Co, S-MnSe / N-rGO composite material with photothermal effect and application of Co, S-MnSe / N-rGO composite material in zinc-air battery

Abstract

According to the invention, Co, S-MnSe / N-rGO with a nano structure is successfully synthesized through a hydrothermal method. Under the photo-thermal condition, delta E of Co, S-MnSe / N-rGO is reduced to 0.584 V, which exceeds that of the most advanced difunctional electrocatalyst (delta Egt; and 0.700 V). The liquid ZAB and the flexible ZAB which take Co and S-MnSe / N-rGO as catalysts both show the power density of 301.7 mW cm <-2 > and the power density of 140 mW cm <-2 > under photo-thermal assistance, and show good cycle stability. The flexible ZABs based on Co, S-MnSe / N-rGO show excellent overall performance under various conditions, especially in a thermal optical challenging environment, a deformation condition and a low-temperature environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic materials, and particularly relates to a Co,S-MnSe / N-rGO composite material with a photothermal effect and its application in a zinc-air battery. Background Art

[0002] The development of clean and renewable energy needs to address the unsustainability of fossil fuels, the discontinuity of wind and solar energy, and other negative impacts on the environment in modern society. Zinc-air batteries (ZABs), as the forefront of the next-generation energy storage solutions, have great prospects, mainly due to their unique characteristics, including impressive energy density, cost-effectiveness, and strong safety features. Flexible ZABs (FZABs), with their simple preparation process and excellent safety, make them strong competitors for the next-generation wearable devices. However, the current development of flexible zinc-air batteries (FZABs) still faces huge performance bottlenecks, especially low power density and poor adaptability to low-temperature environments. This mainly stems from the poor electrochemical performance of the cathode reaction, resulting in high polarization, low round-trip efficiency (below 65%), and limited cycle durability. In addition, the complexity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) mechanisms on the air cathode further exacerbates the inherently slow reaction kinetics, especially under adverse external conditions such as low temperature. Summary of the Invention

[0003] The purpose of the present invention is to overcome the drawbacks and deficiencies of the prior art, and to provide a Co,S-MnSe / N-rGO composite material with a photothermal effect and its application in a zinc-air battery.

[0004] The technical solution adopted by the present invention is as follows: A Co,S-MnSe / N-rGO composite material with a photothermal effect, which is formed by depositing cobalt and sulfur-doped manganese selenide nanoparticles on graphene oxide nanosheets.

[0005] Preferably, the cobalt and sulfur-doped manganese selenide nanoparticles are obtained by reacting Na2SeO3, MnCl2·4H2O, CoCl2·6H2O, and thiourea through a hydrothermal method.

[0006] Preferably, the hydrothermal reaction temperature is 160°C - 200°C.

[0007] Preferably, after the cobalt and sulfur-doped manganese selenide nanoparticles are mixed with GO, ammonia water is added, and heated at 130 - 170°C for 4 - 6 hours to obtain the Co,S-MnSe / N-rGO composite material.

[0008] Application of the Co,S-MnSe / N-rGO composite material as described above as an electrocatalytic material.

[0009] Application of the Co,S-MnSe / N-rGO composite material as described above in preparing an electrode material.

[0010] A bifunctional electrocatalytic material, comprising the Co,S-MnSe / N-rGO composite material as described above.

[0011] Application of the bifunctional electrocatalytic material as described above in preparing a zinc-air battery.

[0012] A zinc-air battery, comprising the electrocatalytic material as described above.

[0013] Preferably, the zinc-air battery is a liquid-phase or flexible zinc-air battery.

[0014] The beneficial effects of the present invention are as follows: The present invention successfully synthesized a nanostructured composite material, especially Co,S-MnSe / N-rGO, by a hydrothermal method. Specifically, cost-effective MnSe was used as an intermetallic catalyst, and then cobalt and sulfur doping were combined with nitrogen-doped graphene, which is responsive to the photothermal effect, ultimately improving the overall performance of the catalyst. This effort significantly improved the catalytic activity for OER and ORR with the help of the photothermal effect, thereby improving the overall performance of ZABs. Under photothermal conditions, the ΔE of Co,S-MnSe / N-rGO decreased to 0.584 V, exceeding that of the state-of-the-art bifunctional electrocatalysts (ΔE > 0.700 V). The liquid ZAB and flexible ZAB with Co,S-MnSe / N-rGO as the catalyst both exhibited power densities of 301.7 mW cm -2 and 140 mW cm -2 , and showed good cycle stability. The liquid ZAB had more than 5000 cycles, and the flexible ZAB had more than 1000 cycles. It is worth noting that the flexible ZABs based on Co,S-MnSe / N-rGO showed excellent overall performance in various situations, especially in thermo-optical challenging environments, deformation conditions, and low-temperature environments (e.g., more than 3000 cycles at -40 °C and a power density close to 120 mW cm -2 ) at -20 °C. The present invention achieved a significant progress in the development of non-precious metal-based nanostructured electrocatalyst composites, and has the potential to promote the progress of renewable energy conversion and storage technologies. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0016] Figure 1 Synthesis schematic diagram of Co,S-MnSe / N-rGO;

