Theory of Direct Solar Thermal Hydrogen Generation

2 Theory of Direct Solar Thermal Hydrogen Generation 

Kogan has calculated that, at a pressure of 0.05 bar, water dissociation is barely discernible at 2000 K.1 By increasing the temperature to 2500 K, 25% of water vapor dissociates at the same pressure. A further increase in temperature to 2800 K under constant pressure causes 55% of the vapor to dissociate.1 These basic facts indicate the difficulties that must be overcome in the development of a practical hydrogen production by solar thermal water splitting  

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