(Invited) Coating-Stabilized Particulate Photocatalysts for Solar H2 Production

Abstract

Particulate photocatalysts that are suspended in water or sprayed onto a panel promise solar-to-fuel energy conversion at scale. The fabrication processes for these photocatalysts to achieve efficient energy conversion should be simpler than panel-based photoelectrodes. However, the design principles for reaching their performance limit are still elusive. Herein, our group uses stabilization coatings to enable an entire class of otherwise unstable particulate semiconductors for coevolution photocatalysis. CdS particles that are sprayed onto a panel and stabilized by an ALD coating produce H2 at a record rate of 48.5 mmol∙h-1∙g-1 or 2.5 mL H2∙h-1∙cm-2 under 1-sun solar illumination in ambient air. We systematically advance towards the solar-to-fuel efficiency limit of photocatalysts. Moreover, we demonstrate a redox-mediated particulate reactor that produces H2 and O2 gases at two separated compartments. The O2-evolution processes are separated spatially and temporally from photocatalytic H2 production, which is safe. We will discuss new design principles based on the holistic understanding of the photophysical, electrocatalytic, and transport processes that are coupled at the nanoscale. Figure 1