Platinized Titanium as Alternative Cost‐Effective Anode for Efficient Kolbe Electrolysis in Aqueous Electrolyte Solutions

Five commercial materials were assessed for electrochemical conversion of n‐hexanoic acid by Kolbe electrolysis. Platinized titanium performed best, achieving a coulombic efficiency (CE) of 93.1±6.7 % (n=6) for the degradation of n‐hexanoic acid and 48.3±3.2 % (n=6) for the production of n‐decane, which is close to the performance of pure platinum (89.7±14.4 and 55.5±3.5 %; n=6). 56.7 mL liquid fuel was produced per mole n‐hexanoic acid, converting to an energy demand of 6.66 kWh and 1.22 € per L. Using optical profilometry and scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy, it was shown that the degree of coverage of the titanium surface with platinum played the most important role. An uncovered surface of as little as 1–3 % already led to a deterioration of the CE of approximately 50 %. Using platinized titanium requires >36 times less capital expenditure at only <10 % increased operational expenditure; an electrode lifetime of 10000 h can be expected.