Mesoporous In2O3/ZnO heterogeneous microtubes replicated from waste willow catkins for high response and rapid detection of NO2 gas at low temperature.

Development of low-temperature NO 2 sensors has recently gained extensive interests. However, how to realize their over-all sensing abilities of high response and rapid detection is still challenging. Herein, adhering to the concept of sustainable development, waste willow catkins have been selected as template and soaked in Zn/In nitrates solution with two types of molar ratios. Then, the obtained precursors were placed in a furnace to undergo calcination at 500 ℃, generating two biomorphic In 2 O 3 /ZnO heterogeneous microtubes. All the tubes were assembled by well-crystallized small-size nanoparticles. Thereinto, 16.4 wt% In 2 O 3 /ZnO sensor exhibits well comprehensive gas-sensing performances towards trace NO 2 at low 92 °C. That is, its response value (S = 883) and recovery time (10 s) to 10 ppm NO 2 are higher and faster than those of most one-dimensional ZnO-based NO 2 sensors reported so far. Meanwhile, it also has good selectivity and low detection limit (10 ppb), as well as satisfactory long-term stability and humidity resistance. Therefore, the mesoporous 16.4 wt% In 2 O 3 /ZnO heterogeneous microtubes rich in oxygen vacancy defects are available as a candidate for detecting trace NO 2 at low temperature. [Display omitted] • In 2 O 3 /ZnO hetero-tubes rich in oxygen vacancies were simply prepared using waste catkins as template. • The synergism of multiple favorable structure factors answers for well over-all gas-sensing performance. • At 92 °C, 16.4 wt% In 2 O 3 /ZnO shows the highest response to NO 2 among 1-D ZnO-based sensors. • The simple and sustainable biotemplate method offers a new way for preparing tubular metal oxides. [ABSTRACT FROM AUTHOR]