Chitin carbon-based metal-loaded self-supporting electrode as well as preparation method and application thereof

Abstract

The invention discloses a chitin carbon-based metal-loaded self-supporting electrode as well as a preparation method and application thereof, and belongs to the technical field of carbon material catalysts. According to the preparation method, rich renewable biomass resources are used for synthesizing a new material, the carbon precursor is rich, cheap and easy to obtain, the modifiability of the carbon substrate is high, the metal load variety is wide, and the system compatibility is good; the scheme has the advantages of simple steps, wide raw material sources, environmental protection and economy, and is beneficial to sustainable development and circular economy. The chitin carbon-based metal-loaded self-supporting electrode prepared by the invention has strong electrochemical corrosion resistance, can promote the action of an electrochemical mediator, and has the advantages of good conductivity, strength, modifiability, uniformity, universality, activity, stability and the like in an organic solvent system; good catalytic activity is shown in water electrolysis and organic electrosynthesis, and a new way is provided for exploring a new reaction or organic electrosynthesis.

Description

Technical Field

[0001] This invention relates to the field of carbon material catalyst technology, and in particular to a chitin-based carbon-supported metal self-supporting electrode, its preparation method, and its application. Background Technology

[0002] In recent years, organic electrosynthesis has experienced a resurgence due to its unique reactivity, high safety, atom economy, and low energy consumption. Many manufacturers are now utilizing electrosynthesis to improve production processes, aiming to reduce costs and greenhouse gas emissions in the chemical industry. However, some significant challenges remain, including the conversion of substrates with high redox potentials and the synthesis of high-value, important chemicals.

[0003] Alkyl groups are ubiquitous structural units in organic chemistry, and most best-selling commercial drugs contain an alkyl moiety. C(sp...) 3 C(sp)-H bonds typically possess high bond dissociation energies and oxidation potentials, making their direct electrochemical activation challenging. In recent years, hydrogen atom transfer (HAT) and indirect electrolytic activation of C(sp) bonds have been employed. 3 Breakthroughs have been achieved in the study of the -H bond. For example, in 2016, Baran's group reported the use of tetrachloro-N-hydroxyphthalimide (Cl4NHPI) as a mediator. t BuOOH is used as the oxygen source for allylic CH oxidation. Subsequently, using the quinine ring as a HAT mediator, C(sp) 3 Electrochemical oxidation of the -H bond to ketones or alcohols. In 2018, Stahl's group demonstrated that I₂ is an effective free radical scavenger, and that the CH bond of methyl aromatics can be oxidized to benzyl iodine using electrochemical NHPI-mediated oxidation. In 2020, Lambert's team and Xu Haichao's team reported photoelectrochemical C(sp) oxidation of ethers and alkanes using trisaminocyclopropenium (TAC) ions and chloride anions as mediators. 3 )-H functionalization. Subsequently, the Ackermann, Lei, and Ye groups, using Mn complex catalysts, 4-chloro-N-isopropylbenzenesulfonamide, and sulfate anions as mediators, respectively, achieved C(sp... 3 Electrochemical azidation, arylation, and amination of the )-H bond. The work reported above focuses on finding new catalytic systems and mediators to achieve the target reactions, and almost all of the reactions use commercially available metal sheets and carbon electrodes as electrodes.

[0004] Traditional electrodes generally possess good stability, but due to their size effect and inherent properties, they exhibit low activity and poor selectivity in certain reactions. With the continuous growth of global energy demand, electrocatalytic reactions such as the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) have attracted widespread attention, and various advanced electrocatalysts have been reported to reduce reaction overpotentials. Organic electrosynthesis also requires advanced electrodes for further development. Therefore, preparing highly active electrodes to enhance the role of mediators, such as reducing their overpotential, thereby improving Faradaic efficiency, yield, and selectivity of target reactions, is a promising research direction. Recently, modified electrodes using traditional electrodes as supports have shown good activity in organic electrosynthesis. For example, in 2018, Zhang Bing's research group prepared NiSe nanorod array anodes by directly selenizing commercially available nickel foam, and used these NiSe anodes to electrochemically oxidize primary amines to the corresponding nitrile compounds. Subsequently, they prepared a series of modified electrodes, such as Ni2P nanosheet array anodes, copper nanowire array cathodes, and Pd-P alloy nanoparticle network cathodes, for various electrochemical reactions, such as the half-dehydrogenation of tetrahydroisoquinoline, the deuteration of halides, and the half-hydrogenation (deuteration) of alkynes. In 2020, the Berlinguette group prepared Pd film cathodes for the reductive deuteration of alkynes, aldehydes, and imines. Recently, the Lei Aiwen group reported a nitrogen-doped Ru carbon felt electrode for the electrocatalytic reductive deuteration and defluorination of (hetero)aromatics, yielding fully deuterated products. Although modified electrodes have shown promising results, there are few reports on using modified electrodes to promote mediator effects and improve the efficiency of target reactions. Furthermore, modified electrodes cannot escape the constraints of the support material, resulting in poor uniformity and stability. Given the rapid development of electrosynthesis, the development of novel electrodes is urgently needed. A promising approach is to rationally design and prepare electrodes using a bottom-up method, rather than modifying existing electrodes. However, conductivity, strength, modifiability, uniformity, versatility, activity, and stability are all significant challenges in the fabrication of novel electrodes.

