Hot electron-driven electrocatalytic hydrogen evolution reaction on metal-semiconductor nanodiode electrodes.

Hot electrons generated on metal catalysts influence atomic and molecular processes, leading to hot electron-driven catalytic reactions. Here, we show the acceleration of electrocatalytic hydrogen evolution caused by internal injection of hot electrons on Pt/Si metal-semiconductor electrodes. When a forward bias voltage is applied to the Pt/Si contact, hot electrons are injected. The excess energy of these electrons allows them to reach the Pt/electrolyte interface and reduce the adsorbed hydrogen ions to form H2 (2H+ + 2e-→H2). We show that the onset potential of the hydrogen evolution reaction shifts positively by 160 mV while the cathodic current exhibits an 8-fold increase in the presence of hot electrons. The effect disappears when the thickness of the Pt film exceeds the mean free path of the hot electrons. The concept of a hot electron-driven reaction can lead to the development of a novel mechanism for controlling reactivity at liquid-solid interfaces.