About the Seminar
Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. In this talk I will discuss the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. Through quantitative, coordinate-based colocalization of different probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of hydroxyl radicals also possess a greater concentration of oxygen vacancies. Chemical modifications to remove or block access to surface oxygen vacancies, supported by calculations of binding energies of adsorbates to different surface sites on tungsten oxide, show how these defects control catalytic activity at both the ensemble and single-particle level. These findings reveal that oxygen vacancies activate surface-adsorbed water molecules towards oxidation by using photogenerated holes to produce hydroxyl radicals, a critical intermediate in the photocatalytic oxidation of water, methane, and environmental pollutants.
About the Speaker
Bryce Sadtler is a native of Indiana and graduated from Purdue University with a B.S degree in Chemistry in 2002. He conducted his graduate studies at the University of California, Berkeley under the guidance of Paul Alivisatos, where he developed chemical transformations in colloidal semiconductor nanocrystals. He received a Ph.D. in Physical Chemistry in 2009. He was then a Beckman Institute Postdoctoral Fellow at the California Institute of Technology, where he worked with Nathan Lewis and Harry Atwater to develop light-driven growth processes in inorganic nanostructures. Bryce joined the Department of Chemistry at Washington University in St. Louis in the fall of 2014. His research interests include solid-state chemistry and light–matter interactions in nanoscale materials for applications in solar energy conversion, catalysis, and photonics. As an assistant professor, he has received a NSF Career award (2018), an ACS PRF Doctoral New Investigator Award (2017), and was named an Emerging Investigator by the Journal of Materials Chemistry (2017).