We believe the present mechanistic insight holds value for electrocatalyst design, not only towards optimizing steady-state operation, but also in the context of catalyst aging and degradation. Roughness is, after all, most often a dynamic property under reaction conditions. According to the "desorption-re-adsorption-reaction" mechanism, a dynamically evolving catalyst morphology (e.g. due to reconstruction, particle agglomeration, or dissolution) will change the resulting product selectivity and thus the targeted catalytic per- With the "desorption-re-adsorption-reaction" mechanism in mind, our final remark concerns system design strategies. In this study we purposefully put focus on catalyst morphology and, to a second extent, the electrode potential as tunable parameters that can control product selectivity. Correspondingly, we also limited our literature search to lab-scale studies that usually rely on conventional H-cell or flow cell setups. While such setups leave little room for manipulating the electrolytes' macroscopic hydrodynamics, this situation changes when up-scaling towards the practical device level. Here, careful reactor design to control the diffusion properties of volatile intermediates may prove particularly important to the resulting selectivity. In this context, unexplored effects due to special pore catalyst geometries 10,12 or particle arrangements