Postsynthesis Modulation of the Catalytic Interface inside a Hollow Nanoreactor: Exploitation of the Bidirectional Behavior of Mixed-Valent Mn₃O₄ Phase in the Galvanic Replacement Reaction

This paper proposes a postsynthesis strategy to modulate the synergy of the catalyst/support interface of the preformed hollow nanoreactor by replacing preloaded support material inside the cavity, which therefore enhances the variability of the nanoreactor approach. This strategy exploits the newly explored bidirectional behavior of an Mn 3 O 4 nanoparticle of mixed-valent state, which either sequentially or simultaneously templates reduction of noble-metal ions and oxidation of Ce 3+ ions during galvanic replacement. The application of this process to the modification of the preformed hollow silica nanoreactor led to the replacement of the catalyst-immobilizing Mn 3 O 4 layer inside the cavity with CeO 2 while preserving the tiny size and well-dispersed state of supported catalysts and, as a result, allowing for the introduction of a synergistic noble-metal/CeO 2 interface exerting the highly improved catalytic performance in CO oxidation reaction.