Advances in understanding contact electrification via DFT and molecular dynamics simulations

Contact electrification (CE) has been studied for many years, yet its mechanism remains unclear and theories are inconsistent. This Review discusses experimental and theoretical studies on CE, highlighting how CE may be dominated by the competition and coupling among electron transfer, ion transfer and material transfer between two surfaces under different conditions. These transfer mechanisms have been found experimentally, but their quantitative impact on CE has not yet been determined owing to the limited spatial and temporal resolution of instruments. Fortunately, density functional theory and molecular dynamics yield the possibility of solving this obstacle. Electron transfer is driven by work function changes or frontier orbital matching, and it is regulated by strain-induced electronic state restructuring and the flexoelectric effect. Ion transfer is promoted by the formation of capillary water bridges and is regulated by the disruption of hydrogen-bond networks in the interfacial water layer, and material transfer arises from mechanical stress. Lastly, we highlight future work hat is important for further studies of CE.