZABs, thus laying the foundation for future advancements in catalytic processes and equipment development.

[0108] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An externally reinforced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material, characterized in that, Its preparation process includes the following steps: (1) Preparation of NiCo2S4 hollow spheres: CoSO4·7 H2O was dispersed in a mixed solvent of EG and DMF, and gradually heated to 130-160℃ in an argon atmosphere. Then, thiourea was slowly added and the reaction was maintained under reflux for 4-6 hours. Ni(OAc)2·4 H2O was dispersed in a mixed solvent of EG and DMF, and then the mixture was added dropwise to the reaction solution and reacted at 160-180℃ for 4-6 hours. The dark precipitate obtained by centrifugation was washed multiple times with deionized water and ethanol, and finally dried in a vacuum oven. (2) Synthesis of NiCo2S4@NiFe LDH: Iron source, nickel source and alkali are dissolved in water, NiCo2S4 hollow spheres are added, transferred to high pressure vessel, and placed in continuous rolling oven for heating reaction. The reaction temperature is 110 ℃-130℃ and the reaction time is 8-12 hours. NiCo2S4@NiFe LDH is synthesized by hydrothermal method. (3) Then NiCo2S4@NiFe LDH is combined with graphene to obtain an external field reinforced NiCo2S4@NiFe LDH / N-rGO heterostructure composite material: NiCo2S4@NiFe LDH, graphene dispersed in ethanol, NH3·H2O and ethanol are added to a high-pressure reactor and reacted for 4-6 hours. After ultrasonic centrifugation and washing three times, the final product NiCo2S4@NiFeLDH / N-rGO is obtained.

2. The NiCo2S4@NiFe LDH / N-rGO heterostructure composite material according to claim 1, characterized in that: The molar ratio of CoSO4·7H2O and Ni(OAc)2·4H2O is 2:1; In the mixed solvent of EG and DMF, the volume ratio of EG to DMF is 1:

4.

3. The NiCo2S4@NiFe LDH / N-rGO heterostructure composite material according to claim 1, characterized in that: In step (2), the iron source is Fe(NO3)3·9 H2O, the nickel source is Ni(NO3)2·6 H2O, and the alkali is urea.

4. The application of the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material as described in any one of claims 1-3 as an electrocatalytic material, wherein the electrocatalytic material is enhanced under photothermal conditions.

5. Application of the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material as described in any one of claims 1-3 to prepare electrodes.

6. The application of the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material as described in any one of claims 1-3 to prepare zinc-air batteries, wherein the zinc-air battery is a liquid-phase zinc-air battery or a flexible zinc-air battery, and the zinc-air battery is enhanced under near-infrared light source irradiation.

7. A battery device comprising an electrode prepared from a NiCo2S4@NiFe LDH / N-rGO heterostructure composite material as described in any one of claims 1-3, characterized in that: It also includes a near-infrared light source, which irradiates the electrode prepared by the NiCo2S4@NiFe LDH / N-rGO heterostructure composite material.

Images