PerspectiveSolar Fuels

A quick look at how photoelectrodes work

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Science  27 Nov 2015:
Vol. 350, Issue 6264, pp. 1030-1031
DOI: 10.1126/science.aad6060

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Summary

It is appealing to harvest solar energy directly into chemical bonds with photo-electrochemical (PEC) cells—for example, by splitting water into hydrogen (H2) and oxygen (O2), as first demonstrated by Fujishima and Honda (1). Achieving the highest possible efficiency requires rapid transfer of the charge carriers generated by semiconductor photoabsorbers (2) to the catalysts for H2 and O2 evolution. Long-term stability requires protection layers for the semiconductors against strong acid or base. Direct experimental observation of charge carrier dynamics at these complex interfaces, which is critical for optimization, has been a major challenge. On page 1061 of this issue, Y. Yang et al. (3) show how transient photoreflectance spectroscopy can reveal information about the carrier dynamics and the electric field near the semiconductor surface.