Boron doped diamond electrode for efficient persulfate generation: The modulation of boron doping level on interfacial electron transfer

Abstract

The inefficient Faradaic efficiency of electro-synthesis of sodium persulfate (Na2S2O8) hinders its industrial application. In this work, modulated high-performance boron-doped-diamond (BDD) electrodes were used to Na2S2O8 electro-synthesis. The effect of boron doping level of BDD electrode on Na2S2O8 generation was studied for the first time. Based on electro-synthesis results, BDD (0.05% B) electrode produced more Na2S2O8 (41.85 mM at 120 min) with the Faradaic efficiency of 90% that is the highest value reported in the literatures. Na2S2O8 was generated by ·OH mediated indirect oxidation, and the BDD (0.05% B) electrode produced more ·OH. Furthermore, the less C-O functional groups on the BDD (0.05% B) electrode surface inhibited the interfacial electron transfer of H2O to O2, and therefore promoted ·OH formation. These findings highlight the relationship between boron doping level, surface functional groups, interfacial electron transfer process and Na2S2O8 generation, providing a theoretical guidance for efficient Na2S2O8 electro-synthesis.