Fabrication of porous α-Fe2O3 nanoshuttles and their application for toluene sensors

Abstract

1D unique porous α-Fe₂O₃ nanoshuttles (NSs) were synthesized by a template-/surfactant-free low temperature hydrothermal approach (60 °C, 48 h), followed by a simple annealing process (300 °C, 1 h). The prepared α-Fe₂O₃ NSs (ca. 40 nm in diameter and 250 nm in length) have a rugged surface and a porous structure with numerous nanopore inlets (about 1–10 nm in diameter). The hydrothermal time dependent experiment demonstrated that the formation of the NSs is a gradual process, which underwent growth, strong, spilt, and re-spilt processes as reaction times were prolonged from 6 to 48 h. The reaction temperature also has a significant influence on the morphology of the α-Fe₂O₃ products. Increasing reaction temperature to 100 and 120 °C led to the formation of rod-like nanostructures instead of NSs, and a higher reaction temperature of 140 °C produced a large solid sphere-like morphology (700 nm–1 μm in diameter). Gas sensing properties of the porous α-Fe₂O₃ NSs were investigated for toluene detection. The sensor showed excellent gas sensing performance for toluene with good reproducibility, short response and recovery time (3–8 and 2–4 s, respectively), and high response. Notably, the α-Fe₂O₃ NS sensor showed a nearly linear response in the range of 10–100 ppm of toluene, indicating the potential for application in ppm-level toluene gas sensors. The present work is expected to provide new insights into the easy and effective development of 1D porous α-Fe₂O₃ nanostructures.