Key Goals and Systems for Large-Scale Solar Hydrogen Production

Abstract

Practical photocatalytic water splitting systems for renewable solar hydrogen production processes must be efficient, scalable, and inexpensive. This chapter examines the scalability and durability of particulate photocatalysts and photocatalytic reactors, and also describes various key targets. The fixation of particulate photocatalysts on substrates is anticipated to address scale-up issues, and interesting concepts such as photocatalyst sheets and panel reactors have recently emerged. At atmospheric pressure, some particulate photocatalyst sheets can split water into hydrogen and oxygen at a solar-to-hydrogen energy conversion efficiency (STH) of 1%, while other sheets can maintain 80% of their initial activity and an STH greater than or equal to 0.3% over a span of 1300 h under constant illumination. Panel reactors containing photocatalyst sheets have also been shown to be extensible to the 1 m2 scale and above. Although substantial improvements in STH are still required, the data suggest the feasibility of large-scale sustainable solar hydrogen production based on particulate photocatalytic systems.