Photoelectrochemical Hydrogen Production on α-Fe2O3 (0001): Insights from Theory and Experiments.

The photoelectrochem. (PEC) decompn. of org. compds. in wastewater is investigated by using quantum chem. (DFT) methods to evaluate alternatives to water splitting for the prodn. of renewable and sustainable hydrogen. Methanol is used as a model org. species for the theor. evaluations of electrolysis on the surface of the widely available semiconductor hematite, α-Fe2O3, a widely studied photocatalyst. Three different α-Fe2O3 surface terminations were investigated, including the predominant surface found in aq. electrolytes, (OH)3-R. The PEC oxidn. of methanol is energetically downhill, producing CO2 and protons. The protons are reduced to hydrogen on the cathode. Exptl. PEC measurements were also performed for several polyalcoholic compds., glycerol, erythritol, and xylitol, on α-Fe2O3 as the photocatalyst and showed high incident-photon-to-current-efficiencies (IPCE) that were much greater than those of water splitting. Interestingly, high IPCEs were obsd. for hydrogen prodn. from polyalcs. in the absence of any applied bias, which was not thought to be possible on hematite. These results support the potential application of PEC for hydrogen prodn. by using widely available hematite for the PEC oxidn. of selected components of org. wastewater present in large quantities from anthropogenic and industrial sources. [on SciFinder(R)]