[0005] Hydrogen production through water electrolysis has become a global research hotspot in recent years due to its green (water as the reaction medium and hydrogen source), mild conditions, and sustainability (direct utilization of renewable energy sources such as solar energy), and is a crucial technology for green hydrogen production. Compared to traditional alkaline electrolyzers, proton exchange membrane (PEM) water electrolysis offers advantages such as lower resistance loss, higher current density, and higher energy efficiency. However, because the oxygen exchange reaction (OER) involves a slow four-electron transfer process involving various oxygen intermediates, the reaction has a high catalytic overpotential, and the efficiency of water electrolysis is often significantly limited by the OER. This necessitates the use of large quantities of precious metal electrocatalysts such as iridium, platinum, and ruthenium as anode and cathode catalysts, while also facing challenges such as easy deactivation and insufficient stability of the electrocatalysts. Coupled with a simple organic anode reaction while maintaining the hydrogen release performance at the cathode is crucial for the development of water electrolysis engineering. However, maintaining the stability of the electrode within the organic system and preventing corrosion remains a significant challenge. Therefore, developing efficient, stable, and inexpensive self-supporting electrodes as catalysts is of great importance for electrochemical applications. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, in a first aspect of the present invention, a method for preparing a chitin-based carbon-supported metal self-supporting electrode is provided, which is simple and rapid in process, has wide availability of raw materials and low cost, and is suitable for large-scale production, comprising the following steps: (1) Chitin was dissolved using a low-temperature alkaline dissolution method to prepare an alkaline chitin solution; (2) Prepare a suspension of chitin microspheres or a metal oxide precursor loaded with a metal precursor; The preparation steps of the chitin microsphere suspension loaded with metal precursors include preparing chitin microspheres from an alkaline chitin solution using emulsion polymerization, mixing the metal salt solution with the chitin microspheres to achieve adsorption loading, and obtaining the chitin microsphere suspension loaded with metal precursors; the metal oxide precursors include metal oxides or metal oxide complexes. (3) Mix the chitin microsphere suspension or metal oxide precursor loaded with metal precursor with alkaline chitin solution to obtain chitin mixture; then add crosslinking agent, crosslink and solidify to form hydrogel, and then replace and dry to obtain metal composite chitin aerogel. (4) The metal-composite chitin aerogel is annealed to obtain a chitin carbon-based metal-supported self-supporting electrode.

[0007] Preferably, in step (1), the method for preparing the alkaline chitin solution includes the following steps: chitin, sodium hydroxide, urea, and water are mixed together, frozen at -40~-30 ℃, thawed at room temperature, and repeatedly mixed until the solution is uniform and transparent to obtain the alkaline chitin solution.

[0008] More preferably, the mass ratio of chitosan, sodium hydroxide, urea, and water is 2~6:10~100:1~10:100.

[0009] The chitin raw materials used in the above steps are widely available, including shellfish products such as shrimp and crab shells from the ocean. The mixing and dispersion methods include one or more of mechanical stirring, high-pressure homogenization, and ultrasonic cell disruption. Based on the formation of an alkaline chitin solution, those skilled in the art can select appropriate raw materials and processing methods according to actual needs.

[0010] Preferably, in step (2), the preparation method of the chitin microsphere suspension loaded with metal precursor includes the following steps: mixing an alkaline chitin solution with an emulsifier, maintaining the reaction temperature at -5~0 ℃, then adjusting the pH of the solution to neutral, filtering, washing with ethanol, water and tert-butanol, and drying to obtain chitin microspheres; mixing and dispersing the metal salt solution with the chitin microspheres to obtain the chitin microsphere suspension loaded with metal precursor.

[0011] More preferably, the emulsifier includes Tween 85 and Span 60; the mass ratio of chitosan to added Tween 85 and Span 60 in the alkaline chitosan solution is 4:5~10:10~50.

[0012] Preferably, in step (2), the metal type of the metal salt solution includes at least one of Pt, Pd, Ru, Cu, Ni, Co, Fe, and Ti; the loading amount is 1 wt.% to 5 wt.% of the chitin microspheres; the metal type of the metal oxide precursor includes at least one of Pt, Pd, Ru, Cu, Ni, Co, Fe, and Ti.

[0013] In the above steps, depending on the type of metal required, transition metal salts or oxides of Pt, Pd, Ru, Cu, Ni, Co, Fe, and Ti are added in a single or mixed manner, thereby allowing the chitin microspheres to adsorb and load different types of metals.

[0014] Preferably, the volume of the alkaline chitosan solution in step (2) is the same as the volume of the alkaline chitosan solution in step (3).

[0015] Preferably, in step (3), the crosslinking agent includes at least one of epichlorohydrin (ECH), citric acid, and benzoyl peroxide; the volume ratio of the crosslinking agent to the chitin mixture is 1:10~100.

[0016] In the above steps, epichlorohydrin is a bulk chemical with low price and has the advantages of fast linkage speed and the ability to maintain crosslinking effect at low temperature, making it a particularly suitable crosslinking agent for this application.

[0017] Preferably, in step (4), the annealing process is carried out in an inert or air atmosphere, the processing temperature is 400~900℃, and the processing time is 1~5 h.

[0018] In a second aspect of the present invention, a chitin-based carbon-supported metal self-supporting electrode with uniform metal catalytic sites, high specific surface area, high activity, good conductivity, and suitable for water electrolysis or anodic oxidation of alkane functionalization is provided, which is prepared by the method of the first aspect of the present invention.

[0019] In a third aspect of the invention, an application of the chitin carbon-based supported metal self-supporting electrode of the second aspect of the invention is provided, including: for water electrolysis reaction or anodic oxidation of alkane functionalization reaction.

[0020] Preferably, the anodic alkane functionalization reaction includes one of the following: chlorine radical-mediated alkane chlorination, bromine radical-mediated alkane bromination, nitro radical-mediated alkane nitration, and chlorine radical-mediated alkane etherification.

[0021] The chitin-based carbon-supported metal self-supporting electrode provided by this invention exhibits excellent performance in both water electrolysis and anodic oxidation of alkane functionalization reactions. As presented in one or more embodiments of this invention, in specific applications, it can be adapted to different types of reactions in the following ways: For water electrolysis, a chitin-based carbon-supported metal self-supporting electrode can be directly applied to the water electrolysis test, eliminating the need for coating the conductive carbon paper with Nafion mixed solution. In 0.5 M H₂SO₄ solution, a three-electrode system is used, with a self-supporting metal-based carbon electrode, a carbon rod, and a silver / silver chloride (Ag / AgCl) electrode serving as the working electrode, counter electrode, and reference electrode, respectively, to perform water electrolysis on an electrochemical workstation.

[0022] For chlorine radical-mediated alkane chlorination reactions, a chitin-based carbon-supported metal self-supporting electrode can be used as both the anode and cathode, employing a hydrochloric acid-organic solvent blend system. The organic solvent is one or a mixture of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. The hydrochloric acid concentration is between 0.01 and 3 M, and the volume ratio of hydrochloric acid to organic solvent is between 1:0.1 and 100. The alkane compound is a C2-C20 straight-chain, branched, or cyclic alkanes containing alkyl groups, or an aromatic compound containing alkyl groups. The electrolysis current density is 5–500 mA / cm². 2 The electrolysis temperature is 0~60 ℃, and the electrolysis time is 1~10 h.

