Visible and UV light are demonstrated to significantly enhance the sensing properties of an n-type porous silicon (PS) extrinsic semiconductor interface to which TiO2 and titanium oxynitride (TiO2-xNx) photocatalytic nanostructures are fractionally deposited. The acid/base chemistry of NH3, a moderately strong base, and NO2, a moderately strong acid, couples to the majority charge carriers of the doped semiconductor as the strong acid (TiO2) enhances the extraction of electrons from NH3, and the more basic TiO2-xNx decreases the efficiency of electron extraction relative to the untreated interface. In contrast, NO2 and a TiO2 or TiO2-xNx nanostructure-decorated PS interface compete for the available electrons leading to a distinct time dependent electron transduction dynamics as a function of TiO2 and TiO2-xNx concentration. Only small concentrations of TiO2 and its oxynitride and no self-assembly are required to enhance the response of the decorated interface. With light intensities of less than a few lumens/cm(2)-sterad-nm, responses are enhanced by up to 150% through interaction with visible (and UV) radiation. These light intensities should be compared to the sun's radiation level, approximate to 500 lumens/cm(2)-sterad-nm suggesting the possibility of solar pumped sensors. The observed behavior in these systems is largely explained by the recently developed Inverse Hard/Soft Acid/Base (IHSAB) concept.