Water splitting observed on the nanometer scale

It is a well-known school experiment: Applying a voltage between two electrodes inserted in water produces molecular hydrogen and oxygen. Researchers seek to make water splitting as energy-efficient as possible to advance industrial applications. The material of the electrode and its surface quality are crucial aspects that determine splitting efficiency. In particular, rough spots of only few nanometers in size, called reactive centers, determine the electrochemical reactivity of an electrode.