[0017] Figure 2 Among them, (a-c) Magnification diagrams of Co,S-MnSe / N-rGO composite materials at different sizes;

[0018] Figure 3 Among them, (a) XPS full spectrum of Co,S-MnSe / N-rGO nanocomposite, (b) Mn 2p spectrum, (c) Co 2p spectrum, (d) Se 3d spectrum;

[0019] Figure 4 Among them, (a) XRD pattern of Co,S-MnSe / N-rGO nanocomposite, (b-c) Raman spectra of Co,S-MnSe / N-rGO nanocomposite;

[0020] Figure 5 Among them, (a) ORR polarization curve of Co,S-MnSe / N-rGO nanocomposite, (b) LSV curves of ORR of Co,S-MnSe / N-rGO at different rotation speeds, (c) RRDE LSV polarization curve of Co,S-MnSe / N-rGO nanocomposite at 1600 rpm in 0.1 M KOH, (d) LSV curves of ORR of Co,S-MnSe / N-rGO at different rotation speeds, (e) corresponding Koutecky-Levich diagrams at different potentials, (f) OER polarization curve of Co,S-MnSe / N-rGO nanocomposite;

[0021] Figure 6 Among them, (a) UV-visible absorption spectrum of Co,S-MnSe / N-rGO, (b) Temperature change of Co,S-MnSe / N-rGO electrode with time in 1 M KOH electrolyte under 808 nm laser irradiation, (c) Temperature change of Co,S-MnSe / N-rGO and Electrolyte with time in 1 M KOH and electrolyte under 808 nm near-infrared irradiation;

[0022] Figure 7Among them, (a) polarization curve, (b) corresponding overpotentials of various electrodes for OER in 1 M KOH at 10 mA cm -2 −2, where Co,S-MnSe / N-rGO-Light represents the Co,S-MnSe / N-rGO electrode under light illumination, (c) stability test of the catalyst in Co,S-MnSe / N-rGO for OER with and without light illumination at 10 mA cm -2 −2, and RuO2, (d) polarization curve, (e) corresponding E 1 / 2 and J L of various electrodes for ORR in 0.1 M KOH, (f) stability test of the catalyst in Co,S-MnSe / N-rGO at a fixed potential of 0.6 V vs. RHE, with and without light illumination, and Pt / C without light illumination;

[0023] Figure 8 Among them, (a) bifunctional curves of the catalyst with and without light illumination, (b) ΔE of the electrocatalyst;

[0024] Figure 9 Among them, (a) schematic diagram of the photothermal-assisted liquid ZAB. (b) Open-circuit voltage diagrams of liquid ZABs with Co,S-MnSe / N-rGO and Pt / C+RuO2 (mass ratio 1:1) as air cathodes at 25 °C, respectively. (c) Power density curves of liquid ZABs with materials such as Co,S-MnSe / N-rGO and Pt / C+RuO2 under light and dark conditions at 25 °C and (d) corresponding power density curves at 25 °C. (e) Discharge curves of ZABs prepared with Co,S-MnSe / N-rGO and Pt / C+RuO2 at different current densities. Comparative diagram of the bifunctional performance of the photothermal-assisted Co,S-MnSe / N-rGO-based liquid ZAB with other reported cathodes (blue dots) at 25 °C. (f) Specific capacities of Co,S-MnSe / N-rGO and Pt / C+RuO2 at 25 °C;

[0025] Figure 10 Among them, (a) cyclic tests of the liquid-phase ZAB based on Co,S-MnSe / N-rGO at a current density of 10 mA cm -2 −2 with (without) light illumination and Pt / C+RuO2, and (b) cyclic test diagrams at a current density of 10 mA cm -2 −2;

[0026] Figure 11Among them, (a) Schematic diagram of FZAB under photothermal assistance, (b) Open circuit voltage diagram of Co,S-MnSe / N-rGO at different temperatures, (c) Discharge and power density curves, (d) Charge-discharge polarization curves, (e) Power density at different temperatures, (f) Specific capacity test of FZAB of Co,S-MnSe / N-rGO and Pt / C+RuO2 at different temperatures;

[0027] Figure 12 Tests with light and without light at different temperatures: (a) Cycle curves, (b) Cycle curves of FZAB under various mechanical deformations. Specific implementation mode

[0028] 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.

