Scientists have developed a groundbreaking technique for producing thin films using only water and oil in one minute. This method simplifies a typically complex process.
On Monday, researchers at the Ulsan National Institute of Science and Technology (UNIST) announced that a team led by Gang Hee Oh from the Department of Energy and Chemical Engineering has created a novel process to manufacture catalytic thin films using oil droplets dispersed in water.
This innovative method allows nanoparticle-sized thin film materials attached to oil droplets to rise and assemble on the water’s surface. When hydrogen peroxide is added, it decomposes due to the thin film materials, generating bubbles. These bubbles lift the materials to the surface and assemble within 60 seconds.
This technique allows for precise film thickness control, starting from 350 micrometers (μm), and can produce thin films up to 100 square centimeters (cm²) using various raw materials. The resulting thin films boast a porous structure with high surface area, excellent mechanical strength, and remarkable flexibility.
These films have a dense bonding structure that enables damage-free transfer to substrates from underwater using a lift-on method. This addresses a common challenge in thin film manufacturing, where damage often occurs during the transfer process to substrates.
The team demonstrated the technique’s versatility by successfully transferring films to substrates with various 3D patterns and materials, including those with intricate micrometer-scale patterns for precise coating.
In a striking demonstration, the researchers created catalytic thin films using platinum-coated carbon nanoparticles (Pt/C). They transferred the nanoparticles onto leaves and gold-plated them to produce flexible electrodes. The electrodes maintained consistent conductivity even after repeated bending and could power small bulbs.
Oh described the technology as a paradigm shift, drawing inspiration from Pickering emulsions used in cosmetics production. Pickering emulsions use solid nanoparticles instead of molecular surfactants to cover the oil-water interface, reducing interfacial energy.
Building on this concept, the team developed a platform where nanoparticles spontaneously move from the oil-water interface to the air-water interface, leveraging their energetically favorable positioning at fluid interfaces.
Oh highlighted the method’s cost-effectiveness, versatility in nanoparticle combinations, and potential applications in flexible electrodes, catalysts, and energy storage devices. The findings were published in the prestigious nanoscience journal ACS Nano on February 4.
The Ministry of Science and ICT’s National Research Foundation supported this research through various initiatives, including the Nano Future Material Source Technology Development Project, the Basic Research Laboratory Support Project, and the Excellent Young Researcher Project.
