Investigations on the contact-electro-catalysis under various ultrasonic conditions and using different electrification particles

Contact electrification (CE), as a well-known physical phenomenon, is widely used in energy, purifying applications. However, employing the electron-transfer in heterophase interfaces CE during mechanical stimulation to induce chemical reactions is rarely reported. Recently, the concept of contact-electro-catalysis (CEC) was proposed, which represents the reactivity of charge exchange at heterogeneous interfaces and the catalytic performance of pristine dielectric powders. In this study, we aim to investigate the optimal parameters for CEC under the ultrasonic reaction condition. We investigated the degradation of methyl orange (MO) solution by Fluorinated Ethylene Propylene (FEP) powder under different ultrasonic powers of 120 W, 240 W, 360 W, 480 W, 600 W, and different frequencies of 20 kHz, 28 kHz, 40 kHz and 89 kHz, in 240 min. The experimental results showed that the final degradation rate of MO increases with the increase of ultrasonic power. And the highest final degradation rate was obtained at the ultrasonic frequency of 40 kHz. Meanwhile, it is found that a highest reaction rate was achieved around 22 ℃ with the FEP as the catalyst in our experiment. Furthermore, we studied the effect of different dielectric particles on the organic solutions’ decolorization. It is found that the CEC degradation is more prone to occur in the catalyst with strong electron-withdrawing ability (e.g. FEP vs. MO), while apparent physical adsorption occurs when the catalyst and the targeted organic ions possess opposite electric polarity (e.g. Nitrile Butadiene Rubber (NBR) vs. MO, or FEP vs. Rhodamine B (RhB)). This study helps to characterize the optimal conditions and the further understanding of CEC reactions and catalysts.