Depositphotos
Scientists from Southeast University in China have developed new material is a cement-based system capable of generating and storing electricity from heat.
It is noted that this is a mixture of cement and hydrogel, which was developed by a group of scientists led by Professor Zhou Yang. The scientists were inspired by the layered structure in the middle of the plant stem to create a material that would convert thermal energy into electricity and store it.
New material based on cement and hydrogel exhibits a thermal power factor (Seebeck coefficient) of — 40.5 mV/K and a Q factor
Cement has the properties of an ionic thermoelectric effect, i.e., it can generate electricity. However, this effect is mostly too weak to be used in practice. The reason is that the structure of cement is too dense, which limits the speed of the ions.
«The difference in diffusion rate between cations and anions in a cement solution with pores due to the difference in interaction with the pore walls endows the cement with ionic thermoelectric properties. However, the isolation of the pores by the dense cement matrix prevents the rapid transport of ions with a higher diffusion rate, preventing an increase in the mobility difference between the ions and limiting the increase in the Seebeck coefficient», — the researchers explain.
To solve this problem, scientists have created a multilayer structure. In this structure, layers of cement alternate with hydrogel layers polyvinyl alcohol. The layers of hydrogel quickly allow hydroxide ions (OH-) to pass through. At the same time, the areas between the cement and the hydrogel are designed to bind strongly to calcium ions (Ca²⁺) and weaker to OH-.
This imbalance allows for an increase in the thermoelectric effect, accelerating the movement of certain ions and creating a significant difference in mobility. However, the innovative material is not only capable of generating electricity, it can also store it as a battery. Its multilayer structure gives it both the properties of a durable material and the ability to store electrical energy. In the future, it will will allow buildings to the material can be used to power sensors and wireless communication systems directly integrated into structures, bridges, and roads built from this material.
According to the researchers, the multilayer structure they developed allows for a large number of interaction sites that will enhance the ions in the cement and contribute to improved thermoelectric characteristics Imagine sidewalks that power streetlights, or bridges that control their own structural condition without external power sources.
The results of the study were published in the journal Science Bulletin
Another significant achievement in the field of energy efficiency was the development of scientists from the Canadian National Institute of Scientific Research.
The scientists managed to create a thin film based on titanium oxide A special phase of Ti₄O₇ known as the «phase of Magnesia», these are titanium suboxides in powder form with unique electrical and chemical properties. A new material that can directly convert sunlight into heat with surprisingly high efficiency.
«Ti₄O₇ is classically synthesized by thermal reduction methods in powder form. These methods usually do not allow the synthesis of a pure phase of Ti₄O₇ material and/or precise control of its composition, morphology, and nanostructure», — explains one of the study’s lead authors, a PhD student at the National Institute of Scientific Research, Louis Pichon.
According to him, these methods most often produce mixed phases that limit the material’s properties, including electrical conductivity. In addition, the usable material is limited to the size of small granules.
To solve this problem, the team led by Professor El Hakany used the magnetron sputtering method. This method allows the application of thin films and is widely used in the semiconductor industry. With the help of this technology, the developers were able to apply thin Ti₄O₇ films with a thickness of several hundred nanometers to metal, silicon, and glass coatings.
«The Ti₄O₇ coating applied in this way completely changes the surface properties of the substrate, which can otherwise be quite large or have a heterogeneous structure (metal wafers, silicon wafers, or glass wafers)», — explains the study leader, Professor El Hakany.
The researchers note that the thin films they have developed based on Ti₄O₇ can be used in the production of high-performance anodes for water treatment. In addition, the material can be significantly useful in the production of hydrogen and ammonia. This type of coating can be used for smart heated windows, which will help improve the energy efficiency of buildings.
Professor of the Department of Mechanical Engineering at the University Duke University in the United States, Adrian Bejan, together with Associate Professor of Mechanical Engineering and Materials Science at Florida International University Pezhman Mardanpour defined the shape of roofs for houses that perfectly retain heat.
According to the results of the calculations, the scientists found that a squat or high roof line will affect how the air inside behaves. If you take one vertex on an A-frame or round cone, and if this vertex is less than 0.9 m in height, the air will flow smoothly and evenly over it, like water flowing down the edge of a sink.
Based on the physics of these air flows and heat transfer, if the roof ridge is shorter than about 0.9 m, it should be about three or four times wider than its height to minimize heat loss.
The results of the study were published in the journal International Communications in Heat and Mass Transfer
Based on the materials Interesting Engineering; TechXplore