Breakthrough material converts sunlight into heat, can lead to energy-efficient buildings
Scientists have made a major breakthrough in solar energy technology by creating a novel material capable of directly converting sunlight into heat with unprecedented efficiency.
The development centers on thin films of a specific titanium oxide phase, Ti₄O₇, and could lead to advances in areas ranging from energy-efficient buildings to clean water and sustainable fuel production.
“The ability to create thin photothermal coatings on reasonably sized surfaces holds particular promise for passive desalination in niche applications, using only direct sunlight and requiring no external electrical energy input, unlike the commonly used reverse osmosis process,” said Professor My Ali El Khakani, who led the research team.
Limitations of traditional titanium oxide phase
The researchers at the Institut national de la recherche scientifique (INRS) focused on overcoming limitations associated with traditional methods of producing Ti₄O₇.
This material belongs to a group known as “Magnéli phases,” which are sub-stoichiometric forms of titanium oxide with unique electrical and chemical properties. While its potential was already recognized, practical application was hindered.
“Ti₄O₇ is classically synthesized by thermal reduction methods under the powdered form,” said Loick Pichon, a PhD student at INRS and the first author of the publication.
“These methods do not generally allow the synthesis of the pure phase of the Ti₄O₇ material and/or enable the fine control of its composition, morphology, and nanostructure.”
He explained that these methods often yielded mixed phases and limited the material’s potential, particularly its electrical conductivity, while also restricting its usable form to small pellets.
Using plasma deposition technique
To overcome these limitations, Professor El Khakani’s team employed magnetron sputtering, a thin film deposition technique commonly used in the semiconductor industry.
This plasma deposition technique allowed them to deposit Ti₄O₇ coatings, just a few hundred nanometers thick, onto various substrates, including metal, silicon, and glass.
“The Ti₄O₇ coating thus deposited (films of a few hundred nanometers thick) completely changes the surface properties of the substrate, which can otherwise be quite large or of different natures (metal plates, silicon wafers, or glass plates),” highlighted Professor El Khakani, who specializes in plasma-laser processes for nanostructured materials.
Advances across several sectors
The development of these thin photothermal coatings using Ti₄O₇ opens the door to a diverse array of practical applications.
“Rightly so, Ti₄O₇ coatings will be used to manufacture high-performance anodes for the decontamination of water containing persistent pollutants,” remarked the team in a press release.
The material’s inherent corrosion resistance and high electrical conductivity make it exceptionally suitable for creating high-performance anodes, which can effectively remove persistent pollutants from water. Besides, the material can also be significantly useful in the production of hydrogen and ammonia.
“With its exceptional photothermal conversion capacity, this type of coating is also relevant for manufacturing smart heating windows, a significant asset in terms of economy and energy efficiency,” added the press release.
This development marks a crucial step in harnessing solar energy more effectively and offers versatile solutions for energy efficiency.
“Scientifically, the results of our work have made a major contribution because they establish for the first time the fundamental relationship between the optical absorbance capacity of Ti₄O₇ films and their photoconversion efficiency,” concluded the professor.