Cobalt oxides with abundant defects, including those with fully exposed active sites and abundant oxygen vacancies, exhibit superb catalytic activities towards oxygen evolution reaction (OER). Herein, we report a facile in-situ electrochemical self-optimization strategy to produce carbon-fiber-supported defective CoO_x (E-CoO_x/CF), in which the partial self-dissolution of acidic oxides under alkaline OER operational conditions and releasing of in-situ generated oxygen molecules are taken as advantages for reconstruction of Co species with abundant defects, Co²⁺ and oxygen vacancies. The resultant E-CoO_x/CF can achieve 10 mA cm⁻² at a low overpotential of 249 mV with a remarkable stability (>100 h without performance decay). Moreover, this electrochemical etching method can also be extended to the preparation of highly active transition metal nickel oxides for enhanced OER. This study represents a new yet efficient strategy for rationally designing and developing advanced transition metal oxides for various electrochemical applications and beyond.

具有大量缺陷的氧化钴，包括那些具有完全暴露的活性位点和大量氧空位的氧化物，对氧析出反应（OER）表现出极好的催化活性。在这里，我们报告了一种简便的原位电化学自优化策略，以生产碳纤维负载的有缺陷的CoO _x（E-CoO _x / CF），其中酸性氧化物在碱性OER操作条件下部分自溶并释放利用原位产生的氧分子来重建具有大量缺陷，Co ²⁺和氧空位的Co物种。生成的E-CoO _x / CF可以达到10 mA cm ^-2在249 mV的低超电势下具有出色的稳定性（> 100 h，而性能没有衰减）。此外，该电化学蚀刻方法还可扩展到制备高活性过渡金属氧化镍以增强OER。这项研究代表了一种新的但有效的策略，可以合理地设计和开发用于各种电化学应用及其他领域的高级过渡金属氧化物。