Understanding fundamental mechanisms for surface electronic excitation is of great importance in surface chemistry. Charge transport through metal-oxide interfaces plays a significant role in heterogeneous catalysis. Over the last several decades, a number of experimental and theoretical results suggest that this charge flow through metal-support interfaces leads to catalytic enhancement often observed in mixed catalysts. Direct measurement of charge flow on actual catalysts is a rather challenging task because it requires the use of an electronic circuit. This approach has been enabled by a catalytic nanodiode that is mainly composed of a catalytic metal and semiconducting oxides that form a Schottky contact. In this article, we describe the advances in this approach. We show that there is close connection between the phenomena of hot-electron creation and chemical reaction that occur at both gas-solid and liquid-solid interfaces. The intensity of hot-electron flow is well correlated with the turnover rates of corresponding reactions, which opens the possibility for developing new operando methodologies to monitor catalytic reactions as well as a novel scheme for the electronic control of chemical reactions.