时间：2024年12月9日（周一） 10:00-11:30

Time:10:00-11:30, Monday, December 9, 2024

地点：西湖大学云谷校区E10-306

Venue:E10-306, Yungu Campus

主持人: 西湖大学工学院 陆启阳 博士

Host:Dr. Qiyang Lu, Assistant Professor, Westlake University

语言：英文

Language:English

主讲嘉宾/Speaker：

Prof. Christoph Baeumer

Associate Professor

MESA+ Institute of Nanotechnology

 University of Twente

主讲人简介/Biography:

Christoph Baeumer is an Associate Professor at the MESA+ Institute of Nanotechnology at the University of Twente, Netherlands, and guest scientist at Forschungszentrum Jülich, Germany. His Electrochemical Thin Films and Interfaces group focuses on operando characterization and fundamental structure-function relations in model electrocatalysts. He obtained his MSc in Materials Science from the University of Illinois, his PhD in Physics from RWTH Aachen University and Forschungszentrum Jülich (2016, mentors Regina Dittmann and Rainer Waser) and he was a Marie Skłodowska Curie Fellow at Stanford University (2018-2020, mentor William Chueh). He received several awards and personal grants, including the Helmholtz Doctoral Prize (2017) and the ERC Starting Grant (2022).

讲座摘要/Abstract:

Perovskite oxides are attractive electrocatalysts to catalyze the oxygen evolution reaction (OER) because they allow tuning electronic and atomic structure through compositional variations. This allows catalyst design based on so-called descriptors that relate materials properties to binding energies of reaction intermediates and therefore to catalytic activity. In this talk I will highlight recent developments in the exploration of the vast compositional space for earth-abundant perovskite oxide electrocatalysts and discuss the growing understanding of surface transformations during the reaction. In both cases, in situ or operando characterization with sufficient surface sensitivity are needed.

First, I will discuss how the multi-cation composition in so-called high entropy perovskite oxides (HEO) can maximize the catalytic activity. The HEO LaCr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2O_3-δoutperforms all of its parent compounds (single TM-site element in the LaTMO₃perovskite).¹X-ray photoemission studies reveal a synergistic effect of simultaneous oxidation and reduction of different transition metal cations during adsorption of reaction intermediates. HEOs are thus found to be a highly attractive, earth-abundant new material class for high-activity OER electrocatalysts, possibly allowing OER activities beyond the theoretical scaling limits of mono- or bimetallic oxides.

Secondly, I will describe structural and chemical transformations of the outermost surface layer– i.e. the location of the active sites – during or preceding the electrocatalytic reaction.^2,3Using the example of LaNiO₃epitaxial thin films, we demonstrated that Ni-(001)-facets are approximately twice as active for the OER as the La-(001)-facets. Using a suite of ex situ, in situ and operando spectroscopy tools, we found that the reason for the activity-enhancement lies in a surface transformation of the Ni-rich perovskite surface towards a catalytically active Ni hydroxide-type surface, revealing the importance of phase transformations down to a single atomic layer.

Lastly, I will introduce our laboratory-based multicolor X-ray photoelectron spectroscopy⁴platform for in situ and operando characterization, using examples of heterogeneous catalysis and alkaline water electrolysis. This platform is similar to recent implementation at Westlake University, implying tremendous opportunities for knowledge exchange and collaboration.

References

1.    Kante,  M. Vet al.A High-Entropy Oxide as High-Activity Electrocatalyst for  Water Oxidation.ACS Nano17, 5329–5339 (2023).

2.    Baeumer,  C.et al.Tuning electrochemically driven surface transformation in  atomically flat LaNiO3 thin films for enhanced water electrolysis.Nat  Mater20, 674–682 (2021).

3.    Füngerlings, A.et al.Crystal-facet-dependent  surface transformation dictates the oxygen evolution reaction activity in  lanthanum nickelate.Nat Commun14, 8284 (2023).

4.    Baeumer, C. Operando characterization of  interfacial charge transfer processes.J Appl Phys129, 170901  (2021).

讲座联系人/Contact:

朱云云

zhuyunyun@westlake.edu.cn