[0023] For bromine radical-mediated alkane bromination reactions, a self-supported metal electrode supported on chitin carbon can be used as the anode, and metal electrodes such as nickel or platinum sheets can be used as the cathode. The organic solvent is one or a mixture of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, with a bromide ion concentration between 0.01 and 3 M. The alkane compound is a C2-C20 straight-chain, branched, or cyclic alkanes containing alkyl groups, or an aromatic compound containing alkyl groups. The bromide salt is a bromide-containing salt such as lithium bromide, sodium bromide, or tetrabutylammonium bromide. The electrolysis current density is 5–500 mA / cm². 2 The electrolysis temperature is 0~60 ℃, and the electrolysis time is 1~10 h.

[0024] For nitro radical-mediated alkane nitration reactions, a chitin-based carbon-supported metal self-supporting electrode can be used as both the anode and cathode, employing a nitric acid-organic solvent blend system. The organic solvent is one or a mixture of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone. The nitric acid concentration is between 0.01 and 3 M, and the volume ratio of nitric acid to organic solvent is between 1:0.1 and 100. The alkane compound is a C2-C20 straight-chain, branched, or cyclic alkanes containing alkyl groups, or an aromatic compound containing alkyl groups. The electrolysis current density is 5–500 mA / cm². 2 The electrolysis temperature is 0~60 ℃, and the electrolysis time is 1~10 h.

[0025] For chlorine radical-mediated alkane etherification reactions, a self-supporting electrode with chitin carbon-based loaded metal can be used as both the anode and cathode. The organic solvent is one or more of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, with a hydrochloric acid concentration between 0.001 and 1 M, and a volume ratio of hydrochloric acid to organic solvent between 1:1 and 1000. The alkane compounds are C2-C20 straight-chain, branched, or cyclic alkanes containing alkyl groups, aromatic compounds containing alkyl groups, and alkyl heterocyclic or straight-chain / branched compounds containing oxygen, nitrogen, or other heteroatoms. The alcohol compounds are C2-C20 straight-chain, branched, or cyclic mono- or poly-ols containing hydroxyl groups, and aromatic compounds containing hydroxyl groups. The electrolysis current density is 5-500 mA / cm². 2 The electrolysis temperature is -10~60 ℃, and the electrolysis time is 1~10 h.

[0026] In addition to the above-mentioned methods and corresponding parameter guidance, those skilled in the art can also choose appropriate operating methods according to actual conditions or application needs.

[0027] It should be noted that the inventors previously provided a chitin-based single-atom platinum catalyst for hydrogenated unsaturated aldehydes and ketones and its preparation method and application (CN118403660A), a method for preparing chitin-derived single-point nickel cathode composite materials, and a lithium-sulfur battery (CN116072849A). The material in CN118403660A is still chitin, while in this application, chitin is converted into carbon materials, with chitin as the precursor. The method used in CN116072849A is tempo oxidation to modify chitin, obtaining two-dimensional nanosheets, while this application uses an alkaline urea system to dissolve chitin for preparing three-dimensional aerogel materials. The significant difference between this application and prior research results is that this invention is applied in the field of electrocatalysis, which is significantly different from the application scenarios and indicator requirements of organic synthesis thermochemistry and battery energy storage; the carbon material of this application directly possesses conductivity and is suitable as an electrode material for the target electrochemical application; this scheme utilizes the self-assembly property of chitin to autonomously obtain a three-dimensional self-supporting material without the need for additional templates.

[0028] Based on the above technical solutions, the design concept and principle of this invention are as follows: In this invention, porous carbon materials are ideal carriers for nanoelectrodes, enhancing mass transfer and the interaction between the metal and the carrier. Biomass is an inexpensive and readily available source of porous carbon materials. Cellulose and chitin are two of the most abundant natural biopolymers on Earth. They are typically considered waste at the end of their life cycle, directly contributing to carbon dioxide emissions. Chitin, in particular, generates approximately 6 to 8 million tons of crab, shrimp, and lobster shells annually from the global seafood processing industry. These discarded shells are often dumped in landfills or the ocean, resulting in significant resource waste. Utilizing abundant and renewable biomass resources to synthesize new materials is of great significance for sustainable development and the circular economy. Chitin naturally fixes oxygen and nitrogen in the form of hydroxyl, ether, and amide groups, providing abundant coordination sites for anchoring active metal species. This invention leverages these properties to improve the stability of heterogeneous catalysts in organic solvent systems, which is crucial for electrodes in organic electrosynthesis.

[0029] The conductivity, strength, modifiability, uniformity, versatility, activity, and stability of electrode materials represent significant technical obstacles to overcome in the preparation of novel electrodes in this invention. To address these challenges, this invention selects chitin, a biomass polymer, as the carrier material. As a naturally occurring renewable and sustainable material, the strong hydrogen bonds in its molecular chains allow chitin molecules to self-assemble quickly and easily, forming a three-dimensional interpenetrating network of self-supporting aerogels. Furthermore, its well-defined structure, abundant metal anchoring sites, and numerous functional groups facilitate modification, making it an excellent candidate for a self-supporting carbon-based electrocatalyst carrier. Introducing different metal salt solutions allows for the construction of a universally applicable self-supporting electrode, enabling the electrochemical acidic water splitting and anodic alkane functionalization reactions.

[0030] To address this issue, this invention presents a simplified synthetic route for preparing chitin-based carbon-based metal-supported self-supporting electrodes. This method prepares a chitin microsphere suspension (Chitin-M) to form the metal-supported precursor. Utilizing the hydrogen bonding between chitin molecules, it facilitates direct self-assembly into a metal-composite chitin aerogel (Chitin-M / AG). Simultaneously, the molecular chain structure is well-defined, with numerous nitrogen- and oxygen-containing functional groups that can directly anchor the metal and are easily modified. The interpenetrating network formed by nanofibers can transport small molecule reactants. The self-formed microspheres effectively reinforce the chitin aerogel network, disperse metal sites, and prevent aggregation. After annealing, nitrogen- and oxygen-doped chitin-based carbon-based self-supporting electrocatalytic electrodes (M-CAE, M-MAE) are obtained. x N y -CAE, MO x -CAE) has good conductivity and reactivity, enhanced resistance to electrochemical corrosion, forming a highly loaded, highly active, and highly stable acidic water electrolysis catalyst material. At the same time, the self-supporting electrode morphology can be well applied to organic electrosynthesis systems (for example, avoiding the instability of Nafion solution in organic electrochemical systems, further improving the activity and stability of the electrocatalyst).

