Cattelan Mattia, Yang Jijin, Cielo Leonardo, Nappini Silvia, Carlotto Silvia, Nalesso Marco, Azcona Ilargi Napal, Yivlialin Rossella, Sun Xiaoming, Bussetti Gianlorenzo, Magnano Elena, Agnoli Stefano
Department of Chemical Sciences, University of Padova, via Marzolo 1, Padova, 35131, Italy.
INSTM Istituto Nazionale Scienza e Tecnologia dei Materiali, Padova Research Unit, Firenze, 50121, Italy.
Small. 2025 May;21(19):e2412351. doi: 10.1002/smll.202412351. Epub 2025 Apr 2.
This work reports a comprehensive study on the morphology, composition, and electronic structure of CoAl layered double hydroxide (CoAl-LDH) during the oxygen evolution reaction (OER). To capture electrochemically induced transformations, operando spectroscopic and microscopic methods are combined. The complementary data provided by operando near-edge X-ray absorption fine structure (NEXAFS), supported by density functional theory (DFT) calculations, and electrochemical atomic force microscopy (AFM), reveal that under OER conditions, CoAl-LDH is fragmented into smaller particles due to Al leaching. This process forms a "resting" phase with an average Co oxidation state of 2.5+, which readily transforms into the OER-active β-CoOOH phase upon further potential increase. This work exemplifies how operando methods enable precise tracking of oxidation state changes, element dissolution, and structural transformations at the nanoscale while the electrocatalyst is active. This approach contrasts with conventional pre- and post-mortem characterization, which would instead suggest CoO formation. These findings extend beyond the specific example of CoAl-LDH, emphasizing the crucial importance of selective cation leaching, recrystallization, and morphological restructuring, since these processes play a key role not only in designing advanced multi-element materials but also in understanding the complex nanoscale mechanisms that govern the activation and durability of practical electrocatalysts.
这项工作报道了关于钴铝层状双氢氧化物(CoAl-LDH)在析氧反应(OER)过程中的形态、组成和电子结构的全面研究。为了捕捉电化学诱导的转变,将原位光谱和显微镜方法结合起来。由原位近边X射线吸收精细结构(NEXAFS)提供的补充数据,得到密度泛函理论(DFT)计算以及电化学原子力显微镜(AFM)的支持,揭示了在OER条件下,CoAl-LDH由于铝的浸出而破碎成更小的颗粒。这个过程形成了一个平均钴氧化态为2.5+的“静止”相,在进一步提高电位时,它很容易转变成OER活性的β-CoOOH相。这项工作例证了原位方法如何能够在电催化剂处于活性状态时,在纳米尺度上精确跟踪氧化态变化、元素溶解和结构转变。这种方法与传统的事前和事后表征形成对比,传统表征反而会表明形成了CoO。这些发现不仅适用于CoAl-LDH这个具体例子,强调了选择性阳离子浸出、重结晶和形态重组的至关重要性,因为这些过程不仅在设计先进的多元素材料中起着关键作用,而且在理解控制实际电催化剂的活化和耐久性的复杂纳米尺度机制方面也起着关键作用。