LAUSR

Generating solar fuels such as H2 from water will require photocatalysts that can absorb visible light and facilitate charge separation/migration for surface electrochemical reactions. Photocatalysts containing mixed metal oxide (MMO) interfaces between TiO2 and CeO2, both of which are UV-absorbers on their own, have garnered attention due to their ability to drive H2/O2 evolution from water under visible light [1,2]. Visible light absorption is hypothesized to originate from partially-occupied Ce-4f states that arise from an enrichment of Ce at the MMO interface and act as donor levels within TiO2’s bandgap [2]. In this view, TiO2-supported CeO2-x photocatalysts may offer a unique hierarchical geometry that confines visible light harvesting (and charge generation) near the surface. Local probing of the optical properties about such MMO interfaces would provide insights into the unique supported CeO2-x morphologies that produce strong, and potentially tunable, visible light absorption.