Metal-Organic Framework Induced Prenucleation to Construct Solid Solution Semiconductor Metal Oxides With Synergistic...

Accurately resolving trace acetone against the highly humid background of exhaled breath remains a central obstacle to non-invasive diabetes diagnosis. Here we develop a metal-organic framework (MOF)-conversion-induced prenucleation strategy for the controlled construction of Fe2TiO5-δ (FTO) solid solutions. During the topological transformation of MIL-125(Ti), Ti-derived oxide nuclei form within the pores of a daughter Fe-based MOF, enabling the generation of FTO enriched with mixed-valence Fe3+/Fe2+ and Ti4+/Ti3+ centres and abundant oxygen vacancies. The optimized FTO-3.49 sensor selectively detects acetone across 30-90% relative humidity, reaches a detection limit of 100 ppb and distinguishes ppb-level acetone concentrations in simulated exhaled breath. This performance is underpinned by mixed-valence centres that limit water-induced hydroxyl accumulation and oxygen vacancies that create additional adsorption sites and strengthen acetone binding, as supported by spectroscopic and computational evidence. This defect-valence synergy enables stable acetone sensing under highly humid conditions and provides a materials-design route towards humidity-resilient metal-oxide sensors for breath-acetone analysis.