First, previous studies have revealed significant electric double layer effects, so that this extension is highly needed for reliable screening of electrocatalysts. Secondly, electrochemical CO 2 RR has recently emerged as an attractive prospect towards a sustainable carbon cycle and energy society. The focus on CO is due to the economical relevance of this process and the simple and well-established reaction mechanism allowing for a more reliable kinetic model. From this, we reveal the PZC and CO formation energies as the relevant descriptors and also discover that the same descriptors can be also quite generally used to discuss product selectivity of electrochemical CO 2 RR. Thus the descriptor space might be used to find new CO 2 RR electrocatalysts for a defined product. This work makes a significant step forward in the screening of electrocatalysts and opens new design avenues based on the PZC of materials that has been neglected so far.