At present, nanotechnology is in the ascendant after decades of development. As an innovative technology at the micro-nano scale, nanotechnology can produce new materials with high flexibility, conductivity, durability, the use of nano-instruments and the preparation of nanoparticles have also made significant changes in various fields of science, industry and daily life, although the nano is small, its use is large, especially in the energy field.
People have never valued energy as much as they do today, and when people are once again facing an energy iteration, it also means that a new era of energy is accelerating. The key to the energy transition is to be able to develop and use new energy sources on a large scale, which first needs to ensure that energy development and utilization are technically and economically feasible, rather than just saving energy and reducing emissions from a simple policy level.
In this context, the development of the nanotechnology industry is empowering the transformation of energy in the new era with unparalleled advantages, and completing the puzzle of the last piece of technology to achieve carbon neutrality.
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Although the nano is small, its use is large
The length unit of nanometers is one billionth of a meter, while a molecule is 1 nanometer, a hair is 75,000 nanometers, the needle for injection is 1 million nanometers, and a basketball player with a height of 2 meters can reach 2 billion nanometers. Obviously, this is very different from the macroscopic world as we know it, the nano is a unit of length that measures the microscopic world, and the special length of the nano also gives the nanometer a special property.
We all know that constantly dividing an eraser will increase the area exposed by the eraser, which means that the number of atoms exposed outside will also increase. When we cut an object to the size of only a few nanometers, then a gram of such a substance will have a surface area of several hundred square meters.
Thus, as the particles decrease, more atoms are distributed to the surface. When the particles are 10 nanometers in diameter, about 20% of the atoms are exposed on the surface. On the surface of the object we usually come into contact with, the proportion of atoms is less than one in ten thousand. At the same time, atoms need to rely on chemical bonds to connect with each other, which causes the atoms on the surface to be unstable and highly active because they are not connected with enough atoms.
For example, with a high-magnification electron microscope on the gold nanoparticles for visual observation, it will be found that these particles have no fixed form, with the change of time will automatically form a variety of shapes, it is different from the general solid, but also different from the liquid; under the electron beam irradiation of the electron microscope, the surface atoms seem to enter the "boiling" state, and the size is greater than 10 nanometers before the instability of this particle structure can not be seen, then the microparticles have a stable structural state.
Specifically, in terms of optical properties, the particle size of the nanoparticles is smaller than the wavelength of the light wave, so there will be a complex interaction with the incident light. Nanomaterials can be applied to infrared sensing materials because of their large light absorption rate. When gold is subdivided to a size smaller than the wavelength of light, it loses its original rich luster and turns black. In fact, all metals appear black in the ultrafine particle state. The smaller the size, the darker the color, the silver-white platinum (platinum) becomes platinum black, and the metallic chrome becomes chrome black.
It can be seen that the reflectivity of metal ultrafine particles to light is very low, usually less than 1%, and the thickness of about a few microns can be completely eliminated. Using this property, nanoparticles can be made into conversion materials such as photothermal and optoelectronics, so as to efficiently convert solar energy into thermal and electrical energy. In addition, it is possible to apply infrared sensitive components, infrared stealth technology, etc.
In terms of thermal properties, when the solid material is in its form of large size, its melting point is often fixed, and after ultra-fine, it is found that its melting point will be significantly reduced, especially when the particles are less than 10 nanometers. For example, the conventional melting point of gold is 1064 ° C, when the particle size is reduced to 10 nanometers, the melting point is reduced by 27 ° C, and the melting point at 2 nanometers is only about 327 ° C; the conventional melting point of silver is 670 ° C, while the melting point of ultra-micro silver particles can be less than 100 ° C.
Therefore, conductive pastes made of ultra-fine silver powder can be sintered at low temperatures, at which time the substrate of the component does not have to use high-temperature resistant ceramic materials, or even plastics. The use of ultra-fine silver powder slurry can make the film thickness uniform, cover the area is large, and it is both material-saving and high-quality.
In terms of magnetic properties, a classic example is the special regression ability of organisms such as pigeons, dolphins, butterflies, bees, and magnetotropic bacteria living in water. The presence of ultra-fine magnetic particles in such organisms enables such organisms to discern directions under the navigation of the geomagnetic field. Magnetic ultrafine particles are essentially a biological magnetic compass, and the magnetotropic bacteria living in the water rely on it to swim to the nutrient-rich bottom.
In terms of mechanical properties, ceramic materials are usually brittle, but nano-ceramic materials made of nano-ultrafine particles have good toughness. Because nanomaterials have a large interface, the atomic arrangement of the interface is quite chaotic, and the atoms are easily migrated under the condition of external force deformation, so the nano-ceramic material can show excellent toughness and certain ductility, making the ceramic material have novel mechanical properties.
