Triboelectric Nanogenerator As a Probe for Investigating Charge Transfer at Liquid–Solid Interfaces

The liquid-solid interface plays a fundamental role in a wide range of phenomena, including reaction kinetics, charge transfer, and fluid behavior. However, the underlying physicochemical mechanisms governing these interfacial interactions remain a topic of ongoing debate. Recently, the concept of the triboelectric nanogenerator probe (TENG probe) has been introduced to investigate the charge transfer at liquid-solid interfaces by recording the triboelectrification of liquid droplets sliding on insulating surfaces with both spatial and temporal resolution. Variations in interfacial properties directly influence charge transfer dynamics, such as ion concentration, chemical composition, flow rate, and structure of electric double layer (EDL), making the TENG probe a powerful and sensitive tool for quantitative studying charge transfer at liquid-solid interfaces. This review summarizes the fundamental principles and key features of TENG probes and highlights their applications in liquid-solid charge transfer studies, in situ chemical analysis, fluid status monitoring, and sensing systems. The perceived challenges and opportunities that face this multidisciplinary research field are also outlined, with special attention on experimental efforts linking chemical, physical, and mechanical factors in liquid-solid interfacial charge transfer dynamics.