Visualisation of single atom dynamics in water gas shift reaction for hydrogen generation
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The water gas shift (WGS) reaction, CO+H2O = CO2 + H2, is the basis of heterogeneous catalysis important in the generation of clean hydrogen energy for fuel cells, transportation fuels and in ammonia manufacture. Ceria supported gold and related nanoparticles are potentially viable catalysts for the low temperature WGS reaction. The WGS catalytic reaction is a dynamic process and takes place on the solid catalyst surface at the atomic level. The current understanding of the reaction is inferred from studies of static catalysts and from indirect chemical studies without single atom sensitivity. Therefore the nature of dynamic atomic processes in the WGS reaction has remained inaccessible. Since the catalyst reaction site and atomic processes by which it activates and deactivates, change both in magnitude and mechanism with the reaction environment it is of fundamental importance to visualise the dynamic catalyst at the atomic level in WGS (CO + water mixture) environments, in real time. Novel environmental (scanning) transmission electron microscope with singe atom resolution is used herein to directly visualise and characterise, in real time, evolving atomic structures and processes in practical gold/ceria catalysts in controlled WGS environments. The in-situ observations in WGS have revealed the formation of clusters of only a few gold atoms resulting from single atom dynamics and the catalytic effect of low coordination surface sites. The new insights have important implications for applications of nanoparticles in chemical process technologies including for transportation fuels and emission control.
Gai , P L , Yoshida , K , Ward , M R , Walsh , M , Baker , R , van der Water , L , Watson , M J & Boyes , E D 2016 , ' Visualisation of single atom dynamics in water gas shift reaction for hydrogen generation ' Catalysis Science & Technology , vol 6 , no. 7 , pp. 2214-2227 . DOI: 10.1039/c5cy01154j
Catalysis Science & Technology
Copyright 2015 the Authors. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1039/C5CY01154J
This work is supported through the EPSRC (UK) critical mass research grant EP/J0118O58/1 awarded to PLG and EDB. PLG and EDB thank the EPSRC and Johnson Matthey Plc for the award of studentships to MRW and MW. KY thanks the Japan Society for the Promotion of Science (JSPS) for a visiting Fellowship at the Nanocentre of University of York during the early part of the work and the Japan Fine Ceramic Center for the AC-Titan facility.