Vanadium pentoxide hierarchical structure networks for high performance ethanol gas sensor with dual working temperature characteristic

Gas sensors based on V2O5 hierarchical structure networks were formed through a direct seed-induced hydrothermal growth of nanostructured V2O5 on the substrate attached a pair of patterned Pt electrodes. Porous flower- or honeycomb-like V2O5 hierarchical structures could be controlledly synthesized under different precursor (NH4VO3) concentrations. The as-prepared hierarchical structures of V2O5, especially the flower-like network with radially oriented ultrathin nanoneedles and nanoribbons and the overlaped nanowires as constituents, show favorable microstructure features for gas-sensing application. The ethanol gas sensing properties of V2O5 network-structured sensors were investigated at room temperature (20 °C) up to 300 °C over ethanol concentration ranging from 5 to 1000 ppm. The sensor based on V2O5 hierarchical structure network showed temperature-dependent p- to n-type response characteristic reversal, resulting in dual working temperature characteristic with the dual response extremes reached at room temperature (20 °C) and 250 °C respectively. The flower-like V2O5 network sensor exhibits perfect reversibility, high response value and fast response–recovery characteristic to ethanol gas at the dual working temperatures, due to the good interface performance and gas adsorption–desorption properties of the directly assembled porous network. At 250 °C, the flower-like V2O5 network sensor is much sensitive to both ethanol gas and NH3, while at room temperature, the sensor presents very good selectivity to ethanol gas.