Plasmonic in-situ imaging of zeta potential distributions at electrochemical interfaces of 2D materials in water

Understanding the electrical double layer (EDL) at solid-liquid interfaces is pivotal across various fields, including energy storage, electrowetting, and electrocatalysis, yet probing its structure and heterogeneity remains a considerable challenge. Here, we report an optical method for the direct visualization and quantification of the zeta potential (ζ) across the interfaces between 2D materials and aqueous solutions. By modulating surface charge density, we map the heterogenous distribution of ζ potential across the MoS₂ nanosheet interface, revealing how both external factors and intrinsic material properties shape interfacial charge. This approach overcomes the drawbacks of conventional methods for evaluating ζ potential in 2D materials, providing insights into elucidate the complex interplay between the ζ potential and the catalytic activity of 2D materials. Furthermore, it establishes a robust framework for exploring the EDL in various electrochemical systems. Our findings reveal a deeper understanding of complex electrochemical interface interactions, offering valuable insights into the fundamental processes governing these systems.