Continuously improved gas-sensing performance of Zn2SnO4 porous octahedrons by structure evolution and further ZnSnO3 nanosheets decoration

To optimize the structure and composition of the metal oxide semiconductor is one of effective approaches to improve its gas-sensing performance. In this paper, Zn2SnO4 solid octahedrons were first synthesized by a hydrothermal method, then converted to hollow structures with a shape preserved through a simple and practical acid etching process. Ultimately, the hierarchical ZnSnO3/Zn2SnO4 hollow composite with porous structure was designed and prepared by in situ growth of ZnSnO3 nanosheets on the surface of Zn2SnO4 hollow octahedrons in the seed mediated wet-chemical way. It was found that through the structure evolution from solid octahedron to hollow structure, the sensitivity of gas sensor toward triethylamine (TEA) was visibly improved. Significantly, superior TEA-sensing properties, such as lower optimal working temperature, higher sensitivity, wider linear response range, more rapid response/recovery speed and more excellent selectivity were further achieved by decorating Zn2SnO4 hollow octahedrons with ZnSnO3 nanosheets. It was remarkable that the sensor based on hierarchical ZnSnO3/Zn2SnO4 porous hollow octahedrons displayed long-term stability to TEA and anti-humidity property, suggesting its potential practical applications in detection of highly toxic TEA. The improved sensing mechanism on the strength of structure and composition evolution for the gas sensor was discussed in detail.