Homogeneous coating of photonic macroporous oxides with inorganic nanocrystals

Abstract

A very simple method is described to achieve quantitative sub-monolayer nanoparticle (TiO2, Fe3O4 or CdS) coverage of photonic macroporous oxides.

Enhancement of hydrogen production using photoactive nanoparticles on a photochemically inert photonic macroporous support

“…We have previously reported the detailed synthesis and characterisation of nan-TiO 2 @mac-ZrO 2 composites. 25 Red shifts in the DRUVS data for the samples prepared here (Fig. S5d and S5e †) confirm the addition of TiO 2 and show that coverage is homogeneous, which was also supported by TEM.…”

“…2, where  is the volume fraction of nan-CdS. 25 Red shifts of 6-11 nm are observed for 1-CdS -4-CdS which is consistent with the addition of 9.5 wt % of CdS (n = 2.4) to 1 -4. The volume fraction = 1.9 %, showing that the composite volume remains principally air as indicated by SEM (Fig.…”

“…25 Using a method analogous to 1-CdS -5-CdS, 70 mg of OAnan-TiO 2 dispersed in oleic acid in chloroform (0.1 M, 1 mL) by sonication was added to 15 mg of oleic acid coated ZrO 2 followed by evaporation of the volatiles at 40 °C over 2 hr. The composites were calcined at 450 °C for 4 hr with a heating rate of 1 °C min -1 ) to give 1-TiO 2 -5-TiO 2 .…”

“…Prior to nanoparticle deposition, mac-ZrO 2 was coated with oleic acid (OAmac-ZrO 2 ). 25 Thermogravimetric analysis of OAmac-ZrO 2 showed a mass loss of 2.2 % (Fig S1a †), which corresponds to removal of a monolayer surface coating of oleic acid with an estimated footprint of 48 Å 2 . 29 In the absence of an oleic acid coating, homogeneous nanoparticle deposition was not observed.…”

“…Previous work has shown that addition of nanoparticles to macroporous ZrO 2 results in a small increase in surface area. 25 The quantity of nanoparticles added to 1-CdS -4-CdS was identical, and therefore, the surface area and dispersion of nan-CdS does not account for the variation in hydrogen production.…”