Identifying the dynamic behaviors in complete reconstruction of Co-based complex precatalysts during electrocatalytic oxygen evolution

Zhang Jingfang, Wu Danyang, Cai Linke, Lu Youluan, Cheng Fanpeng, Shi Lijuan, Yi Qun*, Liu Yao*, Huang Yi*

DOI:10.1016/j.jechem.2024.08.043

Abstract

Transition metal-based nanomaterials have emerged as promising electrocatalysts for oxygen evolution reaction (OER). Considerable research efforts have shown that self-reconstruction occurs on these nano materials under operating conditions of OER process. However, most of them undergo incomplete reconstruction with limited thickness of reconstruction layer, leading to low component utilization and arduous exploration of real catalytic mechanism. Herein, we identify the dynamic behaviors in complete reconstruction of Co-based complexes during OER. The hollow phytic acid (PA) cross-linked CoFe-based complex nanoboxes with porous nanowalls are designed because of their good electrolyte penetration and mass transport ability, in favor of the fast and complete reconstruction. A series of experiment characterizations demonstrate that the reconstruction process includes the fast substitution of PA by OH to form Co(Fe)(OH)_x and subsequent potential-driven oxidation to Co(Fe)OOH. The obtained CoFeOOH delivers a low overpotentiaof 290 mV at a current density of 10 mA cm^-2 and a long-term stability. The experiment results together with theory calculations reveal that the Fe incorporation can result in the electron rearrangement of reconstructed CoFeOOH and optimization of their electronic structure, accounting for the enhanced OER activity. The work provides new insights into complete reconstruction of metal-based complexes during OER and offers guidelines for rational design of high-performance electrocatalysts.

过渡金属基纳米材料是一种很有前途的析氧反应电催化剂。大量的研究表明，在OER工艺条件下，这些纳米材料发生了自重构。然而，它们大多是不完全重构，重构层厚度有限，导致组分利用率低，对真正催化机理的探索困难。本文研究了钴基配合物在OER过程中完全重构的动力学行为。由于具有良好的电解质渗透能力和质量传递能力，设计了具有多孔纳米壁的中空植酸（PA）交联cofe基复合纳米盒，有利于快速和完全的重建。一系列实验表征表明，重构过程包括：PA被OH快速取代生成Co(Fe)(OH)_x，随后电位驱动氧化生成Co(Fe)OOH。获得的CoFeOOH在电流密度为10 mA cm^-2时具有290 mV的低过电位，并且具有长期稳定性。实验结果和理论计算表明，Fe的掺入导致重构CoFeOOH的电子重排和电子结构的优化，是OER活性增强的原因。这项工作为金属基配合物在OER过程中的完全重构提供了新的见解，并为高性能电催化剂的合理设计提供了指导。