AbstractA large potential can be generated when one end of 1D and/or 2D semiconducting nanostructures such as zinc oxide (ZnO) and molybdenum disulfide is exposed to a wide spectrum of chemical molecules. A nanoenergy generator that comprises vertically aligned ZnO nanowires and poly(vinyl chloride‐co‐vinyl‐co‐2‐hydroxypropyl acrylate) is fabricated, and it can generate electricity from various molecules including gaseous species exhaled from human breath. The generated voltage, which depends sensitively on the molecular dipole moment of adsorbed chemical species and surface coverage, is significantly larger than the streaming or piezoelectric potentials and is powerful enough to directly drive a single carbon nanotube field‐effect transistor. It is demonstrated that the notion of voltage generation through molecule‐surface interactions bears general implications to other semiconducting materials, and has the advantages of simplicity, cost‐effectiveness, fast response to a wide range of molecules, and high power output, making our approach a promising tool for energy conversion and sensing applications.