[0029] Example 1 Preparation of Co,S-MnSe / N-rGO composite material:

[0030] As Figure 1 shown, first dissolve 1 mmol of Na2SeO3, 0.1 mmol of CoCl2·6H2O, 0.2 mmol of CH4N2S and 1 mmol of MnCl2·4H2O in 8 mL of deionized water and stir vigorously for 20 minutes. Then, add 2 mL of N2H4·H2O and continue stirring for 20 minutes. Then transfer the obtained mixture to a 50 mL high-pressure reactor, keep it at 180 °C for 24 hours, and let it cool naturally. Then, the obtained black product is centrifuged and washed several times with a mixture of ethanol and deionized water, and then dried in a vacuum oven at 60

[0031] °C. Subsequently, the dried product is mixed with graphene oxide (GO) at a ratio of 1:2. Introduce 2 mL of ammonia water into the high-pressure reactor and heat it at 150 °C for 5 hours. After this reaction, the obtained black product is centrifuged, washed several times with an ethanol-deionized water mixture, and finally dried in a vacuum oven at 60

[0032] °C to obtain the Co,S-MnSe / N-rGO composite material.

[0033] In this example, the Co,S-MnSe / N-rGO composite material was synthesized by a simple hydrothermal method. Na2SeO3 and MnCl2·4H2O were used as the basic components of manganese selenide, and at the same time, the transition metal Co was introduced as a bimetallic catalyst. To achieve the doping of Co and S, CoCl2·6H2O and a trace amount of thiourea were added. The addition of GO helped to form the Co,S-MnSe / N-rGO composite material through high-temperature pyrolysis, thereby generating a nanostructure rich in defects.

[0034] Morphological analysis by transmission electron microscopy (TEM) showed the presence of irregularly shaped MnSe nanoparticles (NPs) in the range of 20 - 50 nm, as Figure 2 (a)-(c) shown. Uniform deposition of cobalt and sulfur-doped manganese selenide nanoparticles (Co,S-doped MnSe NPs) on graphene oxide nanosheets was observed. After closer examination of the particle surfaces in the sample, it was evident that they contained a large number of small nanoparticles in the range of 30 to 60 nm. Figure 2 (a) shows the TEM image of Co,S-MnSe / N-rGO, revealing the distribution of these nanoparticles at the nanoscale.

[0035] To elucidate the elemental composition and chemical state of the hybrid nanomaterials, X-ray photoelectron spectroscopy (XPS) measurements were carried out, revealing the presence of carbon, nitrogen, oxygen, manganese, and selenium elements in the Co,S-MnSe / N-rGO nanocomposite, as Figure 3 (a) shown. Figure 3 The peaks at 638.8 eV and 652.6 eV in (b) belong to the Mn 2p3 / 2 and 2p1 / 2 states, respectively. In addition, the peak persistently fixed at 645.7 eV is attributed to the chemical bond of Mn-O, which is strong evidence of the strong interaction between Mn and n-doped carbon. In addition, the XPS peaks at 779.41 and 795.72 eV can be attributed to Co 3+ presence, while the XPS peaks at 783.85 eV and 778.52 eV are characteristic of Co 2+ ( Figure 3 (c)). These findings indicate the coexistence of Co 2+ and Co 3+ oxidation states. In the Se 3d spectrum, the two prominent peaks observed at 53 eV and 54.6 eV can be determined to be Se 3d 5 / 2 and Se 3d3 / 2, respectively ( Figure 3 (d)). In contrast, the broader feature appearing at 57.8 eV indicates the presence of SeOx species. This observation suggests a certain degree of oxidation on the surface of the Co,S-MnSe / N-rGO material.

[0036] The crystal structure of the as-prepared Co,S-doped MnSe / N-rGO nanocomposite was evaluated by X-ray diffraction (XRD), as Figure 4(as shown in (a)). It is worth noting that diffraction peaks were observed at 33°, 47°, 58° and 78°, corresponding to different (200), (220), (222) and (420) of the MnSe crystal plane, in line with JCPDS card number 11 - 0683. The existence of the hybrid nanomaterial composed of nitrogen-doped graphene oxide (N-rGO) and MnSe can be further confirmed by Raman spectroscopy ( Figure 4 (b) and (c)). The vibration signal of the Mn - Se bond at 660 cm -1 was observed, as well as the D band at 2693.3 cm -1 and the G band at 2588.73 cm -1 , which confirmed the coexistence of MnSe and graphene in the hybrid material catalyst [106,107] . The intensity ratio of the D band and G band of the Co,S-doped MnSe / N-rGO sample (ID / IG ∼ 1.08) was significantly higher than that of GO (ID / IG ∼ 0.88), providing clear evidence for the success of Co,S-doped MnSe / N-rGO.

