Electron transfer induced contact-electrification at oil and oleophobic dielectric interface

The oil dielectric has been used for enhancing the performance and durability of triboelectric nanogenerators (TENGs), but little is known about the contact-electrification (CE) (or triboelectrification) characteristics of the oil. Here, the CE behavior of different oil droplets with oleophobic surfaces is systematically investigated by dropping oil on a single-electrode TENG. The electrification trace is clearly imaged using a high-voltage scanning probe approach. Thermally stimulated discharge techniques are adopted for studying the detailed trapping characteristics of contact-generated charges with a homemade instrument, and the results are consistent with the thermionic emission model. The research provides systematic understandings on oil CE with oleophobic surfaces, together with general investigation paradigms and characterization methods for electrification phenomena on surfaces. Meanwhile, because typical oils are regarded as free of ions, their CE is attributed to electron transfer, which may contribute to the understanding of fundamental CE mechanisms.