Preparation, characterizaton and formaldehyde gas sensing properties of walnut-shaped BiFeO3 microspheres

•Walnut-shaped BiFeO3 microspheres have been successfully synthesized.•The gas sensing properties to different gases of BiFeO3 were systematically studied.•BiFeO3 based sensor exhibited superior gas sensing performance to formaldehyde.•The optimum operating temperature of BiFeO3 based sensor is 240 °C. In this paper, well-crystallized walnut-shaped BiFeO3 microspheres have been successfully synthesized via a facile hydrothermal process. Meanwhile, the morphology growth process of walnut-shaped microspheres was investigated. The gas sensing properties of fabricated sensor based on BiFeO3 microspheres to different gases concluding formaldehyde, acetic acid, acetone and ethanol etc. were systematically studied. The results revealed that at the optimum operating temperature of 240 °C, the gas sensor exhibited typical p-type semiconductor gas sensing behavior concluding high response value, good repeatability and fast response/recovery time to formaldehyde, which also provides an experimental basis for bismuth ferrite to become a new multi-metal oxide semiconductor gas sensing materials in the future.