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.