Physical adsorption of OH - causes anomalous charging at oxide-water interfaces.

This study reveals a charging mechanism at oxide-water interfaces, solving the puzzle that challenges the traditional electrical double layer (EDL) model. We found that the experimentally measured zeta potential is caused by physically adsorbed OH - , instead of acidic dissociation of surface OHs and the first-layer water. This mechanism should apply for a wide range of material interfaces and could find applications in future.