Speaker
Description
Photoelectrochemical (PEC) water splitting is an auspicious approach to convert solar energy directly into fuel. Hitherto, TiO$_2$, WO$_3$, and α-Fe$_2$O$_3$ have been the most studied metal oxides as photoelectrodes. However, their large bandgap and extremely short charge carrier diffusion lengths are hurdles to attain higher solar-to-hydrogen conversion efficiencies. Recently, copper tungstate (CuWO$_4$) has garnered significant attention owing to its relatively smaller bandgap and improved charge mobility characteristics [1,2]. Nonetheless, only a few seminal studies have been reported to understanding the fundamental electronic structure of CuWO$_4$ [3]. Femtosecond (fs) XAS has flourished as a potent technique that concurrently reveals both electronic and atomic structures and potentially sheds light on their nonequilibrium dynamic interplay, which has a preponderant role in most of the ultrafast mechanisms [4,5]. Besides, fs-RIXS delves into ultrafast electronic structure changes in an element- and site-specific manner at intrinsic fs-time scales of photoinduced dynamics [4]. We intend to deploy both table-top fs soft x-ray sources (for 3p XAS of Fe and Cu) and compare their results with RIXS performed at XFELs and static RIXS performed at synchrotrons, both with hard x-rays for the Cu 1s XAS/RIXS and tungsten 2p XAS/RIXS at SACLA/European XFEL and soft x-rays for the Cu 2p XAS/RIXS at Pohang XFEL. In addition, we will perform RIXS calculations based on first-principle calculations coupled to multiplet calculations for the excited state and RIXS experiments.
References:
[1] J. E. Yourey, B. M. Bartlett, J. Mater. Chem. 2011, 21, 7651.
[2] C. R. Lhermitte, B. M. Bartlett, Acc. Chem. Res. 2016, 49, 1121.
[3] C. M. Tian et al., J. Mater. Chem. A 2019, 7, 11895.
[4] A. S. M. Ismail et al., Phys. Chem. Chem. Phys. 2020, 22, 2685.
[5] Y. Uemura et al., J. Phys. Chem. C. 2021. (https://doi.org/10.1021/acs.jpcc.0c10525)
