1. Natural nanomaterials

Sea turtles lay their eggs on the beaches of Florida in the United States, but after hatching, the tiny hatchlings must swim all the way to waters near Britain in search of food if they are to survive and grow. Once they’ve grown up, these sea turtles return once again to the beaches of Florida to lay their own eggs. This round-trip journey takes about 5 to 6 years. So how do sea turtles manage to undertake such long-distance migrations spanning tens of thousands of kilometers? The answer lies in the nanomagnetic materials housed in their heads, which enable them to navigate with pinpoint accuracy.

When biologists studied why creatures such as pigeons, dolphins, butterflies, and bees never get lost, they also discovered that these organisms contain nanomaterials within their bodies that help them navigate.

2. Nanomagnetic Materials

Most nanomaterials used in practical applications are artificially synthesized. Nanomagnetic materials exhibit highly unique magnetic properties: due to their small particle size, they possess a single-domain structure and exhibit exceptionally high coercivity. Magnetic recording materials made from these nanoparticles not only deliver superior sound quality, image clarity, and signal-to-noise ratios but also boast a recording density that is several dozen times higher than that of γ-Fe2O3. Furthermore, strongly magnetic superparamagnetic nanoparticles can be formulated into magnetic fluids, which find applications in electroacoustic devices, damping components, rotary seals, lubrication systems, and mineral processing.

3. Nanoceramic Materials

In traditional ceramic materials, grain boundaries do not easily slide, making these materials brittle and requiring high sintering temperatures. By contrast, nanoceramics feature small grain sizes, allowing grains to move more readily over one another. As a result, nanoceramic materials exhibit exceptionally high strength, remarkable toughness, and excellent ductility. These unique properties enable nanoceramic materials to undergo cold working at room temperature or near-room-temperature conditions. If nanoceramic particles are shaped at near-room-temperature conditions and then subjected to surface annealing treatment, the resulting material can possess both the hardness and chemical stability typical of conventional ceramics on its surface, while maintaining the high ductility inherent to nanomaterials in its interior—thus yielding a high-performance ceramic with superior overall performance.

4. Nanosensors

Ceramics such as nano-zirconium dioxide, nickel oxide, and titanium dioxide are highly sensitive to temperature changes, infrared radiation, and automobile exhaust gases. Therefore, they can be used to fabricate temperature sensors, infrared detectors, and automobile exhaust gas detectors with significantly higher sensitivity than conventional ceramic sensors of the same type.

5. Nano-tilted functional materials

In hydrogen-oxygen engines used in aerospace applications, the inner surface of the combustion chamber must be able to withstand high temperatures, while its outer surface needs to be in contact with a coolant. Therefore, the inner surface is made of ceramic, whereas the outer surface is made of a metal with excellent thermal conductivity. However, it is extremely difficult to bond bulk ceramics and metals together. If, during manufacturing, the composition between the metal and ceramic is allowed to vary continuously and gradually—so that the metal and ceramic “interpenetrate each other”—they can be joined to form a functionally graded material. The term "functionally graded" here means that the compositional variation within the material resembles a sloping ladder. When metal and ceramic nanoparticles are mixed according to a gradual variation in their respective contents and then sintered and shaped, this approach enables the material to meet the requirements of high-temperature resistance on the combustion chamber’s inner side and excellent thermal conductivity on its outer side.

6. Nanoscale Semiconductor Materials

When semiconductor materials such as silicon and gallium arsenide are fabricated into nanomaterials, they exhibit many outstanding properties. For example, the quantum tunneling effect in nanoscale semiconductors causes anomalous electron transport in certain semiconductor materials, leading to reduced conductivity. Moreover, the thermal conductivity coefficient also decreases as particle size diminishes, and can even become negative. These unique characteristics play a crucial role in fields such as large-scale integrated circuits and optoelectronic devices.

Semiconductor nanoparticles can be used to fabricate new types of solar cells with high photoelectric conversion efficiency that can function normally even on cloudy or rainy days. Because the electrons and holes generated when nanoscale semiconductor particles are exposed to light possess strong reducing and oxidizing capabilities, they can oxidize toxic inorganic substances and degrade most organic compounds, ultimately producing non-toxic, odorless substances such as carbon dioxide and water. Therefore, semiconductor nanoparticles can be harnessed to catalyze the decomposition of both inorganic and organic materials using solar energy.

7. Nanocatalytic Materials

Nanoparticles are excellent catalysts because of their small size, which results in a large surface-to-volume ratio. The chemical bonding and electronic states on the surface differ from those inside the particles, and the surface atoms have incomplete coordination. These factors lead to an increase in active sites on the surface, giving nanoparticles the essential conditions required to function as catalysts.

Nanoparticles of nickel or copper-zinc compounds serve as excellent catalysts for the hydrogenation of certain organic substances, offering a viable alternative to the expensive platinum or palladium catalysts. Nanoscale black platinum catalysts can reduce the temperature required for the oxidation of ethylene from 600 ℃ down to room temperature.

8. Medical Applications

Red blood cells in the bloodstream measure between 6,000 and 9,000 nanometers in diameter, whereas nanoparticles are only a few nanometers in size—significantly smaller than red blood cells. As a result, nanoparticles can move freely throughout the bloodstream. If various therapeutically active nanoparticles are injected into different parts of the human body, they can be used to detect abnormalities and deliver targeted treatments, offering far superior efficacy compared to traditional methods such as injections and oral medications.