[0037] Synthesis of Comparative Example 1 MnSe / N-rGO:

[0038] Dissolve 1 mmol of Na2SeO3 and 1 mmol of MnCl2·4H2O in 8 mL of deionized water to prepare a solution, and then stir the mixture evenly for 20 minutes. Subsequently, add 2 mL of N2H4·H2O and continue stirring for 20 minutes. Transfer the resulting solution to a 50 mL high-pressure reactor and keep it at 180 °C for 24 hours. Then, the obtained black product was centrifuged and washed several times with a mixture of ethanol and deionized water, and then dried in a vacuum oven at 60 °C. Subsequently, the dried product was mixed with GO at a ratio of 1:2. Introduce 2 mL of ammonia water into the high-pressure reactor and heat it at 150 °C for 5 hours. Subsequently, let the mixture cool naturally. The obtained black product was separated by centrifugation and washed several times with ethanol and deionized water solution. Finally, the product was dried in a vacuum oven at 60 °C until a consistent dry state was reached.

[0039] Preparation and testing of the Co,S-MnSe / N-rGO zinc-air battery in Example 2:

[0040] (1) Pretreatment of the glassy carbon electrode

[0041] First, wipe the electrode surface clean with absolute ethanol. Then, start polishing with 1 μm, 0.3 μm, and 0.05 μm deerskin sandpaper with alumina polishing powder as the polishing agent for 3 minutes. When polishing, draw an "8" shape or circle in one direction, and ensure that the electrode is in a horizontal state during the polishing process without tilting. After each polishing cycle, ultrasonic for about 15 s in a mixed solution of absolute ethanol and ultrapure water with a ratio of 1:1. Finally, after cleaning, blow-dry the electrode with dry nitrogen gas.

[0042] (2) Preparation of the working electrode

[0043] The working electrode is the electrode for preparing the supported catalytic material. First, weigh 4 mg of the catalyst sample and 2 mg of the conductive agent Ketjen black and pour them into a 1 mL centrifuge tube. Then, add 1000 μL of absolute ethanol to the centrifuge tube, and then add 35 μL of 5% Nafion solution to the centrifuge tube. Then, perform ultrasonic dispersion in an ultrasonic machine for 1 h, shaking the centrifuge tube while ultrasonicating to make the sample evenly dispersed. After the ultrasonic treatment is completed, use a pipette to suck 20 μL of the catalyst ink and evenly drop it on the surface of the polished glassy carbon electrode. Wait for it to dry naturally or dry it in an oven at 60 °C, and then perform relevant electrocatalytic performance tests. At the same time, prepare commercial 20% wt Pt / C and RuO2 catalyst inks by the same method and drop them on the surface of the working electrode.

[0044] (3) Electrochemical performance test

[0045] Test and evaluate the electrochemical OER and ORR performance of the catalyst under a traditional three-electrode system. The working electrode is a rotating disk electrode (RDE) loaded with the catalyst, and its geometric area is (0.196 cm -2 ), a carbon rod is used as the counter electrode, and an Ag / AgCl (saturated with KCl) or Hg / HgO (1 M KOH) electrode is used as the reference electrode for ORR and OER, respectively. Perform linear sweep voltammetry (LSV) test for ORR in 0.1 M KOH with a test scan rate of 5 mV s -1 , and perform OER test in 1 M KOH with 90% iR compensation. The curve slope is calculated according to the Tafel equation η = blog(j / j0):

[0046] Electrochemical impedance spectroscopy (EIS) analysis was carried out in the frequency range of 0.01 to 100 k. The ECSA was determined by the double-layer capacitance (Cdl). The stability of the catalyst was obtained through i-t tests. The potential was calibrated using the Nernst equation with a reversible hydrogen electrode (RHE): ERHE = EAg / AgCl + 0.0591×pH + 0.197, ERHE = EHg / HgO + 0.0591×pH + 0.098 - iR. RRDE measurements were based on the following formulas (1) and (2) for calculating the percentage of H2O2 and the number of transferred electrons (n):

[0047]

[0048] where I d is the disk current, I r is the ring current, and N is the current collection efficiency of the Pt ring, which was determined to be 0.40 by the reduction of K3Fe[CN]6.

