Hierarchical hollow BiFeO₃ microcubes with enhanced acetone gas sensing performance

Metal oxide-based gas sensors have drawn tremendous research interests owing to their various compositions and selective and improved performance. However, the development of a targeted metal oxide with controlled microstructures via a facile preparation procedure is still a challenge. In this work, hierarchical BiFeO3 nano-microstructures are successfully developed through the post-modification of Bi3+ encapsulation with Fe-based Prussian blue microcubes followed by a sequential annealing strategy. The microstructures of the hierarchical BiFeO3 architectures can be effectively modulated by tuning various thermolysis temperatures. Among them, the hierarchical hollow BiFeO3 microcubes assembled from ultrathin nanosheets exhibit optimum acetone selective sensing performances with a gas response value (Ra/Rg) of 5.2 at 240 °C, rapid response/recovery times (10 s/9 s), and excellent long-term stability (for at least 30 days). The high and reproducible acetone-sensing properties are mainly attributed to the unique interior loose and porous structures with good permeability. The corresponding acetone sensing mechanism relying on the microstructure of BiFeO3 was also discussed. This work highlights the key role of morphological evolution in the fabrication of multi-functional multimetal oxides, and thus offers new opportunities for the rational design of novel gas sensing materials.