Exploring novel p-n core/shell structure in single ?-Fe2O3 nanorods of hierarchical hollow microspheres for ultrasensitive acetone gas sensor

초록

Fabricating metal oxide sensors with super-sensitivity and good distinguishing properties for gases is a challenge due to the difficulties in controlling vacancy-type structural defects of nanomaterials and the data processing. In this paper, we reported the fabrication of hierarchical alpha-Fe2O3 hollow microsphere (HFHM)-based sensor using a facile and scalable method with uniform-micro spherical carbon templates, as well as the data analysis using artificial intelligence (AI). The shell of the unique hollow microspheres was built by connecting many alpha-Fe2O3 nanorods, so the superstructures have 0D, 1D, and 3D structural features. In these alpha-Fe2O3 nanorods, positron annihilation measurements revealed abundant oxygen-vacancy clusters (11 atoms), nanopores (0.53 nm) and p-n core/shell structure. The HFHM-based sensors, hence, exhibited an extremely high sensitivity toward acetone (Response = 320 (200 ppm), limited detection (DL) - 250 ppt) and ethanol (Response = 300 (200 ppm), DL 500 ppt), as well as a super-fast response time (1-2 s). In particular, by using the Principal Component Analysis (PCA), an applied AI tool, we were able to significantly improve the distinguishing and selective abilities of acetone and ethanol (high-response gas groups) as well as H2, CO and NH3 (low-response gas groups).

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