Research paperEnhanced NO2 gas sensing properties by Ag-doped hollow urchin-like In2O3 hierarchical nanostructures

•Ag-doped hollow urchin-like spheres In2O3 were synthesized via a one-step hydrothermal method.•Sensor response to NO2 was greatly enhanced by slight Ag doping.•Sensor response varied linearly within a certain NO2 concentration.•Excellent NO2 selectivity and high stability were achieved.

Ag-doped hollow urchin-like spheres In2O3 hierarchical nanostructures are developed for NO2 detection. Such unique architectures are synthesized by a facile and efficient solvothermal route combined with the subsequent thermal treatment. Various techniques, including X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were employed to acquire the crystalline and morphological information of the as-obtained samples. Gas sensing performances of the sensor devices fabricated from pure and Ag-doped In2O3 were systematically investigated. The results indicate that the sensors based on Ag-doped In2O3 in certain molar ratio of AgNO3 to In2O3 (1:100) exhibit the largest response toward 1 ppm NO2, which is almost 23 times higher than that of the sensor based on pure In2O3 at the optimum operating temperature. It demonstrates that the Ag-doping can significantly improve the response to NO2. The excellent and enhanced NO2 sensing performances of Ag-doped In2O3 can be attributed to its novel hierarchical structure and the catalytic activity of Ag nanoparticles.