Structural Evolution of a High-Temperature Oxygen Evolution Catalyst under Transient Working Conditions

固体氧化物电解槽作为一种用于间歇性可再生能源化学储存的高效功率-能量转换技术，在稳态和动态运行条件下的降解过程知之甚少。在第一个项目阶段，获得了对阳极/电解液界面的定性的新描述，该界面被鉴定为纳米级的复合体。这一发现构成了下一个资助期的基础，在此期间，我们建议研究SOEC在动态运行条件下的空气电极/电解液界面。我们将建立在我们在第一个项目阶段开发的紧密交织的多模式微观、光谱和第一原理理论方法的基础上，并将其扩展到近环境操作区和准现场条件。这项多模式研究的结果将使影响催化剂活性和相关降解过程的结构因素合理化。我们将专注于基于LSM的电解槽，它将在恒定和动态反应条件下进行电化学表征。该项目的目的是评估在反应条件下的络合情况，以便为其在电化学过程中的作用提供证据。表面和空气电极/电解液界面的非原位分析将通过电子显微镜和光电子能谱进行。为了用相关的环境扫描电子显微镜(ESEM)和OPANDO X-射线光电子能谱研究阳离子的结构和氧化状态，将制备特殊的电池。这种电池将通过在YSZ衬底上沉积LSM(&lt；10 nm)来产生。这层非常薄的电极层将允许从皮肤发出的光电子离开电化学活性区域。将研究在恒定和动态载荷下薄壁细胞中络合物的形成和稳定性。相同位置的透射电子显微镜成像(ILI)将补充非原位分析，并作为后续手术实验的结构基础。实验研究将得到密度泛函计算的补充。从基于力场的采样技术产生的YSZ/LSM界面的大面相模型出发，我们将生成DFT可处理的模式单元系综，其中每个系综代表平行于YSZ/LSM界面的面相中的一个薄截面。为了确定络合物作为催化活性界面结构的混合电导(MIEC)的性质，将在所产生的小的DFT单元系综中使用NEB DFT模拟来计算沿氧离子传导路径的跳跃过程的激活势垒。最优的MIEC切片将用于构建平板模型，表示催化活性部位的可能表面构型。

Solid oxide electrolysis cells (SOECs) as an efficient power-to-X (P2X) conversion technology for chemical storage of intermittent renewable energy suffer from poorly understood degradation processes under steady and dynamic operating conditions. In the first project phase a qualitatively new description of the anode/electrolyte interface was gained which was identified as a nano-scale complexion. This finding forms the basis of the following funding period in which we propose to investigate, the air electrode/electrolyte interface of the SOEC under dynamic operating conditions. We will build upon our tightly interwoven multi-modal microscopic, spectroscopic, and first-principle theoretical approach developed during the first project phase and extend it to near-ambient operando and quasi in situ conditions. The outcome of this multi-modal study will rationalize structural factors that influence the catalytic activity and related degradation processes. We will focus on LSM based electrolysis cells, which will be characterized electrochemically under constant and dynamic reaction conditions. The aim of this project is the evaluation of the complexion under reaction conditions in order to deliver evidence for its role in the electrochemical process. Ex situ analysis of the surface and the air electrode/electrolyte interface will be performed by electron microscopy and photoelectron spectroscopy. For the study of the structure and the oxidation states of the cations with correlative environmental scanning electron microscopy (ESEM) and operando X-ray photoelectron spectroscopy special cells will be prepared. The cells will be produced by the deposition of LSM (< 10 nm) on an YSZ substrate. This very thin electrode layer will allow the photoelectrons emanating from the complexion to leave the electrochemically active domain. The formation and stability of the complexion in the thin cells will be studied under constant and dynamic loads. Identical location TEM imaging (ILI) will complement the ex situ analysis and act as a structural basis to subsequent operando experiments. The experimental investigations will be complemented by DFT calculations. Starting from large complexion models of the YSZ/LSM interface, produced by force-field based sampling techniques, we will generate ensembles of DFT tractable model cells where each ensemble is representative of a thin section within the complexion that is parallel to the YSZ/LSM interface. To establish the properties of the complexion as a mixed conductivity (MIEC) of catalytically active interface structure, activation barriers for the hopping processes along the oxide ion conduction pathways will be computed using NEB DFT simulations within the small DFT cell ensembles generated. The optimal MIEC slice will be used to construct slab models representing possible surface configurations at the catalytically active site.