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Journal article(2026)
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Christine Gonsalves, Jänis Järvilehto, Saeed Saedy, Jorge A. Velasco, Thomas Grehl, Philipp Brüner, Niko Heikkinen, Juha Lehtonen, J. Ruud van Ommen, Riikka L. Puurunen
Uniform material distribution by atomic layer deposition (ALD) inside porous materials is needed in multiple applications, including batteries and catalysis. Attaining this uniformity is not trivial, diffusion within the porous network being one of the main limiting factors. This work used a fluidized bed atmospheric ALD reactor to coat millimeter-size mesoporous alumina spheres with platinum, using the process based on (methylcyclopentadienyl)trimethylplatinum [MeCpPtMe3] and oxygen. Using different exposure times and five reaction cycles, materials with platinum loading up to ∼4 wt% were prepared. The growth per cycle, expressed as average areal number density, was approximately 0.1 Pt atoms per nm2. Cross-sectional analysis done using low-energy ion scattering indicated that with increasing exposure time, platinum distribution evolved from egg-shell to macroscopic uniform distribution through the particles. Diffusion–reaction modeling was done to support the experiments and showed a saturation of the Pt weight loading after uniform distribution. This work shows that it is possible to get a uniform distribution of platinum through mesoporous particles with an aspect ratio on the order of 100 000 : 1, when the ALD process is properly optimized.
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Uniform material distribution by atomic layer deposition (ALD) inside porous materials is needed in multiple applications, including batteries and catalysis. Attaining this uniformity is not trivial, diffusion within the porous network being one of the main limiting factors. This work used a fluidized bed atmospheric ALD reactor to coat millimeter-size mesoporous alumina spheres with platinum, using the process based on (methylcyclopentadienyl)trimethylplatinum [MeCpPtMe3] and oxygen. Using different exposure times and five reaction cycles, materials with platinum loading up to ∼4 wt% were prepared. The growth per cycle, expressed as average areal number density, was approximately 0.1 Pt atoms per nm2. Cross-sectional analysis done using low-energy ion scattering indicated that with increasing exposure time, platinum distribution evolved from egg-shell to macroscopic uniform distribution through the particles. Diffusion–reaction modeling was done to support the experiments and showed a saturation of the Pt weight loading after uniform distribution. This work shows that it is possible to get a uniform distribution of platinum through mesoporous particles with an aspect ratio on the order of 100 000 : 1, when the ALD process is properly optimized.
In this study, we investigated the wettability and agglomeration characteristics of polymer microspheres coated with low-temperature deposited SiO2 in a fluidized bed atomic layer deposition (ALD) setup. Surface characterization revealed the presence of a significant amount of deposited Si-OH groups within the first cycles. A drastic decrease in agglomerate size, water contact angle (WCA), and droplet absorption time of the powder was observed when coating was applied. Furthermore, we observed an increase in the amount of Si-OH present on the particle surface with increasing coating cycles, while no significant improvement in water affinity was found after the first coating cycles. Our findings suggest that surface coverage is the primary factor in improving the colloid stability of particles, coated at low temperatures. The low temperature operation of our system introduced a chemical vapor deposition (CVD) component to our coating process, which allowed full surface coverage to be achieved within the first two coating cycles.
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In this study, we investigated the wettability and agglomeration characteristics of polymer microspheres coated with low-temperature deposited SiO2 in a fluidized bed atomic layer deposition (ALD) setup. Surface characterization revealed the presence of a significant amount of deposited Si-OH groups within the first cycles. A drastic decrease in agglomerate size, water contact angle (WCA), and droplet absorption time of the powder was observed when coating was applied. Furthermore, we observed an increase in the amount of Si-OH present on the particle surface with increasing coating cycles, while no significant improvement in water affinity was found after the first coating cycles. Our findings suggest that surface coverage is the primary factor in improving the colloid stability of particles, coated at low temperatures. The low temperature operation of our system introduced a chemical vapor deposition (CVD) component to our coating process, which allowed full surface coverage to be achieved within the first two coating cycles.