[0031] The core of the above steps lies in dissolving chitin in an alkaline aqueous solution and mixing it with pre-prepared metal ion-modified chitin microspheres. These uniform metal ion-modified composite chitin solutions are gelled to obtain metal ion-modified composite chitin hydrogels, which are then dried to obtain metal ion-modified composite chitin aerogels. The solidification process to form the hydrogel and subsequent aerogel formation achieves uniform dispersion and morphology control of the metal nanoparticles. Finally, a metal nanoparticle-modified composite carbon aerogel electrode is prepared by annealing the composite chitin aerogel. In practical applications, the efficiency of the chitin-carbon-based metal-supported self-supporting electrode in water electrolysis tests is close to that of commercially available electrodes. Besides electrocatalytic reactions in aqueous phases such as water electrolysis, when applied to electrosynthetic reactions, these self-supporting nanoelectrodes are compatible with organic solvent systems and exhibit excellent performance (e.g., in the chlorination of alkanes, the Faraday efficiency is significantly improved compared to commercial graphite felt electrodes because the ruthenium oxide nanoparticles in the electrode can stabilize chlorine free radicals and improve the mediating efficiency). Under the action of a mediator, in the electrochemical oxidation of C(sp...)... 3 It exhibits excellent catalytic performance in chlorination, bromination, nitration, and etherification reactions, solving the compatibility problem between organic electrosynthesis and the preparation of highly active electrodes.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides a method for preparing a chitin-based carbon-supported metal self-supporting electrode. It utilizes abundant renewable biomass resources to synthesize new materials. The carbon precursors are plentiful, inexpensive, and readily available. Furthermore, the carbon substrate is highly modifiable, the range of metal loading types is wide, and the system has excellent compatibility. This method has the advantages of simple steps, wide availability of raw materials, and environmental friendliness and economy, which is conducive to sustainable development and the circular economy.

[0033] This invention provides a chitin-based carbon-supported metal self-supporting electrode. This electrode has strong resistance to electrochemical corrosion, can promote the action of electrochemical mediators, and has advantages such as good conductivity, strength, modifiability, uniformity, versatility, activity and stability in organic solvent systems. It also exhibits good catalytic activity in water electrolysis and organic electrosynthesis.

[0034] This invention provides an application of a chitin-based carbon-supported metal self-supporting electrode, which improves the mediating efficiency of electrochemical mediators in organic electrosynthesis and provides a new approach for exploring new reactions or organic electrosynthesis. Attached Figure Description

[0035] Figure 1 A double aberration scanning electron microscope image of the self-supporting electrode of chitin carbon-based platinum supported by Example 1 is shown. Figure 2 A double aberration scanning electron microscope image of the self-supporting electrode of chitin carbon-based palladium prepared in Example 2 is shown. Figure 3 A double aberration scanning electron microscope image of the self-supporting electrode of chitin carbon-based ruthenium supported by Example 3 is shown. Figure 4 A transmission electron microscope (TEM) image of the chitin-based nickel-supported self-supporting electrode prepared in Example 4 is shown. Figure 5 A transmission electron microscope (TEM) image of the chitin-based carbon-supported copper self-supporting electrode prepared in Example 5 is shown. Figure 6 The diagram shows a test of the hydrogen evolution reaction at the cathode of water electrolysis using a self-supporting electrode of chitin carbon-based palladium prepared in Example 2. Figure 7 The diagram shows a test of the oxygen evolution reaction at the anode of water electrolysis using a self-supporting electrode with chitin-based carbon-supported ruthenium prepared in Example 3. Figure 8 The 1H NMR spectrum of the tetrahydrofuran etherification product of Example 12 is shown; Figure 9 The carbon NMR spectrum of the tetrahydrofuran etherification product of Example 12 is shown. Detailed Implementation

[0036] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0037] In the following embodiments: Both the platinum sheet electrode and the graphite felt electrode were obtained through commercial purchases; the platinum sheet electrode was purchased from Goldlink, and the graphite felt electrode was purchased from Cetech.

[0038] Example 1 This embodiment provides a chitin-based carbon-supported platinum self-supporting electrode, which is fabricated using the following steps: (1) Add 6 g chitosan powder, 11 g NaOH and 4 g urea to 85 mL of water and stir evenly. Freeze at -35 ℃ and thaw at room temperature. Stir repeatedly 4 times until the chitosan raw material is completely dissolved to obtain an alkaline chitosan solution. (2) Add 100 mL of alkaline chitin solution to Tween 85 and Span 60 and mix with mechanical stirring. Maintain the reaction temperature at -5 to 0 °C. Then add HCl to adjust the pH of the solution to about 7. After filtration, wash with ethanol, water and tert-butanol, and freeze-dry to obtain chitin microspheres. Disperse the aqueous solution containing 210 mg H2PtCl6 and 600 mg chitin microsphere powder with magnetic stirring for several hours to obtain a chitin microsphere suspension loaded with Pt metal precursor (Chitin-Pt). (3) The obtained chitin microsphere suspension loaded with Pt metal precursor was mixed with another part of alkaline chitin solution with a mass fraction of 5 wt.%; epichlorohydrin was added for crosslinking, and the volume ratio of epichlorohydrin to chitin mixture was 1:20. The mixture was mechanically stirred for several hours; the hydrogel was formed by curing in an oven, and after replacement with deionized water and organic solvent, it was freeze-dried or dried with supercritical carbon dioxide to obtain metal composite chitin aerogel (Chitin-Pt / AG). (4) The dried aerogel material is annealed in an inert or air atmosphere at a temperature of 800 °C and cooled to room temperature to obtain a nitrogen-doped chitin carbon-based platinum nanoparticle self-supporting electrode (Pt-CAE).

[0039] The microstructure of Pt-CAE was observed using double aberration scanning electron microscopy, and the results are as follows: Figure 1 As shown in the figure, platinum nanoparticles are uniformly dispersed on the carbon substrate.

