“…Recent spectroelectroscopic studies have attempted to directly observe the local pH by probing the local concentration of carbonate species which can affect the stabilization of key intermediates (e.g., *CO 2 – , *COOH, and *CO). , The increased local alkalinity, resulting from the mass-transfer limitation of OH – during the CO 2 reduction, can suppress the proton reduction reaction. ,, In particular, nanostructured, porous electrodes can accelerate the increased local alkalinity effect due to the increased surface area (i.e., active sites) as well as the mass limitation of OH – . Although computational simulations can be used to calculate the local pH of electrodes based on thickness or structural changes, there are limitations in applying them to actual electrodes with diverse nanoporous structures.…”