Contact-Electrification Induced Electromagnetic Radiation and Charge Polarization Drive Spontaneous Microdroplet Interfacial Reactions.

Spontaneous chemical reactions occurring at microdroplet interfaces are fascinating and significant, yet uncovering the underlying charge interaction mechanisms remain major challenges. In this study, we integrated triboelectric-assisted atomization with electromagnetic wave detection to investigate spontaneous polarization and charge transfer dynamics at heterogeneous interfaces. Experimental results reveal that microdroplets and their surroundings undergo high-frequency electrical discharge under the influence of a contact-electrification (CE) field. For the first time, real-time monitoring of electromagnetic radiations emitted (∼30 dBm) from the microdroplet discharges was achieved and converted into electrical energy. The CE field also induces interfacial polarization, causing significant spontaneous accumulation of negative charges in the inlet reservoir, reaching 6 nC/mL and kilovolt-level voltages. In our proposed reaction routes, the CE field offer potential energy for the electrons and lower energy barriers, facilitating the formation of radicals, H2O2, and H2. Overall, the current findings offer a new CE-induced approach and perspective to enhance spontaneous chemical reaction at microdroplets interfaces.