Self-cleaning electrode for stable synthesis of alkaline-earth metal peroxides.

Alkaline-earth metal peroxides (MO, M = Ca, Sr, Ba) represent a category of versatile and clean solid oxidizers, while the synthesis process usually consumes excessive hydrogen peroxide (HO). Here we discover that HO synthesized via two-electron electrochemical oxygen reduction (2e ORR) on the electrode surface can be efficiently and durably consumed to produce high-purity MO in an alkaline environment. The crucial factor lies in the in-time detachment of in situ-generated MO from the self-cleaning electrode, where the solid products spontaneously detach from the electrode to solve the block issue. The self-cleaning electrode is achieved by constructing micro-/nanostructure of a highly active catalyst with appropriate surface modification. In experiments, an unprecedented accumulated selectivity (~99%) and durability (>1,000 h, 50 mA cm) are achieved for electrochemical synthesis of MO. Moreover, the comparability of CaO and HO for tetracycline degradation with hydrodynamic cavitation is validated in terms of their close efficacies (degradation efficiency of 87.9% and 93.6% for HO and CaO, respectively).