Surface-doping effect of InVO4 nanoribbons and the distinctive behavior as gas sensors.

Indium vanadate (InVO4) gas sensors were fabricated by depositing InVO4 nanoribbons aqueous suspension onto ceramic substrates. Their resistances distinctively increased in the detection of ammonia and propylamine, indicating an n-to-p semiconductor transition. This novel phenomenon of the InVO4-based sensor may be ascribed to the surface doping effect: electrons were trapped by H2O and O2 and produced OH(-) and O2(-) on the InVO4 surface, which resulted in holes overcompensation in the InVO4 valence band. Moreover, the sufficiently large surface-to-volume ratio of these nanoribbons enables fast carrier transfer on the sensor surface. The InVO4 nanoribbons-based sensors had optimum performance at room temperature and enjoyed good restorability. They also had great response to a wide range of target gas concentration, with ultrahigh sensitivities up to 1100% for ammonia and 760% for propylamine.