Deterioration of Aqueous n-Octanoate Electrolysis with Electrolytic Conductivity Collapse Caused by the Formation of n-Octanoic Acid/n-Octanoate Agglomerates

Electroorganic synthesis performed in water (as a green solvent) bears potential for the selective production of chemicals from renewable power. Yet, the limited solubility of organic molecules hampers their aqueous electrolysis. For the proposed platform chemical n-octanoic acid/n-octanoate, both summarized as C-8, it is shown that the aqueous electrolysis of C-8 can be performed successfully, provided that certain requirements are fulfilled. It is evidenced that the often-overlooked local pH shift in the proximity of the electrode can lead to the formation of large C-8 agglomerates (e.g. vesicles, bilayers), which deteriorate the electrolysis by minimizing the electrolytic conductivity. It is stressed that pH-buffering electrolytes have to be preferred to pH-neutral supporting electrolytes for C-8 electrolysis to achieve improved space-time yields. Cyclic voltammetry, particle-size analysis through dynamic light scattering, and light microscopy characterize the nature of these agglomerates.