Flexible electrocatalytic hydrogen evolution electrode material generated by laser direct writing polyimide composite, preparation method thereof and flexible hydrogen evolution electrode

Abstract

The application discloses a laser direct writing polyimide composite material for generating a flexible electrocatalytic hydrogen evolution electrode material and a preparation method and a flexible hydrogen evolution electrode thereof. The preparation method comprises the following steps: (1) a certain amount of PAA resin is weighed and added into a 250ml three-necked flask containing a proper amount of N,N-dimethylacetamide solvent, after complete dissolution, a certain amount of Fe(acac)3 and a phosphorus source are added, and mechanical stirring is conducted to prepare PAA / Fe(acac)3 / phosphorus source resin with a solid content of 15%; the PAA / Fe(acac)3 / phosphorus source resin is poured on a dry glass plate to generate thermal imidization through ladder temperature rising to obtain a PAA / Fe(acac)3 / phosphorus source composite film, wherein PAA is polyamide acid, and Fe(acac)3 is ferric acetylacetonate; and (2) a laser direct writing PAA / Fe(acac)3 / phosphorus source composite film is prepared to prepare a conductive material. The prepared hydrogen evolution electrode material has good conductive performance and is flexible and bendable.

Description

Technical Field

[0001] This invention belongs to the field of laser direct writing polymer carbonization, specifically relating to a laser direct writing method for generating flexible electrocatalytic hydrogen evolution electrode material from polyimide composite material and its preparation method, as well as the flexible hydrogen evolution electrode. Technical Background

[0002] Hydrogen energy is one of the most promising new energy sources. The high purity of hydrogen produced through water electrolysis, coupled with zero carbon dioxide emissions, has attracted widespread attention from scientists. However, the platinum-based metals currently used in water electrolysis cathodes are relatively expensive, significantly limiting their practical applications. One solution is to optimize and control the composition and structure of non-precious metal catalytic materials. Currently, carbon-based catalytic electrodes are gaining attention due to their wide availability and stable performance. Summary of the Invention

[0003] The present invention aims to provide a flexible electrocatalytic hydrogen evolution electrode material and preparation method for generating a flexible hydrogen evolution electrode by laser direct writing of polyimide composite material, and the flexible hydrogen evolution electrode thereof. The preparation method involves adding a dopant material (e.g., iron triacetylacetone) and a phosphorus source to polyamic acid (PAA) resin, pouring the mixture into a glass mold, and gradually increasing the temperature to prepare a PAA / Fe(acac)3 / phosphorus source composite film. A 1064nm fiber laser is used to perform laser direct writing on the PAA / Fe(acac)3 / phosphorus source composite film, which rapidly carbonizes under photothermal conversion, thus preparing a flexible electrode material with carbon supported on a metal oxide, which can be used as a flexible electrocatalytic hydrogen evolution electrode.

[0004] A method for preparing a flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite materials includes the following steps:

[0005] (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film

[0006] A certain amount of PAA resin was weighed and added to a 250 mL three-necked flask containing an appropriate amount of N,N-dimethylacetamide (DMAc) solvent. After complete dissolution, a certain amount of triacetylacetone iron (Fe(acac)3) and phosphorus source were added, and the mixture was mechanically stirred to obtain PAA / Fe(acac)3 / phosphorus source resin with a solid content of about 15%. The PAA / Fe(acac)3 / phosphorus source resin was poured onto a dry glass plate and subjected to a stepwise heating process to undergo a thermal imidization reaction, thereby obtaining a PAA / Fe(acac)3 / phosphorus source composite film.

[0007] (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film

[0008] Before laser direct writing of PAA / Fe(acac)3 / phosphorus source composite film, the surface of the composite film is first cleaned with deionized water and anhydrous ethanol, and then placed in a drying oven at 80℃ for 5 hours. Then, the composite film is fixed flat on the operating table, the focus of the fiber laser is adjusted to coincide with the surface of the composite film, the laser processing parameters are set, and the laser is directly written by computer control.

[0009] In one embodiment, the addition of Fe(acac)3 in step (1) accounts for 1 to 7% of the mass fraction of PAA.