[0049] The number of transferred electrons can be calculated by testing the LSV curves at different rotation speeds. The number of electron transfers n was calculated according to the following K-L equation:

[0050]

[0051] B = 0.62nFC0D0 23 v -16 Formula (4)

[0052] In the above formulas (3) and (4), j represents the measured current density, jK represents the kinetic density, and jL represents the limiting current density. The angular velocity of the RDE is represented by ω, n represents the number of transferred electrons, the Faraday constant F is 96485 C mol -1 , C0 represents the volume concentration of O2 in the electrolyte (1.2×10-3 mol L -1 ), D0 represents the diffusion coefficient of O2 in the electrolyte (1.9×10-5 cm 2 s -1 ), υ represents the kinematic viscosity of the electrolyte, which is 0.01 cm 2 s -1 .

[0053] As Figure 5 (a) shows, compared with MnSe / N-rGO (E 1 / 2 = 0.79 V), Co,S-MnSe / N-rGO exhibits stronger ORR activity, with an E 1 / 2 value of 0.833 V, and its performance is close to that of the commercial Pt / C catalyst (E 1 / 2 = 0.86 V). To further evaluate the ORR activity, Koutecky-Levich analysis at different rotation speeds was carried out (Figure 5 (b)), the calculated electron transfer number of Co,S-MnSe / N-rGO is close to 4.0( Figure 5 (c)). This is consistent with the measured value (∼3.9) by the rotating ring-disk electrode (RRDE) Figure 5 (d)) method. This indicates that on the Co,S-MnSe / N-rGO composite nanomaterial, the 4e− reduction pathway dominates the entire ORR catalytic process. Figure 5 (e) These results confirm that Co,S-MnSe / N-rGO follows a four-electron transfer process during ORR, with a hydrogen peroxide yield of less than 6%. In addition, the nitrogen-doped graphene composite material co-doped with cobalt and sulfur in manganese selenide, as Figure 5 (f) shown, has better oxygen evolution reaction (OER) performance (E j＝10 = 1.563 V) than the manganese selenide compound of nitrogen-doped graphene (E j＝10 = 1.645 V), and even exceeds the performance of RuO2 (E j＝10 = 1.571 V).

[0054] (4) Photothermal effect cell performance test

[0055] In addition, to study the photothermal assistance performance, the electrode loaded with the catalyst was irradiated with an 808 nm laser (MDL-H-808-5W) in an electrolytic cell containing 0.1 or 1 M KOH solution. The temperature of the electrode was tracked with an infrared thermal imaging camera (FLIR E50), and the temperature-time curve was observed through the measured data until the electrode reached a stable temperature. The irradiation power could be adjusted in the range of 0 to 5.0 W cm -2 . Before each test, the laser was irradiated for two minutes and then the relevant electrochemical tests were carried out.

[0056] As Figure 6 (a) shown, the diffuse reflectance ultraviolet-near-infrared absorption spectrum of Co,S-MnSe / N-rGO shows an obvious broad optical absorption range up to 850 nm. This finding emphasizes its ability to effectively absorb radiation in a wide range of near-infrared spectra to generate heat, which is the most important characteristic in photothermal applications. It is worth noting that during the entire illumination process, the temperature of the surrounding electrolyte remained almost unchanged, staying at about 20 °C, as Figure 6 (b)-(c) shown. This observation strongly indicates that the generated heat is mainly concentrated on the surface of the Co,S-MnSe / N-rGO electrode. These results together demonstrate that the Co,S-MnSe / N-rGO catalyst has a special ultrasensitive photothermal response, which provides an opportunity to effectively utilize its profound photothermal effect to significantly improve its electrocatalytic performance.

