Epitaxial growth of Co3O4/In2O3 p-n heterostructure with rich oxygen vacancies for ultrahigh triethylamine sensing

Although metal oxides based gas sensors have been researched extensively in previous works, there are enormous challenges on improving the deficiencies in poor selectivity, sensitivity, humidity resistance and so on. Hence, we developed an epitaxial growth method to prepare dendritic Co3O4/In2O3-(1-3) heterostructures of distinct Co/In mass ratios through perfect lattice matching between the two crystal domains at the interface, along with introducing large amounts of oxygen vacancies. As a result, the Co3O4/In2O3-2 heterostructure based gas sensor showed enhanced sensing properties towards triethylamine (TEA, 100 ppm) with a high response value of Ra/Rg = 576.1 at an optimal working temperature of 200 degrees C, which is 93 times higher than that of pristine In2O3. Moreover, the Co3O4/In2O3-2 sensor exhibited excellent gas selectivity, quick recovery time, repeatable cycling, long-term stability, as well as outstanding humidity resistance. The improved TEA gas sensing performance can be attributed to the integration of interfacial synergies in Co3O4/In2O3 p-n heterostructure and generation of rich oxygen vacancies, exposing more active sites to facilitate the adsorption/desorption of gas molecules. This work provides a feasible pathway to regulate TEA sensing performance of metal oxide semiconductor (MOS) gas sensors by capitalizing on self-sacrificial template strategy and reconstruction of novel metal oxide heterostructure.