In order to evaluate the technical feasibility of a novel solar hydrogen production process, the molten carbonate electro-reduction behavior of water in the range 505-600°C was examined in this paper. Reaction kinetics and mechanism of the water reduction process was elucidated by using galvanostatic polarization methods and cyclic voltammetry. Two different water electrolysis mechanisms were found to be active in this temperature range, involving either bicarbonate or hydroxide anions as intermediate species, much depending on reaction conditions and melt temperature. Due to lack of knowledge, the bicarbonate mechanism was studied in detail. In accordance with a rapid thermodynamic decrease of bicarbonate stability above the 500°C, the voltammetric data showed a transition from bicarbonate to hydroxide mechanism at around 550°C. The results also indicated that water electrolysis in alkali molten carbonates can be conveniently operated in the 500°C area, where the relatively higher bicarbonate stability may enable a more rapid reaction than at higher temperatures.
|Publication status||Published - 2014|
|Event||Symposium on Solar Fuels and Photocatalysts 3 - 225th ECS Meeting - Orlando, United States|
Duration: 1 Jan 2014 → …
|Conference||Symposium on Solar Fuels and Photocatalysts 3 - 225th ECS Meeting|
|Period||1/1/14 → …|
All Science Journal Classification (ASJC) codes
Frangini, S., Felici, C., & Tarquini, P. (2014). A novel process for solar hydrogen production based on water electrolysis in alkali molten carbonates. Paper presented at Symposium on Solar Fuels and Photocatalysts 3 - 225th ECS Meeting, Orlando, United States. https://doi.org/10.1149/06122.0013ecst