TiO<SUB>2</SUB>-Coated Silica Foams by <I>In-Situ</I> Sol-Gel Reaction

Abstract

In-situ sol-gel method was used to prepare TiO 2 -coated silica foams by minimizing window (i.e., the part formed by the interconnection of pores) blocking caused from the aggregation of TiO 2 particles during the coating process. Specifically, the coating process employed was achieved by performing sol-gel reaction directly onto the surface of silica foams after penetrating precursor solution through the foams. EDX results showed that TiO 2 particles were evenly distributed onto the surface of inner pores in silica foams, indicating that the coating process employed is likely effective for the surface modification of silica foams with 3-dimensional pore network. Additional characterization tests were carried out to evaluate physical properties (pore structure, crystalline structure, specific surface area, permeability, and mechanical strength) of TiO 2 -coated silica foams according to heat treatment temperature (300-1100 C). The anatase phase started to appear at heat treatment temperature of 500 C and had maximum value at 700 C. TiO 2 particles tended to grow with increasing treatment temperature, leading to the change in relevant physical properties (i.e., the decrease in total and open porosity, specific surface area, and gas permeability, and the increase in closed porosity) due to the clogging of micropores (d p 2 mm); however, the mechanical strength was enhanced after TiO 2 coating with no significant change with heat treatment temperature.

Reusable TiO2‐SBA‐15 Synthesized by Different Silica/Titania Ratios for Photodegradation

“…Additionally, the decrease in R values is ideal for promoting an increase in the wall thickness. These effects may be due to the presence of TiO 2 nanocrystals in the SBA‐15 mesopores and complies with the XRD and SEM results [31,32] …”

“…These effects may be due to the presence of TiO 2 nanocrystals in the SBA-15 mesopores and complies with the XRD and SEM results. [31,32] DRS analysis of the synthesized TiO 2 /SBA-15 (R) photocatalysts were performed and are shown in Figure 4. It was observed that all of the samples had an absorption band at wavelengths from 250 to 380 nm, and that the large absorption drop around 380 nm complies with the absorb on the bandgap of anatase TiO 2 .…”

Reusable titania-SBA-15 photocatalyst synthesized by different silica/titania ratios for enhancing methylene blue photodegradation

“…These effects may be due to the presence of TiO 2 nanocrystals in the SBA-15 mesopores and is complied with the XRD and SEM results (Han et al, 2011;Malik et al, 2016).…”

Anatase TiO2 nanocrystals anchored at inside of SBA-15 mesopores and their optical behavior

“…5. This fact can be related to the existence of TiO 2 nanocrystals into the SBA-15 mesopores walls [72], intercalated with SiO 2 groups. In fact, this behavior also can be because the Ti O bonds are longer than the Si-O bonds (c.a.…”