Hydrothermal synthesis of La-doped In₂O₃ nanosheets-assembled microflowers for sensing n-butanol

In this work, La-doped In₂O₃ microflowers were successfully prepared by a one-step hydrothermal method. Doping La into the In₂O₃ lattice causes lattice distortion of In₂O₃, leading to the change of morphology from cubic to nanosheets. The gas sensing tests show that La doping significantly improves the sensing performance to n-butanol compared to the pristine In₂O₃. 5% La-In₂O₃ exhibits the highest sensing response (~ 61.34 to 100 ppm n-butanol) among the various doping amounts of La, which is six times higher than that of the pristine In₂O₃ (~ 10.12) at the optimal operating temperature of 320 °C. This sample also show short response and recovery times, high selectivity and long-term stability. The enhanced sensing performance is mainly attributed to (1) the tunned bandgap by doping La, which effectively improves the electron transfer ability and produces a thicker electron depletion layer, and (2) the unique morphology and abundant lattice defects of the La-In₂O₃ samples, providing increased adsorption and reactive sites.