The development of highly active dual-functional electrocatalysts, especially for oxygen evolution reaction (OER), is highly desirable to electrocatalyze water splitting for hydrogen production. Herein, a cobalt metal-organic frameworks (Co-MOFs) array is employed as the platform to fabricate oxygen-defect-rich Co₃O₄ flakes that are vertical grown on nickel foam substrates. This MOFs-derived Co₃O₄ arrays show a hierarchical interconnected porous flake network structure with tunable oxygen vacancies. The unique structural features obtained from an optimal hydrogenation condition render outstanding catalytic performance toward the oxygen evolution in alkaline media (an ultralow overpotential of 205 mV at 10 mA cm⁻²; a small Tafel slope of 65.3 mV dec⁻¹ as well as high stability). This OER performance is among the best non-noble metal catalysts reported to date. Meanwhile, this defect-rich Co₃O₄ array electrode is also efficient for catalyzing hydrogen evolution in the same basic solution (overpotential of ∼108 mV at 10 mA cm⁻²). The electrolyzer for overall water splitting can deliver a current density of 100 mA cm⁻² at a cell voltage as low as 1.84 V. Density functional theory calculation reveals that the enhanced OER performance mainly arises from the oxygen vacancies and consequently the lowered activation energy as well as improved electrical conductivity.

高度期望的是开发高度活性的双功能电催化剂，尤其是用于氧释放反应（OER）的电催化剂，以电分解水来生产氢。在本文中，采用钴金属有机骨架（Co-MOFs）阵列作为平台来制造富氧缺陷的Co ₃ O ₄薄片，该薄片垂直生长在泡沫镍上。这种由MOF衍生的Co ₃ O ₄阵列显示出具有可调氧空位的分层互连多孔薄片网络结构。。从最佳氢化条件获得的独特结构特征使其对碱性介质中的氧气释放具有出色的催化性能（在10 mA cm ^-2时超低的205 mV过电势； 65.3 mV dec ^-1的小Tafel斜率以及高稳定性）。该OER性能是迄今为止报道的最好的非贵金属催化剂之一。同时，这种富含缺陷的Co ₃ O ₄阵列电极在相同的碱性溶液（10 mA cm ^-2时的过电势为〜108 mV）下也能有效催化氢的释放。用于整体水分解的电解槽可提供100 mA cm ^-2的电流密度 在低至1.84 V的电池电压下。密度泛函理论计算表明，增强的OER性能主要来自氧空位，因此降低了活化能，并提高了电导率。