Monolithic metal-containing TiO2 aerogels assembled from crystalline preformed nanoparticles as efficient photocatalysts for H2 generation

Nanoparticle-based aerogels are 3-dimensional (3D) assemblies of macroscopic size that maintain the intrinsic properties of the initial nanoparticles. Accordingly, they bear immense potential to become an emerging platform for designing new and efficient photocatalysts. However, to take full advantage of this strategy, understanding of the multiscale processes occurring in such 3D-architectures is essential. Here, we prepared aerogels by co-assembling spherical Au, Pd, and PdAu with TiO2 nanoparticles and investigated their photocatalytic properties for hydrogen generation. During gelation, the anatase nanoparticles undergo oriented attachment, homogeneously entrapping the metal nanoparticles in the growing network. The aerogels offer a high porosity with a mean pore size of ca. 34 nm and a large surface area of about 450 m(2)g(-1). The porous structure enhances the light-harvesting, reagent transport, and electron migration process, generating 3.5-fold more hydrogen in comparison to the corresponding powders.