Alkaline-earth metal peroxides (MO₂, M = Ca, Sr, Ba) represent a category of versatile and clean solid oxidizers, while the synthesis process usually consumes excessive hydrogen peroxide (H₂O₂). Here we discover that H₂O₂ synthesized via two-electron electrochemical oxygen reduction (2e⁻ ORR) on the electrode surface can be efficiently and durably consumed to produce high-purity MO₂ in an alkaline environment. The crucial factor lies in the in-time detachment of in situ-generated MO₂ 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⁻²) are achieved for electrochemical synthesis of MO₂. Moreover, the comparability of CaO₂ and H₂O₂ for tetracycline degradation with hydrodynamic cavitation is validated in terms of their close efficacies (degradation efficiency of 87.9% and 93.6% for H₂O₂ and CaO₂, respectively).

碱土金属过氧化物 （MO₂， M = Ca， Sr， Ba） 是一类多功能且清洁的固体氧化剂，而合成过程通常会消耗过量的过氧化氢 （H₂O₂）。在这里，我们发现通过电极表面的双电子电化学氧还原 （2e⁻ ORR） 合成的 H₂O₂ 可以在碱性环境中高效持久地消耗以产生高纯度的 MO₂。关键因素在于原位生成的 MO₂ 与自清洁电极的及时分离，其中固体产物自发地从电极上分离以解决阻塞问题。自清洁电极是通过构建高活性催化剂的微/纳米结构并进行适当的表面改性来实现的。在实验中，MO₂ 的电化学合成实现了前所未有的累积选择性 （~99%） 和耐久性 （>1,000 h， 50 mA ^cm-2）。此外，CaO₂ 和 H₂O₂ 对四环素降解与流体动力学空化的可比性根据它们的接近功效得到验证（H₂O₂ 和 CaO₂ 的降解效率分别为 87.9% 和 93.6%）。