Exfoliation-Derived Hf–O Nanosheets as Nonconventional Oxide Supports for Modulating Pt/Oxide Interfacial Hydrogen Behavior

In oxide-supported catalysts, performance is often interpreted by the crystal phase of the oxide, while the preparation pathway can also determine the real support state, including crystallinity, local order/disorder, and metal–oxide contact. Here, we report a precursor-guided alkali-assisted exfoliation strategy to construct Hf–O nanosheets as nonconventional Pt supports. A K-rich mineralized intermediate is first formed under semiclosed alkaline hydrothermal conditions and then converted through alkali-assisted thermal exfoliation and washing, producing nanosheet-like Hf–O solids with low crystallinity and localized ordered motifs, distinct from commercial monoclinic HfO 2 . After Pt loading, Pt/Hf–O NS shows a more favorable apparent acidic HER response than Pt/ m -HfO 2 . A semiquantitative WO 3 colorimetric/fading assay further reveals stronger hydrogen-mediated coloration and more persistent color retention. These results suggest that multiple pathway-derived structural and interfacial factors collectively modulate Pt/oxide hydrogen-related behavior, highlighting precursor-to-support transformation as a handle for designing oxide-supported interfacial catalysts.