In the previous section, we discussed the importance of considering electrostatic interactions in an electrocatalytical system of molecularly modified electrodes. Being aware that electrocatalysis is initiated by applying current, the effects of electric fields must be considered as well. External electric fields are a general term referring to the uniform electric field generated by a voltage bias. Aligning an electric field along a specific bond axis can either elongate or shorten the bond. By precisely controlling the orientation of an external electric field along a reaction axis (the direction of bond breaking and bond-forming), a reaction can be accelerated or slowed down. 100, 101 Thus, the orientation of the electric field is crucial in catalysis. Additionally, an electrostatic field-induced stabilization of the transition state can lower an activation barrier. An oriented external electric field is an external electric field that is oriented to a specific direction and can be generated by a dipolar field, scanning tunneling microscopy (STM), and charged surfaces in electric cells. Contrary to electrocatalysis, where electrons are gained or lost associated with current applied to promote electrochemical reactions, the electrostatic field exists in charged functional groups and surface, solvent, and electrolytes. A general strategy involving oriented external electric fields in catalysis on the atomic scale is represented by single-molecule experiments via STM. Detailed discussions on theoretical and experimental studies on external electric fields and oriented external electric fields have been elaborated in recent reviews. 100, 102, 103, 106-108 However, harnessing oriented external electric fields by STM has limitations on scalability. As an alternative, the interfacial design of electric cells has been developed to demonstrate the possible application of electrostatic field in catalysis. Herein, we would like to emphasize the significance of electrostatic field resulting from an external voltage applied in an electric cell, and discuss its effects on the catalytic system. We refer to the catalytic system enabled by electrostatic field "electrostatic catalysis" to differentiate from electrocatalysis enabled by electric current. We will focus on interfacial experiments to discuss the potential role of immobilized electrode surfaces.