It is the special scale of the nano that gives the nanomaterials ideal mechanical, chemical, electrical, magnetic, thermal or optical properties, so that these new nanomaterials can be widely used in traditional and emerging industrial manufacturing fields.
Nanotechnology in energy
At present, the most well-known application of nanotechnology is integrated circuits. Although the invention of integrated circuits has created today's "information age", the impact of nanotechnology on society in general will be much greater than that of integrated circuits, and it will be applied not only to electronics, but also to many other aspects, such as energy.
The relationship between global climate change and human activities has become an international focus issue today, which concerns the vital interests and economic development of various countries. People have never paid as much attention to energy as they do today, and sustainable new energy is gradually replacing fossil energy as the main force supporting the operation of society and people's lives.
The key to energy transformation is to be able to develop and use new energy sources on a large scale, based on this, whether it is in the field of batteries, solar energy development and utilization, or hydrogen energy and other energy sources, the development of the nanotechnology industry is empowering the energy transformation of the new era with unparalleled advantages.
In the field of batteries, using nanotechnology, major problems such as safety during charge and discharge in the traditional lithium battery field (using silicon nanowires or S/nanoTiO2 with hollow shell structure, etc.) and slow speed (applying carbon nanotubes, etc.), and battery instability (using ultra-thin two-dimensional BN/graphene composites, etc.) have been properly solved.
In fact, the current research on nanomaterials for lithium batteries has been perfected and industrialized. The energy density of commercial lithium batteries has reached 300Wh/kg, the mileage of lithium battery power vehicles can reach about 470 kilometers, with the further development of nanomaterials, the further optimization of lithium battery performance, its energy density is expected to reach 500Wh/kg, to achieve the endurance goal of 800 kilometers.
In the electronic information industry, the application of nanotechnology will help overcome the physical limitations represented by strong field effects and quantum tunneling effects and the technical limitations represented by power consumption, heat dissipation and transmission delay, so as to create new nano-devices based on quantum effects and promote the development of cost-effective preparation processes.
For solar energy development, in the case of a certain amount of resource reserves, the only way to increase the supply capacity of new energy is to improve the efficiency of energy conversion through advanced technical means. Silicon semiconductors in traditional solar cells only absorb infrared light, while high-energy light waves, including most of the visible spectrum, are wasted in the form of thermal energy. Although in theory, the conversion efficiency of traditional solar cells can be increased to more than 70%, due to energy waste, despite the continuous improvement and progress of its process, the conversion efficiency of advanced photovoltaic power generation currently put into commercial applications is still stagnant at about 25%.
However, the thermoelectric method developed through nanotechnology is expected to increase the conversion efficiency of solar cells to 80%. Researchers in electrical engineering at Stanford University in the United States have developed a new thermal optoelectronic system based on nanotechnology. Unlike traditional solar cells, the new thermoelectric system first compresses sunlight into infrared light, and then converts it into electrical energy through solar cells. The system has an intermediate component that consists of two parts: one is that the absorber can heat up in sunlight; the other is for the emitter to convert heat into infrared light, and then shine it into solar cells, and the key to compressing sunlight into monochromatic light is to maintain the nanostructure of the material.
In the manufacture of hydrogen, hydrogen is a carbon-free, pollution-free environmentally friendly fuel. When hydrogen is burned to generate energy, the only product is water. But in fact, it is very difficult to use water to produce hydrogen, store hydrogen and use hydrogen. Previously, researchers at the University of Wisconsin in the United States said that they used nanotechnology to develop a new molybdenum disulfide structure, which can act as a catalyst in the water-to-hydrogen reaction, which is expected to replace expensive platinum to help human beings enter the era of "hydrogen economy" of economic and environmental protection as soon as possible.
The researchers used nanotechnology to create a new molybdenum disulfide structure, and the results showed that it could significantly speed up the water-to-hydrogen reaction. The researchers deposited the nanostructure of molybdenum disulfide on a plate of graphite and then treated molybdenum disulfide with lithium to create another molybdenum disulfide structure with different properties.
Just as graphite is made up of a bunch of flakes that are easy to peel off, molybdenum disulfide is also made up of flakes that can be separated. Previous studies have demonstrated that the catalytically active points are located at the edges of the flakes. The role of lithium treatment is mainly to transform molybdenum disulfide from a semiconductor state to a metallic state; to separate the flakes, to create more edges, to increase the number of points with catalytic activity, so that the catalytic performance can be greatly improved.
