A team led by Professor Jaeyune Ryu at Seoul National University has identified a hidden variable in electrochemical reactions: the acidity in the immediate vicinity of electrodes, or "local pH." By redesigning a reactor to control electrode spacing and liquid flow, they boosted the proportion of the desired product from roughly 16% to 97%. The work, published in the Journal of the American Chemical Society, focuses on producing lactones and epoxides—key ingredients for biodegradable plastics, adhesives, coatings, and pharmaceuticals—using oxygen and electricity instead of separately added peroxide oxidants.
Local pH can differ sharply from the bulk solution because protons are generated or consumed at electrodes faster than they can diffuse away. Even in a neutral overall solution, the team estimated the region near the cathode can reach about pH 11, while the anode area can drop to about pH 2.5. These extremes can alter reactive oxygen species, change how starting molecules behave, and destabilize products—meaning a reaction can fail even when the bulk conditions look correct.
The researchers also examined more than 600 papers on organic electrosynthesis published since 2010 and found that roughly 89% involved reactions with both electron and proton transfer at electrodes. That suggests the newly highlighted pH effect could influence a wide range of electrochemical processes, not just the specific reactions studied here. The findings point to a previously underappreciated design lever for making chemical manufacturing cleaner and more efficient.