Strong interactions between Au nanoparticles and TiO2 mesocrystal: highly selective photocatalytic reduction of nitroarenes.

Au/TiO₂ mesocrystals (Au/TMCs) were synthesized via a template-free solvothermal approach, followed with in situ photoreduction of gold chloride tetrahydrate for deposition of Au nanoparticles (AuNPs). The microstructure and components of the photocatalysts were characterized with various techniques. The results indicated that the AuNPs selectively anchored on the (101) facet of TiO₂ mesocrystals (TMCs). More interestingly, the strong interactions occurred between AuNP and TMC support, due to the formation of a close Schottky heterointerface, combined with Ti−O−Au chemical bonds partially formed. Unexpectedly, it was found that the AuNPs typically aligned with their [111] direction, parallelling to the [101] direction of TMC in many cases. Au/TMCs exhibited high selectivity and activity for the transformation of nitroarenes to corresponding azoxyarenes, which could be attributed to not only the plasmonic effect of AuNPs and the unique superstructure of TMC, but also the highly strong interaction between AuNPs and TMCs through the close Schottky heterointerface. [ABSTRACT FROM AUTHOR]