Carbon materials exhibit excellent blood compatibility; in the 21st century, artificial heart valves are typically fabricated by depositing a layer of pyrolytic carbon or diamond-like carbon onto a material substrate. However, this deposition process is relatively complex and generally suitable only for producing hard materials.

Interventional balloons and catheters are typically made from highly elastic polyurethane materials. By incorporating carbon nanotubes—materials composed of pure carbon atoms with a high aspect ratio—into this highly elastic polyurethane, we can ensure that the resulting polymer material retains its excellent mechanical properties and ease of processing and molding, while also achieving improved biocompatibility with blood.

The experimental results show that this nanocomposite material causes a reduced degree of hemolysis in blood and also reduces the activation of platelets.

The use of nanotechnology is making pharmaceutical manufacturing processes increasingly sophisticated, enabling the direct manipulation of atoms and molecules at the nanomaterials’ scale to create drugs with specific functions. Nanomaterial particles will facilitate the delivery of drugs within the human body; smart drugs coated with several layers of nanoparticles can actively locate and attack cancer cells or repair damaged tissues once they enter the body. New diagnostic devices employing nanotechnology require only a small blood sample and can detect various diseases by analyzing proteins and DNA contained within it. By modifying the surfaces of nanoparticles through their unique properties, we can create drug-delivery carriers that are targeted, capable of controlled release, and easy to detect—offering novel approaches for treating localized lesions in the body and opening up new avenues for drug development.

9. Nanocomputer

The electronic computer was born in 1945, developed jointly by American universities and the U.S. Army Department. It used a total of 18,000 vacuum tubes, weighed 30 tons, and occupied an area of about 170 square meters—truly a colossal machine. Yet, it could only perform 5,000 calculations per second.

After half a century, thanks to advances in integrated circuit technology, microelectronics, information storage technology, computer languages, and programming techniques, computer technology has undergone rapid development. Today’s computers are compact and exquisite—they can easily fit on a computer desk—and their weight is only one ten-thousandth of that of their predecessors. Yet their computing speed far surpasses that of first-generation electronic computers.

If nanotechnology were used to build the components of electronic computers, the computers of the future would be “molecular computers.” Such computers would be far smaller than today’s computers, and they would also bring substantial societal benefits in terms of material and energy savings.

Card readers that can read from hard disks and nanomaterial-based storage chips with storage capacities thousands of times greater than those of conventional chips have already entered mass production. After computers widely adopt nanomaterials, they could shrink down to become “handheld computers.”

10. Nanocarbon tubes

In 1991, Japanese technicians prepared a material called “nanotubes of carbon,” which consists of tubular structures formed by numerous hexagonal rings of carbon atoms. These tubes can also be composed of several concentrically arranged tubular structures nested one inside the other. Both single-layer and multi-layer tubular structures typically have sealed ends at both ends, as shown in the figure.

These tube-like structures, composed of carbon atoms, have diameters and lengths measured in the nanometer range, which is why they are called carbon nanotubes. Their tensile strength is 100 times greater than that of steel, and their electrical conductivity even surpasses that of copper.

By heating nanotubes in air to around 700 ℃, the carbon atoms at the sealed ends of the tubes are oxidized and broken down, thereby opening up the nanotubes. Next, a low-melting-point metal (such as lead) is vaporized by an electron beam and then condensed onto the open-ended nanotubes. Due to the siphon effect, the metal flows into the hollow core of the nanotubes. Because the diameter of the nanotubes is extremely small, the metal filaments formed inside the tubes are also exceptionally thin—referred to as nanowires. These nanowires exhibit size-dependent effects that give rise to superconductivity. Therefore, combining nanotubes with nanowires could potentially lead to the development of a new type of superconductor.

Nanotechnology is still in its infancy in countries around the world. Although a few nations—such as the United States, Japan, and Germany—have already established initial foundations, they are still actively engaged in research, and the emergence of new theories and technologies remains in full swing. China has been making great efforts to catch up with the world’s leading standards, and its research community is steadily growing.

11. Home appliances

Multifunctional plastics made from nanomaterials possess antibacterial, odor-removing, anti-corrosion, anti-aging, and UV-resistant properties. They can be used as antibacterial and odor-removing plastics in the casings of refrigerators and air conditioners.

12. Environmental Protection

The field of environmental science will see the emergence of uniquely functional nanomembranes. These membranes can detect pollution caused by chemical and biological agents and can also filter out these agents, thereby eliminating contamination.

13. Textile Industry

By adding nano-SiO2, nano-ZnO, and a compounded powder of nano-SiO2 to synthetic fiber resins, and then spinning the fibers and weaving them into fabrics, it is possible to produce underwear and clothing with antibacterial, antifungal, deodorizing, and ultraviolet (UV) radiation-resistant properties. These materials can be used to manufacture antimicrobial underwear and other products, as well as functional fibers that meet the requirements of the defense industry for UV radiation resistance.

14. Mechanical Industry

Using nanomaterial technology to apply nano-powder coatings to the metal surfaces of critical mechanical components can enhance the wear resistance, hardness, and service life of mechanical equipment.