Catalysts and Photoreactors for Photocatalytic Solar Hydrogen Production: Fundamentals and Recent Developments at Pilot Scale

This chapter overviews the state-of-the-art and recent advances in solar photocatalysis water splitting for hydrogen production. Several approaches are described to overcome the main strong handicap, as recombination of photogenerated pairs, fast competitive backward reactions, and the failure to absorb visible light photons. Photoreforming advantages for the overall water splitting reaction are discussed, as it is evident that these combined processes represent an environmentally friendly, cost-effective method for industrial byproducts or wastewater treatment. Factors affecting performance, that is, the structure and morphology of the catalyst in the reactor, light intensity, temperature, pH, and chemical nature of the sacrificial agent, are also described. The limited number of studies done on pilot-scale and the design of pilot-plant scale photoreactors for this purpose are discussed, including advances in photoreactors based on slurry and immobilized catalyst. Essential environmental assessment of photoreforming, since the wastewater generated could potentially harm the environment and human health, is also informed.