In situ dynamic redeposition of Fe sites with high catalytic activity is crucial for enhancing performance of transition metal (TM) catalysts. However, saturated coverage of iron sites on substrate and dynamic deposition control are rarely reported. Herein, bi-metal dynamic balances are analyzed in depth based on interface of double-layer hollow metal-organic framework (MOF). The newly designed catalyst undergoes an accelerated deposition and saturation coverage of Fe ions via controlling the concentration of Fe(III) in electrolyte, as well as electron holes and active host. Importantly, the balance of iron dissolution and redeposition (main cycle) and the oxidation-reduction equilibrium of cobalt ions (by-cycle) are proposed, and also mechanism of their synergistic effect to improve the efficiency of OER is revealed. Furthermore, the formation mechanism of double-layer hollow cage is studied by time-dependent evolution process. This study may inspire a better catalyst system for OER in alkaline medium and further design on complex structured MOFs.

具有高催化活性的 Fe 位点的原位动态再沉积对于提高过渡金属 (TM) 催化剂的性能至关重要。然而，很少报道基板上铁位点的饱和覆盖和动态沉积控制。在此，基于双层中空金属-有机框架（MOF）界面对双金属动态平衡进行了深入分析。新设计的催化剂通过控制电解质中 Fe(III) 的浓度以及电子空穴和活性主体的浓度来加速 Fe 离子的沉积和饱和覆盖。重要的是，提出了铁溶解和再沉积的平衡（主循环）和钴离子的氧化还原平衡（副循环），并揭示了它们协同作用提高OER效率的机制。此外，采用时变演化过程研究了双层空心笼的形成机理。该研究可能会启发在碱性介质中用于 OER 的更好催化剂体系，并进一步设计复杂结构的 MOF。