Contact electrification of organic liquid-metal interfaces induced by interfacial energy level shift

Liquid-solid contact electrification (L-S CE) has become a widely researched topic in recent years, presenting innovative approaches to enriching traditional power supply methods. However, most research on L-S CE has predominantly concentrated on electrolyte solutions interacting with solid surfaces. In this study, we systematically explored, for the first time, the L-S CE of non-electrolytes (organic solvents) and metals. Our experiments demonstrated that a simple system composed of two dissimilar metal electrodes and pure ethanol can achieve a maximum open-circuit voltage (V_OC) of 578 mV, a short-circuit current (I_SC) of 744 nA, and an output power density of 62.29 nW cm⁻². We introduced the classic energy level shift theory as a framework to describe the L-S CE of organic solvents and metals and then employed density functional theory (DFT) and molecular dynamics (MD) simulations to further quantify both the vacuum level shift and the number of transferred electrons at the liquid-solid interfaces. Based on these results, we can successfully interpret the experimentally measured CE voltage characteristics of different metals and organic solvents. Finally, the metal-organic solvent system developed in this study can amplify electrical signals through straightforward series and parallel connections. This work provides a foundation for further exploration of organic solvent-based energy-harvesting systems and electrochemical sensors in L-S CE.