[0040] Example 2 This embodiment provides a chitin-based carbon-supported palladium self-supporting electrode, which is fabricated using the following steps: (1) Add 6 g chitosan powder, 11 g NaOH and 4 g urea to 85 mL of water and stir evenly. Freeze at -35 ℃ and thaw at room temperature. Stir repeatedly 4 times until the chitosan raw material is completely dissolved to obtain an alkaline chitosan solution. (2) Add 100 mL of chitin solution to Tween 85 and Span 60 and mix with mechanical stirring. Maintain the reaction temperature at -5 to 0 °C. Then add HCl to adjust the pH of the solution to about 7. After filtration, wash with ethanol, water and tert-butanol, and freeze-dry to obtain chitin microspheres. Disperse the aqueous solution containing 211 mg Pd(OAc)2 and 600 mg chitin microsphere powder with magnetic stirring for several hours to obtain a chitin microsphere suspension (Chitin-Pd) loaded with Pd metal precursor. (3) The obtained chitin microsphere suspension loaded with Pd metal precursor was mixed with another part of a viscous alkaline chitin solution with a mass fraction of 5 wt.%; epichlorohydrin was added for crosslinking, and the volume ratio of epichlorohydrin to chitin mixture was 1:20. The mixture was mechanically stirred for several hours and cured in an oven to form a hydrogel. After replacement with deionized water and organic solvent, the hydrogel was freeze-dried or dried with supercritical carbon dioxide to obtain metal composite chitin aerogel (Chitin-Pd / AG). (4) The dried aerogel material is annealed in an inert or air atmosphere. After cooling to room temperature at 800 °C, a nitrogen-doped chitin carbon-based palladium nanoparticle self-supporting electrode (Pd-CAE) is obtained.

[0041] The microstructure of Pd-CAE was observed using double aberration scanning electron microscopy, and the results are as follows: Figure 2 As shown in the figure, palladium nanoparticles are uniformly dispersed on the carbon substrate.

[0042] Example 3 This embodiment provides a chitin-based carbon-based ruthenium oxide nanoparticle self-supporting electrode, which is fabricated using the following steps: (1) Add 6 g chitosan powder, 11 g NaOH and 4 g urea to 85 mL of water and stir evenly. Freeze at -35 ℃ and thaw at room temperature. Stir repeatedly 4 times until the chitosan raw material is completely dissolved to obtain an alkaline chitosan solution. (2) Under ice bath conditions, add 8 mL of RuCl3·xH2O solution (13 mg·mL) -1 Add the precursor dropwise to 100 mL of 20 wt.% H2O2 solution, stir at room temperature for 1 h, then add 1.0 g TiO2 (60 nm), stir at room temperature for 3 h; centrifuge to separate the obtained material, and vacuum dry at room temperature overnight; after drying, place the prepared precursor in a muffle furnace and anneal at 450 ℃ (5 ℃ / min) air flow for 4 h to obtain RuO2 / TiO2 composite; (3) The obtained RuO2 / TiO2 composite was mixed with a viscous alkaline chitin solution with a mass fraction of 5 wt.%. Epichlorohydrin was added for crosslinking at a volume ratio of 1:20, and the mixture was mechanically stirred for several hours. The mixture was cured in an oven to form a hydrogel. After being replaced with deionized water and organic solvent, the hydrogel was freeze-dried or dried with supercritical carbon dioxide to obtain a metal-composite chitin aerogel (Chitin-Ru / AG).

[0043] (4) The dried aerogel material is annealed in an inert or air atmosphere; after cooling to room temperature at 800 ℃, a nitrogen-doped chitin carbon-based nano-ruthenium oxide self-supporting electrode (denoted as Ru-CAE) is obtained.

[0044] The microstructure of Ru-CAE was observed using double aberration scanning electron microscopy, and the results are as follows: Figure 3 As shown in the figure, ruthenium oxide and titanium dioxide nanoparticles are uniformly dispersed on the carbon substrate.

[0045] Example 4 This embodiment provides a self-supporting electrode made of chitin-based carbon nano-nickel nanoparticles, which is fabricated using the following steps: (1) Add 6 g chitosan powder, 11 g NaOH and 4 g urea to 85 mL of water and stir evenly. Freeze at -35 ℃ and thaw at room temperature. Stir repeatedly 4 times until the chitosan raw material is completely dissolved to obtain an alkaline chitosan solution. (2) Add 100 mL of chitin solution to Tween 85 and Span 60 and mix with mechanical stirring. Maintain the reaction temperature at -5 to 0 °C. Then add HCl to adjust the pH of the solution to about 7. After filtration, wash with ethanol, water and tert-butanol, and freeze-dry to obtain chitin microspheres. Disperse the aqueous solution containing 443 mg Ni(acac)2 and 600 mg chitin microsphere powder with magnetic stirring for several hours to obtain a chitin microsphere suspension (Chitin-Ni) loaded with Ni metal precursor. (3) The obtained chitin microsphere suspension loaded with Ni metal precursor was mixed with another part of a viscous alkaline chitin solution with a mass fraction of 5 wt.%; epichlorohydrin was added for crosslinking, and the volume ratio of epichlorohydrin to chitin mixture was 1:20. The mixture was mechanically stirred for several hours; the hydrogel was formed by curing in an oven, and after replacement with deionized water and organic solvent, it was freeze-dried or dried with supercritical carbon dioxide to obtain metal composite chitin aerogel (Chitin-Ni / AG). (4) The dried aerogel material is annealed in an inert or air atmosphere. After cooling to room temperature at 800 ℃, a nitrogen-doped chitin carbon-based nickel nanoparticle self-supporting electrode (Ni-CAE) is obtained.

[0046] The microstructure of Pd-CAE was observed using transmission electron microscopy, and the results are as follows: Figure 4 As shown in the figure, nickel nanoparticles are uniformly dispersed on the carbon substrate.

[0047] Example 5 This embodiment provides a self-supporting electrode made of chitin-based carbon-based copper nanoparticles, which is fabricated using the following steps: (1) Add 6 g chitosan powder, 11 g NaOH and 4 g urea to 85 mL of water and stir evenly. Freeze at -35 ℃ and thaw at room temperature. Stir repeatedly 4 times until the chitosan raw material is completely dissolved to obtain an alkaline chitosan solution. (2) Add 100 mL of chitin solution to Tween 85 and Span 60 and mix with mechanical stirring. Maintain the reaction temperature at -5 to 0 °C. Then add HCl to adjust the pH of the solution to about 7. After filtration, wash with ethanol, water and tert-butanol, and freeze-dry to obtain chitin microspheres. Disperse the aqueous solution containing 285 mg Cu(OAc)2 and 600 mg chitin microsphere powder with magnetic stirring for several hours to obtain a chitin microsphere suspension loaded with Cu metal precursor (Chitin-Cu). (3) The obtained chitin microsphere suspension loaded with Cu metal precursor was mixed with another part of a viscous alkaline chitin solution with a mass fraction of 6 wt.%; epichlorohydrin was added for crosslinking, and the volume ratio of epichlorohydrin to chitin mixture was 1:20. The mixture was mechanically stirred for several hours; the hydrogel was formed by curing in an oven, and after replacement with deionized water and organic solvent, it was freeze-dried or dried with supercritical carbon dioxide to obtain metal composite chitin aerogel (Chitin-Cu / AG). (4) The dried aerogel material is annealed in an inert or air atmosphere. After cooling to room temperature at 800 ℃, a nitrogen-doped chitin carbon-based copper nanoparticle self-supporting electrode (Cu-CAE) is obtained.

