As all catalysts of practical relevance to CO 2 ER have a nano and meso structure, the effect of mass transport is expected to be even more complex and significant in the presence of nanometer scale pores and confinements . Nanopores and channels with sizes less than twice the potential screening length can have overlapping double layers which can lead to interesting effects due to selective ion enrichment and depletion with several practical applications . Nanostructuring is therefore a very important tool to influence the reaction environment and thus the performance of the catalyst. Unlike a planar surface, the distribution of charge density over a structured surface will be non-uniform and will lead to a varying double layer structure across the catalyst. Application of models such as the GMPNP in higher dimensions can then be very useful to study such phenomena.