Not only that, in terms of pesticide environmental protection, nano fertilizers have the potential to surpass conventional fertilizers. Compared with traditional fertilizers, nano fertilizers can gradually and controllably release nutrients into the soil, thus preventing soil eutrophication and water pollution. The use of nano-fertilizers can improve the absorption and utilization efficiency of nutrients by crops, reduce the frequency of fertilizer application, and thus avoid the negative impact on the environment caused by excessive use of fertilizers.
In nanofertilizers, nutrients can be wrapped in nanomaterials or delivered to crops in the form of nanoscale particles or emulsions. Studies have shown that foliar spraying of nanofertilizers can promote increased photosynthesis, thereby increasing crop yields. Compounds of SiO2 and TiO2 nanoparticles increase the activity of nitrate reductase in soybeans, enhance the absorption capacity of plants, and make the use of water and fertilizer more efficient.
Nanotechnology, the key to carbon neutrality
In 2015, the 195 member states of the United Nations held a United Nations climate summit in Paris, France, and adopted the Paris Agreement in an effort to jointly curb global warming. According to the United Nations Intergovernmental Panel on Climate Change (IPCC), if the Paris Agreement's projection and temperature control targets on climate change are to be met, the world must reach net zero carbon dioxide emissions by 2050.
The concept of "carbon neutrality" came into being, that is, to emphasize the balance between carbon emissions and carbon removal, that is, to offset the carbon dioxide emissions generated within a certain period of time through energy conservation and emission reduction, afforestation and other ways, and achieve "zero emissions" of carbon dioxide. At present, the carbon neutrality campaign has begun, many countries and regions have announced the intention and target of net zero emissions, and the United States, the European Union, the United Kingdom, Japan and South Korea and other countries and regions have set the time target for 2050 and put forward the vision of a carbon-free future.
However, commitments are meant, challenges are real. Energy is a key element in the infrastructure that supports economic and social development, a large system, a large system composed of large systems and countless subsystems. Reducing greenhouse gas emissions inevitably has corresponding economic costs, and countries will inevitably argue about the allocation of economic costs of reducing emissions until innovative technologies to address the greenhouse effect emerge.
The essence of every industrial revolution in the past has been an energy revolution. The first industrial revolution is the coal-powered steam age; in the second industrial revolution, electricity as a secondary energy source turned out to be the world, leading the world into the electrical age, internal combustion engine also allowed oil to quickly surpass coal in a few decades to become the world's first energy; in the third industrial revolution, we have witnessed the change and promotion of nuclear energy, mobile energy, and information technology to the world.
At present, under the catalysis of information technology, the fourth industrial revolution has begun to sprout ahead of schedule. This means that the energy sector will also usher in a new round of energy revolution. Moreover, this round of innovation will be carbon neutral and oriented to energy cleansing. It can be said that the carbon neutrality goal opens a new track for the energy technology revolution, and whoever takes the lead in mastering the technical key to unlocking carbon neutrality is likely to lead the fourth energy revolution.
Now, nanotechnology is the key technology that can solve the greenhouse effect, and nanotechnology is breaking the original assumptions or laws, so that the related disciplines have undergone a huge transformation, which in turn has led to industrial change. In addition to the energy sector, nanotechnology has also provided innovation impetus for basic disciplines such as physics, materials, chemistry, life sciences, pharmacology and toxicology, and engineering, and has become an important source of manufacturing technology for transformative industries.
Based on the wide application of nanotechnology in the future, the mainland is also constantly laying out the strategy and action of nanotechnology. In 2013, the Mainland Academy of Sciences launched the "Nano-pilot Special Project", hoping to use nanotechnology to promote the transformative innovation of industrial technologies such as long-lasting power lithium batteries and nano-green printing, while cultivating and promoting the application of a number of nano-core technologies in specific energy, environment and health fields, solving a number of key technical bottlenecks restricting the development of national backbone industries, and driving the development of emerging industries.
In 2016, the Ministry of Science and Technology issued the "13th Five-Year Plan" National Science and Technology Innovation Plan, which will take the research and development of new nano functional materials, nano optoelectronic devices and integrated systems, nano biomedical materials, nano drugs, nano energy materials and devices, and nano environmental materials as major special projects for research and deployment. With the support of various projects and programs, the development trend of mainland nanotechnology is good, and it has become a major country in the world's nanotechnology research and development.
In the long run, if China wants to take the lead in the next industrial revolution, it must take the initiative to grasp the disruptive technologies of low-carbon and negative carbon production in the new round of energy revolution, which is also the trend of the times, and there is no other choice.
(The author is a well-known science and technology writer)