[0057] To study the influence of external photothermal assistance on OER / ORR, the performance of OER / ORR under near-infrared irradiation and without irradiation was investigated ( Figure 7 (a), (d)). It can be clearly seen from Figure 7 (a) that, notably, the overpotential of the Co,S-MnSe / N-rGO composite material is reduced compared to MnSe / N-rGO. This observation strongly indicates that the number of active sites for OER is effectively increased by doping with cobalt and sulfur. Therefore, the increase in active sites improves the overall activity of OER while resulting in a decrease in the required overpotential. As can be seen from Figure 7 (b), under near-infrared irradiation, the electrocatalytic performance of Co,S-MnSe / N-rGO is further enhanced and the overpotential is significantly reduced. When Co,S-MnSe / N-rGO is exposed to near-infrared radiation, the OER potential drops significantly from to 1.47 V, intuitively confirming a substantial reduction in OER, indicating that photothermal assistance improves OER activity and accelerates charge transfer. Durability is an important indicator for evaluating the actual performance of electrocatalysts. Notably, even after 16 hours with light (without light), Co,S-MnSe / N-rGO can still maintain approximately 90.1% (84.3%) of its initial OER performance, and this level of stability exceeds that of commercial RuO2, which only retains 47% of its initial performance within the same duration, as shown in Figure 7 (c). Co,S-MnSe / N-rGO has excellent bifunctional activity, with the optimal activity when doped with Co,S, which may mainly be attributed to the Jahn-Teller bending of Mn IV species as the active site for the ORR reaction. Notably, the ORR performance of Co,S-MnSe / N-rGO is significantly enhanced under near-infrared radiation, resulting in an increase in the overpotential from 0.833 V to 0.886 V, as shown in Figure 7 (d). The J L of Co,S-MnSe / N-rGO under light is much higher than that of Pt / C, and its E 1 / 2 has a negative shift of only 0.041 V relative to Pt / C ( Figure 7 (e)). In addition, Co,S-MnSe / N-rGO still retains 92.2% (88.3%) of its initial ORR performance after 16 hours under light (without light) conditions, showing excellent stability. This stability exceeds that of commercial Pt / C, which retains 73% of its performance, as shown in Figure 7 (f). It shows that the Co,S-MnSe / N-rGO nanocomposite has more superior ORR performance under the photothermal effect.

[0058] (5) Performance test of rechargeable liquid zinc-air battery

[0059] The zinc-air battery tests were carried out on a CHI 760e electrochemical workstation. The zinc sheet polished with sandpaper was used as the anode, and the carbon paper loaded with Co,S-MnSe / N-rGO was used as the air cathode. 6M KOH and 0.2M Zn(CH3COO)2 were used as the electrolyte. A small rectangular hole with an area of (0.5 cm * 0.8 cm) was scratched on the zinc sheet for the light irradiation test so that when the NIR lamp was turned on, it could directly irradiate the air cathode. Before the performance test of the cell under the photothermal effect, the ZAB was irradiated with NIR light for two minutes to achieve temperature equilibrium. In addition, all measurements were carried out at room temperature, and the catalyst loading on the air electrode was 1.0 mg cm -2 . The performance test was carried out by linear sweep voltammetry at a scan rate of 5 mV s -1 . The cyclic test was carried out at a current density of 10 mA cm -1 with a cycle of every 20 min.

[0060] Generally speaking, ΔE is an important indicator for evaluating bifunctional activity. The smaller ΔE is, the better the performance of the material as a reversible oxygen electrode. As can be seen from Figure 8 (a), without the irradiation of near-infrared light, the ΔE of Co,S-MnSe / N-rGO is 0.73 V. Under the irradiation of near-infrared light, ΔE decreases to 0.584 V. Among the manganese-based oxides, its bifunctional performance is relatively excellent. As can also be seen from Figure 8 (b), compared with most of the materials reported recently, the photothermal-assisted Co,S-MnSe / N-rGO material shows superior electrocatalytic performance.

[0061] Given the excellent bifunctional catalytic activity of Co,S-MnSe / N-rGO in OER and ORR, Co,S-MnSe / N-rGO was used as the air cathode of a two-electrode rechargeable liquid ZABs device. The electrochemical performance of this device was further evaluated. Co,S-MnSe / N-rGO was used as the air cathode, the polished zinc sheet was used as the anode, and 6M aqueous potassium hydroxide was used as the electrolyte, as shown in Figure 9 (a). As shown in Figure 9 (b), the open-circuit voltage of the Co,S-MnSe / N-rGO liquid ZABs is 1.402 V, which is very close to the performance of the battery using the Pt / C + RuO2 mixed catalyst (open-circuit voltage of 1.400 V). Impressively, it has the ability to power an LED bulb. In addition, as shown in Figure 9 (c)-(d), the Co,S-MnSe / N-rGO liquid ZABs has a lower charging voltage and a narrower charge-discharge voltage gap, thus obtaining 235.2 mW cm -2Ultra-high power density. Under the action of photothermal enhancement, the charge-discharge gap of Co,S-MnSe / N-rGO liquid ZABs is further reduced, and the power density is significantly increased to 301.7 mW cm -2 . This power density exceeds that of liquid ZABs assembled with Pt / C+RuO2 (90 mW cm -2 ), and even outperforms other materials. Compared with Pt / C+RuO2-based ZABs, Co,S-MnSe / N-rGO ZABs exhibit significantly higher discharge platforms at different current densities, and this discharge platform is further enhanced under near-infrared illumination, as shown in Figure 9 (e). In addition, Figure 9 (f) shows the electrostatic current discharge curve, where the discharge current density is normalized to the amount of zinc consumed. The ZABs containing Co,S-MnSe / N-rGO have little change in the discharge voltage before zinc consumption, and the specific capacity is 782.7 mA h g -1 , which is better than that of ZABs containing Pt / C+RuO2. When irradiated by near-infrared light, the ZABs loaded with Co,S-MnSe / N-rGO exhibit the smallest change in discharge voltage and reach a higher specific capacity of 803.3 mA h g -1 .

