Construction of p-n heterojunctions by modifying MOF-derived α-Fe2O3 with partially covered cobalt tungstate for high-performance ethyl acetate detection

Abstract Metal organic framework (MOF)-derived porous metal oxide nanostructures have become a kind of promising material for gas-sensitive detection. A facile solvothermal method was adopted to construct CoWO4/α-Fe2O3 nanocomposites, in which MIL-53(Fe) was used as the precursor of α-Fe2O3. The prepared α-Fe2O3 has a unique three-dimensional nanostructure, resulting in good dispersion of CoWO4 nanoparticles on the surface and a distinct structure of partially CoWO4-modified α-Fe2O3 (PC-Fe2O3). XPS characterization indicates that this PC-Fe2O3 heterostructure exposes the high density of active centers, leading to an increase in the amount of adsorbed oxygen on the material surface. The sensor based on the prepared CoWO4/α-Fe2O3 composite exhibits higher response, faster response/recovery, and better selectivity to ethyl acetate than the pristine α-Fe2O3 octahedra. It is believed that the enhanced sensing performance can be attributed to the resistance modulation effect of the heterojunction, the properties of MOFs-derived material, and the formation of the unique PC-Fe2O3 structure.