[0010] In one embodiment, the phosphorus source added in step (1) is one or a mixture of several of the following: ammonium polyphosphate, aluminum hypophosphite, bisphenol A-bis(diphenyl phosphate), and resorcinol (diphenyl phosphate).

[0011] In one embodiment, the phosphorus source added in step (1) accounts for 8.0-20.0% of the mass fraction of PAA.

[0012] In one embodiment, the conditions for mixing PAA with Fe(acac)3 and phosphorus source in step (1) are: stirring at low temperature in an ice-water bath for 0.5 h, and under the protection of a dry N2 atmosphere.

[0013] In one embodiment, the PAA / Fe(acac)3 / phosphorus source resin step temperature program in step (1) is 50℃ for 1h, 100℃ for 1h, and 200℃ for 2h.

[0014] In one embodiment, the laser mentioned in step (2) is an FMF20W pulsed fiber laser with a maximum pulse frequency of 90KHz.

[0015] In one embodiment, step (2) uses a galvanometer scanning laser head and selects an S-shaped laser line scanning method; the laser processing parameters are: scanning speed of 200mm / s, line spacing of 0.01mm, pulse frequency of 20KHz, and power of 4.2W.

[0016] A flexible electrocatalytic hydrogen evolution electrode material prepared by any of the above-described laser direct writing polyimide composite materials.

[0017] A flexible hydrogen evolution electrode, prepared from any of the flexible electrocatalytic hydrogen evolution electrode materials described above.

[0018] The beneficial effects of this invention are as follows: This invention prepares a composite film by doping Fe(acac)3 and a phosphorus source in PAA resin, and then prepares an iron- and phosphorus-doped carbon-based material using laser direct writing, which can be used as a flexible electrocatalytic hydrogen evolution electrode material. The metal complex Fe(acac)3 exhibits good compatibility with polymers. The technical solution proposed in this invention allows for good carbonization of the PAA / Fe(acac)3 / phosphorus source composite film using laser direct writing, resulting in an iron- and phosphorus-doped carbon-based material. This effectively reduces the activation barrier for water decomposition, enabling the electrode material to achieve 10 mA / cm² in a 1 mol / L KOH electrolyte. 2 The overpotential at that time was 269mV. The laser-written polyimide composite material prepared by this invention has good conductivity, is three-dimensionally porous, has a large specific surface area, is flexible and bendable, and can be customized to draw patterns. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of the preparation of the PAA / Fe(acac)3 / phosphorus source composite film in the embodiments of the present invention;

[0020] Figure 2 This is a schematic diagram of a laser-written PAA / Fe(acac)3 / phosphorus source composite film in an embodiment of the present invention;

[0021] Figure 3 High-resolution transmission electron microscopy image of carbon particles on the surface of PAA / Fe(acac)3 / phosphorus source composite film after laser direct writing in step 2;

[0022] Figure 4 (a) Hydrogen evolution performance test of water electrolysis after laser direct writing of PAA / Fe(acac)3 / phosphorus source composite film in an embodiment of the present invention, and (b) Tafel curve spectrum. Detailed Implementation

[0023] Please see Figure 1-3 This invention provides a method for preparing a flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite materials. Fe(acac)3 and a phosphorus source are added to polyamic acid (PAA) resin, poured into a glass mold, and heated in stages to prepare a PAA / Fe(acac)3 / phosphorus source composite film. The PAA / Fe(acac)3 / phosphorus source composite film is then laser-written using a 1064nm fiber laser, causing it to rapidly carbonize under photothermal conversion, thus preparing an iron- and phosphorus-doped carbon-based composite electrode material.

[0024] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0025] Example 1

[0026] (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film

[0027] A certain amount of PAA resin was weighed and added to a 250mL three-necked flask containing an appropriate amount of DMAc solvent. After complete dissolution, 1% and 8% by mass of Fe(acac)3 and ammonium polyphosphate of PAA were added, and the mixture was mechanically stirred to obtain a PAA composite resin with a solid content of approximately 15%. The PAA composite resin was poured onto a dry glass plate and subjected to a stepwise heating process: 50℃ for 1 h, 100℃ for 1 h, 150℃ for 1 h, and 200℃ for 2 h, to induce a thermal imidization reaction, yielding a PAA / Fe(acac)3 / phosphorus source composite film (referred to as PI composite film).

