(Invited) Theoretical and Experimental Performance Metrics of Doped SrTiO₃ Photocatalyst Particles for Visible-Light-Driven H₂ Evolution

Solar hydrogen production could be a techno-economically viable alternative to steam methane reforming through development of new reactor designs and reaction schemes. Motivated by this fact, my group recently proposed a dual-bed batch reactor for Z-scheme solar water splitting that consists of stacked photocatalyst beds, which aid performance due to serial light absorption and short distances for redox shuttle mass transport. An unexpected discovery based on this design is that an ensemble of optically thin materials is more beneficial to theoretical solar-to-hydrogen conversion efficiencies than a standard single-light-absorber geometry. Through parallel experimental work we have shown that state-of-the-art doped and codoped SrTiO3 H2-evolving photocatalyst particles exhibit variability in homogeneity of dopant distributions, which correlates to overall performance. We have also observed that nanoscale coatings enable selective H2 evolution and desired redox shuttle reactivity over undesired reactions, which theoretically enable increased solar-to-hydrogen conversion efficiencies. Collectively these results provide new design guidelines and additional research pathways for the development of effective composite materials to serve as active components in techno-economically viable solar fuels devices.