Anisotropic Atomic Layer Deposition Profiles of TiO2 in Hierarchical Silica Material with Multiple Porosity

Anisotropic deposition profiles of TiO2 in Zeotile-4 ordered mesoporous silica material are obtained using Atomic Layer Deposition (ALD) involving alternating pulses of tetrakis(dimethylamino) titanium (TDMAT) and water. TiO2 concentration profiles visualized by transmission electron microscopy (TEM) on particle cross sections reveal the systematic deeper penetration of the deposition front along the main channels and the more limited penetration in the perpendicular direction through the narrower slit-like mesopores. In ordered mesoporous material with one-dimensional pore system ALD leads to pore plugging. Diffusion limited ALD is shown to be useful for TiO2 deposition in anisotropic mesoporous support materials.