[0028] (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film

[0029] Before laser direct writing (also known as laser ablation) of the composite film, the surface of the PAA / Fe(acac)3 / phosphorus source composite film was cleaned with deionized water and anhydrous ethanol, and then dried in a drying oven at 50°C for 8 hours. Next, the PAA / Fe(acac)3 / phosphorus source composite film was flatly fixed on the operating table, and the focus of the fiber laser was adjusted to coincide with the surface of the PI4 composite film. The laser processing parameters were set as follows: scanning speed 200 mm / s, line spacing 0.01 mm, pulse frequency 20 kHz, and power 4.2 W. The laser was then used to perform direct writing ablation to prepare the electrocatalytic hydrogen evolution electrode material, controlled by a computer.

[0030] Example 2

[0031] (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film

[0032] A certain amount of PAA resin was weighed and added to a 250mL three-necked flask containing an appropriate amount of DMAc solvent. After complete dissolution, 5%, 8%, and 8% by mass of Fe(acac)3, ammonium polyphosphate, and resorcinol (diphenyl phosphate) were added. The mixture was mechanically stirred to obtain a PAA composite resin with a solid content of approximately 15%. The PAA composite resin was poured onto a dry glass plate and subjected to a stepwise heating process: 50℃ for 1 h, 100℃ for 1 h, 150℃ for 1 h, and 200℃ for 2 h, to induce a thermal imidization reaction and obtain a PAA / Fe(acac)3 / phosphorus source composite film.

[0033] (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film

[0034] Before laser direct writing of the composite film, the surface of the PAA / Fe(acac)3 / phosphorus source composite film was cleaned with deionized water and anhydrous ethanol, and then dried in a drying oven at 50℃ for 8 hours. Next, the PAA / Fe(acac)3 / phosphorus source composite film was flatly fixed on the operating table, and the focus of the fiber laser was adjusted to coincide with the surface of the PI4 composite film. The laser processing parameters were set as follows: scanning speed 200 mm / s, line spacing 0.01 mm, pulse frequency 20 kHz, and power 4.2 W. The laser was then used to directly write and ablate the electrocatalytic hydrogen evolution electrode material using a computer-controlled laser.

[0035] Figure 3 This is a high-resolution transmission electron microscope image of carbon particles on the surface of the PAA / Fe(acac)3 / phosphorus source composite film after laser direct writing in Example 2. Figure 3 (a) and Figure 3 (b) is a graph showing different magnifications. Figure 3 (a) has a scale bar of 100 nm. Figure 3 (b) has a scale of 5 nm.

[0036] from Figure 3 (a) It can be seen that the Fe2O3 nanoparticles generated after laser ablation are loaded on graphene and there is no large-area aggregation. Figure 3 (b) The lattice fringe plane spacing of Fe2O3 is about 0.208 nm, corresponding to the (400) crystal plane of Fe2O3. In addition, the carbon material is about 8 layers of multilayer graphene, with each layer having a thickness of about 0.358 nm.

[0037] Example 3

[0038] (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film

[0039] A certain amount of PAA resin was weighed and added to a 250mL three-necked flask containing an appropriate amount of DMAc solvent. After complete dissolution, 7% and 12% (by mass) of Fe(acac)3 and aluminum hypophosphite of PAA were added, and the mixture was mechanically stirred to obtain a PAA composite resin with a solid content of approximately 15%. The PAA composite resin was poured onto a dry glass plate and subjected to a stepwise heating process: 50℃ for 1 h, 100℃ for 1 h, 150℃ for 1 h, and 200℃ for 2 h, to induce a thermal imidization reaction and obtain a PAA / Fe(acac)3 / phosphorus source composite film.

[0040] (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film

[0041] Before laser direct writing of the composite film, the surface of the PAA / Fe(acac)3 / phosphorus source composite film was cleaned with deionized water and anhydrous ethanol, and then dried in a drying oven at 50℃ for 8 hours. Next, the PAA / Fe(acac)3 / phosphorus source composite film was flatly fixed on the operating table, and the focus of the fiber laser was adjusted to coincide with the surface of the PI4 composite film. The laser processing parameters were set as follows: scanning speed 200 mm / s, line spacing 0.01 mm, pulse frequency 20 kHz, and power 4.2 W. The laser was then used to directly write and ablate the electrocatalytic hydrogen evolution electrode material using a computer-controlled laser.

