Hydrobromic Acid Cracking for Hydrogen Solar Fuel Production
Brady, Matthew D., et al. Journal of the American Chemical Society, 2017, 139, 44, 15612-15615.
Hydrobromic acid (HBr) has great potential as a cheap feedstock for hydrogen solar fuel production via HBr cracking. Using Ru(II) polypyridine complex as a photocatalyst for bromide oxidation, photoelectrochemical HBr splitting can be achieved, and hydrogen gas with a near-quantitative Faradaic yield is produced with a stable yield.
Photoelectrochemical HBr splitting
· Bromide oxidation is a two electron transfer process that has been shown in acetone to result from one-electron Br- oxidation to yield a bromine atom (Br· ), that subsequently reacts with Br- to yield dibromide (Br2·-) as a transient radical that disproportionates to yield Br- and tribromide (Br3-).
· Upon illumination, bromide oxidation products produced at the dye-sensitized "generator" electrodes are reduced back to Br- at a dark collector electrode.
· A 94 ± 2% Faradaic efficiency was calculated with a H2 production rate of 12 µmol/h. A steadystate production of H2 was maintained, highlighting the stability and robustness of the cell.
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