[0062] Through long-term constant current cycling tests, the durability of Co,S-MnSe / N-rGO electrocatalysts in rechargeable ZABs was investigated. Under the condition of 10 mA cm -2 , ZAB-Co,S-MnSe / N-rGO all showed good charge-discharge cycle stability under illumination, which was manifested by no obvious attenuation within 600 cycles, and was more stable compared with Pt / C+RuO2-based ZABs (400 cycles) ( Figure 10 (a)). More satisfactorily, with the assistance of near-infrared light, the round-trip efficiency of Co,S-MnSe / N-rGO-based ZABs increased from 52.4% to 55%. In contrast, the liquid-phase zinc-air battery of Pt / C+RuO2 ZABs was damaged after less than 500 cycles. Under the condition of 25 mA cm -2 , it could also stably cycle up to 3000 times ( Figure 10 (b)). Generally speaking, it has excellent round-trip efficiency performance and outstanding durability with the help of the photothermal effect.

[0063] (6) Assembly and performance testing of rechargeable flexible zinc-air batteries

[0064] The polished zinc sheet after being sanded with sandpaper is used as the anode, and the Co,S-MnSe / N-rGO catalyst is dropped onto the current collector composed of carbon cloth and nickel foam as the air cathode. The CHI 760e electrochemical workstation and Na-PAA hydrogel are used as the solid electrolyte. All solid-state flexible rechargeable ZABs consist of an air cathode and a zinc anode, with a hydrogel layer in the middle to form a sandwich-type flexible rechargeable zinc-air battery, and the hydrogel layer is fixed by a breathable and waterproof tape. The F-ZAB is tested at temperatures from 25 °C to -40 °C, and the test is carried out in a low-temperature stirring reaction bath (DHJF-4002), and its test method is the same as that for the performance test of rechargeable liquid-phase zinc-air batteries.

[0065] The following are the preparation steps of the Na-PAA hydrogel: The sodium hydroxide solution (5 mL, 4 g) is dropped into the aqueous solution of acrylic acid monomer at 0 °C (7.2 mL of AA is added to 10 mL of H2O). The AA monomer is obtained by vacuum distillation in advance. The initiator is ammonium persulfate (APS) (0.11 g), and the crosslinking agent is 12 mg of N,N'-methylenebisacrylamide (MBAA), and they are added to the neutralized solution, while stirring at 0 °C for 30 min. Then N2 is introduced into the mixed solution to remove O2. Then free radical polymerization is initiated at 75 °C for 2 h. Finally, it is completely dried at 50 °C, and then soaked in a mixed solution (100 mL) of 6 M KOH and 0.2 M Zn(Ac)2 for 12 h. Finally, the polymer is dried in filter paper, and the obtained polymer is the hydrogel as the electrolyte for the experimental rechargeable F-ZABs.

[0066] The performance test is carried out by linear sweep voltammetry at a scan rate of 5 mV s -1 The cyclic test is carried out at a current density of 1 mAcm -2 with each cycle being 6 min.

[0067] With the continuous progress of flexible electronic devices and the increasing demand for flexible electronic products, rechargeable FZABs are assembled using Co,S-MnSe / N-rGO as the air cathode, as shown in Figure 11 (a). The results show that the open-circuit voltage of the Co,S-MnSe / N-rGO-based FZABs reaches 1.40 V at 25 °C, which is slightly higher and close to that of F-ZAB-Pt / C+RuO2 (1.39 V), as shown in Figure 11 (b). When connected in series, they can normally power an LED bulb (~2.5 V). In addition, as shown in Figure 11 (c), the corresponding power density of the Co,S-MnSe / N-rGO cathode under near-infrared light irradiation reaches 140.2 mW cm -2 (compared with 110.8 mW cm without near-infrared light irradiation) -2), significantly exceeding Pt / C+RuO2(55mW cm -2 ) and most other available FZABs. Additionally, as Figure 11 (d) shows, the charge-discharge gap of the FZABs with Co,S-MnSe / N-rGO is further reduced from 0.95 V to 0.5 V through photothermal enhancement. Excellent performance is also presented at different low temperatures ( Figure 11 (e)). Notably, the specific capacity under photothermal assistance is significantly higher, being 733.5 mA h g -1 , 740 mA h g -1 and 794.4 mA h g -1 at 25 °C, -20 °C and -40 °C respectively. These capacities significantly exceed those achieved without light illumination, as Figure 11 (f) shows.

