Solar energy is the most abundant energy source available to humankind, but this energy cannot be harnessed on demand due to the variability of sunlight. Artificial photosynthesis overcomes that variability through the direct photocatalytic storage of solar power into chemical fuels; however, most of the stable photocatalysts in use today rely on metal oxide semiconductors whose bandgap does not match the solar spectrum. The fractional substitution of the metal cations that compose a metal-oxide compound is an effective means to tune the bandgap of these materials. However, this approach introduces compositional disorder that increases the rate of electron–hole recombination. In contrast, the intercalation of functional layers into metal oxides provides an effective method to control the bandgap while preserving or enhancing charge separation. Here, we study the surface stability of the layered Bi2WO6 and Bi2MoO6 photocatalysts, which have been proposed as efficient visible-light absorbers, and we examine the competing structural and electrical factors that underlie their photocatalytic activity for water splitting. Time permitting, recent work on the charge storage performance of related layered compounds will also be discussed.

First-principles modeling of layered electrodes for water splitting and charge storage

2019 Fall National Meeting

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