Electrospinning Equipment: Electrospun Carbon Nanofiber Mats for Air Pollutant Detection

1. Research Background

Air pollution has become a global environmental issue, posing a serious threat to human health and the ecosystem. There is an urgent need for technologies that can efficiently detect air pollutants. In recent years, electrospun carbon nanofiber mats (ECNMs) have attracted significant attention in the sensor field due to their unique structural properties, such as high specific surface area, porosity, and excellent electrical conductivity. They show great potential, especially in air pollutant detection. It is worth mentioning that during the preparation of ECNMs, an electrospinning machine is a crucial device that enables the formation of nanofibers with desired characteristics.

2. Research Abstract

This article reviews the latest progress of electrospun carbon nanofiber mats in sensor technology for air pollutant detection. It details the preparation methods, functionalization approaches, and applications in the detection of gases, particulate matter, and heavy metals. By optimizing the material structure and surface modification, ECNMs exhibit significant advantages in selectivity, sensitivity, and stability, and are expected to become highly efficient sensor materials in the fields of environmental monitoring and health protection in the future. The use of an electrospinning machine is fundamental in obtaining ECNMs with tailored properties for these applications.

3. Main Research Content

(1) Preparation of Electrospun Carbon Nanofiber Mats

The preparation of electrospun carbon nanofiber mats involves a multi-step process, and material selection is the first step. Polymer materials are divided into natural and synthetic types. Natural polymers such as lignin and synthetic polymers such as polyacrylonitrile (PAN) are commonly used in the preparation due to their good carbonization properties. After selecting the polymer, it needs to be dissolved in a suitable solvent, such as dimethylformamide (DMF). The solubility and volatility of these solvents are crucial for the electrospinning process.

The next is the key electrospinning step. In this process, an electric field is applied to the polymer solution or melt, causing the solution to form a Taylor cone under the action of the electric field force. When the electric field force exceeds the surface tension of the solution, nanofibers are formed, and the solvent evaporates. This process is carried out using an electrospinning machine, which allows for precise control of parameters to obtain nanofibers with specific diameters and morphologies. Taking PAN as an example, the preparation process also requires stabilization and carbonization treatments. First, stabilization is carried out in an oxygen-rich environment to improve thermal stability, usually by heating to 280°C. Then, high-temperature carbonization is carried out in an inert atmosphere, usually at a temperature higher than 800°C, so that the polymer is converted into a pure carbon nanofiber mat.

The article explores the impact of multiple electrospinning techniques on fiber properties: The needle-based electrospinning technique can precisely control the fiber diameter and alignment but has a relatively low production efficiency; the needleless electrospinning technique generates fibers directly from the liquid surface through a rotating or stationary spinneret, with high production efficiency but slightly inferior fiber uniformity (see Figure 1).

Figure 1a and Figure 1b show the microstructures of electrospun carbon nanofiber mats, imaged by atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM) respectively, intuitively presenting the surface characteristics and alignment of the fibers.

(2) Functionalization and Surface Modification of Carbon Nanofiber Mats

To improve the selectivity of sensors, researchers modify the surface of carbon nanofiber mats through covalent and non-covalent functionalization methods. For example, chemical vapor deposition (CVD) technology can deposit metal nanoparticles on the fiber surface, significantly enhancing the detection sensitivity to specific gases; the molecular imprinting technique creates specific binding sites in the fibers to achieve highly selective detection of target pollutants (see Figure 2).

Figure 2 shows the experimental setup of a ZnO-MWCNT nanocomposite sensor and its detection performance for ammonia, demonstrating the crucial role of functionalization in improving sensor performance.

(3) Sensor Applications

The article summarizes various applications of electrospun carbon nanofiber mats in air pollutant detection. Functionalized carbon nanofiber mats can be used to detect gas pollutants such as volatile organic compounds (VOCs), nitrogen oxides (NOx), sulfur dioxide (SO2), and carbon monoxide (CO), showing high sensitivity and low detection limits. For example, the detection sensitivity of N-doped carbon nanofibers to heavy metal ions is an order of magnitude higher than that of undoped fibers; porous carbon nanofibers significantly enhance the adsorption capacity for low-concentration pollutants through their rich pore structures (see Table 1).

Table 1 lists different types of carbon nanofibers and their applications in pollutant detection, including graphitized carbon nanofibers (GCNFs), doped carbon nanofibers (such as N-doped CNFs), and porous carbon nanofibers (PCNFs).

(4) Innovations and Discoveries

Remarkable Material Performance Advantages: Through surface modification and functionalization treatments, electrospun carbon nanofiber mats exhibit remarkable sensitivity and selectivity in gas detection. For example, ZnO/Pd nanofibers show excellent detection performance for ammonia and hydrogen in a low-oxygen environment, with response speed and sensitivity superior to traditional materials.

Diverse Functionalization and Modification Techniques: The research uses a variety of functionalization and surface modification methods, such as covalent functionalization, non-covalent functionalization, CVD, molecular imprinting, and surface activation, effectively improving the selectivity and sensitivity of electrospun carbon nanofiber mats and providing technical support for the precise detection of specific pollutants.

Extensive and Innovative Application Scenarios: Carbon nanofiber-based sensors not only play a role in traditional environmental monitoring but are also innovatively applied to wearable devices, enabling real-time monitoring of personal exposure to air pollutants and expanding the application scope of sensors.

4. Conclusions

This research not only demonstrates the great potential of electrospun carbon nanofiber mats in air pollutant detection but also provides new ideas for the development of future sensor technologies. By optimizing the material structure and surface modification, these nanofiber mats are expected to be widely used in fields such as environmental monitoring, industrial safety, and health protection.

Electrospinning Nanofibers Article Source:

https://doi.org/10.3390/engproc2024067082