Electrostatic Properties of Semiconductor-Electrolyte Interface with Surface Charge Regulation

The interface between a semiconductor material and an electrolyte solution has interesting and complex electrostatic properties. Its behavior depends on the density of mobile charge carriers that are present in both phases as well as on the surface chemistry at the interface through surface charge regulation. The latter is driven by chemical equilibria involving the immobile surface groups and the potential determining ions in the electrolyte solution. All these lead to an electrostatic potential distribution that propagates in such a way that the electrolyte and the semiconductor are dependent on each other. Any variation in the charge density in one phase will lead to a response in the other. This has significant implications on the physical properties of a single semiconductor-electrolyte interface and on the electrostatic interactions between semiconductor particles suspended in electrolyte solutions. We show that doped nanocolloids are less stable in comparison with pure dielectric particles with identical surface chemistry. The Figure shows the electrostatic potential distribution inside and outside two interacting semiconductor spherical colloids. Our results have potential implications for applications such as sensing and detection, catalysis, and self-assembly of semiconductor nanoparticles.