Core–Shell Au@SnO2 Nanostructures Supported on Na2Ti4O9 Nanobelts as a Highly Active and Deactivation-Resistant Catalyst toward Selective Nitroaromatics Reduction

Catalysis using gold (Au) nanoparticles has become an important field of chemistry. However, activity loss caused by aggregation or leaching of Au nanoparticles greatly limits their application in catalytic reaction. Herein, we report a facile and green synthesis of a core-shell Au@SnO₂ nanocomposite, exhibiting excellent activity toward selective nitroaromatics reduction under mild conditions. The core-shell Au@SnO₂ nanocomposite (Au size = ∼50 nm; shell thickness = ca. 16 nm) is conceived and validated by a direct redox reaction between HAuCl₄ and SnF₂. Optimization of the core size, shell thickness, and dispersion of Au@SnO₂ has been introduced by an alkaline surface supported by negatively charged metal oxide Na₂Ti₄O₉. The as-obtained Au-Sn-Na₂Ti₄O₉ catalyst with much smaller Au cores (ca. 5 nm) and thinner SnO₂ nondensed shells (ca. 4 nm) exhibits highly improved catalytic activities for nitro reduction compared to most of the known Au-based catalysts. Moreover, the core-shell Au@SnO₂ structure inhibits the leaching and agglomeration of Au nanoparticles and thus leads to superior catalytic durability.