NSRRC Activity Report 2022

Energy Science 061 mechanism, a more rational material design of HEO electrodes can be implemented for improving battery performance. (Reported by Jeng-Kuei Chang, National Yang Ming Chiao Tung University) This report features the work of Jeng-Kuei Chang and his collaborators published in Adv. Sci. 9 , 2201219 (2022). TPS 44A Quick-scanning X-ray Absorption Spectroscopy • XANES, EXAFS, XAFS • Materials Science, Physics, Energy Etorage Devices, Battery Materials, Chemistry, Condensed Matters, Functional Materials Reference 1. X. F. Luo, J. Patra, W. T. Chuang, T. X. Nguyen, J. M. Ting, J. Li, C. W. Pao, J. K. Chang, Adv. Sci. 9 , 2201219 (2022). Fig. 3 : Summarized transition behaviors of all the constituent elements of the HEO electrode during the first (a) charging and (b) discharging. [Reproduced from Ref. 1] Uncovering Catalyst Synergies Under redox reaction conditions, the chemical states and structures of catalysts can potentially undergo dynamic transformations. D eveloping efficient catalysts with low overpotentials and fast reaction kinetics for large-scale electrochemical production is crucial. When evaluating a catalyst’s performance in water splitting, factors such as overpotential, current density, and the Tafel slope can accurately describe their corresponding activity. Catalytic activity is closely linked to the atomic configuration and electronic structure of the reactive sites during catalysis, but it is challenging to capture the dynamic reactive sites using most ex situ characterization methods. Recent advances in in situ characterization techniques have provided new insights into real-time catalytic behaviors. Typically, the superior catalytic activity of electrocatalysts is attributed to the synergistic catalytic effect, which results from the combination of foreign components that facilitate electron transfer. However, it is still unclear how this synergistic effect promotes reaction performance, especially at the atomic level of the corresponding potential-driven reactive sites. In situ techniques, particularly those that employ synchrotron-based X-rays, have successfully revealed potential-induced or pressure-driven changes in the local geometry of the active sites. Recently, Hao Ming Chen (National Taiwan University) and his coworkers created a Co-substituted Ru–Ru 2 P structure to serve as a catalyst model for studying the synergistic effects of Ru-based electrocatalysts during the hydrogen evolution reaction (HER) and identifying the potential- driven reactive sites. By conducting in situ X-ray absorption spectroscopy (XAS) measurements at TLS 01C1 , TLS 16A1 , and TLS 17C1 , 1 they were able to determine that the active moiety of Co( µ -O) 2 Ru was responsible for the HER performance. They also found that there was a strong correlation between the resulting HER performance and the bridged O–Co–O bond angles, demonstrating that potential-driven bond strain could have a dominant effect