Biotemplate-derived mesoporous Cr2O3 tube bundles for highly sensitive and selective detection of trace acetone at low temperature

Abstract

The development of Cr2O3-based acetone sensor is challenging due to no report on its high sensing ability. To this end, we simply dipped poplar branches into chromic chloride solution to obtain immersed precursors, which were then calcined in air to controllably synthesize two biomorphic Cr2O3 tube bundles. Amongst, the hierarchical tube structure (Cr2O3-500) calcined at 500 °C is replicated from small-size nanoparticles, so that it has uniform mesopore distribution and large specific surface area. Such microstructural features not only favor the rapid accessibility of gas molecules to sensing layer, but also provide an effective platform of more active sites for facilitating surface adsorption and chemical reaction. Especially, under the synergism of few non-stoichiometric CrO3-x species, Cr2O3-based sensor achieves highly sensitive and selective detection to trace acetone gas for the first time. At 133 °C, Cr2O3-500 exhibits high response value (S = 110.1) to 100 ppm acetone gas and low actual detection limit (10 ppb, S = 1.3). Simultaneously, it also has rapid response-recovery characteristics, good stability and moisture resistance. In addition, the sensing mechanism is discussed in details.