[0042] Example 4

[0043] (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film

[0044] A certain amount of PAA resin was weighed and added to a 250mL three-necked flask containing an appropriate amount of DMAc solvent. After complete dissolution, 3% and 15% (by mass) of Fe(acac)3 and ammonium polyphosphate of PAA were added, and the mixture was mechanically stirred to obtain a PAA composite resin with a solid content of approximately 15%. The PAA composite resin was poured onto a dry glass plate and subjected to a stepwise heating process: 50℃ for 1 h, 100℃ for 1 h, 150℃ for 1 h, and 200℃ for 2 h, to induce a thermal imidization reaction and obtain a PAA / Fe(acac)3 / phosphorus source composite film.

[0045] (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film

[0046] Before laser direct writing of the composite film, the surface of the PAA / Fe(acac)3 / phosphorus source composite film was cleaned with deionized water and anhydrous ethanol, and then dried in a drying oven at 50℃ for 8 hours. Next, the PAA / Fe(acac)3 / phosphorus source composite film was flatly fixed on the operating table, and the focus of the fiber laser was adjusted to coincide with the surface of the PI4 composite film. The laser processing parameters were set as follows: scanning speed 200 mm / s, line spacing 0.01 mm, pulse frequency 20 kHz, and power 4.2 W. The laser was then used to directly write and ablate the electrocatalytic hydrogen evolution electrode material using a computer-controlled laser.

[0047] Comparative Example 1 (LIG-PI)

[0048] A certain amount of PAA resin was weighed and added to a 250mL three-necked flask containing an appropriate amount of DMAc solvent. After complete dissolution, the mixture was mechanically stirred to obtain PAA resin with a solid content of approximately 15%. The PAA resin was poured onto a dry glass plate and subjected to a stepwise heating process: 50℃ for 1 hour, 100℃ for 1 hour, and 350℃ for 2 hours, to induce a thermal imidization reaction and obtain a PI film.

[0049] Laser direct writing of thin films: Before laser direct writing, the PI film surface was cleaned with deionized water and anhydrous ethanol, and then dried in a 50℃ drying oven for 8 hours. Then, the PI film was flatly fixed on the operating table, and the focus of the fiber laser was adjusted to coincide with the surface of the PAA / Fe(acac)3 / phosphorus source composite film. The laser processing parameters were set as follows: scanning speed 200 mm / s, line spacing 0.01 mm, pulse frequency 20 kHz, and power 4.2 W. The laser was then used to directly write and ablate the electrocatalytic hydrogen evolution electrode material using a computer-controlled laser.

[0050] Comparative Example 2 (Fe5C2-Fe3C@NC)

[0051] Glucose (25 mmol) and poly(vinylpyrrolidone) (PVP) (37.5 mmol) were dissolved in 25 mL of deionized water and slowly heated to 100 °C for approximately 20 minutes with continuous magnetic stirring. Subsequently, Fe(NO3)3·9H2O (12.5 mmol) was melted at 50 °C and added to the glucose-PVP solution. The mixture was then stored at 100 °C for 1 hour. During this process, a large amount of gas was generated, requiring the process to be carried out in a fume hood. Afterward, the mixture was allowed to cool naturally to room temperature and centrifuged. Finally, the resulting yellow precipitate was washed several times with deionized water and ethanol and dried in an oven at 60 °C for 12 hours. The resulting yellow powder was the precursor.

[0052] 0.2 g of the yellow powder was transferred to a ceramic boat inside a tube furnace. A ceramic boat containing 4 mL of ethylenediamine was then placed in front of the furnace, and the mixture was incubated at 20 °C for [time missing]. -1 The furnace was heated to the target temperature at a controlled heating rate and maintained at the target temperature for 1 hour under a nitrogen flow. Afterward, the furnace was cooled to room temperature, and the resulting black product was ground and collected. Labelled Fe5C2-Fe3C@NC.

[0053] The HER performance of the electrocatalytic materials prepared in Examples 1-4 and Comparative Examples 1-2 was investigated using a standard three-electrode system in 1M KOH solution. See Table 1 for details. Figure 4 .

