Preparation of hollow bidirectional porous 3D peony-flower structure ZnCO₃/ZnO with gas sensitive properties at room temperature

ZnO is the most common gas sensitive material, but it can only respond at high temperature for its extremely high initial resistance, and its recovery time is often longer. The construction of porous structure can improve the gas adsorption capacity, and electrolyte doping can reduce the initial resistance and recovery time. In this study, the Zn₅(OH)₆(CO₃)₂ precursor was prepared and then calcined to prepare the 3D hollow peony flower-like ZnCO₃/ZnO nanocomposites with vertical and parallel bidirectional pores. The bidirectional porous structure increased the specific surface areas to 350.280 m²·g⁻¹. For 100 ppm NO_x (NO₂: NO=17:5) gas detection, the electrolyte (ZnCO₃) doping decreased the recovery time to 15 s at room temperature (25 ℃), and its gas response reached to 159 at room temperature and 233 at 45 ℃. Due to electrolyte doping, the gas-sensitive property was sharply increased, and the recovery time was much shorter than the response time, both them were much very rare. The excellent and unique gas sensitivity could be attributed to the larger specific surface area, flower-like porous structure and the ionic lattice field interactions.