[0048] The microstructure of Cu-CAE was observed using transmission electron microscopy, and the results are as follows: Figure 5 As shown in the figure, copper nanoparticles are uniformly dispersed on the carbon substrate.

[0049] Example 6 This embodiment uses Pd-CAE and Ru-CAE for water electrolysis to study the application performance of self-supporting electrodes. In 0.5 MH₂SO₄ solution, a three-electrode system is used, employing a self-supporting metal-carbon-based electrode (1 × 1 cm⁻¹). 2 A carbon rod and a silver / silver chloride (Ag / AgCl) electrode were used as the working electrode, counter electrode, and reference electrode, respectively, and the electrolysis of water anode and cathode was tested on a CHI760E electrochemical workstation. Figure 6 The test diagram shows the hydrogen evolution reaction at the cathode of Pd-CAE during water electrolysis; Figure 7 The diagram shows a test pattern of the oxygen evolution reaction at the anode of Ru-CAE during water electrolysis. In the hydrogen evolution reaction at the cathode, 10 mA cm⁻¹ -2 At a current density of only 43 mV, the Pd-based electrode (Pd-CAE) exhibited the lowest overpotential. Simultaneously, the material was tested in the anodic oxidation reaction in a 0.5 M H₂SO₄ electrolyte solution at a current density of 10 mA cm⁻¹. -2 The Ru-CAE overpotential is 288 mV, and it is stable for more than 10 hours in both HER and OER reactions, demonstrating excellent stability.

[0050] Example 7 As shown in Formula 1, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) of Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3The cathode was used as a cathode. The reaction chamber was then purged with nitrogen, and concentrated hydrochloric acid [HCl (12.0 mol / L)] (0.25 mL, 3.0 mmol), cyclohexane (2.0 mL), and MeCN (8.0 mL) were added sequentially. The reaction mixture was stirred and electrolyzed at 25 °C and 20 mA constant current for 3 h. After the reaction was complete, the solution was extracted with ethyl acetate. The yield, determined by gas chromatography with internal standard (using biphenyl as an internal standard), was 34%, with a corresponding Faraday efficiency of 91%.

[0051] In this embodiment, the same method was used to test the Faraday efficiency of commercially available platinum sheet electrodes and graphite felt electrodes, respectively. In comparison, the Faraday efficiencies of commercially available platinum sheet electrodes and graphite felt electrodes were only 55% and 66%, respectively, far inferior to the results of this invention.

[0052] Formula 1: .

[0053] Example 8 As shown in Formula 2, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) of Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The cathode was used as a cathode. The reaction chamber was then purged with nitrogen, and concentrated hydrochloric acid [HCl (12.0 mol / L)] (0.25 mL, 3.0 mmol), toluene (2.0 mL), and MeCN (8.0 mL) were added sequentially. The reaction mixture was stirred and electrolyzed at 25 °C and 20 mA constant current for 3 h. After the reaction was complete, the solution was extracted with ethyl acetate. The yield, determined by gas chromatography with internal standard (using biphenyl as an internal standard), was 19%, with a corresponding Faraday efficiency of 50%.

[0054] Formula 2: .

[0055] Example 9 As shown in Formula 3, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is placed into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) of Example 3. 3 As the anode, a nickel sheet (1.5×1.5×0.03cm) is used. 3The reaction vessel was then purged with nitrogen. LiBr (43.5 mg, 0.5 mmol) and nBu4NBF4 (164.5 mg, 0.5 mmol) were added to the glove box. After removing the reaction vessel from the glove box, cyclohexane (2.0 mL), MeCN (8.0 mL), and H2O (0.2 mL) were added sequentially. The reaction mixture was electrolyzed at 25 °C with a constant current of 20 mA for 3 h. After the reaction was complete, the solution was extracted with ethyl acetate. The yield, determined by gas chromatography with internal standard (using biphenyl as an internal standard), was 84%.

[0056] Formula 3: .

[0057] Example 10 As shown in Formula 4, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, a nickel sheet (1.5×1.5×0.03cm) is used. 3 The reaction vessel was then purged with nitrogen. LiBr (43.5 mg, 0.5 mmol) and nBu4NBF4 (164.5 mg, 0.5 mmol) were added in a glove box. After removing the reaction vessel from the glove box, toluene (2.0 mL), MeCN (8.0 mL), and H2O (0.2 mL) were added sequentially. The reaction mixture was electrolyzed at 25 °C with a constant current of 20 mA for 3 h. After the reaction was complete, the solution was extracted with ethyl acetate. The yield, determined by gas chromatography with internal standard (using biphenyl as an internal standard), was 69%.

[0058] Formula 4: .

[0059] Example 11 As shown in Formula 5, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is placed into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3The electrode was used as the cathode. The reaction cell was then purged with a nitrogen atmosphere, and concentrated nitric acid [HCl (68 wt.%)] (0.2 mL, 3.0 mmol), cyclohexane (2.0 mL), and MeCN (8.0 mL) were added sequentially. The reaction mixture was stirred and electrolyzed at 25 °C and 20 mA constant current for 3 h. After the reaction was complete, the solution was extracted with ethyl acetate. The yield, determined by gas chromatography with internal standard (using biphenyl as an internal standard), was 8%, corresponding to a Faradaic efficiency of 21%. The electrode activation efficiency of this embodiment is significant; without the electrode prepared in this application, the product could not be obtained from the electrochemical reaction.

[0060] Formula 5: .

