Three-dimensionally ordered porous In-doped SmFeO3 perovskite gas sensor for highly sensitive and selective detection of formaldehyde

This article presents the fabrication and characterization of a three-dimensional ordered macroporous (3DOM) indium-doped samarium iron oxide (SmFeO3) gas sensor for formaldehyde detection. The 3DOM structure, achieved using a polymethylmethacrylate (PMMA) template, provides a high specific surface area (SSA) and facilitates gas diffusion. The effect of indium doping on the sensing performance of SmFeO3 is investigated, by modulation of the band gap at the appropriate value of 3.88 eV. Structural and morphological characterization using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) confirms the orthorhombic perovskite and highly ordered inverse opal structure of the synthesized materials. The gas sensing measurements indicate the enhanced formaldehyde sensing ability of the 3DOM 1.5%In-doped SmFeO3 gas sensor. A high response value of 9.05 towards 10 ppm formaldehyde was obtained at 210 °C, which was about 8 times higher than the reference sample. Moreover, the selectivity test reveals the improved performance of the 3DOM 1.5%In-doped SmFeO3 gas sensor to formaldehyde rather than ethanol, methanol, and acetone. Further BET and XPS analysis suggest that improved sensitivity can be related to the perfect SSA of 130.81 m2/g and high oxygen vacancies. This study provides valuable insights into the development of highly sensitive and selective formaldehyde gas sensors.