High performance porous LaFeO3 gas sensor with embedded p-n junctions enabling ppb-level formaldehyde detection

Metal oxides based semiconductors promise high performance gas sensing owing to their robustness and low cost, but are limited by their unsatisfied adsorption ability and intrinsic low carriers' mobility. We herein demonstrate an efficient strategy of reducing the adsorption energy and improving the carrier mobility via bulk implanted TiO 2 nanocrystals (NCs) in LaFeO 3 porous structure . By implanting laser generated sub-3 nm TiO 2 NCs in LaFeO 3 samples, the response value (221.8 for 100 ppm formaldehyde) increases about 4 times comparing with that of pristine. Additionally, the sample exhibits high sensitivity and fast response/recovery speed toward formaldehyde steam. The detailed analyses and theoretical calculation proves that the TiO 2 NCs could cause the increase of adsorbed oxygen levels as well as the carrier mobility through forming the heterojunction with LaFeO 3 . This work verifies that TiO 2 NCs implanted LaFeO 3 is a promising formaldehyde sensing material, which provides a new approach to improve sensing ability of metal oxide semiconductor (MOS) based gas sensors.