Hollow CuFe2O4/α-Fe2O3 composite with ultrathin porous shell for acetone detection at ppb levels

Hollow CuFe2O4/α-Fe2O3 composites with ultrathin porous shell were successfully prepared by a facile template-induced method, which involves the self-assembly of Fe3+ ions on the surface of Cu@carbon microspheres and the subsequent transformation to CuFe2O4/α-Fe2O3 through thermal oxidation and solid phase reaction. The as-prepared CuFe2O4/α-Fe2O3 hollow spheres are characterized by uniform diameter of about ∼210 nm and ultrathin porous shell, which could facilitate the diffusion of reactant gases and enhance the utility ratio of the sensing body. To demonstrate such unique materials might bring about more excellent gas sensing property, a comparison of the sensing performance between CuFe2O4/α-Fe2O3 composites and pure α-Fe2O3 was carried out. As expected, the sensors based on the as-prepared CuFe2O4/α-Fe2O3 composites exhibit much higher sensitivity, faster response/recover speed, and lower detection limit than the pristine α-Fe2O3 hollow spheres. It is believed that the enhanced sensing performance could be attributed to hollow and porous architectures of CuFe2O4/α-Fe2O3 composites, the resistance modulation effects of heterojunction as well as catalytic properties of CuFe2O4.