Pd@Fe₂O₃ Superparticles with Enhanced Peroxidase Activity by Solution Phase Epitaxial Growth

Compared to conventional deposition techniques for the epitaxial growth of metal oxide structures on a bulk metal substrate, wet-chemical synthesis based on a dispersible template offers advantages such as low cost, high throughput, and the capability to prepare metal/metal oxide nanostructures with controllable size and morphology. However, the synthesis of such organized multicomponent architectures is difficult because the size and morphology of the components are dictated by the interplay of interfacial strain and facet-specific reactivity. Here we show that solution-processable two-dimensional Pd nanotetrahedra and nanoplates can be used to direct the epitaxial growth of γ-Fe₂O₃ nanorods. The interfacial strain at the Pd−γ-Fe₂O₃ interface is minimized by the formation of an Fe_xPd “buffer phase” facilitating the growth of the nanorods. The γ-Fe₂O₃ nanorods show a (111) orientation on the Pd(111) surface. Importantly, the Pd@γ-Fe₂O₃ hybrid nanomaterials exhibit enhanced peroxidase activity compared to that of isolated Fe₂O₃ nanorods with comparable surface area because of a synergistic effect for the charge separation and electron transport. The metal-templated epitaxial growth of nanostructures via wet-chemical reactions appears to be a promising strategy for the facile and high-yield synthesis of novel functional materials.