Highly accessible SnO2 nanoparticle embedded SBA-15 mesoporous silica as a superior photocatalyst

We address the accessibility of tin oxide (SnO2) nanoparticles synthesized inside the pores of mesoporous silica (SBA-15) host. On using a low-temperature route for in situ synthesis of SnO2 and hence eliminating interparticle aggregation, SnO2 nanoparticles of diameter much smaller (3.5 nm) than the cylindrical pore diameter (6.3 nm) of the SBA-15 could be synthesized. This enables molecules diffusing into the SBA-15 pores to access the very high specific surface area of SnO2; enabling the diffusing species to react easily with the latter. This is demonstrated by an enhanced photocatalytic degradation rate constant of an aqueous solution of rhodamine B dye, on contacting the latter with the SnO2-SBA-15 composite.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Surface-modified SBA-15 helps synthesize SnO2 particles smaller than pore diameter. ► 3.5 nm diameter SnO2 nanoparticle within 6.3 nm pore prevents pore blockage. ► Smaller nanoparticles show faster degradation rate of rhodamine B dye. ► This emphasizes the importance of accessibility of dye molecule to SnO2 surface.