General Route to Indirect and On-Demand Electrosynthesis of (Various) Peroxy Acids via In Situ Generated Hydrogen Peroxide on a Gas Diffusion Electrode

Most established synthesis routes in the chemical industry are based on high-energy-demanding processes and rely on the consumption of fossil fuels. Organic peracids, which can be used as ecofriendly and highly effective disinfectants, are typically synthesized by the reaction of a carboxylic acid and hydrogen peroxide (H2O2), which can be electrochemically synthesized with renewable electricity. In particular, the use of gas diffusion electrodes can open a new field for indirect and on-demand electrochemical peracid production. In this paper, the implementation of an electrochemical in-cell synthesis of various peracids building up on the improved synthesis of performic acid (PFA) is described. H2O2 was obtained at high current densities of 100 mA cm–2 and directly reacted with the formate catholyte solution. The reaction was improved using a buffered system and 1 wt % H3PO4 ending up with 1.47 mol L–1 H2O2 and 0.24 mol L–1 PFA and current efficiencies of 37.5% and 6.1% after 24 h of electrosynthesis, respectively. Finally, the reaction conditions were successfully transferred, demonstrating the first comprehensive approach to the indirect electrosynthesis of various carboxylic peracids and introducing a general electrochemical in-cell synthesis route.