Westlake University

报告摘要：

Ionic defects are essential building blocks for properties of complex oxides, including mixed ionic and electronic conductivity, surface kinetics and reactivity, lattice expansion and dynamics, which are important for applications ranging from energy (e.g., fuel cells and electrocatalysts) to information (e.g., memristors, neuromorphic computing devices). In this talk, I am going to cover three fronts of harnessing ionic defects for tailed oxide thin film properties. Firstly, to accurately predict electrochemical driving force needed for manipulating ionic defects for designed properties, constructing phase diagrams that correlates physical properties (conductivity, (chemical) diffusivity, lattice constant, etc.) and ionic defect concentration is essential. To tackle this challenge, we have developed a new electrochemical device that can introduce spatially-graded ionic defect concentrations in one single oxide thin film sample. Combined with materials characterization tools with high spatial resolution, we achieved high-throughput construction of phase diagrams controlled by ionic defect concentration [1,2]. Secondly, we studied the kinetics of incorporation of ions or ionic defects into transition metal oxides by combining insights from operando optical and electrochemical characterizations. We revealed that both surface and bulk processes can co-exist during the ion intercalation in oxides [3]. Lastly, we established a comprehensive theoretical framework to understand the pivotal role of ionic defects (e.g., oxygen vacancies) in determining the activity of oxide electrocatalysts for both high-temperature [3] (>500°C, solid/gas interfaces) and low-temperature [4] (<100°C, solid/liquid interfaces) oxygen evolution reactions (OER). Overall, our work provides a holistic understanding of both “static” and “dynamic” effect of ionic defects in determining the properties and functionality of oxide thin films.

Reference

[1] H. Chen, Q. Lu* et al., Nano Letters, 22 (2022), 8983-8990

[2] Y. Lu, Q. Lu* et al., ACS Nano, 17 (2023), 14005−14013

[3] L. Wei, Q. Lu* et al., JACS 146 (2024), 24167–24176

[4] K. Yang, Q. Lu* et al., JACS 145 (2023), 25806–25814

报告人简介：

Dr. Qiyang Lu is currently an assistant professor in School of Engineering at Westlake University. He received his bachelor’s degree from Tsinghua University and his PhD degree from Massachusetts Institute of Technology (MIT), both in Materials Science and Engineering. His PhD work was focused on understanding and controlling ionic defect chemistry of functional oxide thin films, which was awarded the best PhD thesis award from MIT. He did postdoctoral research at Stanford University with a joint fellowship at Advanced Light Source, Lawrence Berkeley National Laboratory. He is the recipient of the Ross Coffin Purdy award from American Ceramic Society and Faculty Award of Excellence in Services (2021) and Teaching (2023) from School of Engineering, Westlake University. He is also one of the finalists of the Young Scientist Award of International Society for Solid State Ionics in 2024. His current research interest is focused on designing mixed electronic and ionic conducting oxide thin films for reversible solid state electrochemical cells, electrocatalysts and iontronic devices.

邀请人：鲁年鹏（9122）

联系人：张坚地（9454）