Construction of mesoporous Fe ₂ O ₃ /Cr ₂ O ₃ n‐p heterojunctions for efficient improvement of low‐concentration acetone detection and gas‐sensing mechanism

Abstract Low‐concentration acetone detection is of great importance for acetone sensor in the fields of environmental protection and noninvasive diagnosis. In this work, mesoporous Fe 2 O 3 /Cr 2 O 3 n‐p heterojunctions were constructed for efficient improvement of low‐concentration acetone gas sensing. The gas‐sensing results indicated that the mesoporous Fe 2 O 3 /Cr 2 O 3 composites with a significantly large specific surface area exhibited significantly enhanced acetone gas‐sensitive performance compared to pure Fe 2 O 3 . The Fe 2 O 3 /Cr 2 O 3 composites demonstrated a high response, good selectivity and excellent stability over 200 days to 10 ppm acetone at 220 °C. And the theoretical detection limit was calculated to reach 0.285 ppm acetone. A feasible acetone sensing mechanism was proposed through electronic band structure and density functional theory. The improved low‐concentration acetone sensing performance was due to the formed mesoporous Fe 2 O 3 /Cr 2 O 3 n‐p heterojunctions with a large specific surface area. The Fe 2 O 3 /Cr 2 O 3 composites showed excellent acetone gas‐sensitive performance, which could be a promising candidate for developing low‐concentration acetone sensing devices at low working temperatures.