MOF-derived hierarchical ZnO/ZnFe2O4 hollow cubes for enhanced acetone gas-sensing performance

Abstract

ZnO/ZnFe₂O₄ hollow cube composites with heterogeneous structure are synthesized by a facile strategy through simple and direct pyrolysis of Fe^III-modified Zn-based metal–organic frameworks. The as-synthesized ZnO/ZnFe₂O₄ hollow cubes have well-defined cube morphology with an ∼2 μm and multiple porous shell constructed from interpenetrated ZnO and ZnFe₂O₄ heterogeneous nanoparticles, providing structurally combined mesoporous channels for facilitating the diffusion and surface reaction of gas molecules. In addition, a comparative sensing performance investigation between ZnO/ZnFe₂O₄ hollow cubes and singular ZnO demonstrates that, in contrast with ZnO, the ZnO/ZnFe₂O₄ hollow cubes show significantly enhanced chemical sensing sensitivity towards low-concentration acetone. Furthermore, the ZnO/ZnFe₂O₄ hollow cubes exhibit good reproducibility and selectivity towards gaseous acetone. The enhanced sensing performance of the MOF-derived ZnO/ZnFe₂O₄ hollow cubes is ascribed to the unique hierarchical structure with high specific surface area, abundant exposed active sites with surface-adsorbed oxygen species and heterojunctions formed at the interfaces between ZnO and ZnFe₂O₄.