In-situ fabrication of porous-silica-microsphere-supported platinum nanocluster catalyst by γ-ray radiation

The synthesis and stable loading of metal nanoclusters have always been a hot and difficult topic in the field of nano-metal catalysts. In this work, micron-sized inverse opal SiO 2 microspheres (IO-SiO 2 ) are firstly prepared as the carrier of platinum nanoclusters (PtNCs) through a sol-gel process of tetraethyl orthosilicate (TEOS) on sacrificed polystyrene (PS) colloidal crystal microspheres template. After the IO-SiO 2 carriers are dispersed into the aqueous solution of H 2 PtCl 6 and irradiated by 60 Co γ-ray radiation for a certain absorbed dose in a deoxygenized atmosphere, PtNCs with a size of less than 2 nm are in situ synthesized based on a redox equilibrium of Pt(0)/Pt(IV) induced by effect of the reductive species (e aq − , H ) and oxidizing radicals (HO ) produced by the radiolysis of water, and immobilized on IO-SiO 2 without the help of any stabilizer. Due to the large pore volume of the IO-SiO 2 , the loading capacity of PtNCs can reach as high as 18.63 μg/mg microsphere . The prepared IO-SiO 2 -supported PtNCs (PtNCs@IO-SiO 2 ) show excellent catalytic activity and recyclability for the reduction of o-nitroaniline by NaBH 4 as the model reaction. This work offers a new route to prepare stable and high-performance metal nanocluster catalysts loaded on porous microspheres using γ-ray radiation technique.