Interface Engineering of Fe₂O₃@Co₃O₄ Nanocubes for Enhanced Triethylamine\nSensing Performance

Abstract

The\nformation of p–n junctions has attracted much attention\nfor improving the gas-sensing performances in the field of gas detection.\nAlthough the p–n heterojunctions with a defined interfacial\ncontact are crucial in investigating their roles on gas-sensing properties,\nthe design of such well-defined p–n heterojunctions has been\nsparse until now. Herein, a p–n heterostructure composed of\nwell-defined {001}-faceted Co₃O₄ as backbones\nand Fe₂O₃ nanorods as shells was synthesized\nusing a simple hydrothermal method without the requirement of seed\ncrystals. During the reaction, it was demonstrated that the acetic\nacid holds the key to the epitaxial growth of Fe₂O₃ nanorods on the surface of Co₃O₄ nanocubes.\nThe response of this as-designed Fe₂O₃@Co₃O₄ composite (<i>R</i>_a/<i>R</i>_g = 134.9) toward 100 ppm triethylamine was\nabout 6 times higher than that of pristine Co₃O₄ (<i>R</i>_a/<i>R</i>_g =\n23.1) and 5 times higher than that of pristine Fe₂O₃ (<i>R</i>_a/<i>R</i>_g = 28.9). The highly boosted gas-sensing performances were attributed\nto the positive effects of the heterointerface on the gas adsorption\nprocess that were revealed through the first-principles method based\non the defined heterointerfacial contacts, as well as the enlarged\nsignal of gas–solid reactions through the heterojunctions.\nThis work not only provides a strategy to improve gas-sensing performances\nbut also provides guidance for the investigation of the effects of\np–n heterojunctions on gas-sensing properties by designing\ninterfacial contact with defined crystal facets.