Distinct crystal-facet-dependent gas-sensing performances for n-Fe2O3/p-Co3O4 heterostructure

Abstract

In this work, Co3O4 enclosed with specific facets that anchored with Fe2O3 nanorods was prepared by a facile hydrothermal method. To reveal the role of heterojunctions on their gas-sensing performances, the exposed facets of Co3O4 crystals were varied from nanocubes enclosed with six {100} (denoted as Fe2O3/C-Co3O4) to truncated nanocubes enclosed with six {100} and eight {111} (denoted as Fe2O3/TC-Co3O4). It revealed that the growth of Fe2O3 on the surface of Co3O4 nanocrystals can remarkably improve their gas-sensing performances. The response value of Fe2O3/TC-Co3O4 can reach as high as 318.7 (Ra/Rg) towards 100 ppm triethylamine (TEA) which is 6–7 and 1.6 times higher than its pristine counterparts and Fe2O3/C-Co3O4, respectively. The highly facet-dependent gas-sensing performances of these p-n heterostructures were contributed to the effect of hetero-contact on charge transfer as well as gas adsorption which were confirmed by First-principles calculation. This study opens an avenue to investigate the effect of p-n heterojunctions on gas-sensing properties by designing interfacial contact with defined crystal facets, as well as guidance for the preparation of sensing materials with super performances.