Electrocatalysis is gaining impetus as a key technology in fuel cells and for the medium-term energy storage in the context of intermittent, renewable energy sources such as wind and solar power. Furthermore, electrocatalysis promises to convert rather inert molecules such as CO 2 and N 2 into reduced products such as CO and ammonia under relatively mild conditions (1, 2). Harnessing the full power of electrocatal-ysis is, however, hampered by a lack of understanding of the governing physical and chemical processes at the metal-electrolyte interface. In PNAS, Cheng et al. (3) bring key insight to the characterization of reaction intermediates during CO 2 electroreduction via first-principles molecular dynamics modeling. This reaction is timely and has, over the last few years, served as the playground for advanced atomistic modeling of elec-trocatalysis (4-9). The general lack of understanding is due to the inherent complexity of the electrified interface and its characterization. The characterization is difficult since most metal-liquid interfaces are amorphous. Therefore, no long-range ordering can be detected. Experimentally , the characterizations heavily rely on spectroscopy that provides average molecular orientations [infrared (IR) and Raman] or elemental composition and oxidation states (X-ray photoelectron, X-ray absorption near-edge, etc.) (10