Electrochemical reactions typically occur at the interface between a solid electrode and a liquid electrolyte. The charge exchange behaviour between these two phases determines the kinetics of electrochemical reactions. In the past few years, significant advances have been made in the development of metal oxide electrocatalysts for fuel cell and electrolyzer reactions. However, considerable gaps remain in the fundamental understanding of the charge transfer pathways and the interaction between the metal oxides and the conducting substrate on which they are located. In particular, the electrochemical interfaces of metal oxides are significantly different from the traditional (metal) ones, where only a conductive solid electrode and a liquid electrolyte are considered. Oxides are insulating and have to be combined with carbon as a conductive mediator. This electrode configuration results in a three-phase electrochemical interface, consisting of the insulating oxide, the conductive carbon, and the liquid electrolyte. To date, the mechanistic insights into this kind of non-traditional electrochemical interface remain unclear. Consequently conventional electrochemistry concepts, established on classical electrode materials and their two-phase interfaces, are facing challenges when employed for explaining these new electrode materials. 

电化学反应通常发生在固体电极和液体电解质之间的界面处。这两个相之间的电荷交换行为决定了电化学反应的动力学。在过去的几年中，在用于燃料电池和电解器反应的金属氧化物电催化剂的开发方面已经取得了重大进展。然而，在对电荷转移途径以及金属氧化物与它们所位于的导电基底之间的相互作用的基本理解上，仍然存在相当大的空白。特别地，金属氧化物的电化学界面与传统的（金属）界面显着不同，在传统的金属界面中，仅考虑导电固体电极和液体电解质。氧化物是绝缘的，必须与碳结合作为导电介质。该电极配置导致三相电化学界面，该界面由绝缘氧化物，导电碳和液体电解质组成。迄今为止，对于这种非传统电化学界面的机械学见解仍然不清楚。因此，当用于解释这些新的电极材料时，建立在经典电极材料及其两相界面上的常规电化学概念正面临挑战。