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CN-121975178-A - Aerogel with vertical pore gradient structure, and preparation method and application thereof

CN121975178ACN 121975178 ACN121975178 ACN 121975178ACN-121975178-A

Abstract

The invention discloses aerogel with a vertical pore gradient structure, a preparation method and application thereof, wherein the method comprises the steps of pulping and purifying cellulose raw materials, providing a uniform substrate for structure regulation and control, and stabilizing moisture response performance; the method comprises the steps of preparing a porous nano-fiber, carrying out catalytic oxidation on the surface of cellulose by a TEMPO/NaBr/NaClO system, introducing hydrophilic groups such as carboxyl groups, improving the hygroscopicity and ionic conductivity of the fiber, carrying out filter pressing homogenization treatment to form a fiber network with high specific surface area, reducing local resistance difference, stabilizing output voltage and current, carrying out directional freezing to induce vertical arrangement of the nano-fiber, constructing a vertical pore gradient structure, enabling moisture to rapidly diffuse to form a stable humidity gradient field, driving ions to continuously and directionally migrate, improving energy conversion efficiency and output power stability, and finally enhancing the bonding force among the fibers by metal salt crosslinking to form a three-dimensional network, improving mechanical strength and swelling resistance, preventing structural collapse, ensuring long-term reliability of a device in a wet environment, and prolonging service life.

Inventors

  • HAO LIJUAN
  • LIU CHAO
  • WANG YAQI
  • SONG YIHAO

Assignees

  • 陕西科技大学

Dates

Publication Date
20260505
Application Date
20260310

Claims (10)

  1. 1. A method for preparing an aerogel having a vertical pore gradient structure, comprising the steps of: S1, pulping and purifying a cellulose raw material to prepare purified cellulose; S2, placing the purified cellulose in a catalytic oxidation solution for catalytic oxidation treatment, performing filter pressing treatment, and dispersing the obtained filter cake in water to obtain oxidized nanofiber homogenate, wherein the catalytic oxidation solution consists of sodium hypochlorite, 2, 6-tetramethylpiperidine-1-oxygen free radical and sodium bromide; s3, directionally freezing the oxidized nanofiber homogenate to prepare frozen gel; s4, immersing the frozen gel into a metal salt solution for standing and crosslinking reaction, and then performing vacuum freeze drying treatment to obtain the aerogel with the vertical pore gradient structure.
  2. 2. The method of claim 1, wherein the cellulosic feedstock comprises at least one of paper, wood, cotton, and silk cocoons.
  3. 3. The preparation method of the aerogel with the vertical pore gradient structure, according to claim 1, is characterized in that the ratio of the cellulose raw material to the catalytic oxidation solution to the metal salt solution is (10-15): (8-16): (5-8) in parts by weight.
  4. 4. The method for preparing aerogel with a vertical pore gradient structure according to claim 1, wherein in the step S2, mechanical stirring treatment is performed first and then ultrasonic crushing treatment is repeated for a plurality of times during catalytic oxidation treatment, wherein the stirring speed is 2500-3500r/min and the stirring time is 3.5-4.5 h during the mechanical stirring treatment.
  5. 5. The method for preparing aerogel having a vertical pore gradient structure according to claim 1, wherein in step S2, the pH of the system is adjusted to 9-11 during the catalytic oxidation treatment.
  6. 6. The method for preparing aerogel having a vertical pore gradient structure according to claim 1, wherein in step S3, the time of directional freezing is 20-30 min.
  7. 7. The method according to claim 1, wherein in the step S4, the metal salt solution is at least one of Ca 2+ 、Al 3+ 、Mg 2+ 、Zn 2+ 、Ti 4+ and a soluble salt of Zr 4+ metal ion.
  8. 8. The method for preparing aerogel having a vertical pore gradient structure according to claim 1, wherein in step S4, the time of the standing crosslinking reaction is 24-48 h.
  9. 9. Aerogel having a vertical pore gradient structure, characterized in that it is obtainable by a process according to any one of claims 1 to 8.
  10. 10. Use of an aerogel having a vertical pore gradient structure as claimed in claim 9 in a moisture vapour generator.

