Ultra-sensitive ethanol gas sensors based on nanosheet-assembled hierarchical ZnO-In2O3 heterostructures

[Display omitted] •A novel strategy to construct 3D structures assembled by 2D mesoporous nanosheets was proposed.•The unique architectures were obtained by thermal conversion of 3D hierarchical mixed metal glycerolate.•Numerous heterojunction interfaces with intimate contacts were formed in the 2D nanosheets.•The 3D ZnO/In2O3 heterostructures showed a response as high as 170 to 50 ppm ethanol.•The 3D ZnO/In2O3 heterostructures exhibited excellent selectivity, repeatability, and stability. Developing efficient sensing materials with super sensitivity and selectivity is imperative to fabricate high-performance gas sensors for satisfying future needs. Herein, we report the preparation of ultrathin nanosheet-assembled 3D hierarchical ZnO/In2O3 heterostructures for the sensitive and selective detection of ethanol by sintering the 3D hierarchical Zn/In glycerolate precursors consisting of ultrathin nanosheets synthesized through a facile solvothermal method. The obtained ZnO/In2O3 heterostructures were carefully characterized by XRD, SEM, HRTEM, BET and XPS. The results showed that the 20%ZnO/In2O3 heterostructure is built up by many ultrathin nanosheets composed of intimately connected ZnO and In2O3 nanoparticles and have a specific surface area as high as 137.1 m2 g−1. Because of the unique hierarchical structure, abundant mesoporous and formation of ZnO-In2O3 n-n heterojunctions, the 20%ZnO/In2O3 heterostructure based sensor was ultra-sensitive to ethanol gas at 240 °C and exhibited a response as high as 170 toward 50 ppm of ethanol, which is about 3.3 times higher than that of pure In2O3 based sensor. Moreover, the sensor based on 20%ZnO/In2O3 heterostructure has virtues of excellent selectivity, good long-term stability and moderate response and recovery speed (35/46 s) toward ethanol. Therefore, the ultrathin nanosheet-assembled 3D hierarchical heterostructures are promising materials for fabricating high-performance gas sensors.