Attachment of facile synthesized NaCo2O4 nanodots to SiO2 nanoflakes for sodium-rich boosted Pt-dominated ambient HCHO oxidation

Surface alkali metal ions are typically utilized as available promoters for ambient HCHO oxidation. In this study, NaCo2O4 nanodots with two different preferential crystallographic orientations are synthesized by facile attachment to SiO2 nanoflakes with varying degrees of lattice defects. A unique Na-rich environment is established through interlayer Na+ diffusion based on the small size effect. The optimized catalyst Pt/HNaCo2O4/T2 can deal with HCHO below 5 ppm in the static measurement system with a sustained release background and produces approximately 40 ppm of CO2 in 2 h. Combining the experimental analyses with density functional theory (DFT) calculations, the possible catalytic enhancing mechanism is proposed from the support promotion perspective, and the positive synergistic effect of Na-rich, oxygen vacancies and optimized facets for Pt-dominant ambient HCHO oxidation via both kinetic and thermodynamic processes is confirmed.