Description

Aerogel with vertical pore gradient structure, and preparation method and application thereof Technical Field The invention belongs to the technical field of wet gas power generation, and relates to aerogel with a vertical pore gradient structure, and a preparation method and application thereof. Background In the great background of globalization actively advancing the development of clean energy technology, the human society is accelerating to a low-carbon and sustainable future. The wide application of clean energy not only effectively relieves the environmental pollution problem caused by the traditional fossil energy, but also provides strong power for the optimization and upgrading of the global energy structure. People enjoy various benefits brought by clean energy development as much as possible, such as air quality improvement, energy cost reduction and the like, and meanwhile, how to ensure stable and all-weather energy supply becomes an important challenge to be solved in the current energy field. Particularly, wind energy, solar energy and other common clean energy sources have high power generation efficiency depending on natural environment and geographical conditions, such as wind speed, illumination intensity and the like, and the stability and reliability of power supply are limited to a certain extent. In this context, moisture power generation has emerged as an emerging technology that ingeniously utilizes the interaction of materials with moisture in the environment to create a potential difference, thereby enabling efficient conversion of energy. The innovative technology provides a new thought for solving the intermittent problem of clean energy supply, and has important application potential and wide development prospect. In recent years, research on a wet gas power generation technology has been remarkably advanced, and researchers continuously explore novel functional materials to optimize the structural design of a device so as to improve the energy conversion efficiency and the output power. However, despite certain efforts, the prior art moisture generators still have problems. In the structural design aspect, accurate control and uniform distribution are difficult to realize by pore structure construction in the device, the energy conversion process is unstable, the output power fluctuation is large, and the requirement of stable power supply in practical application is difficult to meet. In terms of material stability, functional materials used by the wet gas generator, especially partial biomass derived materials, have serious defects in physical and chemical stability under the continuous wet working condition, and are easy to generate performance attenuation or structural failure, so that the long-term reliability and the cycle life of the device are greatly influenced. In addition, in the aspect of application and popularization, the preparation process of the current wet gas generator is generally complex, so that the production cost is high, and the wet gas generator becomes a main obstacle for restricting the mass production and the wide application of the wet gas generator. Disclosure of Invention Aiming at the problems in the prior art, the invention provides aerogel with a vertical pore gradient structure, and a preparation method and application thereof, thereby solving the technical problems that the energy conversion of a wet gas generator is unstable, the fluctuation of output power is large, and the reliability and the service life of a device are influenced by poor material stability in the prior art. The invention is realized by the following technical scheme: a method for preparing an aerogel having a vertical pore gradient structure, comprising the steps of: S1, pulping and purifying a cellulose raw material to prepare purified cellulose; S2, placing the purified cellulose in a catalytic oxidation solution for catalytic oxidation treatment, performing filter pressing treatment, and dispersing the obtained filter cake in water to obtain oxidized nanofiber homogenate, wherein the catalytic oxidation solution consists of sodium hypochlorite, 2, 6-tetramethylpiperidine-1-oxygen free radical and sodium bromide; s3, directionally freezing the oxidized nanofiber homogenate to prepare frozen gel; s4, immersing the frozen gel into a metal salt solution for standing and crosslinking reaction, and then performing vacuum freeze drying treatment to obtain the aerogel with the vertical pore gradient structure. Preferably, the cellulose raw material comprises at least one of paper, wood, cotton and silkworm cocoons. Preferably, the ratio of the cellulose raw material to the catalytic oxidation solution to the metal salt solution is (10-15)/(8-16)/(5-8) in parts by mass. Preferably, in the step S2, during the catalytic oxidation treatment, mechanical stirring treatment is firstly carried out, and then ultrasonic grinding treatment is repeated for a plurality of times, wherei