Brian Zutter1,Luisa Barrera2,Aliya Lapp1,Austin Bhandarkar1,Zejie Chen3,Kenta Watanabe4,Akihiko Kudo4,Rohini Chandran2,Shane Ardo3,5,A. Talin1
Sandia National Laboratory1,University of Michigan–Ann Arbor2,University of California, irvine3,Tokyo University of Science4,University of California, Irvine5
Brian Zutter1,Luisa Barrera2,Aliya Lapp1,Austin Bhandarkar1,Zejie Chen3,Kenta Watanabe4,Akihiko Kudo4,Rohini Chandran2,Shane Ardo3,5,A. Talin1
Sandia National Laboratory1,University of Michigan–Ann Arbor2,University of California, irvine3,Tokyo University of Science4,University of California, Irvine5
Solar-powered water splitting using nanoparticle photocatalyst suspensions is a promising route to cost-effective, scalable, and clean hydrogen production. By coupling distinct H2 and O2 evolving photocatalysts, such as SrTiO3:Rh and BiVO4, respectively, with a redox shuttle, the Z-scheme approach enables water splitting at wavelengths substantially longer compared to single photocatalyst systems. A critical step in reduction (oxidation) is the transport of photoexcited electrons (holes) to the photocatalyst surface. Here we characterize charge transport in individual SrTiO3:Rh nanoparticles using a nanoprobe, and directly map internal electric fields with electron-beam induced current. Unlike transport models which assume that photoexcited electrons and holes are separated by space-charge layers formed within particles by Schottky-type barriers, we observe defect mediated transport consistent with fully depleted nanoparticles. We will discuss the transport mechanism in detail and its implication for realizing high efficiency water splitting.