In-situ formation of supported Au nanoparticles in hierarchical yolk-shell CeO2/mSiO2 structures as highly reactive and sinter-resistant catalysts

A novel strategy was described to construct Au-based yolk-shell SCVmS-Au nanocomposites (NCs), which combined the sol-gel template-assisted process for the assembly of hierarchical SCVmS NCs with modified CeO 2 /mSiO 2 as yolks/shells, and the unique deposition-precipitation (DP) process mediated with Au(en) 2 Cl 3 compounds for the synthesis of extremely stable supported Au nanoparticles (NPs). Characterization results indicated that the obtained SCVmS-Au NCs featured mesoporous silica shells, tunable interlayer voids, movable CeO 2 -modified cores and numerous sub-5   nm Au NPs. Notably, the Au(en) 2 Cl 3 was employed as gold precursors to chemically modify into the modulated yolk-shell structure through the DP process and the subsequent low-temperature hydrogen reduction induced the in-situ formation of abundant supported Au NPs, bestowing these metal NPs with ultrafine grain size and outstanding sinter-resistant properties that endured harsh thermal conditions up to 750   °C. Benefiting from the structural advantages and enhanced synergy of CeO 2 -Au/mSiO 2 -Au yolks/shells, the SCVmS-Au was demonstrated as markedly efficient catalysts with superior activity and reusability in catalyzing the reduction of 4-nitrophenol to 4-aminophenol, and its pristine morphology still maintained after eight recycling tests.