Developing an efficient strategy to facilitate deep reconstruction of precatalysts to generate more active sites is crucial for fabricating efficient OER-catalysts but remains challenging. Here, an anion-exchange strategy is reported to achieve the complete reconstruction of cobalt molybdate (CoMoO₄·nH₂O) by engineering the ultrathin Co(OH)₂ nanosheets in situ growing on CoMoO₄·nH₂O. The leaching of molybdate during anion-exchange reaction favors the formation of the loose hierarchical nanostructure, which facilitates deep reconstruction of precatalyst under electro-oxidation conditions. In-situ and ex-situ techniques demonstrate that CoMoO₄·nH₂O@Co(OH)₂ undergoes four stages of reconstruction, and the reconstruction degree depend on the electrolyte and the bias voltage. After reconstruction, more CoOOH species are generated in the reconstructed CoMoO₄·nH₂O@Co(OH)₂ compared with the reconstructed CoMoO₄·nH₂O, which is ascribed to the preferential conversion of amorphous Co(OH)₂ to β-Co(OH)₂ and CoOOH under alkaline conditions. As a result, the reconstructed CoMoO₄·nH₂O@Co(OH)₂ catalyst exhibits the significantly enhanced OER activity and excellent long-term durability. This study provides an effective strategy to construct the highly efficient OER electrocatalyst, and investigated the origin of catalytic activity through deep self-reconstruction.

开发一种有效的策略来促进预催化剂的深度重建以产生更多的活性位点对于制造高效的 OER 催化剂至关重要，但仍然具有挑战性。本文报道了一种阴离子交换策略，通过设计在 CoMoO 4 ·nH 2 O 上原位生长的超薄 Co(OH) 2 纳米片，实现了钼酸钴 (CoMoO ₄ · _nH 2 O)_的完全重建_。钼酸盐的浸出在阴离子交换反应过程中，有利于形成松散的分级纳米结构，有利于电氧化条件下预催化剂的深度重建。原位和异位技术表明，CoMoO ₄ ·nH ₂ O@Co(OH)₂经过四个阶段的重构，重构程度取决于电解质和偏置电压。_{重构后，与重构的CoMoO 4 ·nH 2} O相比，重构的CoMoO ₄ · nH ₂ O@Co(OH) ₂中产生了更多的CoOOH物质，这归因于非晶Co(OH) ₂优先转化为β -Co(OH) ₂和 CoOOH 在碱性条件下。结果，重构的CoMoO ₄ ·nH ₂ O@Co(OH) ₂催化剂表现出显着增强的OER活性和优异的长期耐久性。该研究为构建高效OER电催化剂提供了一种有效的策略，并通过深度自重构研究了催化活性的起源。