[0068] The cycling performance of the F-ZAB with Co,S-MnSe / N-rGO was tested at temperatures below room temperature. As Figure 12 (a) shows, the FZABs based on Co,S-MnSe / N-rGO operate at a current density of 1 mA cm -2 , and successfully completed 1000, 3000 and 5000 cycles at 25 °C, -20 °C and -40 °C respectively. In contrast, the FZABs using Pt / C+RuO2 completely failed after only 500 cycles. The enhanced cycling performance can be attributed to the local heating provided by photothermal assistance, which helps prevent electrode corrosion. This key factor ensures the stable operation of the FZABs. Figure 12 (b) confirms that the prepared Co,S-MnSe / N-rGO-based FZABs maintain basically unchanged charge-discharge potentials after experiencing various deformation and damage cycles such as bending, twisting, folding and recovery. Therefore, it paves the way for the development of cost-effective, high-performance, low-temperature-resistant and flexible energy conversion and storage devices with a wide range of practical applications.

[0069] In summary, the present invention successfully synthesized nanostructured composite materials, especially Co,S-MnSe / N-rGO, through a hydrothermal method. Notably, Co,S-MnSe / N-rGO exhibits an obvious photothermal effect and has high catalytic activity for both OER and ORR. Under photothermal conditions, ΔE drops to 0.584 V, exceeding that of the state-of-the-art bifunctional electrocatalysts (ΔE>0.700 V). The liquid ZAB and flexible ZAB with Co,S-MnSe / N-rGO as the catalyst both exhibit 301.7 mW cm -2 and 140 mW cm -2The power density, and exhibits good cycle stability. The cycle times of the liquid ZAB exceed 5000 times, and those of the flexible ZAB exceed 1000 times. Notably, the flexible ZABs based on Co,S-MnSe / N-rGO exhibit excellent overall performance under various conditions, especially in thermo-optical challenging environments, deformation conditions, and low-temperature environments (e.g., over 3000 cycles at -40 °C and a power density close to 120 mW cm -2 ²) This study represents a significant advancement in the development of non-precious-metal-based nanostructured electrocatalyst composites and has the potential to drive progress in renewable energy conversion and storage technologies.

[0070] The above disclosure is only a preferred embodiment of the present invention, and of course it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A Co,S-MnSe / N-rGO composite material with a photothermal effect, characterized in that: It is formed by depositing cobalt- and sulfur-doped manganese selenide nanoparticles on graphene oxide nanosheets.

2. The Co,S-MnSe / N-rGO composite material according to claim 1, characterized in that: The cobalt- and sulfur-doped manganese selenide nanoparticles are obtained by a hydrothermal reaction of Na2SeO3, MnCl2·4H2O, CoCl2·6H2O and thiourea.

3. The Co,S-MnSe / N-rGO composite material according to claim 2, wherein: The hydrothermal reaction temperature is 160 °C - 200 °C.

4. The Co,S-MnSe / N-rGO composite material according to claim 1, characterized in that: After the cobalt- and sulfur-doped manganese selenide nanoparticles are mixed with GO, ammonia water is added and heated at 130 - 170 °C for 4 - 6 hours to obtain the Co,S-MnSe / N-rGO composite material.

5. Application of the Co,S-MnSe / N-rGO composite material according to any one of claims 1 - 4 as an electrocatalytic material.

6. Application of the Co,S-MnSe / N-rGO composite material according to any one of claims 1 - 4 in preparing an electrode material.

7. A bifunctional electrocatalytic material, characterized in that: Comprising the Co,S-MnSe / N-rGO composite material according to any one of claims 1 - 4.

8. Application of the bifunctional electrocatalytic material according to claim 7 in preparing a zinc-air battery.

9. A zinc-air battery, characterized in that: Comprising the bifunctional electrocatalytic material according to claim 7.

10. The zinc-air battery according to claim 9, characterized in that: The zinc-air battery is a liquid-phase or flexible zinc-air battery.

Images