丹麦奥胡斯大学董明东团队报道了层状双氢氧化物纳米片中水氧化产生的纳米级动力学的原位跟踪。相关研究成果发表在2024年6月13日出版的《美国化学会杂志》。

层状双氢氧化物（LDHs）是水氧化的潜在催化剂，人们认识到它们在使用过程中会发生动态演变。然而，人们对工作条件下纳米级的界面行为以及对电催化性能的潜在影响知之甚少。

该文中，研究人员使用电化学原子力显微镜原位观察了LDH纳米片在析氧反应（OER）过程中的非均相演变。通过进一步结合密度泛函理论计算，阐明了非均匀动力学的起源及其对OER效率的影响。研究结果表明，在OER过程中，NiCo-LDHs转变为具有催化活性的NiCoO_x（OH）_2–x相，并且两者之间的氧化还原转变伴随着压缩和拉伸应变，导致纳米片的面内收缩和可逆膨胀。

由于缺陷和颗粒间相互作用导致的非各向同性应变和平面外应变弛豫导致纳米结构中的开裂和褶皱，这是LDH电催化剂向OER的部分活化和长期劣化的原因。有了这些知识，研究人员提出并验证了工程缺陷可以精确地调节这些动态行为，提高LDH基电催化剂的OER活性和稳定性。

附：英文原文

Title: In Situ Tracking of Water Oxidation Generated Nanoscale Dynamics in Layered Double Hydroxides Nanosheets

Author: Yuqing Wang, Chao Chen, Xuya Xiong, Sebastian Amland Skaanvik, Yuge Zhang, Espen Drath Bjesen, Zegao Wang, Wei Liu, Mingdong Dong

Issue&Volume: June 13, 2024

Abstract: Layered double hydroxides (LDHs) are potential catalysts for water oxidation, and it is recognized that they undergo dynamic evolution during the operation. However, little is known about the interfacial behaviors at the nanoscale under working conditions nor the underlying effects on electrocatalytic performance. Herein, using electrochemical atomic force microscopy, we in situ visualize the heterogeneous evolution of LDH nanosheets during oxygen evolution reaction (OER). By further combining density functional theory calculations, we elucidate the origin of the heterogeneous dynamics and their impact on the OER efficiency. Our findings demonstrate that NiCo LDHs transform to the catalytically active NiCoOx(OH)2–x phase during OER, and the redox transition between is accompanied by compressive and tensile strain, leading to in-plane contraction and reversible expansion of the nanosheets. Nonisotropic strain and out-of-plane strain relaxation due to defects and interparticle interactions result in cracking and wrinkling in the nanostructure, which is responsible for the partial activation and long-term deterioration of LDH electrocatalysts toward the OER. With this knowledge, we suggest and validate that engineering defects can precisely tune these dynamic behaviors, improving the OER activity and stability among LDH-based electrocatalysts.

DOI: 10.1021/jacs.4c01035

Source: https://pubs.acs.org/doi/full/10.1021/jacs.4c01035