title: Visualizing Redox Dynamics of a Single Ag/AgCl Heterogeneous Nanocatalyst at Atomic Resolution.
abstract: Operando characterization of gas-solid reactions at the atomic scale is of great importance for determining the mechanism of catalysis. This is especially true in the study of heterostructures because of structural correlation between the different parts. However, such experiments are challenging and have rarely been accomplished. In this work, atomic scale redox dynamics of Ag/AgCl heterostructures have been studied using in situ environmental transmission electron microscopy (ETEM) in combination with density function theory (DFT) calculations. The reduction of Ag/AgCl to Ag is likely a result of the formation of Cl vacancies while Ag(+) ions accept electrons. The oxidation process of Ag/AgCl has been observed: rather than direct replacement of Cl by O, the Ag/AgCl nanocatalyst was first reduced to Ag, and then Ag was oxidized to different phases of silver oxide under different O2 partial pressures. Ag2O formed at low O2 partial pressure, whereas AgO formed at atmospheric pressure. By combining in situ ETEM observation and DFT calculations, this structural evolution is characterized in a distinct nanoscale environment.
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Yimin A
authors.initials: YA
authors.lastname: Wu
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Alper
authors.initials: A
authors.lastname: Kinaci
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Maria K Y
authors.initials: MK
authors.lastname: Chan
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Yugang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Guest
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Ian
authors.initials: I
authors.lastname: McNulty
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Tijana
authors.initials: T
authors.lastname: Rajh
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Yuzi
authors.initials: Y
authors.lastname: Liu
keywords: Ag/AgCl heterogeneous nanocatalyst; density functional theory; environmental TEM; in situ TEM