Studying of contact electrification and electron transfer at liquid-liquid interface

Triboelectric nanogenerator (TENG) provides an effective approach for studying transferred charges at solid-solid or liquid-solid interfaces. Here, by dripping a liquid droplet through an immiscible organic solution (transformer oil), we used single-electrode mode TENG to measure the transferred charges on the liquid droplet once it goes down in the solution. The falling droplets (with volume of 25 μL) can generate negative charges on its surface and the output charges amount can reach − 5.3рC by passing through the transformer oil. In addition, we found that both the рH value and the electrostatic shielding effect of free ions greatly hinder the electron transfer efficiency at L-L contact electrification. Combining the experimental results and previous research, we infer that there are both ion transfer and electron transfer happening in the L-L electrification.