[0054] Table 1 Comparison of HER performance of different materials in 1M KOH solution

[0055]

[0056] Figure 4 (a) Hydrogen evolution performance test of water electrolysis after laser direct writing of PAA / Fe(acac)3 / phosphorus source composite film in an embodiment of the present invention, and (b) Tafel spectral curve. The linear voltammetry scan range was 0 to -0.6 V (vs. RHE), and the scan rate was 2 mV / s. Figure 4 As can be seen in (a), the PAA / Fe(acac)3 / phosphorus source composite films in different embodiments of laser ablation reached 10 mA / cm². -2 The trend of overpotential variation required for the current density was observed. In Example 2, the overpotential reached a minimum of 269 mV, demonstrating that the iron-phosphorus co-doped carbon-based material generated by laser ablation possesses certain catalytic water electrolysis performance under alkaline conditions. From Figure 4 (b) It can be seen that the Tafel slope of the laser ablation PI composite film in Example 2 is also the smallest, indicating that hydrogen desorption is the rate-controlling step, and the hydrogen evolution process may be the Volmer–Heyrovsky (RDS) mechanism.

[0057] Table 1 compares the measured hydrogen evolution overpotential and Tafel slope with different catalysts, showing that the iron-phosphorus co-doped carbon-based material prepared by this invention has certain hydrogen evolution performance under alkaline conditions.

Claims

1. A method for preparing a flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite material, comprising the following steps: (1) Preparation of PAA / Fe(acac)3 / phosphorus source composite film A certain amount of PAA resin was weighed and added to a 250 mL three-necked flask containing an appropriate amount of N,N-dimethylacetamide solvent. After complete dissolution, a certain amount of Fe(acac)3 and a phosphorus source were added, and the mixture was mechanically stirred to obtain a PAA / Fe(acac)3 / phosphorus source resin with a solid content of 15%. The PAA / Fe(acac)3 / phosphorus source resin was poured onto a dry glass plate and subjected to a stepwise heating process to undergo a thermal imidization reaction, yielding a PAA / Fe(acac)3 / phosphorus source composite film, wherein PAA is polyamic acid and Fe(acac)3 is iron triacetylacetone. wherein The Fe(acac)3 accounts for 1-7% of the PAA by mass; the phosphorus source is one or a mixture of several of ammonium polyphosphate, aluminum hypophosphite, bisphenol A-bis(diphenyl phosphate), and resorcinol (diphenyl phosphate), and the phosphorus source accounts for 8.0-20.0% of the PAA by mass. (2) Preparation of conductive materials by laser direct writing of PAA / Fe(acac)3 / phosphorus source composite thin film Before laser direct writing of PAA / Fe(acac)3 / phosphorus source composite film, the surface of the composite film is first cleaned with deionized water and anhydrous ethanol, and then placed in a drying oven at 80℃ for 5 hours. Then, the composite film is fixed flat on the operating table, the focus of the fiber laser is adjusted to coincide with the surface of the composite film, the laser processing parameters are set, and the laser is directly written by computer control.

2. The method for preparing flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite material according to claim 1, characterized in that: The conditions for mixing PAA with Fe(acac)3 and phosphorus source in step (1) are: stirring at low temperature in an ice-water bath for 0.5 h, and under the protection of a dry N2 atmosphere.

3. The method for preparing flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite material according to claim 1, characterized in that: The PAA / Fe(acac)3 / phosphorus source resin step temperature program in step (1) is 50℃ for 1h, 100℃ for 1h, and 200℃ for 2h.

4. The method for preparing flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite material according to claim 1, characterized in that: The laser mentioned in step (2) is an FMF20W pulsed fiber laser with a maximum pulse frequency of 90KHz.

5. The method for preparing flexible electrocatalytic hydrogen evolution electrode material by laser direct writing of polyimide composite material according to claim 1, characterized in that: In step (2), a galvanometer scanning laser head is used, and an S-shaped laser line scanning method is selected. The laser processing parameters are: scanning speed of 200 mm / s, line spacing of 0.01 mm, pulse frequency of 20 kHz, and power of 4.2 W.

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