The conversion of heavy oil fractions into lighter oil fractions is highly essential for meeting the growing demand for fuels in continuous depletion of oil reserves and for environmental remediation. We demonstrate an oil degradation approach where oil microdroplets are sprayed in air at room temperature onto untreated TiO2 nanoparticles-coated filter paper to which we apply an electrical potential. Two model polycyclic aromatic hydrocarbons as well as a crude oil sample show degradation on the microsecond time scale. Heterogeneous catalysis of a biphasic (organic/aqueous) reaction occurs at the interface of microdroplets and the charged TiO2 surface. The fragmentation yield is increased by cycling the process. The relative fragmentation yield of a model compound (rubrene) increased from 16.9% in the first cycle to 32.6% in the third cycle. This convenient and efficient method suggests possible future industrial applications.