Core–Shell In₂O₃/ZnO Nanoarray Nanogenerator as a Self-Powered Active Gas Sensor with High H₂S Sensitivity and Selectivity at Room Temperature

Abstract

Self-powered active gas sensing has been realized from core–shell In2O3/ZnO nanoarray nanogenerator, and extremely high H2S sensitivity and selectivity at room temperature have been obtained. In2O3/ZnO nanoarrays have two functions: one is an energy source because In2O3/ZnO nanoarrays can produce piezoelectric output power; the other is a H2S sensor because the piezoelectric output of In2O3/ZnO nanoarrays varies with the concentration of H2S. Upon exposure to 700 ppm of H2S at room temperature, the piezoelectric output of In2O3/ZnO nanoarrays decreases from 0.902 V (in air) to 0.088 V, and the sensitivity is up to 925, much higher than that of bare ZnO nanoarrays. The heterostructure conversion of In2O3/ZnO to In2S3/ZnO, in which the electron depletion layer on the surface of ZnO changes to the accumulation layer, has stronger adjustment on the free-carrier piezo-screening effect of ZnO than the gas adsorption. Our results demonstrate that a heterostructured nanoarray nanogenerator has potential applications in actively detecting toxic gas without using any external electricity power.