[0061] Example 12 As shown in Formula 6, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is placed into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The reaction vessel was then purged with nitrogen. In a glove box, nBu4NBF4 (164.5 mg, 0.5 mmol) was added sequentially. After removing the reaction vessel from the glove box, tetrahydrofuran (2.0 mL), MeCN (8.0 mL), concentrated hydrochloric acid [HCl (12.0 mol / L)] (17 μL, 0.2 mmol), and benzyl alcohol (108.0 mg, 1.0 mmol) were added. The reaction mixture was electrolyzed at 0 °C with a constant current of 20 mA for 6 h. After the reaction was complete, the solution was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography using petroleum ether and ethyl acetate as eluents, yielding a pure product in 52% yield.

[0062] Figure 8 , Figure 9 The proton NMR spectra of the tetrahydrofuran etherification product are shown below, with the corresponding NMR spectral data as follows: 1 H NMR (400 MHz, CDCl3) δ 7.35-7.24 (m, 5H), 5.23-5.21 (m, 1H), 4.72(d, J = 12.0 Hz, 1H), 4.47 (d, J = 11.6 Hz, 1H), 3.98-3.88 (m, 2H), 2.10-1.80 (m, 4H). 13 C NMR (101 MHz, CDCl3) δ 138.23, 128.30, 127.81, 127.44, 103.01, 68.70, 66.96, 32.28, 23.40. Formula Six: .

[0063] Example 13 As shown in Formula 7, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The reaction vessel was then purged with nitrogen. In a glove box, nBu4NBF4 (164.5 mg, 0.5 mmol) was added. After removing the reaction vessel from the glove box, tetrahydrofuran (2.0 mL), MeCN (8.0 mL), concentrated hydrochloric acid [HCl (12.0 mol / L)] (17 μL, 0.2 mmol), and n-hexanol (102.0 mg, 1.0 mmol) were added sequentially. The reaction mixture was electrolyzed at 0 °C with a constant current of 20 mA for 6 h. After the reaction was complete, the solution was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography using petroleum ether and ethyl acetate as eluents, yielding a pure product in 85% yield.

[0064] The nuclear magnetic resonance spectral data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.11(dd, J = 4.4, 2.0 Hz, 1H), 3.92-3.83 (m,2H), 3.65 (dt, J = 9.6, 6.8 Hz, 1H), 3.36 (dt, J = 9.2, 6.4 Hz, 1H), 2.05-1.78(m, 4H), 1.59-1.52 (m, 2H), 1.36-1.27 (m, 6H), 0.89 (t, J = 7.2 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 103.67, 67.24, 66.67, 32.25, 31.58, 29.64,25.80, 23.45, 22.56, 13.98. Formula 7: .

[0065] Example 14 As shown in Formula 8, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The reaction vessel was then purged with nitrogen. In a glove box, nBu4NBF4 (164.5 mg, 0.5 mmol) was added. After removing the reaction vessel from the glove box, tetrahydrofuran (2.0 mL), MeCN (8.0 mL), concentrated hydrochloric acid [HCl (12.0 mol / L)] (17 μL, 0.2 mmol), and 5-hexen-1-ol (100.0 mg, 1.0 mmol) were added sequentially. The reaction mixture was electrolyzed at 0 °C with a constant current of 20 mA for 6 h. After the reaction was complete, the solution was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography using petroleum ether and ethyl acetate as eluents, yielding a pure product in 90% yield.

[0066] The nuclear magnetic resonance spectral data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.86-5.76 (m, 1H), 5.10 (d, J = 4.4 Hz, 1H),5.03-4.93 (m, 2H), 3.92-3.83 (m, 2H), 3.66 (dt, J = 9.6, 6.8 Hz, 1H), 3.37 (dt, J = 9.6, 6.8 Hz, 1H), 2.10-1.78 (m, 6H), 1.61-1.54 (m, 2H), 1.47-1.40 (m, 2H). 13C NMR (101 MHz, CDCl3) δ 138.72, 114.39, 103.68, 66.95, 66.71,33.46, 32.26, 29.14, 25.45, 23.45. Formula 8: .

[0067] Example 15 As shown in Equation 9, in this embodiment, a dried three-necked flask (15.0 mL) containing a magnetic magnet is loaded with the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) from Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The reaction vessel was then purged with nitrogen. In a glove box, nBu4NBF4 (164.5 mg, 0.5 mmol) was added. After removing the reaction vessel from the glove box, tetrahydrofuran (2.0 mL), MeCN (8.0 mL), concentrated hydrochloric acid [HCl (12.0 mol / L)] (17 μL, 0.2 mmol), and L-menthol (156.0 mg, 1.0 mmol) were added sequentially. The reaction mixture was electrolyzed at 0 °C with a constant current of 20 mA for 6 h. After the reaction was complete, the solution was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography using petroleum ether and ethyl acetate as eluents, yielding a pure product in 70% yield.

[0068] The nuclear magnetic resonance spectral data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.32-5.19 (m, 1H), 3.97-3.81 (m, 2H), 3.48-3.26 (m, 1H), 2.20-1.78 (m, 6H), 1.67-1.57 (m, 2H), 1.46-1.31 (m, 1H), 1.21-1.14 (m, 1H), 1.05-0.75 (m, 12H). 13C NMR (101 MHz, CDCl3) δ 105.32, 99.34, 78.63, 73.53, 66.72, 66.52,48.70, 48.02, 43.45, 40.01, 34.58, 34.40, 32.57, 32.51, 31.67, 31.40, 25.54,25.34, 23.59, 23.48, 23.26, 23.10, 22.35, 22.26, 21.13, 21.04, 16.25, 15.49. Formula Nine: .

[0069] Example 16 As shown in Formula 10, a dried three-necked flask (15.0 mL) containing a magnetic magnet was placed into the ruthenium-loaded chitin-based carbon-based self-supporting electrode Ru-CAE (2.0 × 1.0 × 0.2 cm) of Example 3. 3 As the anode, the palladium-loaded chitin-based self-supporting electrode Pd-CAE (2.0 × 1.0 × 0.2 cm) of Example 2 was used. 3 The reaction vessel was used as the cathode. The reaction chamber was then purged with a nitrogen atmosphere. In a glove box, nBu4NBF4 (164.5 mg, 0.5 mmol) was added sequentially. After removing the reaction chamber from the glove box, tetrahydrofuran (2.0 mL), MeCN (8.0 mL), concentrated hydrochloric acid [HCl (12.0 mol / L)] (17 μL, 0.2 mmol), and fructose diacetone (260.0 mg, 1.0 mmol) were added. The reaction mixture was electrolyzed at 0 °C with a constant current of 20 mA for 6 h. After the reaction was complete, the solution was extracted with ethyl acetate. The combined organic phases were dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The product was purified by silica gel column chromatography using petroleum ether and ethyl acetate as eluents, yielding a pure product in 71% yield.

