Interface Engineering of Fe2O3@Co3O4 Nanocubes for Enhanced Triethylamine Sensing Performance

The formation of p-n junctions has attracted much attention for improving the gas-sensing performances in the field of gas detection. Although the p-n heterojunctions with a defined interfacial contact are crucial in investigating their roles on gas-sensing properties, the design of such well-defined p-n heterojunctions has been sparse until now. Herein, a p-n heterostructure composed of well-defined {001}-faceted Co3O4 as backbones and Fe2O3 nanorods as shells was synthesized using a simple hydrothermal method without the requirement of seed crystals. During the reaction, it was demonstrated that the acetic acid holds the key to the epitaxial growth of Fe2O3 nanorods on the surface of Co3O4 nanocubes. The response of this as-designed Fe2O3@Co3O4 composite (Ra/Rg = 134.9) toward 100 ppm triethylamine was about 6 times higher than that of pristine Co3O4 (Ra/Rg = 23.1) and 5 times higher than that of pristine Fe2O3 (Ra/Rg = 28.9). The highly boosted gas-sensing performances were attributed to the positive effects of the heterointerface on the gas adsorption process that were revealed through the firstprinciples method based on the defined heterointerfacial contacts, as well as the enlarged signal of gas-solid reactions through the heterojunctions. This work not only provides a strategy to improve gas-sensing performances but also provides guidance for the investigation of the effects of p-n heterojunctions on gas-sensing properties by designing interfacial contact with defined crystal facets.