Hydrogen production by splitting water on solid acid materials by thermal dissociation

Conventionally, there have been three basic ways of research on H2 production from H2O-splitting with solar energy: photo-catalytic, photo-electrochemical and thermochemical. Among them the thermal dissociation of H2O has been considered the most efficient, because it is a single step energy conversion process and gives much higher conversion efficiency than those resulted from other methods. However, the major stumbling block of thermal dissociation of H2O has been the requirement of a high dissociation temperature which causes problems both with materials for the reactor and with energy conversion efficiency for the process. In this study, we show that the dissociation temperature can be drastically lowered when H2O is thermally dissociated on solid acid materials. A probable mechanism of the thermal H2O-splitting on solid acid materials is also presented, based on some experimental results of this study and reports in the literature.

► H2 can be produced from H2O-splitting on solid acid materials. ► H2O seems to be electrolyzed on a solid acid to produce H2 upon heating. ► The amount of H2 produced increased with increasing temperature and H2O content in a solid acid. ► Different solid acids have different kinds of temperature dependency in H2 production. ► Appreciable amount of H2 can be produced on a solid acid from > 573 K.