[0070] The nuclear magnetic resonance spectral data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 5.23-5.17 (m, 1H), 4.61-4.58 (m, 1H), 4.33(d, J = 3.2 Hz, 1H), 4.24-4.22 (m, 1H), 3.96-3.44 (m, 6H), 2.04-1.79 (m, 4H), 1.54-1.34 (m, 12H). 13C NMR (101 MHz, CDCl3) δ 108.84, 108.81, 108.24, 108.17, 104.09,103.73, 102.66, 102.50, 70.92, 70.89, 70.18, 70.07, 69.99, 68.16, 67.69,66.81, 66.74, 60.89, 60.86, 32.12, 32.09, 26.48, 26.42, 25.78, 25.77, 25.22,25.11, 23.99, 23.95, 23.22, 23.08. Formula 10: .

[0071] Based on the above preparation and application, it can be seen that the preparation method provided by this invention utilizes the hydrogen bonding between chitin molecules to facilitate direct self-assembly into an aerogel. Simultaneously, the molecular chain has a well-defined structural unit, with numerous nitrogen- and oxygen-containing functional groups that can directly anchor metals and are easily modified. The interpenetrating network formed by nanofibers can transport small molecule reactants. The self-formed microspheres can effectively reinforce the chitin aerogel network, disperse metal sites, and prevent aggregation. The nitrogen- and oxygen-doped chitin carbon-based aerogel obtained after calcination exhibits good conductivity and reactivity, and enhanced resistance to electrochemical corrosion. This results in a highly loaded, highly active, and highly stable acidic water electrolysis catalyst material. Furthermore, the self-supporting electrode morphology can be well applied to organic electrosynthesis systems.

[0072] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a self-supporting electrode of chitin carbon-supported metal, characterized by, The method comprises the following steps: (1) dissolving chitin by low-temperature alkaline dissolution method to prepare an alkaline chitin solution; (2) preparing a chitin microsphere suspension loaded with a metal precursor or a metal oxide precursor; The preparation of the chitin microsphere suspension loaded with the metal precursor comprises the following steps: preparing chitin microspheres from the alkaline chitin solution by emulsion polymerization, mixing a metal salt solution with the chitin microspheres to achieve adsorption and loading, and obtaining the chitin microsphere suspension loaded with the metal precursor; the metal oxide precursor comprises a metal oxide or a composite of metal oxides; (3) mixing the chitin microsphere suspension loaded with the metal precursor or the metal oxide precursor with the alkaline chitin solution to obtain a chitin mixture; then adding a crosslinking agent, crosslinking and solidifying to form a hydrogel, and then replacing and drying to obtain a metal-composite chitin aerogel; (4) annealing the metal-composite chitin aerogel to obtain a self-supporting electrode of chitin-carbon-loaded metal.

2. The method for preparing a self-supporting electrode of a chitin-carbon-supported metal according to claim 1, characterized by, In the step (1), the preparation method of the alkaline chitin solution comprises the following steps: mixing chitin, sodium hydroxide, urea and water, freezing at -40 to -30 ℃, thawing at room temperature, and repeatedly mixing until the solution is uniform and transparent as a whole to obtain the alkaline chitin solution; the mass ratio of the chitin, sodium hydroxide, urea and water is 2 to 6:10 to 100:1 to 10:

100.

3. The method for preparing a self-supporting electrode of a chitin-carbon-supported metal according to claim 1, characterized by: In the step (2), the preparation method of the chitin microsphere suspension loaded with the metal precursor comprises the following steps: mixing the alkaline chitin solution with an emulsifier, keeping the reaction temperature at -5 to 0 ℃, then adjusting the pH of the solution to neutral, washing with ethanol, water and tert-butyl alcohol after filtration, and drying to obtain chitin microspheres; mixing and dispersing a metal salt solution with the chitin microspheres to obtain the chitin microsphere suspension loaded with the metal precursor.

4. The process for the preparation of a self-supporting electrode of chitin carbon-based supported metal according to claim 3, characterized by the fact that: The emulsifier comprises Tween 85 and Span 60; the mass ratio of chitin in the alkaline chitin solution to the added Tween 85 and Span 60 is 4:5 to 10:10 to 50.

5. The method for preparing a self-supporting electrode of a chitin carbon-supported metal according to claim 1, characterized by: In the step (2), the metal type of the metal salt solution comprises at least one of Pt, Pd, Ru, Cu, Ni, Co, Fe and Ti; the loading amount is 1 wt.% to 5 wt.% of the chitin microspheres; and the metal type of the metal oxide precursor comprises at least one of Pt, Pd, Ru, Cu, Ni, Co, Fe and Ti.

6. The process for the preparation of a self-supporting electrode of chitin carbon-based supported metal according to claim 1, characterized by the fact that: In the step (2), the volume of the alkaline chitin solution is the same as the volume of the alkaline chitin solution in the step (3); in the step (3), the crosslinking agent comprises at least one of epichlorohydrin, citric acid and benzoyl peroxide; and the volume ratio of the crosslinking agent to the chitin mixture is 1:10 to 100.

7. The process for the preparation of a self-supporting electrode of chitin carbon-based supported metal according to claim 1, characterized by the fact that: In the step (4), the annealing treatment is carried out in an inert or air atmosphere, the treatment temperature is 400 to 900 ℃, and the treatment time is 1 to 5 h.

8. A self-supporting electrode of chitin carbon-supported metal, characterized by: The method is prepared by any one of claims 1 to 7.

9. Use of a chitin carbon-based metal-supported self-supporting electrode according to claim 8, characterized in that, It comprises: a water electrolysis reaction or an anodic oxidation alkane functionalization reaction.

10. Use of a chitin-carbon based metal-loaded self-supporting electrode according to claim 9, characterized in that: The anodic oxidation alkane functionalization reaction includes one of a chlorine radical-mediated alkane chlorination reaction, a bromine radical-mediated alkane bromination reaction, a nitro radical-mediated alkane nitration reaction, and a chlorine radical-mediated alkane etherification reaction.

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