How is catalytic activity in Cu2O affected by visible light illumination?
Yimin Wu from the University of Waterloo, Tijana Rajh and Yuzi Liu from Argonne National Laboratory, along with their colleagues from City University of Hong Kong published recent work using the Hummingbird Scientific gas flow X-ray sample holder to characterize the dependence of CO2 reduction site activity in Cu2O. The team combined multi-modal correlated scanning fluorescence X-ray microscopy (SFXM) and environmental transmission electron microscopy (ETEM) with high resolution X-ray powder diffraction (HRXRD) and electron paramagnetic resonance (EPR) to better understand how facets become active and inactive depending on the facet and oxidation state of active sites.
a) Schematic illustration of the setup showing the gas-flow cell. b) Schematic of the electron beam and X-ray directions for SFXM and TEM imaging on particle I, a truncated cube. c) TEM overview of Cu2O particles inside the nanoreactor. The red circle indicates particle I. d) TEM image showing particle I with the electron beam parallel to the direction of the Cu2O cube. e) Low-resolution SFXM image of the particles using Cu Kα and Ni Kα emission with a white circle indicating particle I. f) High-resolution SFXM image of particle I from Cu Kα emission with the incident X-ray beam parallel to the [001] direction. Copyright © 2019 Springer Nature Limited
With no light stimulation, the (110) facet of a single Cu2O photocatalyst particle is photocatalytically active for CO2 reduction to methanol while the (100) facet is inert. The oxidation state of the active sites shifts due to CO2 and H2O co-adsorption, and shifts back under visible light illumination. The crystal lattice correspondingly expands with CO2 adsorption then contracts after CO2 conversion. The Hummingbird holder enabled this multi-modal nanospectroscopy and TEM, revealing valuable information about this structural and orientation dependence of site-specific photocatalyst activation.
Reference: Yimin A. Wu, Ian McNulty, Cong Liu, Kah Chun Lau, Qi Liu, Arvydas P. Paulikas, Cheng-Jun Sun, Zhonghou Cai, Jeffrey R. Guest, Yang Ren, Vojislav Stamenkovic, Larry A. Curtiss, Yuzi Liu, Tijana Rajh, Nature Energy 4 (2019) DOI: 10.1038/s41560-019-0490-3
Full paper Copyright © 2019 Springer Nature Limited
View All News