Preparation of Pt/CeO2 nanoparticles by supercritical CO2 antisolvent micronization process using swirl mixer for colorimetric glucose sensing based on TMB oxidation

• Supercritical CO 2 (SC-CO 2 ) provides an environmentally friendly process • SC-CO 2 antisolvent with swirl mixer is effective for Pt/CeO 2 nanoscale preparation • Rapid supersaturation through swirl mixing produces uniform precursor nanoparticles • Enhancing peroxidase-like activity and exhibited superior catalytic behavior Pt-containing noble metal nanoparticles are attracting significant attention as high-performance catalysts. However, conventional liquid-phase reduction methods generate large amounts of waste solution, thereby imposing a substantial environmental burden. To address this issue and explore a more sustainable route for fabricating noble metal-supported nanoparticles, this study employs solution-enhanced dispersion by supercritical fluid, thereby establishing a foundation for its application. Initially, Pt/CeO 2 nanoparticles serve to confirm the basic concept of the proposed approach and verify the effectiveness of this environmentally friendly process that achieves supercritical fluid-based, solution-enhanced dispersion using a swirl mixer. A precursor solution consisting of Cerium(III) acetylacetonate hydrate (C 15 H 23 CeO 7 ), polyvinylpyrrolidone, and hydrogen hexachloroplatinate (IV) hexahydrate (H 2 PtCl 6 ·6H 2 O) dissolved in ethanol is mixed with supercritical CO 2 in the swirl mixer. Pt/CeO 2 nanoparticles are obtained through rapid supersaturation to form precursor nanoparticles, followed by heat treatment in air. Field-emission scanning electron microscopy reveals particle sizes of 14–16 nm. Fourier-transform infrared and X-ray photoelectron spectroscopy confirm complete polyvinylpyrrolidone removal by pyrolysis. Furthermore, X-ray diffraction and elemental mapping reveal localized Pt aggregation on the CeO 2 nanoparticles, which is likely attributable to the influence of residual Pt 2+ on the surface. UV-vis measurements demonstrate peroxidase-like activity in the oxidation of 3,3′,5,5′-tetramethylbenzidine. Furthermore, the glucose sensor utilizing 3,3′,5,5′-tetramethylbenzidine oxidation-based colorimetric detection exhibits a detection limit of 8.20 μM within a linear range of 100–500 μM, outperforming conventional Pt/CeO 2 nanoparticles. Overall, this study demonstrates that the proposed supercritical fluid-based process can be utilized to fabricate Pt/CeO 2 nanoparticles, serving as an environmentally friendly platform for designing high-performance noble metal-supported catalysts.