Metal-organic framework-derived Co3O4/CoFe2O4 double-shelled nanocubes for selective detection of sub-ppm-level formaldehyde

Constructing complex interior nanostructures by metal-organic framework (MOF)-assisted strategy have attracted tremendous attention in the field of material science. Herein, the Co3O4/CoFe2O4 double-shell nanocubes (CCFO DSNCs) were synthesized by a metal-organic framework (MOF) route. The approach included the formation of a zeolite imidazolate framework-67 (ZIF-67)/Co-Fe Prussian blue analogue (PBA) core-shell nanocubes (CSNCs) precursor and then transformation to CCFO DSNCs by thermal annealing in air. A series of techniques were employed in order to investigate the morphology and structure of the CCFO DSNCs. The gas sensing properties of CCFO DSNCs were studied systematically. The results showed that the CCFO1 DSNCs sensor showed a high response toward formaldehyde with fast response and recovery speeds, and low detection limit (300 ppb). The enhanced properties were attributed to the double-shell nanostructure and the heterojunction between Co3O4 and CoFe2O4.