Wang Yuqing, Chen Chao, Xiong Xuya, Skaanvik Sebastian Amland, Zhang Yuge, Bøjesen Espen Drath, Wang Zegao, Liu Wei, Dong Mingdong
Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C, Denmark.
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
J Am Chem Soc. 2024 Jun 26;146(25):17032-17040. doi: 10.1021/jacs.4c01035. Epub 2024 Jun 13.
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 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 NiCoO(OH) 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.
层状双氢氧化物（LDHs）是水氧化的潜在催化剂，并且人们认识到它们在运行过程中会发生动态演变。然而，对于工作条件下纳米尺度的界面行为以及对电催化性能的潜在影响知之甚少。在此，我们使用电化学原子力显微镜，可视化了析氧反应（OER）过程中LDH纳米片的异质演变。通过进一步结合密度泛函理论计算，我们阐明了异质动力学的起源及其对OER效率的影响。我们的研究结果表明，NiCo LDHs在OER过程中转变为催化活性的NiCoO(OH)相，并且两者之间的氧化还原转变伴随着压缩应变和拉伸应变，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引起的各向异性应变和面外应变弛豫导致纳米结构中的开裂和起皱，这是LDH电催化剂对OER部分活化和长期劣化的原因。基于这些认识，我们提出并验证了设计缺陷可以精确调节这些动态行为，提高基于LDH的电催化剂的OER活性和稳定性。
